manufacturing procedure for coil mill

Your Trust and Success, Our Tomorrow

POSCO

Manufacturing Procedure Specification

For Hot Rolled Coil

Hot Rolled Products Technical Service Group

Document No Revision No Date Prepared by Approved by

P-MPS-H1202 0 29. Mar. 2012 Park, Yong Keun Jung, Hyo An

Steel Grade : API 5L X60MS PSL2

Project : ONGC Cluster 7

Customer : JINDAL SAW LTD.

Size (mm) : 17.50 x 1211 x C

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P-MPS-H1202 Rev. 0

PARTⅠ. General Information

1. General Item

2. Main Production Facilities

PARTⅡ. Manufacturing Procedure

1. Steel making

2. Continuous casting

3. Hot rolling

PART Ⅲ. Quality Assurance System

1. The System of Quality Planning & Quality Control

2. Identification System of Slab, Hot Coil in Manufacturing Process

3. Control of Manufacturing Process

PART Ⅳ. Quality Specification

1. Chemical Composition

2. Mechanical Property

3. Dimensional Property

C O N T E N T S

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P-MPS-H1202 Rev. 0PARTⅠ. General Information

1. General Item

1) Name : Pohang Iron ＆ Steel Co., Ltd. (POSCO)

2) Address

- Head Office : 1, Koedong-dong, Pohang City, Kyungsangbuk-do, Korea

TEL : 054-220-0114, FAX : 054-220-6000

- Seoul Office : POSCO CENTER, 892 Daechi-4dong Kangnam-gu Seoul, Korea

TEL : 02-3457-0114, FAX : 02-3457-1999

- Pohang Works : 5, Dongchon-dong, Pohang City Kyungsangbuk-do, Korea

TEL : 054-220-0114, FAX : 054-220-6000

- Gwangyang Works : 700, Kumho-dong, Kwangyang City Chunranam-do, Korea

TEL : 061-790-0114, FAX : 061-790-7000

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P-MPS-H1202 Rev. 0

2. Main Production Facilities

Blast furnace

Iron making process by ore reduction and melting

Converter

Steel making process by removing impurities

Continuous casting

Hot rolling

Hot coil making process by rolling slabs

Roughing

Mill

Reheating

Furnace

Finishing

MillCOIL

PARTⅠ. General Information

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P-MPS-H1202 Rev. 0PARTⅡ. Manufacturing Procedure

1. Steel making

1) Raw materials

- Raw materials making steel are basically Molten iron which is made by ore reduction

and melting in blast furnace process and subsidiary raw materials such as Scrap, Fe-Si,

Si-Mn, Fe-Mn, Al wire, Fe-Nb, LC Fe Mn, H C Fe Mn, etc. Ore and subsidiary raw

materials are mainly imported. These are tested at the Quality Control Laboratory for

suitability before unloading in the plant. The quality of raw materials is guaranteed by

the supplier with a test certificate.

- Quality control of molten iron used at steel making plant is to reduce impurities

involved in molten iron. Main elements affecting the quality of steel in steel making

process are P [Phosphorus], S [Sulfur], Si [Silicon] and Mn [Manganese]. Si, S and P

level of Hot metal made in blast furnace is finally reduced by hot metal pretreatment

process before Steel making process.

Generally ,the chemical composition levels of molten iron after hot metal pretreatment

are as follows:

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1. Steel making

Ar, N2

Refining of slags

Mn ore

Hot Metal Pretreatment

▶Scale, CaO, CaF2

mill scale

Blast furnace

Desiliconization De [S], [P]

slag removal slag removal

< Hot metal pretreatment follow >

Generally ,the chemical composition levels of molten iron after hot metal pretreatment

are as follows : C: 4.0 ~4.5%, Mn: 0.3 ~0.4%, Si: < 0.35%, P: < 0.10%, S: < 0.010%

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1. Steel making

Hot Matal

Flux + N2

2) Hot metal pretreatment station (HMPS)

- Before pouring hot metal steel into the converter, pretreatment will be done to control

S and P content, to meet sour service. Through this re-treatment, for CDPS(Charring

Ladle dephosphorus & desulfurizing), Na2CO3 and CaF2, etc. will be injected into

Torpedo Ladle Car through the lance while hot metal is being stirred for 50-60 minutes

and slag is removed. After CDPS, the level of S and P is : S <0.010%, P <0.030%.

