2013/12/10

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Stahl-Zentrum

STAHL 2013

1 | 28.11.2013 · STAHL 2013 · © Stahlinstitut VDEh | Wirtschaftsvereinigung Stahl

Neue HSS Arbeitswalzen für die hinteren Gerüste

der Fertigstraße von Warmbandwerken

Stahl in Bewegung

Steel in Motion

Neue umformtechnische Entwicklungen

Toshiyuki Hattori, Hitachi Metals Wakamatsu, Ltd. Christian Haberkorn, voestalpine Stahl GmbH Nozomu Oda, Hitachi Metals Wakamatsu, Ltd. Nagato Maeda, Hitachi Metals Europe GmbH

Roll Development for Hot Strip Mill Finishing Trains

Indefinite chilled

Adamite

High Cr Iron HSS

Indefinite chilled

ICDP Enhanced-ICDP

HSS

Static Centrifugal casting

CCC-method *

*CCC: Continuous casting process for cladding H1

‘70 ‘80 ’90 ’00 ‘10

Finisher (Earlier)

Finisher (Middle Later)

Casting Process

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Target of New HSS development

H2 Typical example of roll changes

Reduce

roll changes in

middle & later stands

HSS

Why HSS rolls cannot be used in middle and later stands ?

Rolling Incident Strip sticking Fire cracks

Crack growth

H3

Rolling

Direction

Strip Cobble

Incident

Work

Roll

Back up Roll

Stuck

strip

Cracks

Steel strip sticking : Principal cause of Inferior crack resistance of HSS

Heavy contact stress at the stuck part

Stuck strip

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Roll evaluation (Strip sticking): FTS test

Mild Steel

Weight

Speci- men

Fall

Rack

Mild Steel

Specimen Sticking Surface

after test

Indentation area

Sticking area

Evaluation of

Strip sticking Sticking surface ratio (%)

(Sticking area)

(Indentation area) ×100

H4

Roll evaluation (Strip sticking): FTS test

Actual roll after cobble FTS test

Cross-sectional view of steel stuck Roll surface

Roll Roll Stuck steel

Austenized layer

Austenized layer

Stuck steel

1mm 200μm

H5

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Roll evaluation (wear resistance) : Hot rolling simulator

wear profile

Roll surface

H6

Strip sticking evaluation of Conventional Materials

*Alloy content: V+Nb+Mo+1/2W

FTS test result Alloy content*

mass%

Graphite

ratio %

Carbide

ratio %

Sticking surface

ratio %

A:Conventinal ICDP <1.0 2-3 28-38 16-36

B:Enhanced ICDP 2.0-2.8 2-3 28-38 16-40

C:HSS1 7.9-8.7 0 15-25 58-79

D:HSS2 10.2-12.28 0 15-25 61-85

100μm MC

100μm MC

Graphite

100μm M3C

100μm M6C

B: Enhanced ICDP

D:HSS2

Matrix ratio

Carbide ratio

Graphite ratio

＋ ＋＋ ＋

＋＋ ＋ －

H7

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Strip sticking evaluation of Graphite iron & steel

Alloy content*

mass%

Graphite

ratio %

Carbide

ratio %

Sticking surface

ratio %

A:Conventinal ICDP <1.0 2-3 28-38 16-36

B:Enhanced ICDP 2.0-2.8 2-3 28-38 16-40

C:HSS1 7.9-8.7 0 15-25 58-79

D:HSS2 10.2-12.28 0 15-25 61-85

E:Spheroidal Graphite Iron

(SGI) <1.0 6-7 <1.0 4-9

F:Graphitic steel

(G-Steel) <1.0 3-4 <1.0 6-19

FTS test result

*Alloy content: V+Nb+Mo+1/2W

E: Spheroidal Graphite Iron (SGI) F:Graphitic Steel

100μm 100μm

Graphite Graphite

Spheroidal graphite and graphitic steel matrix are bainite and martensite by quenching. = same matrix of ICDP and HSS H8

