Furnace TechnologyProduct Portfolio, Technology & References

economical and environ-menT-Friendly Furnace Technology From The sysTem supplier SMS group is able to deliver nearly all thermal

processing equipment which is required to pro-

duce modern steel and aluminum products. SMS

designs, erects and commissions furnaces for the

different production steps of carbon steel, electrical

silicon-steel, stainless steel, and aluminum. This

includes furnaces for heat treatment of strip and

hot-formed materials like heavy plates, tubes and

bars as well as reheating furnaces. Common to all

furnaces is high cost-effectiveness that results from

constant improvement, quality consciousness, and

a focus on saving resources. Drawing on the com-

bined strength of SMS group, the furnaces can be

supplied from one single source.

Key FacTor Furnace

Technology

Furnace technology is considered to be the core

process for the production of modern materials,

since it determines the material properties and the

quality of the final product. Controlled heating or

cooling is the only way for the manufactures to pro-

duce high-quality, marketable finals goods. Often,

cooling is more important than heating but at the

same time more difficult. With SMS as a technolo-

gy partner the complete know-how for heating and

cooling throughout the complete process chain can

be supplied from one source and high material qua-

lity can be ensured.

In this brochure you‘ll find comprehensive informa-

tion about our products, technologies, services and

references of furnace technology.

3

conTenTs

General

Introduction 2

Highlights 4

Processes 6

Product Portfolio 8

System Supplier 10

SMS-FLAME® 12

Effective Lining Solutions 14

SMS-PrometheusTM 16

DFC-Model (Dynamic Furnace Control) 18

Service 20

Workshop 22

Heat Treatment of Strip 24

Carbon Steel Annealing & Galvanizing 26

I-Furnace 30

Batch Annealing 36

Continuous Tinplate Annealing 38

Electrical Silicon Steel Strip Processing 40

Stainless Steel Strip Annealing 46

Color Coating 52

Aluminum Heat Treatment 56

Furnaces for Slabs, Bars and Tubes 58

Roller Hearth Furnaces 60

CSP®-Roller Hearth Tunnel Furnaces 62

Chamber Furnaces 64

Walking Beam Furnaces 66

Walking Hearth Furnaces 70

Pusher Furnaces 72

Fields of Application

Long Products 73

Flat Products 74

Pipes and Tubes 76

Forged Products 80

Heat Treatment of Hot-Formed Material 82

Heavy Plates 84

Roller and Platen Quench 86

MultiFlex-Quench® 88

Tubes and Pipes 92

SMS-Quench® 96

Bright Tubes 100

Bars 102

4

numerous reFerences Since 2000, SMS group has attracted orders for more than

150 furnaces for carbon steel silicon steel, stainless steel

and aluminum to produce high quality strips, plates, bars or

tubes including all important types of furnaces and cooling

technologies.

sTeel and nF-meTal producers

using Furnaces From sms (examples)

Acroni

Amag Rolling

AM/NS Calvert

Angang Steel Company

Aperam

ArcelorMittal

ASAŞ Alüminyum

Baosteel

Baoxin

Bengang

Big River Steel

China Steel Corporation

Deutsche Edelstahlwerke

Handan Iron & Steel

Henan Zhongfu

Hyundai Steel

Ilva

Jisco

Ma‘aden-Alcoa Joint Venture

Maanshan Iron & Steel

MMK

NAS North American Stainl.

NLMK

Nucor Steel

Outokumpu

Panzhihua Iron & Steel

POSCO

PRO-TEC Coating Company

Salzgitter Flachstahl

Severstal

Shagang Group

Shandong Nanshan

Shougang Jingtang

Shougang Corporation

SSAB

Steel Dynamics Incorporated

Stefana

Taigang

TKAS Terni

ThyssenKrupp Steel

Tianjin Tiantie

Tianjin Zhongwang

Timken

TMK Artrom

Toscelik

US Steel

Voestalpine

Wuhan Iron & Steel

5

marKeT leadership

The majority of market leading steel and NF-metal producers rely on SMS group's technology.

high producT qualiTy

Significant to all furnaces is the high quality of the final product. Thus, the furnaces are

especially designed to ensure flawless surfaces and homogenous material characteristics.

Flexible producTion

Flexible production conditions allow a quick reaction to changing market demands with

the greatest economic efficiency. SMS group has developed several furnace solutions for

highest flexibility.

sysTem supply

SMS group is capable to deliver almost all furnaces completely from one single source.

This means, you get everything you need out of one hand and without any interface

problems.

producTion Know-how

SMS group offers process support for all materials and qualities. This covers both metal-

lurgical and design actvities as well as support during commissioning, operation, quality

control and certification.

ecoplanTs

All furnaces are designed to keep resource consumptions as low as possible. All technol-

ogies and processes are continuously evaluated in order to improve their eco-friendliness.

projecT managemenT

A professional project management aligned with latest knowledge and international

standards ensures in combination with modern design methods, a consistent and

reliable fulfillment.

manuFacTuring

The set-up includes several modern and well equipped manufacturing locations worldwide

to ensure a high level of quality control and proximity to the customers.

modernizaTions

SMS possesses rich experience and offers comprehensive services for refittings and

upgrades. Starting from the exchange of a single parts up to major modernizations of

complete furnaces with several measures.

indusTry 4.0

The furnaces use production and process models which are deeply

integrated in the automation system and linked with other systems.

Furnace Technology based on Thermal processesFurnace technology is driven by thermal processes

to change material characteristics and enhance the

material quality – and therewith the value of the

material – step by step. SMS group has extensive

know-how and understanding of all thermal pro-

cesses of the steel and NE-metal production route.

Depending on the different materials requirements

and material developments, SMS offers special solu-

tions to fulfill highest demands.

6

energy source

Combustion gas Electrical energy

Furnace aTmosphere

Open atmosphere with exhaust gas Closed atmosphere with shielding gas

7

heaTing processes

Convection Radiation Induction

cooling agenTs

Gas Water Mist

8

producT porTFolio-Furnace Technology: overview

heaT TreaTmenT oF sTrip

Furnaces For slabs, bars & Tubes

heaT TreaTmenT For hoT-Formed maTerial

carbon sTeel annealing

and galvanizing

roller hearTh Furnace

heavvy plaTes

See pages 26-35

See pages 60-61

See pages 84-93

sTainless sTeel sTrip annealing

walKing beam Furnace

See pages 46-51

See pages 66-69

9

baTch annealing

csp®-roller hearTh Tunnel Furnace

Tubes

TinplaTe annealing

chamber Furnace

bars

elecTrical silicon sTeel sTrip processing

See pages 36-37

See pages 62-63

See pages 94-101

See pages 38-39

See pages 64-65

See pages 102-103

See pages 40-45

color coaTing

walKing hearTh Furnace

aluminum heaT TreaTmenT

pusher Furnace

See pages 52-55

See pages 70-71

See pages 56-57

See pages 72-73

Besides those main furnace types and

heat treatment processes, SMS group

offers various other concepts or vari-

ations of processes depending on the

individual customer requirements.

Modernizations – from small improve-

ments to vast revamps – are also a

part from SMS group's product port-

folio

10

sysTem supplier

SMS group is the only company worldwide capable

of delivering nearly all furnaces and heat treatment

systems for steel and NF-metal production route as a

full system supplier. That’s because all products and

services are available within the SMS group.

auxiliaries heaTing sysTem cooling sysTem

Handling equipment

Roller tables

Charging/discharging machines

Guiding systems

Water treatment plants

Hydraulic systems

Radiant tube furnaces

Direct fired furnaces

Floatation furnaces

Catenary furnaces

Reheating furnaces

Inductive heating

Gas cooling

Water spray cooling

Roller/platen quenches

Mist cooling

Laminar cooling

Air cooling

11

advanTages due To

compleTe sysTem supply:

Perfect match of all components

Clear responsibility

cooling sysTemelecTrical and

auTomaTion sysTemspecial services

Gas cooling

Water spray cooling

Roller/platen quenches

Mist cooling

Laminar cooling

Air cooling

Level 1 to level 3

Process and production models

Quality monitoring systems

Measuring systems

Plug & Work integrations tests

Operation and visualization

Production know-how

Startup assistance

Continuous production assist-ance and process optimization

Qualification assistance

Certification support

12

sms-Flame®

High-efficiency burners for varied application.A new concept in burner development

SMS applies a new concept in burner design and

development and is capable for offering a full line

of advanced SMS-Flame® burners. These are availa-

ble in a wide range of power sizes and in different

models suitable for varied application:

SMS-ZERO Flame®, the new frontier of natural gas-

flameless combustion. Extra-Low NOx emissions at

any rating and combustion air temperature

SMS-ECO Flame®, a reliable unit combining low NOx

capability and high efficiency, available for any gas or

liquid fuel – also available in radiant configuration for

roof installation

SMS-DUAL Flame®, capable of dual fuel utilization,

gaseous fuel and oil

eFFicienT by design

A strong synergic approach between research and

experience in furnace realization allows designing

burners suitable for any kind of furnace.

“Flexibility” is the keyword of the research approach,

based on field tests, performed in combustion labora-

tory, and Computational Fluid Dynamics (CFD).

Before manufacturing and testing the prototypes in

the laboratory, SMS identities the most promising

design using detailed CFD-based modelling. Prediction

of flame reaction zone profile, temperature gradients

and pollutants generation are only some of the

aspects that are modelled and optimized with CFD

software before starting the test campaign on a real

burner.

13

versaTile burners For opTimised

combusTion

Different products require different temperature profiles. With SMS-

FLAME® burners, plant engineers can flexibly adapt the combustion

parameters to diverse process conditions.

Measured NOx emission with SMS-ZERO Flame® burners,

in flame and in flameless mode.

Burners are studied and developed by

means of most advanced techniques:

the first phase foresees CFD modell-

ing, often followed by 3D printer

proto-typing.

Later the burners need to go through

extensive laboratory tests, in order to

assess their genuine capability to

steadily meet the emission parameters

foreseen by the software simulations.

The shape and temperature control of

the flame outline helps to contain the

overall emissions: when firing in flame-

less mode, the SMS-ZERO Flame®

burners not only dramatically decrease

the NOx formation, (<70 mg/Nm3 at

3% O2 DFG), but also improve the

temperature homogeneity inside the

furnace chamber.

14

eFFecTive lining soluTionsTailored to the particular properties of each plant

SMS group pays great attention to design and com-

ponent features that allow for the lowest possible

energy consumption. The furnace specialists continu-

ously test new materials, components and concepts.

The results are self explaining: energy requirements

below 260 kcal of heat input per kilogram of steel

reheated from 20 to 1,200 °C minimise energy costs

in long product rolling mills. Another example is a

total fuel energy consumption of less than 280 kcal

per kilogram required in a quench and temper cycle,

where the workpieces are heated from ambient tem-

perature to 900 °C for hardening then, having been

quenched, reheated again to over 500 °C to com-

plete the tempering process.

advanced lining

Refractories play a key role in containing energy

dissipation and in improving the efficiency of old

furnaces. In extensive field tests SMS examined

different lining materials and their impact on energy

efficiency. Based on the test results, the furnace spe-

cialists select the best material for each furnace.

Form Follows FuncTion

When designing a new reheating furnace or a

heat treatment plant, the experienced SMS en-

gineers use both their know-how and advanced

computational modelling tools. With state-of-the-

art CAD and FEM software they create smooth,

fast and precise mechanical designs for any heat-

ing task.

3D modelling is also an invaluable benefit for the

field engineers and erection crews on site, as all

details can be clearly understood at a glance. One

example is pipe routing detail engineering with

3D CAD programs: it simplifies and speeds up

the erection works so costs are reduced and the

plants can be commissioned earlier.

The digital modelling of a walking beam frame

is an efficient tool in removing interferences and

quota errors from the design. Loads and forces

are calculated rapidly with no risk of errors.

15

opTimized resisTance

Improvements in material quality, durability and safety

allow for the utilisation of modern light-weight fibre

insulations for applications traditionally reserved for

castable and plastic refractories. Low thermal inertia

and optimised resistance to repeated thermal cycles

make this class of lining materials especially

beneficial for heat treatment furnaces. The modern

fibres are characterised by an enhanced resistance

to higher temperature conditions and by a certified

absence of hazardous compounds, compared to

similar linings available in the past.

16

With SMS-PrometheusTM, plant operators are able

to boost their furnace’s overall performance. The ad-

vanced combustion optimisation system improves

those parameters that can make the difference in

special steel quality production. SMS-PrometheusTM

allows for targeted improvements of the metallurgi-

cal properties, for example increased temperature

uniformity or minimised negative effects such as

steel decarburisation or high scale formation.

Fuel – only as much as you need

SMS-PrometheusTM helps to reduce fuel consumpti-

on by adopting those heating strategies that minimise

the temperature set points and yet guarantee the

required final stock target temperature. The core of

the program is a sophisticated mathematical model

capable of simulating the heating curves inside the

furnace for each stock loaded. The system shows

the overall furnace efficiency by visualising heating

balance diagrams. It also provides consumption and

emission trends that can be correlated to actual pro-

duction data.