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1. Steel making

Molten iron

Reaction on slag

2nd conbustion of CO

SRM

DegassingO2

Slag formation

dissolution of

Subsidiary

Aw materials

Oxidation on

Melting point

Scrap Melting

3) Steel Making in the LD Converter (Basic oxygen furnace)

- Steel is made in the 250~300 Ton LD Converter (Basic oxygen furnace) having top

oxygen blowing lance. This process is mainly to reduce impurities such as carbon, silicon,

phosphorus, sulfur by blowing oxygen and to make Steel having chemical compositions

required for customer by mixing Ferro alloy into hot metal. A Charge mix of 90 % Hot

metal and 10% shredded scrap is added to the converter. After the scrap is charged

through clamshell type scrap bucket, the hot metal is charged using a Pelican type ladle.

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1. Steel making

4) Procedure

- The scrap and hot metal are charged into the LD converter. When oxygen blowing

starts after hot metal charging into converter, Lime and dolime are added in a regulated

manner for proper slag. Using a Lance Manipulator, oxygen is continuously lanced in

the furnace at the rate of 700 ~900 ㎥/min for 16~17 minutes to reduce carbon, silicon

contents and to ensure the formation of foamy slag. Formation of foamy slag reduces

nitrogen pick-up, helps remove nitrogen/hydrogen, prevents radiation losses and

enhances the slag-metal reaction. Carbon, oxygen and temperature are checked two

times using a sub lance probe during oxygen blowing. When the level of dissolved

oxygen is reached below 900 ppm, he heat is tapped. Level of oxygen, carbon and

temperature at this moment are as follows: C:≤ 0.05 % , P:≤ 0.020% , O2: 600~ 900

ppm, Temperature : 1720 ±25 ℃. Slag -free tapping is done using a plug and slag

check ball at tap hole. During tapping, the metal is deoxidized using alloys like Fe-Al,

Fe-Si. Fe-Mn add to achieve the range of chemical composition of API Grade.

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1. Steel making

O2 Lance

Upper vesselO2 Blowing

(CO(g)+ ½ O2)

lower vessel

Argon gas

5) Vacuum Degassing

- Ladle is placed to the VD vessel named as RH by crane. The vessel is closed and

vacuum pumps are started. For the purpose of degassing process (H, N, etc.), operate

decreasing the pressure in the vacuum state and stirring the ladle. The same time molten

iron in VD vessel is controlled for reducing non-metallic inclusion, temp/chemical comp.

- After releasing the vacuum, cover is moved out. Steel temperature and chemistry are

checked by the final aim chemistry of API Grade. Any corrective additions required are

made. Ladle is lifted by crane for casting.

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1. Steel making

Ca-Si Wire

Transient

Reaction

Permanent

Reaction

SLAG

Molten Steel

Cover

Bubbling Ladle furnace

Or Powder

6) Steel refining in the Powder Injection (Ca-Si)

- Powder Injection ( capacity 250~300 Ton ) is used to refine the steel by ensuring

temperature and chemistry homogenization, alloying adjustment, removal of oxide and

alumina inclusion, desulphurization and spheroidizing of inclusion by Ca-Si powder or

wire injection. Purging with argon and Ca-Si powder or wire injection is done

continuously during the entire processing period.

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LADDLETURRET

LADLE

TUNDISH

MOLD(Primarycooling)

Pinch roll

BENDING DEVICE

Secondary

cooling

Torch cutter

MOLD OSCILLATION

Reforming roll

Soft Reduction

1) Process of continuous casting

- Slabs are continuously cast in slab caster with 2 strands. The slabs can be cast on the

casting machine. Slabs can be cut to length as per requirement of Hot Strip Mill. The

process of continuous casting is as follows:

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1) Procedure

- The ladle sits in the ladle turret and the turret is rotated 180 degrees to the Casting

position. Protection of liquid steel from ladle to tundish and tundish to caster mould.

