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

1. 1 Max-Planck-Institut für Eisenforschung, ThyssenKrupp 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) Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf, Germany 2) ThyssenKrupp Nirosta GmbH, 47797 Krefeld, Germany

3. Experimental

4. Strip casting microstructure

5. In-line forming strategies

7. 4 Introduction and motivation

9. Higher and locally different heat flux

10. Much lower hot reduction

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

13. Experimental

14. Strip casting microstructure

15. In-line forming strategies

17. 8 Normal Rolling Principle of measurement phase content Texture, austentite Local misorientation (KAM1) IQ and interfaces Local misorientation (KAM1) Texture, ferrite and martensite

18. 9 Sheer normal Martensite (sharp) Delta (round) Rolling Details from electron microscopy Texture ferrite and martensite Phase

19. 10 Martensite (strong distorsion) Martensite (strong distorsion) Details from electron microscopy Texture austentite Local misorientation (KAM1)

20. 11 ThyssenKrupp Nirosta, Krefeld Strip Casting Plant

22. Experimental

23. Strip casting microstructure

24. In-line forming strategies

27. Experimental

28. Strip casting microstructure

29. In-line forming strategies

31. 16 In-line forming and final heat treatment

32. 17 In-line forming and final heat treatment

33. 18 700 600 500 400 Stress [N/mm²] 300 200 100 0,00 0,00 10 20 30 40 50 60 70 80 Strain [%] Mechanical properties, deformation martensite

34. 19 Mechanical properties, deformation martensite Phase discrimination+pattern quality+grain boundaries

36. 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.