A model for strain-induced martensitic transformation of TRIP steel with strain rate

摘要

Strain rate is one of the key factors which induce martensitic transformation. In this study, a constitutive model, which can describe the transformation-induced plasticity (TRIP) accompanying the strain-induced martensitic transformation in TRIP steel, is developed. The increase of nucleation site in the austenite due to the plastic deformation is formulated as the increase of the shear band intersection. The nucleation site probability is derived not only by stress state, plasticity strain and constant environment temperature, but also by strain rate, where shear band intersection decrease through strain rate adiabatic thermal to simulate the transformation-induced plasticity characteristic for TRIP steel. Anisotropic yield function is used to describe the sheet anisotropic property. A mixture hardening law with four phases is developed instead of the mixture hardening law with two phases used commonly. The constitutive model is implemented into ABAQUS/UMAT for the analysis of the material deforming processes. The martensitic volume fraction is tested by X-ray to describe the comparison between experimental data and simulation. Stress-strain curve is measured under strain rate from 0.001/s to 0.1/s to identify the simulation results based on the new constitutive model. All the results are agreeable. (c) 2006 Elsevier B.V. All rights reserved.