Steel temperature in tundish is about 1545 °C (-15/+25 °C) To avoid any contamination

(pickup of oxygen and nitrogen) from the atmosphere, shrouding is used from ladle to

tundish and from tundish to mould. Shroud is pressed by a manipulator onto the outer-

nozzle of the ladle slide gate. Sealing is done by a gasket introduced into this joint.

Argon is also passed through this shroud. Shroud material alumina graphite between

tundish and the mould a submerged entry nozzle (SEN) of alumina graphite is used.

The SEN dips 140 mm into the liquid steel in the mould. The liquid steel in the mould is

covered with a mould powder, which prevents contact of liquid steel with air and also

provides mould lubrication.

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2) Tundish preheating

- Spray mass with 60% Al2O3 is used in tundish. Appropriate preheating is essential for

trouble free casting and satisfactory quality. Too cold a tundish, cools the first incoming

liquid steel so that it freezes in the SEN nozzle or causes skulling on the outside of

submerged nozzle. Excessive tundish preheating may damage the refractory material or

melt the tundish lids so causing inclusions in slabs. Preheating is normally done for

about 2.0~3.0hrs and temperature of 1150 °C ~ 1350 °C. Liquid steel in the tundish is

covered with rice husk to prevent contact with air and temperature loss.

3) Secondary cooling

- It can be selected as per the steel grade and water flow rate varied according to the

casting speed.

4) The oscillation stroke length

- It is ± 3.5 mm. The pressure at the pinch rolls varies from 40~80 bars based on the

steel grade and section size being cast.

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5) Casting speed

- Maximum casting speed is 2.2 m/min. However, actual casting speed is adjusted with

respect to quantity of molten steel being poured into mold per hour and superheat in the

tundish as per process standard.

6) Slab surface temperature at the exit end is generally 900 ~1050 °C

7) Charge No. & Slab No. are marked using a marking machine to maintain the identity

and traceability.

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T 250mmSlabThickness

Center of slab width

1/2w

8) Center Segregation Evaluation Procedure

- Method: Slab macro etching Ammonium Persulphate ,(NH4)2S2O8 solution

- Density and Etching Time: 15~20%, 5 minutes

- Sampling: Samples for macro-etching shall be cut from the head of the 2nd or 3rd slab

of each strand of cast while first slab is rejected. Sampling will be per strand per casting

sequence and its position is 1/2w

Casting direction

.. .. ..

L 100mm

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Classification Definition

Class1

Segregation shall be dot pattern(not continuous).

Density: 10 or less dots/100mm for dot of size 1mm≤dot≤3mm

No dots of size more than 3mm shall be identified.

Class2

Segregation shall be dot pattern(not continuous).

Density: 11 to 18dots/100mm for Dot of size 1mm≤dot<5mm, with the limitation of

maximum 5 dots/100mm for dot of size 3mm<dot<5mm.

Class3

Degregation shall be dot pattern

Density: 1) At least one dot/100mm for dot of size≥5mm or

2) 19 dots/100mm for dots of all sizes or

3) 6 dots/100mm for dots of size 3mm<dot<5mm.

Class4 Continuous black dots more than 10mm in length and more than 1mm in thickness.

Definition

Dot Clear black indications of diameter 1mm and greater.

ContinuousSome clear black indications combined with each other for the total width greater than

10mm, with no area of thickness<1mm.

Size of DotLength of clear black indication for the direction of either thickness or width whichever

is greater.

9) Center Segregation Classification level allowed for API Steels : Class 1, Class 2

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3. Hot rolling

#1 #2 #3

F1 ~ F7E/H C.S FSB

RHF

VSB

R2R1

Lamnar flow

#1 #2Thickness gauge

D.C

Shape Meter

1) General Process

2) Reheating Furnace

- Three walking beam reheating furnaces are used to reheat the slab for rolling. The

slabs are heated at a temperature of 1100 ~ 1290 ºC. The heating time is 3 to 4 hours

with a soaking time of 20~80 minutes. Slab of maximum 12.0 m length can be charged

into furnace.

- Slabs are charged in the furnace as the schedule given by the Production Process

Control Department. A coil number is assigned to each slab scheduled to be rolled.

- Uniform slab heating and soaking within a preset is automatically accomplished.