SMS-PrometheusTM constantly monitors the heating

history parameters of each single workpiece. The

system works predictively, meaning it makes con-

sistent projections to estimate the development of

the heating path. On this basis, SMS-PrometheusTM

continuously chooses and modifies the temperature

set points. When coupled with SMS-Digiburn®, the

system also optimises the digital firing pattern.

energy savings – even during

nonproducTive Time

SMS-PrometheusTM is highly efficient in optimising

the combustion parameters during events like sud-

den stoppages, furnace heating-up time or changes

to the product campaign. This tool ensures proper

heating repeatability, even with inexperienced opera-

tors, although even highly experienced staff benefit

substantially from the mathematical model guidance

during transitory events.

eFFiciency index

SMS-PrometheusTM tracks the consumption and the

other efficiency related parameters and stores the

trends over time in order to allow prompt monitoring.

advanced FeaTures – roughing

mill pyromeTer FeedbacK

This function adapts the mathematical model accord-

ing to the roughing mill pyrometer measurements.

The temperature of the piece measured by the pyro-

meter is compared to the expected one and adapts

the model accordingly.

sms-promeTheusTm

Combustion optimization for tailored steel quality and reduced fuel consumption

Heat flow charts and consumption trend bars help

to control furnace efficiency.

17

advanced FeaTures – sKid

marKs eFFecT predicTion

This function allows to monitor the “skid marks

effect” by means of a specific algorithm which simu-

lates cold spot effect generated by water cooled

skids, managing different parameters of the auto-

mation and combustion system according to the

process requirements.

advanced FeaTures – pacing

model

The model forecasts the time in which each piece

inside the furnace will be ready to be discharged to

fulfill the minimum heating/soaking time requirement

of each piece inside the furnace and get the maxi-

mum productivity.

From deTailed inFormaTion

To comprehensive overview

The overview screen shows the furnace loading

pattern and provides the main data relevant to the

temperature set points of the different heating

zones.

By selecting a specific billet, the engineer obtains

the real-time heating status of any single workpiece.

18

dynamic Furnace conTrol

energy savings and higher

producTion wiTh a csp® Furnace

The Dynamic Furnace Control (DFC) level 2 process

automation system is an integral part of SMS group's

energy saving and high production strategy. Integrated

in a CSP® Furnace it ensures heating of the slab to

the required target temperature with good uniformity

and without energy wastage. It allows the application

of different strategies to heat-up and accerlerate the

slab, which offers several operational advantages.

Therefore, the DFC system calculates the 3D tem-

perature distribution for each slab and the buffer

time. Furthermore, the model provides an effective

emptying of the furnaces after roller change by defin-

ing the sequence of the slabs for rolling. The system

continuously communicates with CSP® Furnaces

Level 1, Level 3, CSP® Caster Level 2 and CSP® Mill

Level 2. It generates several reports and diagrams to

support monitoring and furnace control.

TemperaTure calculaTion and

conTrol

As mentioned above the DFC-system simulates the

temperature of the slabs while going through the

CSP® Furnace in three dimensions. It calculates the

set-point temperature for the furnace zones which

depends on the entry temperature of the slab and

the set-point exit temperature for the slab. During

commissioning, the model for the slab temperature

is adapted to fit the real slab temperature.

The tracking module synchronizes the position of the

slabs in the furnace.The control parameters of the logi-

stics (acceleration point and ferry usage) are comput-

ed. This is of particular interest after mill idle when the

furnace is relatively full and needs to return to statio-

nary position. Moreover, the buffer time is determined

which enables the operator to judge if a roll change in

the mill is possible without scrap cutting.

Furthermore, the DFC calculates the theoretical gas

consumption of the furnace adapted during the com-

missioning of the furnace. If this value differs con-

sistently from the actual gas consumption, it is time

for maintenance. The model can be further used to

identify the part of the furnace that needs to be

checked (for instance rolls or the recuperator). The

heat balance includes walls, rollers, waste gas and

pre-heated air and is calculated for each zone.

caster level 2

caster level 1

mill level 2

mill level 1

level 3

Furnace level 2(dFc)

Furnace level 1

Caster speed, slab dimensions and temp.

Slab ID, target temp. for slab

Slab temp. info

Buffer time Slab request

Zone temp. setpoints Setpoints for logistics

Actual values for temp. logistics and energy.

Communication with other CSP® components.

19

3D calculation and visualization of the slab temperature.

Energy saving due to reduced set-point tempera-

tures for the furnaces zones

Reduced wear on rollers and slabs by shifting

the setpoint for the acceleration roll

Higher yield due to avoidance of slab cutting by

early accerleration of the slabs

Effective emptying of the furnace after roller

change by defining the sequence of the slabs

for rolling

Automatic communication with other automation

levels and moduls (Industry 4.0)

Automatic generation of reports and diagrams

Each heat-up process for every slab is efficiently calculated and controlled.

main advanTages oF dynamic Furnace conTrol (dFc)

20

serviceTaking care of everything

Whether you want spare parts, modernizations,

tailor-made maintenance procedures, or customized

training programs, the Technical Service Division of

SMS group is ready at 50 locations around the world

to offer you service packages geared to your require-

ments along the entire metallurgical process chain.

It’s due to the know-how of the entire SMS group

that our employees provide the services you require –

on schedule, within budget, and in the right quality.

That means you can rely on the quality of our ser-

vices as well as our global presence to reduce down-

times, increase productivity, and ensure the lasting

value of your machinery and plants.

spare parTs & logisTics

OEM spare parts

Spare parts management

Warehousing

mainTenance & repairs

Emergency support

Inspection, repairs, servicing

Maintenance tools

Long term maintenance services

upgrades & modernizaTion

Mechanical & hydraulic

Electric & automation

Value added components

consulTing & Training

Fact finding

Maintenance audits

Feasibility studies

TECademy

The righT parTs in The righT

place aT The righT Time

The right spare parts have to be available at all times

so that production doesn‘t come to a standstill. At

the same time, capital tie-up and storage costs have

to be kept low. That is why SMS group delivers

spare and wear parts for all machines quickly and

reliably.

A web-based, machine-specific parts catalogue

makes the ordering process even easier. On request,

SMS group also takes care of the whole spare part

and stock management. The differing parts stocking

concepts are always geared to the customers‘

individual needs.

Water-cooled furnace rolls with fireproof insulation made of aluminum silicate wool allow higher temperatures and at the same time low energy losses in a CSP® Furnace.

21

conTinuous high perFormance

Whether one-off fact-finding, continuous monitoring

via remote service or regular plant inspections. The

SMS group Service experts analyse and service the

plants. Not only this, the complete maintenance can

be taken over by SMS on request. Plant owners thus

ensure maximum plant availability and optimum pro-

duction results.

always up-To-daTe

Plant owners are engaged in dynamic markets. The

demands on profitability, product quality and produc-

tivity have risen steadily for plant owners in recent

years. New technologies and plants arrive on the

market in ever shorter innovation cycles. Tailored

and customised modernisation concepts from SMS

group ensure that the plants run for decades and that

with reduced operating costs, higher productivity and

improved product quality.

Field service

Even in emergencies, customers can rely on SMS

group Service. The Service technicians help with

troubleshooting and the necessary repairs. With

short reaction times and high availability, they ensure

that the plant is up and running again as quickly as

possible.

corporaTe success due To

Technical Know-how

Whether individual or standardised trainings – our

experts plan individually tailored training programmes

and implement these together with the customer.

The plant operators gain valuable know-how through

time-tested formats and special e-learning offerings

for more operational reliability and more efficient

processes.

higher proFiTabiliTy due To The

righT advice

More efficient processes, optimised technology and

more effective use of resources – those are the

goals of our consulting concepts. SMS group carries

out feasibility studies to establish a sound basis for

management decisions, or develops strategies and

concepts for the optimisation of existing plants and

processes.

examples oF service parTs

CSP® Rolls

- Dry rolls

- Water cooled rolls with fiber insulation

Furnace rolls for strip processing lines

Isolation materials

Energy saving concepts

Consulting for optimal integration of the

furnace operation into the overall process

22

worKshopR&D testing, equipment pre-assembly and inspection under one roof

SMS group runs a fully equipped workshop for the

assembly and testing of key components in Tarcento,

Italy. Prototypes, special equipment and machines

which require extremely accurate tolerances are

assembled here. The workshop operates in close

conjunction with the R&D and technical departments.

A constant and precise exchange of information and

ideas is the basis for the continuous further develop-

ment of all components.

preassembly For FasTer

commissioning

Most machines are completely preassembled –

including hydraulics, lubrication and cooling water

units. The engineers pay great attention to the

details, especially to the electrical pre-wiring of the

sensors and components to the terminal boxes.

Before being disassembled and shipped, each com-

ponent and module is marked for fast and error-free

reassembly at the business partner’s site.

FuncTionaliTy TesTs ensure

maximum reliabiliTy

The workshop is equipped with testing motors,

switchboards and Programmable Logic Controllers

(PLCs) so the SMS group engineers can simulate

production conditions for factory dynamic tests. All

the hydraulic equipment is checked during cold test

runs with hydraulic units and benches.

23

open FacTory policy

SMS business partners are invited to visit the

Tarcento workshop. They can assure themselves of

the strict quality assurance standards and take a

close look at the machines during all assembly phases

according to inspection schedules.

preassembly saves Time

and money

SMS preassembles and tests even large compo-

nents so its business partners save commission-

ing time and labour costs at the erection site.

24

25

heaT TreaTmenT oF sTrip Furnace technology is considered to be the core process for

the production of high-quality strip materials, since it deter-

mines the material properties and quality. Often, cooling

is more important than heating but at the same time more

difficult. SMS offers proven heating and cooling systems for

all strip processing lines.

Carbon Steel Annealing & Galvanizing page 24

Batch Annealing page 36

Continuous Tinplate Annealing page 38

Electrical Silicon Steel Strip Processing page 38

Stainless Steel Strip Annealing page 46

Color Coating page 52

Aluminum Heat Treatment page 56

26

carbon sTeel annealing & galvanizing

excellenT qualiTy, high eFFi-

ciency and enormous capaciTy

During heat treatment in annealing and galvanizing

lines, microstructure is precisely adjusted to meet

requirements strength and formability. Annealing

and galvanizing furnaces by SMS are characterized

in particular by the excellent quality of the end pro-

duct, high efficiency and economy, as well as – if

demanded – enormous capacities. In recent years

various improvements and new technical solutions

have been developed, particularly regarding furnace

concepts, furnace efficiency and cooling technology.

Special efforts were also made to adapt the galva-

nizing furnace to the new challenges which came

up with modern and sometimes high-alloyed steel

grades.

It has been proven that SMS has the competence

to design, engineer, erect and put into operation

furnaces for all kinds of modern annealing and galva-

nizing lines.

High-quality end-products, which are often determined by the furnace technology, are crucial for the economical success of a cold strip processing line.

SMS group‘s strip processing lines feature large vertical furnaces which ensure a high strip speed in the furnace also for big cross-sections in order to achieve high capac-ities.

27

producTion oF auTomoTive

grades

Steel continues to be the most important construc-

tion material for the automotive industry, whereby

particularly the share of high-strength steels in cut-

throat competition with other materials is constantly

increasing. As manufacturers are required to build

light and fuel-efficient vehicles, many new steel

grades with optimized combinations of properties

have been developed. Multi-phase steels, which are

high-strength and very ductile, are increasingly being

used for car components. These high-strength yet

easily deformable steels must meet the highest

quality requirements for use in automobiles, where-

by not only the material properties, but also the

surface quality must be of a high standard.

Hence, furnaces for the production of high-quality

steel strips for use in interior and exterior compo-

nents (usually annealing or galvanizing furnaces)

must be set up to produce high material strengths

and flawless surfaces. A crucial part for flawless sur-

faces is a surface-friendly annealing process, which

for example keeps the surfaces clean and controls

or prevents oxidations processes. In order to

achieve an outstanding material strength, advances

annealing and cooling strategies are implemented.

In automotive construction, a growing number of steel grades with higher strength and good forming properties are used.

28

carbon sTeel annealing & galvanizing: concepTs

In a vertical hot-dip galvanizing line, which is often

used to produce unexposed and exposed automotive

parts, the furnace has two main tasks. Firstly, the

material has to be annealed to restore drawability

and adjust the mechanical properties. Secondly, the

material has to be prepared for galvanizing.

Horizontal galvanizing lines are intended mainly

for the production of material for the construction,

household appliances and furniture industries, but

also in part for automotive applications. The furnace

again has the task to adjust mechanical properties

and to prepare the material for galvanizing.

conTinuous annealing

hoT-dip galvanizing

horizonTal hoT-dip galvanizing

The Full-radiant tube furnace is the biggest part of a

continuous annealing line. The annealing and cooling

process reduces strain hardening from the rolling pro-

cess and gives the material the desired mechanical

properties. In the overaging section carbides are re-

moved from the material to minimize the risk of aging.

29

This universal furnace concept offers two cooling

options: gas and water cooling. On this line, different

products can be produced very flexibly according to

the current market conditions. In this way, it is pos-

sible to produce the most valuable products every

time.

The universal annealing and galvanizing line features

a furnace with both: a hot-dip galvanizing section and

an overaging section. Thus, this line can be used as a

fully equipped continuous annealing line or as a hot-

dip galvanizing line and it is possible to switch be-

tween annealed or galvanized material very flexibly.

The furnace in an all-purpose cold strip processing

line offers two cooling options and the possibility to

produce annealed or galvanized material. With alto-

gether four completely different process routes, this

is the most flexible concept for cold strip production.

universal annealing wiTh gas

and waTer cooling

universal annealing and

galvanizing

all-purpose

30

carbon sTeel annealing & galvanizing: Technology

i-Furnace

The Intelligent Furnace by SMS is a smart furnace

process and production optimization model. The

combination of various tools leads to an optimized

heat treatment and production process. It smartly

combines a mathematical/physical model to control

the furnace and to optimize production with EMGs-

IMPOC system for online strength measurement

and a newly developed annealing microstructure

model to predict material properties after the heat

treatment. This intelligent combination of efficient

tools is a great step forward towards an autonomous

working furnace.

