Incremental Micromechanical Modelling of the Transformation Induced Plasticity

Abstract
Classical plasticity (dislocation motion) coupled to solid-solid phase transformation (lattice changes) is the primary cause of the special behaviour of TRIP (TRansformation Induced Plasticity) steels. Internal stresses associated with the phase change induces in fact a large additional plastic flow inside austenite and martensite. We propose a kinematic description of such a phenomenon based on a local decomposition of strain rate into an elastoplastic part and a given lattice inelastic strain rate field. Based on this description and using usual Green functions method, a concentration tensor for the total strain rate field is obtained. The self consistent approximation allows to determine the behavior of the equivalent material and the équivalent transformation strain rate.