A model for deformation behavior and mechanically induced martensitic transformation of metastable austenitic steel

A microstructure-based computational model, which can describe the transformation-induced plasticity (TRIP) accompanying the mechanically induced martensitic transformation in metastable austenitic steel, was suggested. The martensitic transformation kinetics was assumed as a nucleation-controlled phenomenon. The probability, which the nucleation site would really act, was derived for each martensitic variant as a function of the interaction energy between externally applied stress state and lattice deformation. The increase of nucleation site in the austenite due to the plastic deformation was formulated as the increase of the shear-band intersection. The permanent strain originated from the transformation of austenite into martensite Was evaluated by assessing the difference of the nucleation rate of martensitic variants. A self-consistent model was employed to predict the deformation behavior of each phase in the steel. The model was then implemented in an iterative program based on the radial return method to simulate the deformation behavior of the steel under various stress states. The calculated results were compared with the experimental data measured under the uniaxial tension and simple shear. In addition, when various external forces are acting, the resulting effect on the M-s temperature was calculated by the model and compared with the reported data. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.