Special sophisticated grades can be produced more

easily and homogenous material characteristics over

the whole coil length can be achieved. A capacity

increase up to 15 percent is possible due to a better

utilization of the furnace capacity as well as an efficient

production planning and transition behavior. Also ener-

gy savings can be realized due to a better temperature

control close to its lower limit (in average -10 K).

The annealing microstructure model in combination

with the data collected by the other tools can be

used offline to develop new materials. It’s possible to

predict material characteristics (e.g. tensile strength)

depending on annealing and cooling temperatures as

well as treatment curves. Furthermore, the model

can be used offline to lay-out the furnace exactly

according to the process requirements and limits.

Automatic furnace and line speed control by furnace mathe-matical/physical model.

31

The IMPOC measuring system of EMG Automation

GmbH – integrated in cold strip processing lines

continually checks the material’s tensile strength

and yield strength during production. That allows the

operator to immediately adjust process parameters

whenever necessary. Non-destructive magnetic

measurement shows that homogeneous material

properties over the whole coil length are achieved

even at high tensile strengths.

Since today many automotive manufacturers use this

system for checking materials, the material require-

ments of the automotive industry are increasing

and forcing the steelmakers to check the quality

within their lines. The IMPOC system is perfect for

automatic, non-destructive, online testing of ferro-

magnetic steel strips with thicknesses from 0.15 to 6

millimeters. This system is based on two identically

constructed sensors, which are arranged on the

upper and underside of the strip. Each sensor con-

sists of a magnetizing coil and a magnetic

field probe for recording the remanent magnetic

induction.

only measuremenT oF maTerial

properTies

pre-oxidaTion chamber

Some modern high-strength steel grades contain

high silicon and/or manganese contents. These alloy-

ing elements migrate to the surface during annealing

and create wettability problems which can lead to

bare spots. With a controlled infusion of humid air

into the pre-oxidation chamber the dew point gets

altered. This creates a closed iron-oxide layer on the

surface and suppresses the migration of silicon and

manganese to the surface. At the end of the furnace

a reduction of the iron-oxide layer takes place and

the resulting surface has the required wettability.

As a result, with this technology it is possible to gal-

vanize also high-alloyed high-strength steel grades

which leads to an extension of the product range of

every line. Another economic benefit is the substitu-

tion of expensive alloying elements with silicon.

32

carbon sTeel annealing & galvanizing: Technology

rapid cooling wiTh gas

The ultra-fast cooling System (UFC) allows to realize

uniform cooling rates of up to 150 Kelvin per second

and millimeter of strip thickness in radianttube fur-

naces of galvanizing lines or annealing lines. The

results are excellent strip geometry and optimal sur-

faces. Thus, it is possible to obtain high-strength

multi-phase steel grades such as DP and TRIP having

tensile strengths of up to 1,000 megapascals. Further-

more, some steel grades can be produced using less

alloying elements due to the higher possible cooling

rates. This implies greater product diversity at lower

operating costs.

Higher cooling rates are obtained by adding pure

hydrogen to the cooling chamber without increasing

the total hydrogen consumption of the line. The gas

pressure may be reduced, and the consumption of

electrical power decreases by an amount up to 40

percent. The cooling system takes advantage of the

properties of hydrogen (low density and high thermal

conductivity) to enhance the cooling capacity. A spe-

cial feature of the patented ultra-fast cooling system

is the addition of pure hydrogen directly into the

cooling chamber. The hydrogen content there is up

to 50 percent, thus permitting the high cooling per-

formance. A complicated separation of the cooling

zone from its neighboring sections is not needed

owing to the natural diffusion of the gas to the other

areas. Neither does the system normally requires

more hydrogen than the conventional furnace mode

with the inert gas containing a hydrogen share of five

percent. In customary radiant tube furnaces, the inert

gas is mixed automatically and fed into the furnace at

various places.

The cooling gas is applied to the strip via nozzles

with transverse slots to ensure uniform cooling

over the full strip width, thickness, and length. The

distance between strip and nozzles can be infinitely

varied between 40 and 120 millimeters. Despite the

high flow rate, the cooling chamber, thanks to its

special design, safeguards great strip stability with a

minimum of vibrations.

The ultra-fast cooling system (right) serves for the produc-tion of high-strength steel grades with cooling rates of up to 150 Kelvin per second per millimeter.

quenching and parTiTioning

SMS offers also furnace concepts for quenching and

partitioning of steel grades to produce for example

martensitic steel grades with enhanced levels of

retained austenite. The furnace comprises high-

speed cooling systems and subsequent high-

frequency induction heating modules. Within this

two-step thermal treatment the material is cooled

down with high cooling rates and afterwards heated

up via induction.

33

inTensive cooling wiTh waTer

The water-spray cooling system is specifically de-

signed to produce ultra high-strength steel strips

for internal parts of a vehicle. The system is able to

attain tensile strengths of partly more than 1,700

MPa. These high strength dual phase and complex

phase as well as martensitic grades are mainly used

to produce crashproof core components in the pas-

senger compartment such as the A-pillar and B-pillar,

door beams and roof bows. That's the way steel

products improve the safety of modern automobiles

and, at the same time, reduce their weight.

The water-spray system is able to achieve cooling

rates that are distinctly above those attainable by gas

cooling sections. Due to the high specific heat capac-

ity of water, a large amount of heat energy can be

dissipated through spraying within a very short time.

The cooling rates thus achieved are above 1,000 Kel-

vin per second and millimeter.

In the water-spray section, the strip immerses in

demineralized water and both sides are sprayed with

water by special nozzles. This continuous spraying

action under high pressure creates turbulences that

ensure fast dissipation of the heat energy. In the

nozzle chambers cooling by more than 600 Kelvin is

achieved for example within less than half a second.

During this short period the steel strip microstructure

is completely transformed as a result of dimensional

changes. In co-action with a strip shape control, the

special nozzle configuration ensures a uniform coo-

ling result over the entire strip width, preventing the

formation of distortions or flatness defects.

Flexible annealing curves

A comparison of typical annealing curves for different

high-strength steels shows that cold strip processing

furnaces must offer considerable flexibility with

regard to heat treatment. Equipped with various coo-

ling systems the processing furnaces of SMS group

are capable to produce the latest high-strength steel

grades for the automotive industry. That allows for

lighter and fuel-saving vehicles.

precise Following oF The

heaTing curves

The precise and speed control with the mathematical/

physical control model enables the furnace to follow

the specified annealing curve exactly. Thus, every steel

grade gets just the heat treatment which is demanded

for the required material characteristics. This also

applies to the transitions area around the weld seam

when the material properties or geometry changes.

Comparison of different cooling curves for the production of modern high-strength steel grades.

Water-spray cooling for producing steel grades with tensile strengths of up to 1,700 megapascal with cooling rates of more than 1,000 Kelvin per second per millimeter.

34

carbon sTeel annealing & galvanizing: reFerences

hoT-dip galvanizing line and

universal annealing and

galvanizing line

The two cold strip lines in the MMK plant in

Magnitogorsk, Russia, together produce more than

one million tons of high-quality steel strips, especially

for automotive outer and interior parts. This is where

SMS erected a pure hot-dip galvanizing line and a

universal annealing and hot-dip galvanizing line. It is

a plant array that covers a very wide range of top-

quality materials – from mild to high strength grades

– and produces two different product groups

(annealed and galvanized) as required.

Everything for the lines was supplied from one source:

mechanical equipment and hydraulics, air knives,

posttreatment and of course the powerful full-radiant

tube furnaces. Furthermore, SMS was responsible

for the entire electrical and automation systems

complete with Plug-and-Work integration tests. Both

plants went on stream in summer 2012. As early as

the end of November, MMK issued the final approval

for the lines after an effective start-up phase.

Bypass around the zinc pot for annealing mode.

MMK Magnitogorsk Iron and Steel Works, Russia

Two powerful furnaces serve for the production of more than one million tons of high-quality steel strip, particu-larly for the automotive industry.

35

conTinuous annealing line

wiTh rapid gas cooling and

waTer spray cooling sysTem

PRO-TEC Coating Company (PRO-TEC), USA, suc-

cessfully commissioned a new continuous anneal-

ing line for the production of cold-rolled ultra-high

strength steel coils. The line was completely supplied

by SMS group and is located in Leipsic, Ohio. In

February 2013, the first sellable prime coil was

produced. Besides the design and production of

the mechanical equipment as well as the furnace

and process technology, the complete electrics and

automation package was part of the supply scope of

SMS group.

Each year, 500,000 short tons of steel strips for auto-

motive structural components for cars, trucks and

sport utility vehicles can be produced, with a view

to both improve the safety of vehicles and reduce

their weight. The annealing process and special high

cooling rates, along with tempering, reduce the strain

hardening in the material caused by the rolling pro-

cess and enable the high-grade metallurgical proper-

ties to be attained.

Among other sophisticated technologies, the line fea-

tures a high-capacity furnace with an integrated ultra

fast cooling system and a water-spray cooling system

for particularly high cooling rates, which allow the

manufacturing of fully martensitic grades and ultra-

high-strength multi-phase steels.

PRO-TEC Coating Company, USA

The full radiant tube furnace ensures an economical produc-tion of high-strength and ultra-high-strength materials.

Since in the PRO-TEC line two options for fast cooling of the material are available, different cooling strategies can be applied which leads to a drastically increased product spectrum.

36

baTch annealing

disconTinuous annealing oF

cold sTrip

After cold rolling the steel strip is hard and brittle. It

has to pass a recrystallization annealing process to

achieve the necessary ductility for the later cold

forming process.

Batch annealing furnaces (also called bell type

furnaces) serve to anneal and cool the cold rolled

and already cleaned material in the batch mode.

Depending on the required capacity numerous anneal-

ing bases with several heating and cooling hoods are

installed in a production plant. The heat treatment

process for each hood takes between one and three

days depending on the batch size and material grade.

Each hood can process several coils at once. The

coils are stacked one on the other using intermediate

convector plates for strip edge protection and to

increase the heat transfer. The coil stack is covered

with an inner cover to ensure an oxygen-free protec-

tive atmosphere. A heating or cooling bell is put over

the inner cover depending on the current process

phase.

SMS uses modern batch annealing technology which

is based on the use of 100 percent hydrogen atmo-

sphere to increase the heat transfer and prevent the

strip surfaces from oxidation. The heating bell serves

for the heat-up of the annealing furnace up to recry-

stallization temperatures which differ for each mate-

rial. For the cooling process special cooling bells are

used with a combined air/water cooling technology.

Batch annealing furnaces offer the highest flexibili-

ty when it comes to different material grades with

different strip dimensions. This is because every

anneal-ing base works independently. The size of the

whole plant – i.e. the number of the annealing bases

is always adapted to the required production rate. Of

course, it is easily possible to add some bases to an

existing plant when necessary.

In the annealing base an impeller and a diffuser ensure a high circulation rate of the protective gas.

The inner covers are being put over the coil stack to have an atmosphere containing 100 percent hydrogen around the coils.

37

laTesT baTch annealing

Furnaces

Besides an annealing and hot-dip galvanizing line,

SMS group will establish batch annealing furnaces

for cold strip treatment at Big River Steel’s new mill

complex in Osceola, in the state of Arkansas, USA.

These furnaces serve to anneal and cool cold strip

coils in the batch mode. They are able to process

several coils simultaneously with a maximum batch

height of 6.4 meters, a maximum batch weight of

140 tons and a maximum coil outer diameter of

2,000 millimeters. The treatment takes between

42 and 55 hours. In total, 24 bases with 13 heating

hoods and 11 cooling hoods will be installed to

achieve a throughput capacity of 413,000 tons of

steel per annum.

Reference: Big River Steel, USA

For a high heating and cooling result the gas has to flow through the convector plates.

The gas flow inside the inner cover is optimized with CFD simulation (computational fluid dynamics).

Batch annealing furnaces serve to anneal and cool cold strip coils in the batch mode and are able to process several coil simultaneously. For cooling and heating different bells are used, while the coils remain in the inner cover under 100% hydrogen atmosphere.

38

conTinuous TinplaTe annealing

FasT processing oF Thin sTrips

The full radiant tube furnace is the heart of the

Tinplate annealing line. During the annealing process,

the strip is treated in the individual furnace sections

according to defined annealing curves. This serves

to remove strain hardening. First, the strip is heated

up to about 750 °C. After the soaking section, in

which this temperature is held for a certain time, the

material is cooled down fast to some 100 °C, which

sets the desired microstructure of the material. In

the following overaging zone carbides are eliminated

from the steel which minimizes the risk of aging.

Finally, cooling units lower the temperature of the

strip to about 40 °C. A protective gas atmosphere

with hydrogen content of 5 percent or less prevents

oxidation on the strip surface in the heating zones. A

constant slight overpressure in the furnace prevents

air ingress into the furnace. The product range com-

prises all grades and also contains the qualities T2.5,

T5 and DR 10, which cannot be produced by batch

annealing.

highlighTs

Low resource consumption

Precise following of the heating curve

Mathematical model with speed control

Experience in heating very thin strips up to 750 °C

High process speed (up to 750 m/min)

Special roll profile design

Rapid cooling with temperature transversal control

(edge damper)

The precise furnace and speed control with a mathematical model enables the furnace to follow the specified annealing curve for the different grades exactly.

The material is annealed in a very environment friendly way in a full radiant tube furnace with atmosphere con-trol and special designed rolls.