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3. Hot rolling

3) Roughing Mill

- The roughing mill consists of 2 Hi one stand and 4 Hi one stand reversing mills with

edger for width control and descaling facility on entry and exit sides of the mill. In this

process, slab is made into rolling materials (bar) with proper shape, thickness and width.

In the entry and exit area of the roughing mill, the edger rolls the bar in crosswise

direction using the automatic width control (AWC) system.

- Primary scale is completely removed by using vertical scale breaker (VSB) and

hydraulic descaler of 100~150 kg/cm2. The descaling unit is always maintained for the

best performance.

- Required dimensions are obtained by ensuring proper edger operation and by giving

6~10 number of passes ( R1: 3 ~ 5, R2: 3 ~5 passes )

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3. Hot rolling

4) Finishing Mill

- The finishing mill consists of 4 Hi- 7 stands in tandem & equipped with Hydraulic

Automatic Gauge control, work roll bending and work roll pair crossing systems.

- The finishing scale breaker (FSB) and the crop shear operations are ensured at the

seven stand finishing mill.

- A Quick Roll change system is used for changing the work rolls after every optimum

rolling schedule depending on the thickness and size rolled.

- In finishing mill, Strip thickness and width are controlled according to specified

standards and rolled for top surface and shape quality using finishing temperature at

target ±40 ℃ for API Grade application. The pair cross mill and on-line grinder (ORG)

control the shape and crown of the strip, improving both the productivity and quality.

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3. Hot rolling

5) Cooling & Coiling

- The finishing mill, the strip passes to the run-out table where it is then coiled. While

being rolled along the table, the strip is sprayed with water to cool it to the proper

temperature to have a good mechanical property. For API Grade Coiling temperature

is target ±40℃.

- A hydraulic Automatic Gauge Control (AGC) is used to control the gauge of the Hot

Rolled Coil being manufactured.

- Coil numbers on the strip are marked on each coil.

- Delivery condition is thermomechanically controlled rolling(TMCP) and accelerated

cooling

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3. Hot rolling

6) Inspection and testing

- An X-ray thickness gauge and width gauge checked the dimensions of each coil during

rolling. However, to counter check the dimensions of these coils, one in every ten coils is

measured manually for dimensions. Also, the coils are inspected for any surface.

- Sample drawn from the coil is tested at the Products Inspection Section of Quality

Technology Department, as per sampling plan. 1 coil is tested per heat per size rolled.

- If the test coil does not conform to the specification, the retest carried out on two more

coils from the same heat. If the retest conform to the specified requirement, the heat (or

lot) except the first failed one can be accepted. If the result of the retest fail, all coils in

the heat (or lot) is rejected

- A mill certificate is issued for the coils conforming to the specification and hands over

to the customer.

- All slabs are inspected and All coils are inspected by SDD (Surface Defects Detector)

- Mill Test Certificate shall be issued according to EN 10204. 3.1

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P-MPS-H1202 Rev. 0PARTⅢ. Quality Assurance System

1. The System of Quality Planning & Quality Control

Dept .

Activity

Marketing

Division

Quality

Service

Department

Production

Process

Control

Dept

Plant(Mill) Quality Technology Dept Maintenance,

Electrical

Control

Supporting

Dept.

Testing

Service Sec

(Chemical

test)

Product

Inspection

Sec

(Material Test)

Quality

Improvement

Department

Plan

Do

Check

Action

Customer’s

information

Contract

Quality

Inspection

Standard

Corrective

Action

Order

Sheet

Quality

Design

Manufacturing

Review

Trial

Production

Inquiry

Production

Planning

Manufacturing Specification

Marking

Test & ExaminationQuality

Improvement

Quality

Control

Committee

Quality

System

Control of

Operating

Measuring

& Testing

Equipment

Reject

Accept

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2. Identification System of Slab, Hot Coil in Manufacturing Process

Iron

Marking

Hot Metal

Pretreatment

Oxygen

BlowingBubbling

Powder

Injection

Vacuum

Degassing

Continuous

Casting

Torch

Cutting

Cold Charge

Rolling Slab

Scarfing

(Cutting)

