AluReport

Investments 11

Investments for greater security

and flexibility

The extensive investments of recent years

have resulted in one of the most modern

plant pools in the aluminium industry,

which offers maximum production secu-

rity and customer-friendly flexibility with

regard to the realisation of complex, met-

allurgical demands.

The latest simulation tools for

heat treatment

Irrespective of whether final or essential

process-related, intermediate processing

is involved, heat treatment is always tar-

geted on achieving optimum product char-

acteristics. Basically, all heat treatments

have an effect on the microstructure of

the material, whereby properties relating

to customer-processing and use are influ-

enced (mechanical properties, formability,

corrosion behaviour, distortion, etc.). Heat

treatment is a diffusion-determined proc-

ess, which is why temperature and time

are its most important parameters. In the

case of heat treatable alloys, the classic

heat treatment sequence consists of so-

lution annealing, quenching and artificial

ageing. Solution annealing is aimed at

achieving the dissolving of soluble, hetero-

geneous alloying components in solid so-

lution and their homogeneous distribution.

The higher the temperature, the better the

product characteristics, whereby the major

danger is eutectic melting, which can lead

to internal rejects.Therefore AMAG deter-

mines precisely the furnace parameters

(temperature, time, quenching & quench-

delay, heating and cooling curves, etc.) for

the respective alloy composition, not only

in the course of testing, but increasingly

through the use of the latest simulation

tools (e.g. Nougat) and thermal laboratory

analyses (e.g. DSC). The parameters thus

established permit a marked reduction in

large-scale testing in order to verify the

optimum range of parameters and their

fixing for serial production.

Fulfilment of the strictest aviation

industry demands

Not only is a precise knowledge of mate-

rial behaviour needed in order to be able

to near the feasibility limits, but also exact

furnace temperature management. As is

also the case with regard to other char-

acteristics, the aerospace industry places

the highest demands on equipment for

the heat treatment of sheets and plates.

Of these, the main two relate to tem-

perature uniformity within narrow limits

throughout the entire furnace and sub-

sequently, stringent requirements relating

to the entire temperature measurement

chain and furnace control.

All of AMAG rolling’s registered furnaces

fulfil the requirements for the production

of aerospace products according to the

internationally recognised and widely-used

AMS 2750 standard and even stricter

NADCAP (National Aerospace and De-

fence Contractors Accreditation Program)

directive, which in the meantime are re-

quired by many leading aircraft manufac-

turers. However, it should be added that

all other AMAG product groups, e.g. au-

tomotive, mechanical engineering, sport

applications, etc. benefit from the strict

requirements of the aerospace sector.

As a result of intensive teamwork with

furnace producers, AMAG’s heat treat-

ment expertise in both the metallurgical

and engineering sectors flows into the

company’s choice and design of advanced

heat treatment equipment. This results in

optimum furnaces, for AMAG’s product

portfolio, specialized for sheet and plate

production.

Advanced equipment for precise

heat treatment of high-strength

aluminium alloys

AMAG rolling specialises in the pro-

duction of high-strength aluminium

sheets and plates and disposes over

enormous competence with regard to

the heat treatment of age-hardening

aluminium products. Moreover, new

advanced heat treatment equipment

and new technologies open the way

to previously untapped potential.

▼

Please read the article concerning

the latest investments relating to the

operational furnaces.

Investments12

Horizontal annealing furnace for

solution annealing of plates

As a result of the systematic expansion of

high-quality aerospace plate production

capacity, two virtually identical horizontal

annealing furnaces have been purchased

for the batch solution annealing of heat

treatable plates in the 2xxx (AlCu), 6xxx

(AlMgSi) and 7xxx (AlZn) alloy groups.

Both annealing furnaces are heated

electrically and attain a temperature ac-

curacy of +/-2°C, which surpasses

even the strictest aerospace demands.

This precision is due to the latest con-

trol technology and a specially optimised

heat register. All heating and quenching

parameters are stored in a database, for

correct presetting of the furnace with the

optimum parameter sets and prevents

individual errors during the input of heat

treatment data.

Following heating and the annealing

soaking time, which is necessary from

a metallurgical standpoint, the plates

are quenched. During this process the

plates are cooled from the annealing

temperature to room temperature by

means of individually controllable rows

of high-pressure water jets. In the high-

pressure section well over 1,000 m3/h of

water are sprayed onto the hot plates by

several thousand jets. Subsequently, the

Al plates are air-dried in order to prevent

surface corrosion and water-stains.

Owing to the fact that both horizontal an-

nealing furnaces are of identical system

design, it is possible to use a spare part

pool, which simplifies repairs and thus

facilitates reduced downtimes. Both fur-

naces were “Made in Austria” and were

designed in conjunction with EBNER

Industrieofenbau in a far-sighted move,

which has ensured that the systems of-

fer expansion possibilities to deal with

future increases in the need for heat

treatment.

Artificial ageing furnace for plates

Apart from solution annealing, a major

step in the production of heat treatable

aluminium alloys is artificial ageing to a

defined temper, whereby the alloying el-

ements precipitate out of the quenched

and “frozen” supersaturated solid solu-

tion.

In addition to tempers in line with speci-

fications, AMAG has also developed

customised tempers, which permit spe-

cial combinations of characteristics and

mirror the company’s special expertise

in this field. The express and systematic

response to customer requests, which

extends to small batches, is also par-

ticularly clear within the context of the

installed heat treatment equipment.