39

TinplaTe producTion planTs

Shagang Group, China, has successfully commis-

sioned its new annealing line and the electrolytic

tinning line both supplied by SMS group in 2014.

Being a systems provider, SMS supplied all compo-

nents including electrical and automation equipment.

The annealing line with a yearly capacity of 418,000

tons provides the strip with the required material and

surface properties by annealing and subsequent re-

duction plus surface treatment. In a powerful

radiant tube furnace, the strip is processed according

to an exactly defined annealing curve with a process-

speed of up to 720 meters per minute. The width of

the strips treated here may vary between 700 and

1,250 millimeters, and it is possible to process strip

gauges of 0.18 to 0.55 millimeters.

Reference: Shagang Group, China

In a tinplate annealing line the full radiant tube furnace is the biggest and most quality-decisive part. Annealing and cooling reduces strain hardening from the rolling process and adjusts the desired mechanical properties. Carbides are removed in the overaging section to avoid subsequent aging.

Furnace in the continuous annealing line for tinplate pro-duction which was erected completely by SMS for the Shagang Group.

40

elecTrical silicon sTeel sTrip processing

processing Furnaces To ensure The required

elecTromagneTic properTies

Non-grain oriented electrical strip is used in wind turbines for electricity generation. (©Thorsten Wengert/PIXELIO).

Grain oriented electrical strip is used in energy-efficient transformers. (©Dieter Schütz/PIXELIO).

SMS group supplies processing furnaces for the pro-

duction of electrical silicon steel strips from non-grain

oriented grades to high-permeable grain oriented

grades. The demand for electrical steel strip is grow-

ing steadily due to its electromagnetic properties

that lead to a significant increase in energy efficiency

when this strip is used in electric applications such

as power transformations. Manufacturing electrical

strip requires a highly complex production route

including sophisticated strip treatment strategies.

The main material properties are set through the heat

treatment of cold strip. Thus, furnace technology and

thermal processing are the crucial parts in producing

high-quality materials.

non-grain orienTed and grain

orienTed elecTrical sTeel

There are two groups of electrical steel steel: non-

grain oriented (NGO), and grain oriented (GO). In

NGO electrical strip, the iron grains are distributed

in a non-ordered way so that the material has largely

the same, so called isotropic magnetic properties

in all directions. That is why NGO electrical strip is

mainly used in rotating machines such as electric

motors and generators with alternating field orienta-

tion.

In GO electrical strip, the microstructure (grains) are

arranged in the direction of cold rolling, resulting after

special heat treatments in what is called cube-on-

edge texture. Because of the uniform orientation of

the grains, the electrical strip has a preferred direc-

tion in which the magnetization can occur relatively

easily. Due to the high permeability and lower losses

in this preferred direction, GO electrical strip is typi-

cally used in static machines such as transformers.

41

supporT For all grades and

producTion rouTes

In cooperation with MET/Con, SMS group offers

process support for all grades and production routes.

This covers both metallurgical and design activities as

well as support during commissioning and operation.

The experts involved look back on long production

experience and offer full parameter sets from

steelmaking to final processing. This ensures safe

production also of difficult and high-quality grades.

Furthermore, operational costs can be minimized,

for example through greatly reduced use of alloying

elements.

Process Know-How

Smooth strip running is enshured by heating of the coils as well as the strip edges to avoid strip breaks.

All furnaces and processing lines feature special equipment tailor-made to the particular requirements of silicon steel strip.

42

non-grain orienTed elecTrical silicon sTeel sTrip

Thermal simulation of the heating process in an NGO-furnace.

Furnace in an annealing and coating line.

Furnaces For annealing and

coaTing lines

The most important processing line for fully-finished

non-grain oriented (NGO) material is the annealing

and coating line. One highlight is the recrystalliza-

tion furnace with a hydrogen content of up to 100

percent. For contactless drying of the coating, a

floatation furnace with a high specific heat transfer is

installed.

NGO electrical strip is mainly used in rotating machines such as electric motors and generators with alternating field orientation.

43

new Furnace For an annealing

and coaTing line

In its new annealing and coating line, ArcelorMittal

St-Chély d`Apcher, France, processed the first coil in

March 2013. Thanks to good preparation by all

participants, the commissioning was done quickly

within a few weeks. Already one month after the

furnace had dried out, the production reached the

nominal rate.

With the new line, ArcelorMittal St-Chély d`Apcher is

drastically increasing its production capacity of high-

grade non-grain oriented electrical steel strips (NGO).

Among other products, the furnace processes the

newly developed iCAReTM material by ArcelorMittal

which helps automakers to offer environmentally

friendly mobility solutions for a greener world.

In the annealing and coating line, the internal micro-

structure of the electrical steel strip is adjusted

during the annealing process. The material is then

coated with an insulating layer. The strip is heated

up to 1,100 °C by means of inductors and electrical

heating elements in the horizontal annealing furnace.

The atmosphere in the furnace comprises a nitrogen/

hydrogen mix whereby the furnace can be opera-

ted with hydrogen content up to 100 percent. This

reducing atmosphere helps to achieve a particularly

oxide-free and clean strip surface, which is important

for a high-quality material grade. Furthermore, the

careful and slow cooling of the material is important

for the microstructure. For this reason, the strip is

first cooled down at a very accurate cooling rate in

the slow-cooling section and then in the rapid cool-

ing section. Due to the high annealing temperatures

and the very high hydrogen content in the furnace,

ArcelorMittal achieved very good material properties

right from the start. Especially the core losses are

already at the level of those attained by the best pro-

ducers in the world.

Reference: ArcelorMittal, France

The horizontal furnace in the new annealing and coating line for ArcelorMittal St-Chély d`Apcher.

44

grain orienTed elecTrical silicon sTeel sTrip

seTTing The main maTerial

properTies

The focus in the production of grain oriented silicon-

grades is on the heat treatment of the cold strip, as

the main material properties are set in this stage.

The first heat treatment in the annealing and pickling

line is to recrystallize the steel and to obtain the

appropriate quality and size or inhibitor precipitates.

The furnace is composed of a direct flame furnace,

followed by a radiant tube furnace. The strip is

annealed at a maximum temperature of 1,170 °C.

The strip is then cooled to 900 °C and soaked for a

minute. A cooling air and/or water is used to cool the

strip to the exit temperature. In case of production

of HiB grades, the cooling gradient should be higher

than 35 K/s between 900 °C and 400 °C.

During decarburized annealing, the carbon content

in the steel making process is high in order to avoid

abnormal grain growth in the slab. This carbon has to

be removed at this stage to avoid aging. The heating

is achieved due to radiant tubes. The annealing tem-

perature is between 830 and 900 °C. The cooling is

divided in two stages: slow-cooling at the beginning

and fast-cooling when the strip temperature is less

than 600 °C. In the soaking section, the atmosphere

is humidified to adjust the carbon content. After

annealing, strip is coated with a magnesia solution

and dried.

In batch annealing, the second recrystallization takes

place and the steel is purified from the inhibitor

elements. The strip is annealed at a temperature of

maximum 1,200 °C by a heating hood.

In the flattening and coating line, the goal is to dry

the tension active solution coated just before the

furnace and to improve the strip flatness. The first

section, in which the tension active coating is dried,

is of the catenary type and heated by direct flame

burners. Radiant tubes heat the second section of

the furnace. The annealing temperature is about

870 °C. A pair of flattening rolls is installed when this

temperature is reached. A slow-cooling and a fast-

cooling follow this section when the strip tempera-

ture is below 600 °C. The final cooling is achieved

with air-cooling. The control of the annealing curve

and the furnace atmosphere as well as the strip

tension, which could cause negative impact on final

magnetic properties, and the improvement of the flat-

ness are the most important issues in this stage.

Furnace in an annealing and coating line.

45

Two Furnaces For FlaTTening

and coaTing lines

SMS supplied two furnaces for Wisco’s new two

flattening and coating lines in China. These two lines

are used to enhance the production of HGO grades

around 180,000 tons. Both furnaces were successful-

ly commissioned in 2012. Without a stop for the first

five months after start-up, both furnaces have been

operating and produced, among other grades, HGO

materials in the low-temperature mode. The furnaces

feature new technologies for thermal flattening as

well as for cooling, which improve surface quality

and process control.

Reference: Wisco, China

Strip entering the drying and sintering furnace, which is divided into a radiant tube and a direct-fired section.

Catenary furnace for contact-free drying of the insulation layer.

46

sTainless sTeel sTrip annealing

powerFul Furnaces For sTain-

less sTeel sTrips

SMS group offers perfect concepts for all thermal

process stages of stainless steel strip which are

characterized by their efficiency, sophisticated pro-

duction models and powerful environmental technol-

ogy. All this leads to low production costs, high

energy efficiency and outstanding environmental

compatibility. The scope comprises of all significant

furnaces for stainless steel strip treatment. Besides

furnaces for annealing of hot strip and cold strip SMS

also delivers furnaces for bright annealing lines.

Horizontal furnace in a stainless steel hot strip annealing line.

Horizontal furnace which is capable to anneal stainless steel cold strip.

hoT sTrip annealing and

picKling lines

cold sTrip annealing and

picKling lines

47

In hot strip as well as in cold strip annealing and pickling lines the furnace plays a major part when It comes to mate-rial quality, operational costs and environment friendliness.

48

sTainless sTeel sTrip annealing – Technology

The furnaces are designed to optimize energy utili-

zation and environmental compatibility. The strip is

preheated in a radiation zone which operates with

the exhaust gases from the downstream heating

furnaces. To increase the thermal efficiency, a special

heat recovery system is used. The process para-

meters are set and controlled by a mathematical

model over the entire annealing cycle, which is also

combined with the pickling model to match up and

optimize both processes. More than 25 SMS fur-

naces for stainless steel strip processing have been

ordered since the year 2000 worldwide.

The support rolls in the furnace are designed as easy-to-maintain "carrousel rolls" and can be changed within 15 minutes without disturbing operation.

heaT recovery sysTem

Thanks to an intelligent heat recovery system, the

furnace achieves excellent thermal efficiency. The

strip is heated up in two zones by means of direct

firing. The hot waste gases are then led through the

preheating zone in the opposite direction to strip-

travel and heat up the strip. Finally, the gases are

extracted at the furnace front end and, with the aid

of a recuperator, are used for preheating the combu-

stion air. Thus, the exhaust gases of the furnace are

used to preheat the combustion air as well as the

strip in the first parts of the furnace.

49

waTer cooling For hoT sTrip

In hot strip processing, a special water cooling

technology ensures a better strip quality due to

faster cooling and a better control of the last heat-

ing zone. The efficient system results in a shorter

cooling section and massive electrical savings.

Furthermore, the impact on the environment is mini-

mized because there are no dust emissions and no

vibrations or noise.

misT cooling For cold sTrip

The mist cooling technology reduces the length of

the energy consuming air-cooling section and elimi-

nates the final cooling performed by water, since this

can generate cooling buckles. In total, 17 annealing

and pickling lines have been equipped with mist

cooling sections. Due to reduced blower motor

power and exhaust motor power, electrical energy is

saved. Moreover, water consumption can be re-

duced drastically. This adds up to annual operational

savings which significantly reduce production costs.

50

sTainless sTeel sTrip annealing – reFerences

high-perFormance Furnace For

The producTion oF brighT-

annealed sTainless sTeel sTrip

North American Stainless (NAS), USA, a subsidiary

of the Spanish Acerinox Group, has contracted SMS

group for the supply of a complete bright annealing

line. NAS is erecting a modern, high-performance

production facility for bright-annealed stainless

steel strip in Ghent, in the U.S. state of Kentucky.

The in-stalled plants will be characterized by high

efficiency, flexibility and product quality. The output

capacity of the plant will be 95,000 tons per year.

Commissioning will take place in early 2017.

The new line will manufacture both austenitic and fer-

ritic grades (AISI 300 and 400 series). The end ma-

terial will be between 600 and 1,350 millimeters wide,

and between 0.15 and 1.5 millimeters thick. In addition

to the supply of the mechanical, process, furnace, elec-

trical and automation equipment, also the supervision

of installation, commissioning support and training of

the operating personnel belong to the contract scope.

The bright annealing line will be the highest-perfor-

mance line of its kind in the USA. Here the material

will be annealed with a speed of 50 meters per

minute in an oxygen-free, inert atmosphere with high

hydrogen content, creating a high-grade, reflective

strip surface.

The technological highlight of the bright annealing line

is the entirely electrically powered vertical furnace.

Thanks to the furnace’s high operating efficiency, the

energy consumption, at approx. 220 kilowatt hours per

ton, is 60 percent lower than in a conventional design

with a muffle furnace. Furthermore, the shorter hea-

ting section enables the bay height to be reduced by

50 percent. The high efficiency is achieved by means

of direct heating via electrical heating elements and

dynamic annealing at up to 1,250 °C. The annealing

process takes place in a pressurized inert atmosphere

(up to 90 percent hydrogen). This ensures a low dew

point and produces an immaculately reflective surface.

A special strip stabilization system allows contactless

positioning of the strip, preventing surface damage.

The total furnace construc tion is made gas tight.

Special sealing elements at the entry and exit mini-

mize losses. In order to keep the hydrogen require-

ment low, a recycling unit will be integrated to conditi-

on the used hydrogen and return it to the process. For

strip cooling, the furnace will be fitted with two inert

gas recirculation units.

North American Stainless (NAS), USA

The bright annealing line operated by an electrical furnace convinces through highly efficient production of stainless steel strips with extremely high-grade surfaces.

