Finite element modeling of trip steels

Abstract

In this paper, a constitutive model that describes the mechanical behavior of steels exhibiting the "Transformation Induced Plasticity" (TRIP) phenomenon during martensitic transformation is presented. Multiphase TRIP steels are considered as composite materials with a ferritic matrix containing bainite and retained austenite, which gradually transforms into martensite. The effective properties and overall behavior of TRIP steels are determined by using homogenization techniques for non-linear composites. The developed model considers the different hardening behavior of the individual phases and estimates the apportionment of plastic strain and stress between the individual phases of the composite. A methodology for the numerical integration of the resulting elastoplastic constitutive equations in the context of the finite element method is developed and the constitutive model is implemented in a general-purpose finite element program. The prediction of the model in uniaxial tension agree well with the experimental data. The problem of necking of a bar is studied in detail.