ReheatingHot Charge

Rolling Slab

Hot Direct

Rolling Slab

Converter

R H

P I

Steel making practice No

Order NoHeat No Slab No

Rolling program No

Hot Rolling No

Order. No Sequence No Heat No

Steelmaking Plant Code

1st Cut Piece No

In Strand

Sequence No

Month Code

Descaling Rolling Water Cooling Air Coiling

Skin Pass

Rolling

Dividing

Rolling

Packing &

Marking

Mill Code

Hot Coil No(Casting program No)

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Process Process Simbol Equipment Control Item Record

Hot Metal

PretreatmentLance, Slag Skimmer Desulfurizing

Data Base

Hot Metal Input Lance, Crane Mix Ratio, Input Time

Oxygen BlowingConverter,

Temperature CheckerTemperature, Blowing Time

Bubbling(LF or RH) B/B Stand (LF, RH) Temperature, Time

Continuous CastingTundish, Temperature

Auto CheckerTemperature

1st Cooling Mould, MLACCasting Speed, Cooling

Condition

2nd Cooling Foot Roll, SegmentRoll Gap,Cooling Condition

Torch Cutting Torch Cutting Machine SLAB Profile

Slab Finishing Deburrer, Scarfer Defect. Scarfing Method

Slab Reheating FurnaceReheating Time,

Temperature

Descaling DescalerWater Pressure, Water

Amount

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Process Process Simbol Equipment Control Item Record

Rough Mill Roughing MillPass Schedule,

Temperature

Data Base

Finish MillFinishing Mill,

r-Ray Gauge

Temperature, Profile,

Thickness, Width

Water Cooling Laminar Flow Cooling Pattern

Coiling Down Coiler Coiling Temperature

Inspection &

Material Test

Auto Material Tester

Ruler

Defect,

Mechanical Properties

RecoilingSkin Pass Mill,

Dividing Mill, Gauge

Profile, Defect,

Thickness, Width

Weighing Weigher Weight

Banding Machine,

Label Printer

Parking Pattern,

Marking ItemPacking & Marking

Storage Crane Storage Condition

: Manufacturing : Inspection, Judging : Weighing

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P-MPS-H1202 Rev. 0PART Ⅳ. Quality Specification

1. Chemical Composition

1) Test Frequency: Ladle analysis : One sample per heat

Product analysis : Two samples from different coils per heat

2) CE (IIW) = C+ Mn/6 + (Cr+Mo+V)/5 + (Cu+Ni)/15 (API 5L 44th Ed. 9.2.5)

3) CE (Pcm) = C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B (API 5L 44th Ed. 9.2.4)

4) The soluble aluminium to nitrogen, Al/N shall be at least 2:1

5) Ca/S ratio shall be minimum 2.0 and maximum 3.0. However, there is no restriction on

maximum value of Ca/S ratio in case S<0.0015% and maximum value of Ca is 50 ppm.

ITEM C Si Mn P S Nb V

Range ≦ 0.08 0.15~0.35 ≦ 1.45 ≦ 0.015 ≦ 0.002 ≦ 0.05 ≦ 0.08

ITEM Ni Cr Cu Mo Ti Al N

Range ≦ 0.30 ≦ 0.30 0.05~0.35 ≦ 0.08 ≦ 0.06 0.01~0.06 ≦ 0.01

ITEM B Nb+V Nb+V+Ti Cu+Ni Cr+Mo CE Pcm

Range ≦0.0005 ≦ 0.1 ≦ 0.12 ≦ 0.40 ≦ 0.25 ≦ 0.19

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2. Mechanical Property * All mechanical properties will be guaranteed in coil condition only

1) Tensile Properties (ASTM A370/API 5L)

- Test Frequency : One sample per heat

- Sampling : Rolling tail of the coil and ¼ width

- Direction : Transverse direction

- Value : Table A (→)

※ Longitudinal test result will be submitted by separate sheet for information only.

