Strip Casting Steel Dierk Raabe


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

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Strip Casting Steel Dierk Raabe

  1. 1. 1<br />Max-Planck-Institut für Eisenforschung, ThyssenKrupp<br />Advances in the optimization of thin strip cast austenitic 304 stainless steel microstructures<br />D. Raabe1), R. Degenhardt2), R. Sellger2), B. Sander1), <br />W. Klos2), M. Sachtleber2), L. Ernenputsch2)<br />Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf, Germany<br />2) ThyssenKrupp Nirosta GmbH, 47797 Krefeld, Germany<br />
  2. 2. 2<br />Overview<br /><ul><li>Introduction
  3. 3. Experimental
  4. 4. Strip casting microstructure
  5. 5. In-line forming strategies
  6. 6. Conclusions</li></li></ul><li>3<br />Introduction and motivation<br />
  7. 7. 4<br />Introduction and motivation<br />
  8. 8. 5<br />Process specific features of strip cast (AISI 304) <br /><ul><li>Higher solidification rate
  9. 9. Higher and locally different heat flux
  10. 10. Much lower hot reduction
  11. 11. Properties of final product: cleaner, better corrosion resistance, weldable, good forming behaviour, lower anisotropy, good surface finish
  12. 12. New grades</li></li></ul><li>6<br />Overview<br /><ul><li>Introduction
  13. 13. Experimental
  14. 14. Strip casting microstructure
  15. 15. In-line forming strategies
  16. 16. Conclusions</li></li></ul><li>7<br />3D electron – microscopy, 3D EBSD, texture<br />
  17. 17. 8<br />Normal<br />Rolling<br />Principle of measurement<br />phase content<br />Texture, austentite<br />Local misorientation (KAM1)<br />IQ and interfaces<br />Local misorientation (KAM1)<br />Texture, ferrite and martensite<br />
  18. 18. 9<br />Sheer normal<br />Martensite<br />(sharp)<br />Delta<br />(round)<br />Rolling<br />Details from electron microscopy<br />Texture ferrite and martensite<br />Phase<br />
  19. 19. 10<br />Martensite<br />(strong distorsion)<br />Martensite<br />(strong distorsion)<br />Details from electron microscopy<br />Texture austentite<br />Local misorientation (KAM1)<br />
  20. 20. 11<br />ThyssenKrupp Nirosta, Krefeld Strip Casting Plant<br />
  21. 21. 12<br />Overview<br /><ul><li>Introduction
  22. 22. Experimental
  23. 23. Strip casting microstructure
  24. 24. In-line forming strategies
  25. 25. Conclusions</li></li></ul><li>13<br />304, 1.4301 Strip casting microstructure<br />
  26. 26. 14<br />Overview<br /><ul><li>Introduction
  27. 27. Experimental
  28. 28. Strip casting microstructure
  29. 29. In-line forming strategies
  30. 30. Conclusions</li></li></ul><li>15<br />Increase in equivalent strain and temperature<br />Normal<br />Rolling<br />In-line forming<br />
  31. 31. 16<br />In-line forming and final heat treatment<br />
  32. 32. 17<br />In-line forming and final heat treatment<br />
  33. 33. 18<br />700<br />600<br />500<br />400<br />Stress [N/mm²]<br />300<br />200<br />100<br />0,00<br />0,00<br />10<br />20<br />30<br />40<br />50<br />60<br />70<br />80<br />Strain [%]<br />Mechanical properties, deformation martensite<br />
  34. 34. 19<br />Mechanical properties, deformation martensite<br />Phase discrimination+pattern quality+grain boundaries<br />
  35. 35. 20<br />Conclusions<br /><ul><li>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.
  36. 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.
  37. 37. Precise characterization of the different phases, interfaces, and crystallographic textures can be conducted by using a high resolution EBSD method.</li></li></ul><li>references<br />D. Raabe, M. Hölscher, F. Reher, K. Lücke: Scripta Metall. 29 (1993) 113116, Textures of strip cast Fe-16% Cr<br />D. Raabe, M. Hölscher, M. Dubke, H. Pfeifer, H. Hanke, K. Lücke: Steel Research 4 (1993) 359363, Texture development of strip cast ferritic stainless steels<br />D. Raabe, K. Lücke: Mater. Sc. Techn. 9 (1993) 302312, Textures of ferritic stainless steels<br />D. Raabe: Metal. Mater. Trans. A 26A April (1995) 991998, Microstructure and crystallographic texture of strip cast and hot rolled austenitic stainless steel<br />D. Raabe: Mater. Sc. Techn. 11 (1995) 461468, Textures of strip cast and hot rolled ferritic and austenitic stainless steel<br />D. Raabe: Acta Mater. 45 (1997) 11371151, Texture and microstructure evolution during cold rolling of a strip cast and of a hot rolled austenitic stainless steel<br />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<br />21<br />