strip casting steel dierk raabe

Prof. D. Raabe, lecture, 6th European Stainless Steel Conference, June 10-13 2008, Helsinki

Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany

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Advances in the optimization of thin strip cast austenitic 304 stainless steel microstructures

D. Raabe1), R. Degenhardt2), R. Sellger2), B. Sander1), W. Klos2), M. Sachtleber2), L. Ernenputsch2)

1) Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf, Germany

2) ThyssenKrupp Nirosta GmbH, 47797 Krefeld, Germany

Max-Planck-Institut für Eisenforschung, ThyssenKruppMax-Planck-Institut für Eisenforschung, ThyssenKrupp



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OverviewOverview

Introduction

Experimental

Strip casting microstructure

In-line forming strategies

Conclusions



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Introduction and motivationIntroduction and motivation



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Introduction and motivationIntroduction and motivation



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Higher solidification rate

Higher and locally different heat flux

Much lower hot reduction

Properties of final product: cleaner, better corrosion resistance, weldable, good forming behaviour, lower anisotropy, good surface finish

New grades

Process specific features of strip cast (AISI 304) Process specific features of strip cast (AISI 304)



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OverviewOverview

Introduction

Experimental



Conclusions



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3D electron – microscopy, 3D EBSD, texture3D electron – microscopy, 3D EBSD, texture



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Principle of measurementPrinciple of measurementN

orm

al

Rolling

Texture, austentite Local misorientation (KAM1) phase content

Texture, ferrite and martensite IQ and interfacesLocal misorientation (KAM1)



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Details from electron microscopyDetails from electron microscopyS

heer

nor

mal

Rolling

PhaseTexture ferrite and martensite

Delta

(round)

Martensite

(sharp)



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Details from electron microscopyDetails from electron microscopy

Texture austentite Local misorientation (KAM1)

Martensite

(strong distorsion)

Martensite

(strong distorsion)



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ThyssenKrupp Nirosta, Krefeld Strip Casting PlantThyssenKrupp Nirosta, Krefeld Strip Casting Plant



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OverviewOverview

Introduction

Experimental



Conclusions



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304, 1.4301 Strip casting microstructure304, 1.4301 Strip casting microstructure



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OverviewOverview

Introduction

Experimental



Conclusions



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Increase in equivalent strain and temperature

In-line formingIn-line formingN

orm

al

Rolling



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In-line forming and final heat treatmentIn-line forming and final heat treatment



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In-line forming and final heat treatmentIn-line forming and final heat treatment



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Mechanical properties, deformation martensiteMechanical properties, deformation martensite

0,00

100

200

300

400

500

600

700

0,00 10 20 30 40 50 60 70 80

Strain [%]

Str

ess

[N/m

m²]



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Mechanical properties, deformation martensiteMechanical properties, deformation martensitePhase discrimination+pattern quality+grain boundaries



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Austenitic 304 stainless steels can be produced by thin strip casting, in-line hot rolling, and subsequent heat treatment with equivalent mechanical properties and even better microstructure homogeneity than steels produced by the conventional thick slab processing route.

The formation of deformation-induced α‘ martensite in austenitic stainless steels produced by the thin strip casting route is similar as in conventionally produced 304 steels.

Precise characterization of the different phases, interfaces, and crystallographic textures can be conducted by using a high resolution EBSD method.

ConclusionsConclusions



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references

• D. Raabe, M. Hölscher, F. Reher, K. Lücke: Scripta Metall. 29 (1993) 113116, Textures of strip cast Fe-16% Cr

• D. Raabe, M. Hölscher, M. Dubke, H. Pfeifer, H. Hanke, K. Lücke: Steel Research 4 (1993) 359363, Texture development of strip cast ferritic stainless steels

• D. Raabe, K. Lücke: Mater. Sc. Techn. 9 (1993) 302312, Textures of ferritic stainless steels

• D. Raabe: Metal. Mater. Trans. A 26A April (1995) 991998, Microstructure and crystallographic texture of strip cast and hot rolled austenitic stainless steel

• D. Raabe: Mater. Sc. Techn. 11 (1995) 461468, Textures of strip cast and hot rolled ferritic and austenitic stainless steel

• D. Raabe: Acta Mater. 45 (1997) 11371151, Texture and microstructure evolution during cold rolling of a strip cast and of a hot rolled austenitic stainless steel

• D. Raabe, R. Degenhardt, R. Sellger, W. Klos, M. Sachtleber, L. Ernenputsch: Steel Res. Int. 79 (2008) 440-444, Advances in the optimization of thin strip cast austenitic 304 stainless steel microstructures

strip casting steel dierk raabe

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