Grain Scale Analysis of Variant Selection during the Gamma-Epsilon-Alpha' Phase Transformation in Austenitic Steels

Abstract:

Austenitic steels can exhibit a complex transformation sequence during deformation. Indeed, the austenitic phase transforms first into bands of ε (HCP) martensite. This transformation is then followed by the formation of α’ (BCC) martensite. In this study, the crystallography of the transformation together with the occurrence of variant selection is studied at the scale of individual austenite grains. About ten prior austenite grains deformed at different strain levels in uniaxial tension were analysed by means of EBSD techniques. One of the classical approaches to predict the variant selection phenomenon is based on the calculation of the interaction energy between the macroscopic stress and the shape deformation associated with the formation of the product phase. The formation of the α’ variants was observed to lead to a very strong variant selection that cannot be fully explained by energetic criterion. It is suggested that the crystallography of the transformation sequence can account for the unexpected variants.

• Periodical: Solid State Phenomena (Volumes 172-174)
• Pages: 84-89
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.172-174.84
• Online since: June 2011
• Authors: Loic Malet, Chad W. Sinclair, Pascal Jacques, Stéphane Godet
• Keywords: Electron Backscatter Diffraction (EBSD), Interaction Energy, Martensite, PTMC, Stainless Steel (SS), Variant Selection

References

[1] J.R. Patel, M. Cohen: Acta Metallurgica Vol. 1 (1953), pages 531.

[2] M. Andersson, R. Stalmans, J. A Egren: Acta Metallurgica Vol. 46 (1998), pages 3883-3891.

[3] M. Humbert, B. Petit, B. Bolle, N. Gey: Mat. Sci. And Eng. A Vol 454-455 (2007), pages 508.

[4] S. Kundu and H.K.D.H. Bhadeshia: Scripta Materialia 57 (2007), pages 869.

[5] A. Hladar, S. Suwas and D. Bhattachargee: Microstructure and Texture in Steels and Other Materials, Springer, London, (2009), pages 19-31.

[6] J.S. Bowles and J.K. Mackenzie: Acta Met., Vol. 2 (1954), Pages 129-137.

[7] A. Pétein: On the interactions between Strain-induced phase transformations and mechanical properties in Fe-Mn-Si-Al steels and Fe-Ni-Cr austenitic stainless steels, PhD Thesis (2006) Université Catholique de Louvain-La-Neuve, Belgium.

DOI: 10.1007/978-1-4613-3730-0_3

[8] K. Spencer, J.D. Embury, K.T. Conlon, M. Véron and Y. Bréchet: Mat. Sci. and Eng. A Vol. 387–389 (2004), pages 873–881.

DOI: 10.1016/j.msea.2003.11.084

[9] T. Suzuki, H. Kojima, K. Suzuki, T. Hashimoto and M. Ichihara: Acta Met. Vol. 25 (1977) pages 1151.

[10] Y. He: Grain-Scale Characterization of FCC/BCC correspondence relations and variant selection, PhD Thesis (2005), McGill University, Canada.

[11] H.K.D.H. Bhadeshia: Worked examples in the geometry of crystals, the Institute of Materials, London (2001).

[12] J.F. Nie: Acta Mat. Vol. 56 (2008), pages 3169.