Effect of stacking fault energy and austenite strengthening on martensitic transformation in Fe-Mn-Si alloys

J. Wan; S. Chen; T.Y. Hsu (Xu Zuyao)

doi:doi:10.1051/jp4:2003906

Issue		J. Phys. IV France Volume 112, October 2003


Page(s)		381 - 384
DOI		https://doi.org/10.1051/jp4:2003906

J. Phys. IV France 112 (2003) 381
DOI: 10.1051/jp4:2003906

Effect of stacking fault energy and austenite strengthening on martensitic transformation in Fe-Mn-Si alloys

J. Wan, S. Chen and T.Y. Hsu (Xu Zuyao)

School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, China

Abstract
In the Fe-Mn-Si alloys with very low stacking fault energy ( $\gamma_0$ ), the $\gamma$ (fcc) $\to$ (hcp) martensitic transformation substantially relies on an overlapping-of-stacking-faults mechanism. $\gamma_0$ strongly influences its M_s temperature. M_s gets lowered when $\gamma_0$ increases. It has been shown that both Mn and Si strengthen the austenitic matrix. However, Mn in a certain concentration range raises $\gamma_0$ of the alloy and thus lowers its M_s while Si acts in the other way around. Carefully summarizing and treating the available theoretical and experimental data, an analytical expression is established to describe the M_s as a function of $\gamma_0$ and the strengthening effect that is related with the strain energy. The results show that stacking fault energy plays an overwhelming role on the transformation in such alloys, even though the austenite strengthening also lowers M_s to some extent.