The technological highlight of the new NAS line is the entirely electrically powered vertical furnace with a pres-surized inert atmo-sphere (up to 90 percent hydrogen).

51

annealing and picKling lines

For cold and hoT sTrip

The annealing and pickling line for hot and cold stain-

less steel strip is an integral part of a new cold rolling

mill for stainless steel in Alabama, USA, owned by

Outokumpu Stainless Steel USA. The line is able to

produce flexible hot and cold strip as well as very

thick material (up to 10 millimeters). The yearly

capacity is 750,000 tons including AISI 200, 300 and

400 grades. The line went on stream in 2011 with

excellent results so far. The thermal treatment of the

strip takes place in a modern horizontal furnace with

various innovative features.

Outokumpu Stainless, USA

With a length of almost 140 meters the furnace is capable to heat the strip up to 1,150 °C.

The intelligent heat recovery system ensures a high-thermal efficiency.

The furnace serves for the production of 140 tons of hot strip per hour or 90 tons of cold strip per hour.

52

color coaTing

eFFicienT drying Furnaces For

sTeel and aluminum sTrips

Color coating lines apply a high-quality coating to the

strip so that it can be used directly for processing

into end products. This saves costly process stages.

SMS group delivers color coating lines for various

applications of aluminum and steel strip. The lines

differ depending on the final use of the material.

The lines are delivered completely from a single

source and feature several outstanding processes.

The highlight of the lines is the compact coating pro-

cess. Chemical strip pretreatment, subsequent color

coating and drying oven are ideally synchronized.

This way it is possible to attain a high product quality

at low consumption of resources and energy. The

high-performance floatation or catenary ovens to dry

the solvents stand out for even heating and cooling

performance as well as exceptionally high efficiency

and eco-friendliness. All this requires ideal setting

and control of the process parameters, ensured with

a mathematical model. The air is heated by burners

that work with reheated combustion air, yet require a

very low energy input.

In a floatation oven the strip travels on air cushions without any mechanical contact.

conTacT-Free sTrip Travel

Nozzles in the floatation oven ensure the strip tra-

vels contact-free through the oven and air cooler in

a sinus shape. This is possible because, throughout

the oven length, hot-air nozzles heat the strip evenly

and keep it afloat on an air cushion. With interaction

of the mechanical drive, a fault-free strip transport

is generated. The ovens are designed with several

modular heating and curing zones for best process-

ing and strip quality.

53

A regenerative thermal oxidizer system burns the solvent-containing exhaust air and regains the energy produced.

In a color coating lines – here for aluminum can-end stock material – a floatation oven is used to evaporate the sol-vents without contacting the material to make the color layer curing on the strip.

For products, where the energy demand is in balance with the generated energy of the solvents by the heat recovery system, the curing oven operates with autothermal mode.

regeneraTive Thermal oxidizer

(rTo)

The flue gases of the oven are burned in a regene-

rative thermal oxidizer system (RTO) with a thermal

efficiency of 98 percent. Depending on the solvent

content in the exhaust air, the after burning system

and even the oven itself can be operated without

additional energy input (autothermal mode).In color

coating lines, solvents are evaporated so as to cross-

link the varnish molecules and to cure the varnish.

The type of heating of the ovens is specified on the

basis of the product portfolio and the product mix as

well as an energy balance and economic calculation.

Thus, concepts with autothermic operating practice

of the ovens have already been realized over of a

wide product range. The exhaust gases are extracted

and combusted via a regenerative thermal oxidizing

system (RTO) with a high thermic operating efficiency.

Depending on the solvent content of the exhaust air,

the post combustion system and, if an energy

recovery system is employed, also the ovens them-

selves can be operated without additional energy

supply.

54

color coaTing: reFerences

Two color coaTing lines For

carbon sTeel sTrip

Severstal's new color coating line in Cherepovets,

Russia, was successfully put into operation at the

end of 2011 and production quickly increased in

the following months. The new plant is of identical

design to the SMS color coating line that went into

operation at Severstal at the end of 2005.

Besides the very high process speed, the highlights

of the line are the roll coaters and the high-perform-

ance drying ovens. In the future, a further 200,000

tons per year of hot-dip or electrolytically galvanized

cold strip will be color coated in western Russia.

The strips are mainly used in the construction and

household appliances industries.

A backup roll coater is used to apply a primer on

the surface, which is dried in low-emission catenary

curing oven. Subsequently the strip can be coated

with a finish coat in two back-up roll coaters and

hardened in another horizontal catenary curing oven.

Oven from the operator side.

Severstal, Russia

Drive side of the finish oven.

Two highly efficient ovens are integrated in each color coating line to dry the primer coating and the finish coating.

55

color coaTing line For alumi-

num can maTerial

SMS is supplying a color coating line to the Chinese

aluminum producer Shandong Nanshan. The line will

be designed for an annual production of 50,000 tons

of coated aluminum strip. The line is designed for

strips with a thickness of 0.15 to 0.5 millimeters and

widths ranging from 950 to 2,000 millimeters. The

material is intended to be used predominantly for the

production of beverage cans.

The highlight of the plant design is the compact coat-

ing and curing process. The chemical pretreatment

section, the subsequent strip coating process and the

drying oven are perfectly harmonized.This ensures

high product quality and low consumption of resources

and energy.

The solvents will be evaporated without any contact

in a floatation oven, with the strip surface curing in

the process. Along the entire furnace length, the

strip will be uniformly heated by hot-air nozzles while

being carried by an air cushion in a floating position.

The fact that there is no mechanical contact between

the strip and any part of the furnace guarantees an

impeccable surface quality.

The evaporated solvents will be combusted in a high-

ly efficient thermal process in a regenerative thermal

oxidizer (RTO). This solution makes it possible to

heat-treat a wide range of products without any

external energy input (autothermal operation).

Shandong Nanshan, China

The new color coating line of Shandong Nanshan features a powerful floatation oven to dry-out the color coating which is combined with an integrated regenerative thermal oxidizer system, that makes it possible to heat-treat a wide range of products in an auto-thermal operation mode (i.e. without any external energy input).

56

aluminum heaT TreaTmenT

The use of aluminum as a light weight construction

material in automobiles continues to be on the rise.

Subsequent to the cold rolling process, the aluminum

sheets have to under go a heat treatment to regain

formability as well as the required material strengths.

Especially the heat treatment and the cooling of the

strip play a major role. This happens in combined

heat and chemical treatment lines or in single heat

treatment lines.

The furnace and cooling technology is the heart of

the process. The strip enters a floatation furnace

where it is guided sinusoidal in a contactless floating

mode. It is heated up and kept at the required strip

temperatures in time, so the aluminum-alloy obtains

their structure. Especially 6xxx automotive-alloys as

well as 2xxx and 7xxx aerospace-alloys require high

cooling rates up to approx. 400 Kelvin per second.

The cooling process is executed as a combination of

water and air cooling.

A special feature of the furnace is the eco-friendly

process control. Operation is controlled by a physical

process under consideration of the mechanical prop-

erties model and a production planning model with

physical transient state calculation.

waTer cooling wiTh a pre-

deFined cross-bow

In the aluminum heat treatment furnace a water-

quench ensures at the same time high cooling rates

and good strip shape. Thus, high qualities are

achieved. Controlled and stable cooling is ensured

by a predefined cross-bow. A special sealing unit

prevents premature cooling.

aluminum as lighT weighT consTrucTion maTerial For The

auTomoTive indusTry

57

For a new continuous heat and chemical treatment

line at Ma’aden-Alcoa, all plant components including

electrical and automation systems were supplied by

SMS from a single source. SMS was responsible for

the design, manufacture, erection supervision and

commissioning of the line in the Ras al Khair plant in

Saudi Arabia.

One of the technical highlights of the line is the strip

floatation furnace.The equipment paves the way for

Ma’aden-Alcoa to enter the market for aluminum

car body sheets. The line is able to produce 60,000

tons of annealed,cleaned and chemically treated strip

material. In March 2015 the first aluminum coil was

successfully heated and chemically treated in the

new line.

Reference: Ma‘aden-Alcoa JV, Saudi-Arabia

The heart of the new heat and chemical treatment line for Ma’aden-Alcoa JV is the powerful floatation furnace with water-quench unit.

heaT and chemical TreaTmenT line For

auTomoTive and aviaTion grades

During cold rolling, the aluminum strip solidifies and

must be annealed to regain its formability for further

processing. These lines also homogenize and solution-

anneal alloys that can solidify due to special inter-

metallic precipitates. To achieve the microstructure

necessary for thedesired mechanical properties, the

material is heated to approx. 560 °C, then rapidly

cooled in a controlled way. It is imperative that the

sensitive surfaces are not supported by rolls during

heating, which is where convection strip floatation

furnaces come in. Furthermore,in a combined heat

and chemical treatment line, (which is shown here)

the strip receives a chemical treatment that prepares

the surfaces for subsequent painting.

58

59

Furnaces For slabs, bars and Tubes

Every rolling mill is different and the same should apply to

every furnace. The SMS furnace experts offer tailored solu-

tions for any process and layout. The design capability inclu-

des in general the following furnaces.

Roller Hearth Furnaces page 58

CSP®-Roller Hearth Tunnel Furnaces page 62

Chamber Furnaces page 64

Walking Beam Furnaces page 66

Walking Hearth Furnaces page 70

Pusher Furnaces page 72

60

roller hearTh Furnaces

eFFicienT heaTing oF heavy

plaTes

The roller hearth furnace is often used in a contin-

uous heat treatment process for heavy plate. Its

strengths are, on the one hand, different speeds for

the individual heat treatment of plates and, on the

other, a high maximum speed, which is important,

in the first place, when it comes to transporting the

plates to the quench.

The furnace housing of a roller hearth furnace has

the shape of a long tunnel. The hearth itself consists

of rollers arranged transversely to the direction of

transport. The distance between the rollers must not

exceed a maximum dimension, as otherwise there

would be a risk of the plates “diving” below one of

the rollers. This maximum dimension is thus deter-

mined by the bending behavior of the thinnest plate

at the highest possible temperature. The roller hearth

divides the furnace into a top and a bottom section

which provides the possibility of heating from both

sides.

The hearth usually consists of high-alloy centrifugal

cast rollers and which is the core component. On the

one hand, the rollers are a decisive factor as regards

the costs of such a furnace system, which again

depend to a large extent on the price fluctuations,

especially for the main constituents of Cr and Ni. On

the other hand, the rollers may also impose restricti-

ons on the system design. A sufficient lifetime of the

rollers can only be guaranteed if the hearthload as a

combination of temperature, plate load per roller and

bearing center distance (which again is directly linked

to the plate width) does not exceed certain limits.

Heating is accomplished either by open or indirect

firing through radiant tube burners with the furnace

chamber being rendered inert by flushing with nitro-

gen. The indirect heating method results in less

scale on the plates, but requires considerably higher

investment and operating costs. The radiant tubes of

indirectly heated furnaces are equipped with recupe-

rator burners.

For open fired furnaces, however, it is recommended

to use high speed burners with a central recuperator

for preheating the air.

Cross-section of a roller hearth furnace with radiant tube heating.

Roller hearth furnace for normalizing and tempering

61

SMS delivers two roller hearth furnaces for the

Slovenian steelmaker Acroni, which are integrated

into heat treatment lines for heavy plates. The fur-

naces will be designed for 4 to 13 meter plates

with thicknesses ranging from 3 to 100 millimeters

and a width ranging from 700 to 2,560 millimeters.

The maximum weight of the plates is 16 tons. The

range of materials includes high-strength carbon

steels, stainless and tool steels as well as a range

of special grades.

SMS supplies a roller hearth furnace for hardening,

normalizing and solution annealing and another roller

hearth furnace for tempering, as well as a quench-

ing system and all auxiliary facilities. These will

include the complete plate conveying equipment, all

systems for the water supply and water treatment

as well as the automation of the systems.

The roller hearth furnace for hardening and solution

annealing will be equipped with two chambers, in

which the plates will be annealed in a nitrogen-based

inert gas atmosphere. Heating to up to 1,100 °C will

be carried out indirectly using radiant heating tubes

with recuperator burners. The total furnace length is

33.6 meters.

The roller hearth furnace for tempering is only

slightly shorter with a length of 32.3 meters. In this

open fired furnaces, however heating takes place

via high-speed burners which heat the furnace up

to 800 °C. The achieved plate temperature lies

between 400 °C and 780 °C.

Reference: Acroni, Slovenia

Two roller hearTh Furnaces For special grades

Roller hearth furnace for hardening and normalizing.

62

csp®-roller hearTh Tunnel Furnaces

In the CSP® plant, the roller hearth furnace is the

logistical and technological link between continuous

caster and rolling mill. The first zone of the more

than 1,100 °C hot furnace serves to set the thin slab

temperature required for the rolling process. This is

achieved by using environmental friendly ultra-low

NOx burners. In order to save energy, the combustion

air is preheated by waste heat from the furnace via

recuperators.

The downstream homogenizing zone keeps the tem-

perature at a constant level and harmonizes it over

the cross-section and length of the slab to achieve a

homogenous temperature distribution. This is neces-

sary for an optimized rolling process and makes sure

the finished product is of high quality.

To transport the thin slabs through the furnace, spe-

cial water-cooled rollers are used. They ensure little

heat is dissipated and thus increase the energy effici-

ency of the furnace. To satisfy the high demands on

the final product surface quality, a newly developed

calculation module minimizes the contact pressure

between roller support rings and slab.