Effect of Graphite on sticking resistance

0

20

40

60

80

100

ICDP E-ICDP HSS1 HSS2 SGI G-steel

Stic

kin

g R

atio

%

Graphite prevent direct contact of roll surface and strip

0

10

20

30

40

0

2

4

6

8

Car

bid

e r

atio

%

Gra

ph

ite

rat

io %

Graphite Carbide

Graphite

Stuck material

Cross section microstructure around graphite

ICDP HSS SGI

G-Steel

Carbide % ＋＋ ＋ ±

Graphite% ＋ － ＋＋

Sticking resistance

Good Bad Better

*SGI:：Spheroidal graphite Iron G-steel：Graphitic steel

H9

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Strip sticking evaluation of Developed materials

Alloy content*

mass%

Graphite

ratio %

Carbide

ratio %

Sticking surface

ratio %

A:Conventinal ICDP <1.0 2-3 28-38 16-36

B:Enhanced ICDP 2.0-2.8 2-3 28-38 16-40

C:HSS1 7.9-8.7 0 15-25 58-79

D:HSS2 10.2-12.28 0 15-25 61-85

E:SGI <1.0 6-7 <1.0 4-9

F:G-steel <1.0 3-4 <1.0 6-19

G:Development 1 4.2-5.0 2-3 24-34 18-37

H:Development 2 7.0-7.8 2-3 22-32 18-33

FTS test result

*Alloy content: V+Nb+Mo+1/2W

H: Development 2 Enhanced ICDP

100μm

MC

Graphite

Conventional HSS

H10

Microstructure comparison and other properties 12

Compressive residual stress : Development 2≒ Enhanced ICDP (<<HSS)

Fracture toughness :Development 2≒ Enhanced ICDP

Anti-crack resistance of developed roll is same level as Enhanced ICDP

H11

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Wear resistance evaluation (Hot rolling simulator) 13

0

2

4

6

8

10

12

0

10

20

30

40

50

60

Conventinal ICDP

Enhanced ICDP

HiCr Iron HSS1 HSS2 Develop- ment 1

Develop- ment 2

Allo

y C

on

ten

t m

ass%

We

ar A

mo

un

t μ

m

Wear amount

Alloy content Poor

Ex

celle

nt

Alloy content: V+Nb+Mo+1/2W

GS HSS

H12

Conclusions

A new type of HSS roll for later stands in Hot Strip Mills – “GS HSS”, which has same level of strip sticking resistance and two times or more resistance as ICDP has been developed. Graphite is effective element for strip sticking resistance.

New type of wear and strip sticking resistant HSS roll has been developed, which contains Graphite and carbide forming elements such as V, Nb, Mo and W. Developed rolls are showing excellent performance in actual hot strip mills.

Patent applications covering the developed roll have been applied in countries all over the world.

H13

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voestalpine Stahl GmbH

www.voestalpine.com/stahl voestalpine Stahl GmbH

GS-HSS experience at voestalpine

voestalpine Stahl GmbH

| |

Hot-strip Mill

10.12.2013

Zunderwäscher VG

Zunderwäscher FS

N S

N S

Mill stands

Rougher Work roll diameter Work roll quality Distribution Performance t/mm

R1 1100-980 mm Semi-HSS/ Hi.Cr. 20/80 15.000/13.000

Finisher

F0 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000

F1 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000

F2 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000

F3 780-680 mm HSS/ Hi.Cr. 50/50 16.000/7.000

F4 725-625 mm E-ICDP /GS-HSS 90/10 5.000/9.000

F5 725-625 mm E-ICDP /GS-HSS 90/10 5.000/9.000

F6 725-625 mm E-ICDP /GS-HSS 90/10 5.000/9.000

V1

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voestalpine Stahl GmbH

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Comparison of roll performance in F4 conventional rolls versus GS-HSS trial

10.12.2013

V2

voestalpine Stahl GmbH

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Actual roll performance comparison Silicon steel

10.12.2013

V3

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voestalpine Stahl GmbH

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Actual Roll performance comparison All steel grades

10.12.2013

V4

Stahl-Zentrum

STAHL 2013

20 | 28.11.2013 · STAHL 2013 · © Stahlinstitut VDEh | Wirtschaftsvereinigung Stahl

Stahl in Bewegung

Steel in Motion

THANK YOU FOR YOUR ATTENTION

Neue umformtechnische Entwicklungen

Toshiyuki Hattori, Hitachi Metals Wakamatsu, Ltd. Christian Haberkorn, voestalpine Stahl GmbH Nozomu Oda, Hitachi Metals Wakamatsu, Ltd. Nagato Maeda, Hitachi Metals Europe GmbH

Stahl-Zentru

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