2) Bending Test (ASTM A370/API 5L)




- Specimen when bent on a jig of radius 2 times the thickness shall be free from any cracks

YP (MPa) 415-540 Mpa

TS (MPa) 540-750 Mpa

YR 0.90 maximum

EL (%) 30% min on 2” gauge length

[ Table A ]

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3) Hardness Test (ASTM A370)




- Value : 210 HV 10 maximum

4) Charpy V-notch Impact Test (ASTM A370/API 5L)

- Test Frequency : One set per heat



- Value : Table B (→)

- Temperature : 0℃

- Full size specimen

Enegry

(J)

Individual absorbed energy = 100 Joules min

Average absorbed energy = 100 Joules min

Shear Area

(%)

Shear fracture area per specimen = 85% min

Average Shear fracture area = 85% min

[ Table B ]

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5) DWTT Test ( API RP 5L3)




- Value : Table C (→)

- Temperature : 0℃

6) HIC Test



- Method : NACE TM 0284-2003 Solution A

- Immersion Period : 96 hours

- Temperature : 25 +/- 3℃

- Value : CSR ≤ 1%

Shear Area

(%)

Shear fracture area per specimen = 85% min

Average Shear fracture area = 85% min

[ Table B ]

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7) Four Point Bend Test

- For point bend test specimen preparation & size shall be as per ASTM G39 except that the

thickness shall be minimum 5mm. One set of the three specimens from the steel coil shall be

taken transverse to the direction of rolling.

- Specimen shall be bent using four point loading Jigs to reach a stress level of 72% SMYS

and then immersed in a NACE solution as per standard TM 0177-2005 for aperiod of 96 hrs

with the inner surface/root in tension.

- Reference purpose only for three heats.

8) Ferrite Grain Size (ASTM E112)

- ASTM No.7 or finer

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3. Dimensional Property

1) Thickness

- +0.25mm to +1.0mm

2) Width

- -0mm to +20mm

3) Camber

- 20mm max in 10M

4) Telescopicity

- 50mm max

5) Other

- Value : As per API 5L 44th Ed.

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P-MPS-H1202 Rev. 0

APPENDIX –1

Apparatus for the Determination of Chemical Analysis and Mechanical Test

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P-MPS-H1202 Rev. 0

o Chemical Analyzer

Apparatus Type Quantity MakerElements to be

Determined

C,S DeterminatorC,S-244C,S-444

1 LECO C,S

N,O DeterminatorT/C-136T/C-436

1 LECO N,O

H-Determinator RH-402 1 LECO H2

C-Determinator IR-412 1 LECO C

S-DeterminatorIR-232IR-432

1 LECO S

Automic AbsorptionSpectrometer

PERKIN-5000 1 PERKINELMER

Al,Mn,Pb,Zn,Mo,Na,K,Si,Ni,Cu,B,Cr,Ti,Ag,Ca,

Mg,Co,Cd,V,Fe,Sn,Bi,Cs,Sb,Pd,Se,Hg,Hs,Ta,Zr,Ga,RB

SpectrometerUV150-02

1 SHIMADZU CORP

P,S,Mn,Si,Ni,Cr,Mo,V,Cu,Sb,Co,Nb,Ti,Al,Sn,Mg,B,Zr,Pb,As,Zn,Ca,Ta,Ce,Fe,W,Bi,Ag,

Cd,Ba,Te,Se,La,Pd

Vacuum EmissionSpectrometer

GVM-1016 1 SHIMADZU CORP C,Si,Mn,P,S

X-Ray FluorescenceSIMULTIX-6BRIGAKU-3530VXQ-150A(S)

