Analysis of transformation stasis during the isothermal bainitic ferrite formation in Fe-C-Mn and Fe-C-Mn-Si alloys

The transformation stasis phenomenon during the isothermal bainitic ferrite formation has been investigated in a series of Fe-C Mn and Fe-C-Mn-Si alloys. The Gibbs energy balance (GEB) approach is applied to model the transformation stasis phenomenon, and theoretical predictions are compared with experimental observations. The good agreement over several alloy systems demonstrates that the transformation stasis is caused by diffusion of alloying elements into the migrating austenite/bainitic ferrite interfaces. It is found that the occurrence of transformation stasis in the Fe-C-Mn and Fe-C-Mn-Si alloys depends on the concentration of Mn, while the addition of Si has a negligible effect on transformation stasis. The GEB model clearly outperforms the diffusionless T-0 model. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.