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  • Study of ferrite grain growth and transformation mechanisms, at different stages during steel processing, aided by the use of modern OIM techniques


The final microstructure and texture depend on the composition and processing conditions. When selective dissolution, nucleation and/or preferential growth of certain orientations are involved, the conventional observation techniques (transmission electron microscopy and X-ray texture analysis) are insufficient to some extent. In the present work, OIM (oriented imaging microscopy) techniques have been used to investigate the effect of the local orientations and mesotexture during transformation, recrystallisation and grain growth in steels. It has been found that during recrystallisation after cold rolling, the intensity of the fibre is enhanced by increasing previous cold reduction. The main changes in the deformation texture take place close to the recrystallisation completion. The recrystallised fibre grains have a clear number advantage, but not a size advantage. It turns out that a variant selection is operative during the austenite to ferrite transformation. Normal grain growth is the main factor responsible for the disappearance of ferrite grains during the course of the transformation. An optimum fraction of austenite is found to improve r-value in DP steels. Martensite produces a large systematic difference in measured and calculated r-values. A TRIP steel requires heating rates higher than 3000°C/s in order to transform a deformed ferrite, which opens up possibilities for further structural refinement and alternative texture control. The austenite has been observed to inherit the orientations from the deformed austenite. A statistical model has been developed to account for grain growth in the presence of texture and has been validated on a ferritic stainless steel

Additional information

Authors: GUTIERREZ I, CEIT, San Sebastian (ES);NOVILLO E, CEIT, San Sebastian (ES);VANDENBERGHE L, CRM - Centre de recherches métallurgiques, Zwijnaarde (BE);BARTERI M, Centro Sviluppo Materiali (CSM), Roma (IT);DI SHINO A, Centro Sviluppo Materiali (CSM), Roma (IT);GROßTERLINDEN R, Thyssen Krupp Stahl AG, Duisburg (DE);PETROV R, Universiteit Gent, Zwijnaarde (BE);KESTENS L, Universiteit Gent, Zwijnaarde (BE);HOUBAERT Y, Universiteit Gent, Zwijnaarde (BE)
Bibliographic Reference: EUR 21430 EN (2005), 157 pp. Euro: 25
Availability: Katalogue Number: KI-NA-21430-EN-S The paper version can be ordered online and the PDF version downloaded at:
ISBN: ISBN: 92-894-4319-7
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