A special Dynamic Furnace Control (DFC) level 2 pro-

cess automation system is used in a CSP®-furnace

to ensure heating of the slab to the required target

temperature with good uniformity and without ener-

gy wastage (see page 18).

The slabs are transported through the furnace via cooled and wear resistant rollers.

eFFicienT heaTing and slab TransporT wiTh special cooling rolls

Newly developed rolls with fireproof aluminum silicate wool.

63

For the new steelworks of Big River Steel, SMS

group will supply all thermal processing equipment.

Thus, the complete know-how for heating and cool-

ing throughout the whole processing chain is supplied

from one source and ensures high material quality is

attained. In the first stage, the new complex of Big

River Steel in Osceola, in the state of Arkansas, USA,

will produce 1.5 million tons of hot strip. Part thereof

will be refined in-house to produce high-strength cold

strip for automotive applications.

The CSP® plant is capable of producing strips with

thickness ranging between 1.55 - 25.4 millimeters.

Equally impressive is the strip width of up to 1,930

millimeters, which means Big River Steel owns the

world's widest CSP® plant. The CSP®-roller hearth

furnace features a newly developed calculation mo-

dule to minimize the contact pressure between roll

carrier rings and slab for high surface quality of the

end product. Already in place are plans for producing

sophisicated products that cater to the demands of

the growing market-products such as pipe grades for

pipelines, AHSS grades, and especially silicon steels

for electrical sheet. That's why the CSP®-Furnace is

designed from the start for slab temperatures of up

to 1,220 °C.

This includes water-cooled furnace rollers with fire-

proof insulation made of aluminum silicate wool.

Thus, higher temperatures are possible at low energy

losses via the cooling water. Still to come is an

expansion stage that will substitute the final section

of the tunnel furnace with a muliple module induction

heating system. Carrying out this conversion means

it will be possible to increase the slab temperature

from 1,220 °C to the level of 1,320 °C, required for

the most difficult-to-produce steels.

Reference: Big River Steel, USA

csp®-roller hearTh Tunnel Furnace in a new inTegraTed

sTeel planT

64

chamber Furnaces

baTch operaTed Furnaces wiTh

a Fixed hearTh

Chamber furnaces are batch-operated furnaces with

a fixed hearth. These furnaces are characterized by

their high degree of flexibility and are thus typically

used in the case of low capacity requirements and

frequently changing batches. Depending on the case

of application, the hearth can be subdivided such that

heating of the plate bottoms can be implemented at

least in parts of the furnace. On the longitudinal side,

the furnaces are equipped with a large door. Through

this door, the plates are introduced into batch type

furnace and discharged from the furnace by means

of a machine. For plate transfer to the furnace and

away from the furnace, a conventional roller table is

installed along the longitudinal side of the furnace.

The chamber furnace is often used for normalizing

or solution annealing at elevated temperatures in

the case of high plate loads and large plate widths.

Concerning the combination of plate load and tempe-

rature, this furnace has almost no restrictions.

With the help of loading machines all plates are introduced separately into the batch type furnaces.

The large doors on the longitudinal side of the furnace opens and a glowing plate is discharged out of the furnace.

65

Two chamber Furnaces which

can be connecTed

As part of a complete heat treatment line, SMS deli-

vered two chamber furnaces to Outokumpu Stainless

in Degerfors, Sweden. The two batch-type were deli-

vered completely with charging machines and con-

necting roller tables as well as all the accompanying

electrical and automation equipment.

The new furnaces are used for heavy plates and high

heat-treatment temperatures, as well as for small

batch sizes of niche products. The loading machine

introduces a stainless steel plate into the furnace.

The furnace plant consists of two batch type fur-

naces, both of which have two doors. The reason for

this is that every furnace can be further divided into

two chambers using a special separation gate. In this

way, Outokumpu can occupy a furnace with either

one long plate or two short plates. If two plates are

in the furnace, then these can be heat-treated indi-

vidually using differing annealing temperatures

times, provided that the separation gate is closed.

This offers a high degree of flexibility and thus

optimal hearth utilization at all times, which guaran-

tees energy-efficient plant operation. In this way,

Outokumpu can occupy a furnace with either one

long plate or two short plates.

The batch type furnaces can heat plates to more than

1,200 °C. With such high temperatures, Outokumpu

is capable of manufacturing sophisticated steels such

as high-alloy grades for special applications.The

furnaces meet the high environmental protection

requirements and are equipped with a modern heat-

recovery system. A further special feature is the pro-

cessing of very thin plates. The plate lengths range

from 3,000 to 16,000 millimeters and the widths

from 400 to 3,500 millimeters. The loading and un-

loading machine conveys at approximately 2 meters

per second.

Reference: Outokumpu, Sweden

Solution annealing takes place via high-speed burners in the open fired batch furnace at Outokumpu.

66

walKing beam FurnacesHigh productivity combined with operational flexibility

Walking beam furnaces, both top and bottom-fired,

allow for high production rates and top quality steel

grades. Billets, heavy blooms, slabs and beam blanks

can be charged. Walking beam furnaces feature

many cooled elements as well as special alloy parts

which endure high temperatures and mechanical

stresses. SMS group continuously works on the

development and integration of new designs and

materials. Thanks to the advanced combustion sys-

tem, all SMS walking beam furnaces are highly flexi-

ble in operation.

FasT and reliable maTerial

handling machines

SMS sturdy discharging machines avoid any misalign-

ment in the discharging area, even when handling

workpieces of very different sizes and shapes. They

virtually eliminate vibrations and positioning errors.

The possibility of reverse movement in emergency

situations as well as the choice of manual handling

are further key advantages. SMS group offers a wide

range of kick-in and kick-off machines, both electro-

mechanically and hydraulically operated – so even

the most challenging demands are met.

67

rapid discharge raTe

The record-setting machine delivers one billet every

24 seconds. It is installed in the high-capacity walk-

ing beam furnace at KSC Nizhneserginsky Metizno-

Metallurgichesky Zavod – ZAO “NSMMZ”.

benchmarK eFFiciency

The 180/220 tons per hour walking beam furnace

at United Steel Company, Bahrain, is equipped with

ultra-low NOx burners. It sets benchmarks in

efficiency and low emissions.

68

69

high qualiTy meeTs lowenergy consumpTion

ArcelorMittal Ruhrort operates one of the world's

most modern wire rod mills. The plant was supplied

by SMS group and produces a wide range of special

steel grades for the premium market, primarily the

automotive sector. The walking beam furnace

adequately supports the slender billets with the fixed

and movable skid. The result: 110 tons of billets with

a thickness of 155 millimeters and a length of 16.5

meters are optimally heated every hour, meaning

ArcelorMittal can reliably deliver premium quality pro-

ducts. The double-stage recuperative system allows

for benchmark efficiency and minimum emissions: a

specific natural gas consumption of 250 kcal/kg and

less has been achieved very early after lighting of the

furnace. The waste gas evacuation system is equip-

ped with special filter units which effectively reduce

the release of particulate matter.The walking beam

geometry guarantees perfect overall heating quality:

Faster reheating ensures better control of decarbu-

risation, vital for high-quality rods.

The temperature homogeneity is enhanced by a

large battery of low-NOx radiant burners in the

heating and soaking top roof, and by the digitally

controlled long-flame burners installed in the bot-

tom soaking zone.

70

walKing hearTh FurnacesMinimum specific consumption figures

Walking hearth furnaces are the optimum choice for

many long products mills with production rates of up

to 140 tons per hour. Due to the layout with top heat-

ing only, these are recommended for products with

a maximum thickness of 160 millimeters. A major

advantage of this furnace type is that it allows for

very low specific consumption figures, achieved

thanks to the absence of water-cooled elements

inside the furnace.

71

Stefana S.p.A. set up a 700,000 ton per year bar mill

under a project entitled “Dream Steel”, located in

Ospitaletto, Italy. The furnace specialists designed

a furnace capable of reheating billets with a length

of 16 meters, with the result that Stefana can profit

from the market demand for large coils with a weight

of more than three tons, as well as from the overall

benefits of improved yield. This target was achieved

by constructing a walking hearth furnace with a sus-

pended 16.8 meter wide roof. A battery of 90 radiant

burners guarantees optimum temperature homo-

geneity of the reheated workpieces.

The heat maintenance zone, a series of small burners

that retain the furnace temperature during weekend

stoppages and prolonged mill downtimes, helps

Stefana to reduce energy costs. The reheating fur-

nace is able to supply the mill with a continuous out-

put of 120 tons per hour starting with cold billets, or

140 tons per hour when hot charged.

record-breaKing perFormance:

16 m slender billeTs under a radianT rooF

72

pusher FurnacesLow investment costs combinedwith robust design

When it comes to heavy duty and straight forward

design furnaces for billet reheating, the pusher type

furnace is often the perfect choice. Pusher furnaces

are typically suitable for low-production mills for

common steel grades, for example rebar mills.

adapTable To various needs

Top-fired pusher type furnaces combine the benefits

of a sturdy construction and simplicity in design with

low consumption. Top and bottom-fired pusher type

furnaces are capable of high production rates. Pusher

type furnaces are an inexpensive alternative to more

sophisticated walking hearth furnaces or walking

beam furnaces for the production of simple products.

73

Field oF applicaTion: long producTsLarger furnaces for greater profit

SMS group has decades of experience in the design

and construction of rolling mills for bars, sections

and wire rod. The same goes for reheating furnaces.

Over the years the furnace experts have developed

many benchmark solutions to meet the increasing

demands of the long products market.

One example is the ability to produce coils which

have a weight of 3 tons and more and a higher market

value per ton. For this purpose, billets much longer

than the traditional 12 meters are used as starting

stock. Billets above 12 meters in length are the mar-

ket standard today. SMS group offers furnaces for

even longer billets – the engineers can deliver what-

ever their business partners need to improve their

competitiveness.

The demands in terms of heavy section mills and rail

mills are similar: by using starting blooms longer than

the traditional 12 meters, the plant owners profit

from increased metal yield by reducing crop ends.

74

Field oF applicaTion:FlaT producTsReheating furnaces for optimum slab quality

quicK comissioning, shorT

cycle Time

The enormous kick-off machine for a 30 ton

slab treatment furnace at Outokumpu in

Degerfors, Sweden, was preassembled in the

SMS group workshop

to ensure a minimum

commissioning time.

Cycle times are short

too: the machine can

unload one slab every

20 seconds.

SMS group offers highly productive walking beam

furnaces for slab reheating with capacities of up to

400 tons per hour. They are equipped with a set of

fixed and movable water-cooled skid beams. In order

to minimise skid marks both fixed and movable skids

are staggered between the heating and the soaking

area. Heat losses through the cooling water are mini-

mised using composite double-layer insulation for the

complete skid system.

high qualiTy Through opTimised

TemperaTure disTribuTion

A set of special alloy skid riders is placed on top of

the fixed and movable skids over the entire length of

the furnace chamber. The furnace engineers calcu-

late the height of the riders precisely so the slabs are

at a sufficient distance from the water-cooled skid.

The results: skid marks and dark spots on the slab

are minimised as the temperature of the skid’s

contact spot is very close to the temperature

of the heated slab.

75

wide range oF combusTion sysTems

SMS group equips all walking beam furnaces with highly efficient,

digitally controlled combustion systems and conventional, hybrid or

fully regenerative burners that work using all widely available fuels.

small in capaciTy buT greaT on

FlexibiliTy

SMS group also offers special walking hearth furnaces for small

slabs. These compact solutions are characterised by smart loading

diagrams which allow high loading flexibility. They process a wide

range of slab sizes and thicknesses.

76

Field oF applicaTion:pipes and TubesFully integrated furnaces for any process

Tube rolling is one of SMS group core competencies.

The know-how accumulated by the heating technol-

ogy experts is extensive: they know every detail of

the production process and can handle even critical

reheating profiles.

specialisTs in Tube rolling,

reheaTing and heaT TreaTmenT

SMS combines the benchmark-setting Premium

Quality Finishing (PQF®) mills for producing seamless

tubes with high-end furnaces. Advanced combustion

systems guarantee complete temperature uniformity

and minimum energy consumption. The rotary hearth

furnaces as well as the shell reheating furnaces are

fully integrated into the rolling process. SMS individu-

ally adapts the technically sophisticated systems to

the specifics of every single mill, such that even spe-

cific process requirements are optimally met. Plant

operators benefit from a smooth production process

and optimum tube quality.

SMS has designed and constructed some of the

most advanced and largest rotary hearth furnaces in

the world. They combine high capacities with special

materials and components for maximum temperature

endurance. That’s why for decades SMS furnaces

have been able to withstand the high temperatures

typical for this process – and plant operators have

been able to minimise maintenance costs.

77

shell pipes wiThin a 5 °c

TemperaTure range

SMS walking beam furnaces bring shell pipes

to the required temperature with maximum

precision before final sizing. Thanks to advanced

combustion control systems, the furnaces

achieve a temperature tolerance deviation of

only ±5 °C, more than sufficient for overall

mill process control and thereby ensuring the

final tube quality.

78

inTelligenT energy recovery

Whenever SMS engineers design a plant, they con-

sider the whole production process and combine

the individual process stages to produce the best

results for their business partners. One example is

the further utilisation of the heat energy that exits

the rotary hearth furnace, which is by far the most

energy-demanding unit in a seamless pipe mill. Using

a completely automated fume recirculation system,

SMS rotary hearth furnaces satisfy all the energy

requirements of the mandrel reheating furnace. Plant

operators save all energy costs for mandrel reheating

and reduce emissions here to zero.

zero emissions and zero

energy consumpTion

The energy required for the mandrel reheat-

ing furnace is fully obtained by exploiting the

excess heat from the rotary hearth furnace

exhausts.