The second quarter of 2009 saw the

successful commissioning of a new,

HOFMANN artificial ageing furnace. As

a result, a total of nine ageing furnaces

of the same design are available for the

artificial ageing of plates in the 2xxx, 6xxx

and 7xxx alloy groups.

The furnaces are electrically heated

and due to the use of the latest control

technology and optimised air flow, which

was specially optimised for AMAG roll-

ing, offer temperature precision and uni-

formity that is far above the norm. The

optimisation of air flow was based on the

teamwork between Linz University and

AMAG’s experts, which in addition to

testing with new measurement methods,

also involved the use of simulation tools.

Three new artificial ageing furnaces are

of overhead design, the Al plates being

fed into the furnace from below. This de-

sign saves a great deal of energy, as the

hot air remains in the furnace and does

not escape, which facilitates very high

levels of temperature uniformity in the

furnace chamber.

All three furnaces are filled and emptied

via a single charging station. Following

heat treatment the material is cooled

and the residual heat employed for hall

heating. Therefore, when the material is

removed from the charging station it is

already cool, which is also important from

a safety standpoint (danger of burns).

Furnace control is fully automatic and

The most advanced furnace technology for plates,

strips, coils and sheet bundles

Artificial ageing furnace Horizontal annealing furnace

AluReport

Investments 13

goes so far that the furnace personnel

can be supplied with defect and status

reports directly from the furnace per e-

mail and SMS. The entire artificial ageing

furnace group was also manufactured in

Austria.

Continuous heat treatment line for

strip solution annealing

In order to expand its heat treatment

capacity with regard to heat-treatable

sheets and strips, AMAG rolling recent-

ly invested in another continuous heat

treatment (CHT) line. With this two-digit

million investment, AMAG has strength-

ened its competence and capacity in the

continuous, largely non-contact, strip

heat treatment segment. AMAG rolling

is the world’s only supplier to offer solu-

tion annealing of this type for strips in the

0.3-6.0 mm thickness range.

The CHT line, which went into operation

in mid-2008, was primarily designed for

the continuous annealing of heat treat-

able strips in the 2xxx, 6xxx and 7xxx al-

loy groups.

Strip guidance in the furnace takes place

without any rolls, the strip moving through

the furnace on an air cushion. The lat-

est burner and furnace controls provide

a precisely controllable heating regime,

which extends to very high temperature

gradients. With different furnace zones

the necessary metal temperature can be

controlled very precisely, which is metal-

lurgically essential, prior to quenching

of the material with water and/or air to

room temperature following the appropri-

ate soaking time. When water is used as

a quenching medium, quenching speeds

reach several 100°C/sec.

A great deal of AMAG expertise has

been utilised for the design and layout

of the quenching section and the trans-

fer from the furnace. The experience of

the company’s technology specialists has

been systematically implemented in or-

der to ensure that the highest quality

demands relating to heat treatable sheet

and strip products can continue to be

met in future.

As flatness deviations always occur in the

strip during quenching, the new CHT line

was designed with an integrated, continu-

ous stretcher. This allows the fulfilment of

strict requirements relating to strip flat-

ness for a wide range of thicknesses. In

addition, integrated trimming shears can

be set to tailor the strip to its end width di-

rectly in the line, which means that some

products can be produced on a ready-to-

pack basis.

Single-chamber, hood-type

annealing furnace for coils

and sheet bundles

From 2006-2008, four JUNKER hood-

type annealing furnaces were commis-

sioned for the artificial ageing and an-

nealing of coils and sheet bundles. The

strengths of this furnace concept lies in

its flexibility as compared to conventional

multiple coil furnaces, as it offers the pos-

sibility for the completion of urgent orders

with optimum use of capacity levels. The

heat treatment systems, which allow en-

largement on a modular basis, can be ex-

tended beyond their current status through

the addition of further independent, single

hood-type coil annealing furnaces.

The main heat-treated products consist of

coils, although rings (slit coils) and sheet

bundles can also be charged. Loading

and unloading takes place by means of

a hall stacking crane, whereby the entire

charging process from coil handover to a

shuttle is fully automated. Automatic fan

speed regulation, and the latest gas burn-

er technology with special control charac-

teristics ensures maximum furnace tem-

perature fluctuations of +/-2°C through-

out a temperature range of 100-600°C.

This allows the fulfilment of all demands

regarding precision heat treatment such

as artificial ageing, annealing and stress-

relieving.

High air flow volumes and speeds with

the appropriately dimensioned circulation

capacity in combination with a patented

air flow system, which was optimised in

teamwork with AMAG, guarantees high-

precision temperature management. As

opposed to previous concepts, this sys-

tem permits a marked reduction in heat-

ing speeds, temperature spread and heat

treatment process times.

All furnaces can be operated using a in-

ert gas atmosphere. It is also possible to

cool the furnace by means of nitrogen

and thus achieve high cooling gradients,

which can be varied in line with process

requirements. The regulation and con-

trol of the holding times and tempera-

tures takes place automatically, whereby

throughout the heat treatment process

all that is required is on-the-spot surveil-

lance, or monitoring via a client station.

By means of the optimisation of the pro-

cess parameters of all the heat treatment

steps along the process chain, AMAG’s

specialists have been able to create previ-

ously unattainable property characteritics

for various alloys to the advantage of cus-

tomers worldwide.

Special results from work on 6xxx

alloys will be presented in AluReport

3/2009.

Hood-type annealing furnaceContinuous heat treatment line