1

RIGAKURIGACU

SHIMADZU CORP

Fe,Si,Ca,Al,P,S

ICP Spectrometer ICPV-1015 1 SHIMADZU CORP

Fe,P,S,Mn,Si,Ni,Cr,Mo,V,Cu,Sb,Co,Nb,Ti,Al,S

n,Mg,B,Zr,Pb,As,Zn,Ca,Ta,Ce,Fe,W,Bi,Ag,Cd,

Ba,Te,Se,La,Pd

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P-MPS-H1202 Rev. 0

o Mechanical tester

Apparatus Type Quantity MakerElements to be

Determined

Tensile TestingUniversalTestingMachine

4Zuick,

ShimadzuCorp

TS, YS, EL, YR, n

Bend TestingHydraulicBendingMachine

1Korea

HydraulicCorp

Bending Property

Impact TestingCharpy V

Notch ImpackMachine

2 KawadezAbsorbed Energy,% of Shear Area

Hardness Test

VickersBrinell

RockwellShore

8 Matsuzawa HV, HrB, HB, HRc, HS

MicrostructuralAnalysis

SEMEPMAOptical

113

PhillisCAN

NipponFGS, AGS other

DWTT TestSeries 3120 1 MAEGAWA % of Shear Area

HIC Test NACE TM 02844

(7 Vessel)Sungwha Plant

BLISTER, CLR,CSR, CTR, ETC

SSCC

Tensile Test 14Ea Sunwha PlantStree : TimeTo Failure

Four PointBent Tester

40Ea Sungwha Plant Streres To Failure

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P-MPS-H1202 Rev. 0

APPENDIX 2

Manufacturing Flow Chart and Process Parameters

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P-MPS-H1202 Rev. 0

Manufacturing Process Flow Chart of Gwangyang Works

#1 Blast furnace

De - S

Convert

HSM #3

Continuous casting

#1,#2,#3,#4 M/C of

#1 plant

(Hot Metal Pretretment)

(Steel refining in Ladle furnace)

LF (Ca-Si Treatment)

YES

N ≤ 50ppm

RHNO

(Casting into Slab atContinuous caster)

#2 Blast furnace

De–S

Convert

HSM #3 Continuous casting

#1,#2,#3,#4 M/C of

#2 plant

(Hot Metal Pretretment)

(Steel refining in Ladle furnace)

LF (Ca-Si Treatment)

YES

N ≤ 50ppm

RHNO

(Casting into Slab atContinuous caster)

N ≤ 120ppmYES

De-PNO

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P-MPS-H1202 Rev. 0

Manufacturing Process Flow Chart and Important Process Parameters which are checked

①

PROCESS STAGE PARAMETERS BEING CHECKED EQUIPMENT USED FREQUENCY OF CHECK

Thermocouple probe,

Slag Skimmer

One per torpedo ladle car

Thermocouple probe, Vaccum

Emission Spectrometer

Minimum one per heat


Emission Spectrometer, o2/N2/H2

Analysis(Determinator. Leco)

Minimum two per heat


Emission Spectrometer, o2/N2/H2

Analysis(Determinator. Leco)

Vaccum level constantly is

controled by computer.

hemistry and o2 three per heat

Thermocouple probe and other

Parameters by continuos

Monitoring computer

Temperature 3~4 per heat.

Other parameters. Continuous

Monitor by computer

Raw Materials

Steel Making in LD

Steel refining in

Ladle furnace

Steel refining in

Vaccum degassing

Casting into Slab at

Continuous caster

Molten iron chemical testing,

Slag removing

Temperature and soluble oxygen

Measurement, chemical analysis

of bath sample

Steel chemistry and temperature,

Homogenization through argon

gas injection

Vaccum level, treatment time

and treatment temperature.

Chemistry and dissolved oxygen

Tundish Temperature, casting

speed, osillation frequency of

mould.

Primary and secondary cooling,

mould powder

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P-MPS-H1202 Rev. 0

Slab inspection and

Conditioning

Slab dimentions. S-print and

Surface condition (defects)S-print lab equiped with sample

Preparation equipments and

machine / hand scarfer

S-print : One per heat

Scarfing : Slabs selected

By Quality Evaluation

system

Reheating furnace Temperature profile in SRF,

Reheating rate, soaking time

and temperature

By computer

* ACC : Automatic Combution

Control

Continuous Controling By

ACC, AI(Artificial

Intelligence)

Rolling in Hot strip mill Width, thickness, shape control,

Finishing and coiling temperatures,

Descaling, Weghing and marking

Automatic X-Gauge,

Temperature probe Shape and

Size controled by computer

(ASC, AWC, AGC system)

Automatic X-ray Gauge

Control, continuous full

length FT & CT monitoring

of all coils

Final testing and

inspectionVisual inspection oncoil, Testing

for mechanical properties ( tensile,

bend, Charpy impact test)

Tesile tester, Bend tester,

Impact tester, Microscope,

Image analyzer

Visual inspection : All coils

Mechanical props : 1

sample/thickness/heat

Product chemistry analysis

: one per heat

Packing / Marking As per customer’s specification

or POSCO standardEvery coils

①

of 39

P-MPS-H1202 Rev. 0

APPENDIX 3

Packing / Marking

BAND

BUCKLE

Gwangyang Works

manufacturing procedure for coil mill

Documents