79

80

Field oF applicaTion:Forged producTsFurnaces as versatile as the product mix

SMS group has set new standards in forged product

reheating, in terms of both operational flexibility

and reheating efficiency. The furnace experts trans-

ferred and optimised the comprehensive experience

gained to high-productivity rotary hearth furnaces for

pipe mills. On this basis, they developed advanced

dedicated reheating solutions for forging plants. With

SMS group furnaces, forging plant operators gain a

competitive edge due to increased productivity and a

wide product mix combined with reduced energy and

maintenance costs.

Flexible, eFFicienT and cosT-

eFFecTive

An impressive example of the SMS approach is the

new type of rotary hearth furnace: it is charged and

discharged through two separate doors by a single

elevated-type swivelling machine. This design, com-

bined with state-of-the-art combustion and control

systems, allows for the perfect combination of high

The Forge mill Furnace aT

TosceliK

The furnace for heavy blooms and ingots at

Toscelik, Montenegro: a single motorised

machine, swivelling on a 25° arc, handles both

charging and discharging.

81

energy efficiency and proper operational flexibility.

At the same time, plant operators benefit from low

investment and maintenance costs.

one Furnace, mulTiple

TemperaTure zones

SMS group developed a special furnace design for

forging plants with small to medium capacity and a

wide product range: multi-chamber furnaces which

allow for simultaneous heating of different products

at different temperatures. In these highly flexible

furnaces every product is heated precisely according

to its specific requirements. The temperature zones

are regulated by a digitally controlled single combus-

tion system. Regenerative burners guarantee high

efficiency,

mulTi-chamber Furnace

One control system, multi-stage heating:

the capability of three separate furnaces

combined into one.

82

83

heaT TreaTmenT oF hoT-FormedmaTerial

Highly demanding applications require exceptional qualities

guaranteed for every single plate, tube or bar. SMS’s heat

treatment specialists design and construct benchmark

setting heat treatment solutions combining the sophisticated

heating technology with advanced and proven cooling

systems.

Heavy Plates page 82

Tubes and Pipes page 92

Bright Tubes page 100

Bars page 102

84

heavy plaTe heaT TreaTmenT lines

diFFerenT process rouTes For

heaT TreaTmenT oF hoT-rolled

heavy plaTes

SMS group has been focusing on heat treatment

technology for heavy plates and hot strip to make

production processes more efficient and flexible. The

development of new materials and changing market

environments caused a demand for flexible plant

solutions concentrating on material quality. The

solutions permit a wide range of heat treatment strat-

egies for a great variety of materials.

To produce plates with ever higher strength and

toughness, plant technology must undergo con-

tinuous advancement. New rolling and cooling tech-

nologies often allow the mechanical properties to be

set within the rolling line, but extremely challenging

materials, however, require a final heat treatment in a

special heat treatment line.

The type of furnace normally used in a continuous

heat treatment process for normalizing and temper-

ing is the roller hearth furnace. Its strengths are on

the one hand different speeds for individual heat

treatment of plates and on the other hand a high

maximum speed to transport plates to the quench.

For the heat treatment of stainless and special

steels, double walking beam and chamber furnaces

are also frequently used.

In the face of changing energy costs and rising

environmental requirements, SMS attaches great

importance to high energy efficiency in the rating

and design of the furnaces. For each project, SMS

develops a tailor-made optimum solution in coope-

ration with the customer, taking into consideration

upstream plant areas.

The result of the quenching process is a significant

increase in hardness due to the formation of mar-

tensite. Plate fixing during the quenching process

ensures good flatness even at high cooling rates.

Whereas a continuous quench cools the plates on

their way through the line, a platen quench or a

discontinuous roller type quench cools in batches

plate by plate. Due to their lower throughput, they

are economic solutions especially for low production

volumes. A new type of quench is the newly devel-

oped MultiFlex-Quench® which is no longer rigidly

subdivided into a high-pressure and a low-pressure

section. Instead, the entire range of cooling rates is

available over the full length.

elecTrical and auTomaTion

sysTems

For the effective setting of mechanical properties in

heat treatment, SMS integrates its X-Pact® electrical

and automation systems also in these plants. To

describe the complex and, in part, highly dynamic

processes, mathematical models are used and com-

bined to a holistic approach. The essential target

values for plant control are mechanical properties

(respectively the microstructure), energy efficiency

and plate flatness. Calculation of the cooling rates

which determine the material properties is made on

the basis of SMS’s material data base which is the

foundation of all SMS group process models. For all

steel grades it provides the most important physical

and mechanical properties depending on their chemi-

cal composition and temperature.

85

SMS offers different heating solutions for heavy plate heat treatment lines.

SMS is able to deliver complete heat treatment lines systems for heavy plates with different furnaces and quench types as well as all auxiliary equipment (incl. electrics and automation, water treatment plant, handling and transport systems, cooling beds, levelers).

discontinuousoperation

continuousoperation

Furnaces forheavy plate

heat Treatment

chamber Furnace roller hearthFurnace

double walking beam Furnace(normalizing)

open atmosphere

protective atmosphere

86

heavy plaTe heaT TreaTmenT lines – roller and plaTen quench

quenching oF heavy plaTes

Plates can be quenched in two different types of

quenching units. One of them is the batch-operated

so called platen quench. If this quenching station

is used, the plates are stopped after their rapid dis-

charge from the furnace and clamped by means of

clamping jaws. After clamping, water is applied by

means of nozzle pipes, which are arranged above

and below the plate.

For continuous operation so called roller quenches

are used. In this case, the plates pass through the

plant without being stopped. The major advantage

of the continuous roller quench as compared to the

platen quench is the possibility of using individual

stages with different cooling rates and the associated

implementation of a short section with a higher

cooling intensity. Furthermore, as soon as water is

applied in the case of a platen quench, differences in

temperature will occur between plate head and tail

ends that due to the plant‘s discontinuous operation

cannot be entirely avoided.

For both types of quenching machines, the actual

quenching process is characterized by very high

dynamics. In doing so, extreme cooling rates are

implemented by means of enormous amounts of

water and special nozzle systems. Monitored and

controlled by the plant automation systems, cool-

ing must take place homogeneously across the

entire length and width of the plate, since even the

smallest variations in the cooling conditions may

result in flatness deviations and warped plates.

In a roller quench the heavy plates are cooled down with water while achieving high cooling rates.

87

roller pressure quench

sysTem For ausTeniTizing lines

The roller pressure quench has been delivered

to Magnitogorsk Iron and Steel Works (MMK).

Commissioning of this system took place in 2010.

The roller pressure quench provided by SMS helps

MMK to excel in the areas of cooling speed and

flatness while using less energy than the previous

systems. Thanks to the use of lower pressures in the

high intensity section, the quench system attains the

required cooling performance while consuming less

energy than conventional installations. This provides

substantial savings in operation costs. Improved rol-

ler design ensures better uniformity over the width

of the strip. In the spray lines situated above the

metal, an edge masking system limits water con-

sumption to the quantity strictly necessary for the

width of plate concerned.

The quench for MMK treats plates with a thickness

between 8 and 60 millimeters and a width of 1,500

to 4,650 millimeters. The plates with a length of 6 to

20 meters are mainly used in the construction or ship

building industry.

Reference: MKK, Russia

new quench For larger

producT specTrum

In January 2013, Slovenian steelmaker Acroni com-

missioned a new multimedia roller quench supplied

by SMS. To be able to extend the product range,

especially for thin and wide plates and to improve

plate quality, Acroni invested in a new 2.6-meter

heavy plate mill stand and a new multimedia roller

quench. The supply scope concerning the quench

consisted of the supply and the installation of the

new quenching device, a new pump station, the

interconnected piping, as well as a new electrics and

automation system. The new quench is designed for

plates up to a width of 2,560 millimeters and a thick-

ness between 8 and 130 millimeters.

Due to higher cooling rates, the new quench opens

up new possibilities for the extension of the product

scope (e.g. in the range of Duplex grades). To avoid

different temperatures between the top and bottom

side of the plate, the quench is equipped with spe-

cial cooling headers, which control the water flow to

ensure homogeneous cooling. At the same time they

prevent the formation of flatness deviations on thin

plates. In addition to the high cooling rates by water

cooling, the quench is also able to slowly cool down

grades like tool steel by air. Here, plates are cooled

down by air until a critical temperature is reached,

and then the faster water cooling starts.

Reference: Acroni, Slovenia

heavy plaTe heaT TreaTmenT lines – mulTiFlex quench®

new Technology For more

FlexibiliTy

SMS developed a new type of quench, the MultiFlex-

Quench®. Contrary to conventional continuous

quenches, this type is no longer rigidly subdivided

into a high-pressure and a low-pressure section.

Instead, the entire range of cooling rates is available

over the full length. All cooling patterns from slow

cooling to abrupt quenching can thus be realized to

achieve an even wider product portfolio. By install-

ing different nozzle systems and control valves, the

MultiFlex-Quench® can be individually designed to

suit the customer’s product mix.

SMS also assists customers in determining the opti-

mum heat treatment parameters to new high-quality

plate products on the MultiFlex-Quench®. Material

properties such as time-temperature transformation

characteristics or mechanical core values after dif-

ferent heat treatment steps are integrated into the

automation systems to optimize the process param-

eters. Based on this know-how, it will be possible

to set the mechanical properties achievable by the

heat treatment more precisely, minimize the use of

alloying elements, shorten process times, increase

the output and hence contribute to environment pro-

tection.

exacT conTrol oF The cooling

process via proven level 2

model

Precise setting of the mechanical properties

Minimized use of alloying elements

Short process time

Increased output

Environment friendly production

The MultiFlex-Quench® offers the highest flexibility for heavy plates with variable pressure sections and an optimized plate flatness due to active hydraulic clamping via pinch rolls.

88

89

The process parameters are calculated automatically which ensures an exact control of the cooling process.

The newly developed solution offers a wide process window which allows all cooling patterns from slow cooling to abrupt quenching.

plate data (level 2)online temperature dataphysical reference values

sms cooling model

process parameters

Core Temp.Surface Temp.Martensite Start Temp.

Tem

pera

ture

Time

accelerated cooling (acc)

quenching (dq)

quenching/

self tempering (q+sa)

sensitive cooling/

accelerated cooling (sq)

90

heavy plaTe heaT TreaTmenT lines: reFerences

heaT TreaTmenT line For Flexi-

ble and eFFicienT sTainless

sTeel plaTes

SMS group delivered a heat treatment line for stain-

less steel plates to Outokumpu Stainless in Degerfors,

Sweden. This expansion allowed Outokumpu to

boost its production of heat treated plates and im-

prove the product quality.

As an addition to the existing line, which consists of

a rolling mill, a roller-hearth furnace and a quench-

ing device, SMS has erected a new line for heat

treatment in parallel. The line essentially consists

of two batch type chamber furnaces with charging

machines, a roller quench, the connecting roller

tables, the water supply and treatment system and

all the accompanying electrical and automation equip-

ment. As regards process engineering, the new line

has been integrated with the cooling bed and the

cold plate leveler, also supplied by SMS. As the line

is directly connected to the rolling mill, it is possible

to feed the plates into the furnace or the quench

at rolling temperature, by way of hot charging. The

plate length ranges from 3,000 to 16,000 millimeters

and the widths from 400 to 3,500 millimeters.

The batch-type furnaces can heat plates to more than

1,200 °C. With such high temperatures, Outokumpu is

capable of manufacturing sophisticated steels such as

high-alloy grades for special applications. The furnaces

meet the high environmental protection requirements

and are equipped with a modern heat-recovery system.

In the quench, the plate is guided between the

rollers positioned above and below. The upper and

lower spraying headers use water to quench the

whole width of the plate at a precisely defined cool-

ing rate. Oscillation of the plate makes for an optimal

and uniform cooling process. Two plates can be

treated simultaneously in the quench. The automation

system for the entire heat-treatment line was also

implemented by SMS. This includes all material-

tracking in the individual plant components and on

the roller tables, as well as the furnace recipes and

the quench's cooling strategies which are coordinated

with them. This ensures that all plant components

are harmoniously coordinated with each other when

it comes to the heat treatment processes.

Reference: Outokumpu, Sweden

The plates are heated up discontinuously in two chamber furnaces.

Subsequent cooling takes place in a roller quench unit.

91

world’s FirsT mulTiFlex-

quench® For heaT TreaTmenT

oF heavy plaTes

The Slovenian steelmaker Acroni has placed an order

with SMS, to deliver a heat treatment line. As part

of the heat treatment line, SMS will for the first time

install the newly developed MultiFlex-Quench®, which

offers an outstandingly high degree of flexibility and

high cooling efficiencies in the heat treatment of

heavy plate.

The line will be designed for plates with thicknesses

ranging from 3 to 100 millimeters; the range of

materials includes high-strength carbon steels,

stainless and tool steels as well as a range of spe-

cial grades. For the new line, SMS supplies a roller

hearth furnace for hardening and normalizing, a

quench of the MultiFlex design and a roller hearth

furnace for tempering, as well as all auxiliary facilities.

These will include the complete plate conveying

equipment, all systems for the water supply and

water treatment as well as the automation of the

systems. The hardening furnace will be equipped

with two chambers, in which the plates will be

annealed in a nitrogen-based inert gas atmosphere.

Heting to up to 1,100 °C will be carried out indirectly

using radiant heating tubes. The innovative MultiFlex-

Quench® is characterized by its exceptionally

high degree of flexibility. It sets itself apart from

other quenches by the extremely wide range of

cooling rates, from abrupt water quenching right

down to gentle cooling, achieved by a multiple nozzle

systems. As a result, flexible cooling patterns are

possible for a wide range of different steel grades.

Squeezer rolls fix the plate in place and hence en-

sure good plate flatness, even at high cooling rates.

Following the MultiFlex-Quench®, the plates can be

tempered in an open-heated roller hearth furnace at

temperatures between 400 °C and 800 °C.

Reference: Acroni, Slovenia

The MultiFlex-Quench® ensures a high degree of flexibility when it comes to different cooling strategies for heavy plates.

92

heaT TreaTmenT oFTubes and pipesPremium quality pipes that satisfy even the mostdemanding requirements

Over recent years, the tube industry has enjoyed

a boost from the worldwide upturn in oil and gas

exploration. Deeper conventional wells and non-

conventional oil and gas exploration require a huge

number of quality tubes which are often exposed to

extreme conditions. In this field, the failure of one

single pipe can make the difference between a highly

profitable business and a considerable money loss.

To guarantee the high quality and desired mechanical

properties required for Oil Country Tubular Goods

(OCTG) applications, sophisti-cated heat treatment is

necessary. The pipes must be heated and cooled in

accordance with strictly controlled process cycles.

93

in-depTh conTrol From single Tubes To process overview

An intelligent tracking system ensures traceability of each tube through the line. It enables tracking of the

heat treatment performed on the single tube lots, in order to keep a record of the achieved results.

The producTion inpuT masK

Each lot or tube can be identified and assigned to a

specific heat treatment recipe.

layouT overview

The operator can monitor the functionality of every

single machine and control the position of any

workpiece inside the plant.

94

cenTury long experience in

seamless Tubes producTion

SMS group has already more than 125 years of expe-

rience in the production of seamless tubes: Its roots

go back to 1885, when brothers Reinhard and Max

Mannesmann obtained the first patent for the manuf-

acture of seamless tubes – a pioneering invention. In

the past 50 years alone SMS group has implemented

over 2,000 seamless tube plant projects.

heaT TreaTmenT: The compleTe

range

The heat treatment specialists complement the

company’s tube rolling expertise with a wide range

of advanced heat treatment plants, from quenching

and tempering through normalising to annealing.

SMS group offers benchmark solutions like the SMS-

Quench® system, which enables pipe manufacturers

to achieve the desired quality and to enhance process

consistency from the billet to the pipe fit for sale.

design FeaTures For premium

Tube qualiTy

SMS hardening and tempering furnaces guarantee

the tightest temperature tolerances. This is how

plant operators can ensure consistent properties over

the whole tube length. In most cases, the furnace

specialists install high-speed burners that generate

strong turbulence inside the furnace chamber. The

result is a consistent and homogeneous skin tem-

perature which leads to homogeneous mechanical

properties over the whole pipe length and cross-

section.

eFFicienT handling sysTems For

a smooTh process

SMS individually designs the pipe handling equip-

ment for each heat treatment line. The fully integrat-

ed systems guarantee a proper material flow that

avoids any bottlenecks. Scratch-free pipe handling

machines help to prevent defective tubes.

95

minimum nox emissions

Self-recuperative burners, available in both visible flame and

flameless configurations, minimise NOx emissions.

precise TemperaTure For increased Tube qualiTy

Combining a well-engineered fur-

nace with a fine-tuned combustion

system is the key to maximum pre-

cision: the discharge temperature

of a whole tube lot, measured by

pyrometer, demonstrates that the

surface temperature is kept con-

sistently within a narrow range of a

few degrees.

96

sms-quench®

When it comes to adding value to the pipe

To achieve the desired structure transformation

effectively during the quenching process, it is essen-

tial that the cooling down parameters are accurately

controlled. Especially when it comes to OCTG pipes,

deviations from the demanding mechanical properties

dictated by the relevant norms cannot be tolerated.

The difference between a premium quality pipe and

a failure often comes down to just a few seconds or

degrees. With SMS-Quench®, tube manufacturers

can reliably control and monitor all quenching param-

eters and thus adjust every tube’s qualities with

maximum precision.

Tailor-made quenching

soluTions

SMS-Quench® is an integrated system individually

designed for each tube plant. Based on bain curves

developed by specialized SMS metallurgists, every

tube manufacturer benefits from a tailor-made cool-

ing system that fully covers the specific quenching

requirements of any tube size and steel grade in the

product portfolio.

Despite the fact that single tubes differ from each

other before heat treatment, SMS quenching

machines guarantee a predictable, properly controlled

and repeatable process that generates the targeted

quality precisely. This is especially important as even

the slightest difference in the chemical composition

may lead to wide variations in the final properties.

always righT on spoT

The quenching head is the core element of SMS-

Quench®. It is one of the most effective solutions

97

qualiTy guaranTeed

The temperature-time-transformation function

for a martensitic structure guarantees that the

P110 grade, as stipulated in the API standard,

is reliably met.

98

opTimum quenching oF

ThicK-walled Tubes and bars

The SMS quenching tank and the new-born SMS

quenching shell are fully automatic units, dedicated

to the treatment of heavy tubes and solid bars. The

SMS tank includes rollers to guide the tube and

special stainless steel clamps to firmly hold it in

position. The SMS shell is a synchronous quenching

system where the workpiece is constantly kept

spinning during the water spraying.

99

available for outside quenching and guarantees a

fail-proof process. The quenching head is a ring-type

device which allows for automatic regulation of the

spray nozzles’ angle according to different pipe out-

side diameters. It also automatically aligns the pipe

pass line with the head axis. This ensures that the

water streams strike the pipe in the direction of

travel. The SMS-Quench® system also accurately

controls water pressure and flow and thus ensures

the desired depth and uniformity of the martensitic

structure. A sophisticated automation system is

a key process feature: the quenching head set-up

parameters are managed automatically by the control

system of the upstream austenitising and hardening

furnace.

SMS-Quench® also features devices such as the

quenching lance for internal pipe quenching and the

quenching tank for treating heavy-walled pipes by

complete submersion.

high percenTage oF marTensiTe

even in low carbon sTeel

When treating low carbon steel grades, which are

often used for welded tubes, a considerable and

well directed water flow is necessary from the very

first sprayer module. This is the only way to ensure

a fast transformation and thus a high percentage of

martensite. The results tube manufacturers achieve

with SMS Quenching Head speak for themselves:

the Grossmann quench severity factor, the so called

“H-factor”, is reliably above an index of 2.

precisely The quenching

resulTs you need

The quenching head is the heart of the SMS-

Quench® system. It features over 1,100 stainless

steel nozzles per module to ensure maximum

cooling uniformity. The ideal geometry and work-

ing parameters for the desired quenching result

are determined via CFD analysis.

100

Tube brighT annealing lines

Tube annealing in a proTecTive

gas aTmosphere

Tube bright annealing lines are used to produce

tubes made of stainless steel, nickel and titanium

alloys (e.g. Inconel). In these lines annealing takes

place in an oxygen-free, inert atmosphere with high

hydrogen content. The tubes are characterized by

a shiny, reflective appearance and a high corrosion

resistance. Typical areas of application are nuclear

and power plants, aerospace industry or chemical

processes and some other areas where, in addition

to the characterisics of the material itself, high-grade,

reflective surfaces and increased corrosion resist-

ance are required.

The lines are designed for tubes in a length up to

30 meters and diameters up to 60 millimeters. Tube

thickness is up to 6 millimeters. Three different types

of furnaces can be integrated in these lines: mesh

belt furnaces, multi muffle furnaces or roller hearth

furnaces.

Since the mesh belt furnace offers several advan-

tages, this type is normally integrated in lines built

by SMS. The main advantage of this furnace is the

minimal risk of tube defects. This is very important

because the tubes are often used for safety relevant

parts and subject to intensive quality checks where

even minimal failure leads to rejections. Furthermore,

high and controlled cooling rates can be applied.

mesh belT Furnace wiTh im-

proved mesh belT Trans-

porTaTion sysTem

The line consists of a charging table with fixed rollers

to carry the bundles (set of tubes) to the entry tunnel,

a heating, soaking and cooling section as well as

an exit tunnel and an exit purge. Further important

components are atmosphere analyzing and control

systems.

In the heating and soaking section the tubes are

heated up to more than 1,000 °C and soaked for

several minutes. The section consists of an electri-

cally or gas heated muffle. A newly developed system

improves the mesh belt transportation inside the

muffle. This system uses ceramic rolls. It increases

the lifetime of the mesh belt, reduces furnace stops

for maintenance and last but not least minimizes

surface defects during thermal processing. Especially

the last point is very sensitive to process final

Inconel 690 tubes for nuclear application.

The heat treatment process takes place in a protec-

tive atmosphere (pure hydrogen, hydrogen/nitrogen-

mix or argon depending on the process). At both,

entry and exit section of the furnace, two heaters

are installed to ignite and burn the atmosphere gas

escaping from the tunnel. This is for safety reasons.

convecool sysTem For high

speed cooling

The slow cooling section provides a buffer zone

between furnace and rapid cooling section to

achieve stable pressure distribution. Furthermore, it

is responsible for initial cooling of the belt and work

load by means of a water jacket so that the cooling

in the rapid cool section is alleviated.

The function of the CONVECOOL rapid cooling sec-

tion is to cool down the belt and tube load to their

final temperature to achieve required mechanical

properies. It utilizes the principle of convection cool-

ing with recirculated atmosphere gas. High velocity

convection impingement allows the cooling down

Exit Purge

Exit Tunnel

Jet CoolHeating Entry

Tunnel

Charging Table

101

of the tube temperature rapidly and uniformly from

annealing temperature to below 400 °C. The system

provides the best product quality while at the same

time using less space for cooling than conventional

systems (water jacket cooling).

The system is a single zone unit. The cooled atmo-

sphere gas is discharged at high velocity to impinge

on both top and bottom of the load through a pair of

slot type plenums. The returning gas will be cooled

down by the gas-water exchanger before entering to

the recirculating fan.

Several references worldwide12 Tube brighT annealing lines delivered

SMS delivered altogether 12 tube bright annealing lines mostly with mesh belt furnaces, but also with roller

hearth furnaces. Most lines have been delivered to customers in Europe (France, Sweden, Germany, Czech

Republic) but there are also references on the Asian continent (China, Turkey). The last two lines were deliver-

ed in 2010 to Vallourec, France. These lines feature mesh belt furnaces, CONVECOOL cooling system and the

improved mesh belt transportation system. Vallourec became world's first supplier to hold NSQ-100 certification

(Nuclear Safety and Quality Management System), which is considered to be the strictest standard of its kind

worldwide.

For Baosteel, China, a tube bright annealing line with mesh melt furnace was erected in 2009.

The CONVECOOL cooling system reaches high cooling rates due to convection cooling with recirculated atmosphere gas.

For safety reasons the escaping atmosphere out of the furnace is burned at entry and exit section.

A mesh melt furnace is the best choice for the production of tubes where surface quality is crucial, which is mandatory for most bright annealed tubes.

102

heaT TreaTmenT oF bars

noT only Tubes require heaT

TreaTmenT

Solid bars for numerous different applications need

to be hardened, quenched, tempered or annealed to

improve their mechanical properties. SMS offers a

full range of different heating solutions ranging from

bogie to tunnel furnaces to the more productive

walking beam furnaces, always coupling the com-

bustion expertise with a smooth design of the

complete process line.

103

Top cusTomers deserve

groundbreaKing soluTions

Working together with the worldwide top players in

special steel production has always been a key to

SMS for being at the avantgarde of innovation.

SMS designed a new heat treatment directly con-

nected to the rolling line, enabling for the first time to

treat bars up to the range of 250 millimeters without

stopping the process and saving a large proportion of

the heating energy. Stainless, acid and heat resistant

steel as well as high-grade structural or tool steel are

produced, each deserving a heating/cooling precisely

controlled sequence, managed by the SMS Controlled

Cooling Technology (CCT®) simulation model.

The core of the line is represented by a high-alloyed

skids walking beam furnace, equipped with self-

recuperative burners to enhance the energy saving,

and by a tailor made Quenching Head.

The information provided in this brochure contains a general description of the performance characteristics of the products concerned. The actual products may not always have these characteristics as described and, in particular, these may change as a result of further developments of the products. The provision of this information is not intended to have and will not have legal effect. An obliga-tion to deliver products having particular characteristics shall only exist if expressly agreed in the terms of the contract.

sms group gmbh

Processing Lines and Furnace Technology

Eduard-Schloemann-Strasse 4

40237 Düsseldorf

Germany

Phone: +49 211 881-5100

Fax: +49 211 881-4212

furnace.technology@sms-group.com

www.sms-group.comW

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drever international sa

Allée des Noisetiers 15

4031 Angleur (Liège)

Belgium

Phone: +32 4 366-62 62

Fax: +32 4 367-76 78

info@drever.be

www.drever.be

ares industrial Furnace (Tianjin) co., ltd

K1-5-301 Hi-Tech Green Industrial Base, No. 6 of Rd 6th

Hi-Tech Development Huayuan Industrial Park

Tianjin 300384

China

Phone: +86 22 2378-7828

Fax: +86 22 2378-3828

ares@ares-furnace.com

www.ares-furnace.com

sms group s.p.a.

Via Udine 103

33017 Tarcento

Italy

Phone: +39 0432 799 253

Fax: +39 0432 792 058

furnaces@sms-group.com

www.sms-group.com