Modélisation des effets mécaniques des transformations de phases pour le calcul de structures

Abstract
A set of constitutive equations are proposed to take into account the predominant mechanical effects due to solid state phase transformations in steels under multi-axial loading. The aim of this work is to formalize, for structural computations (heat treatment and welding), the main experimental and theoretical results available in the literature. The interna1 stresses generated by the transformation induced flow are represented by internal variables in the framework of the thermodynamics of the irreversible processes. We propose a mathematical formulation of the strain-hardening effects on the transformation induced plastic flow and of the transformation induced hardening on the "classical" plasticity. The constitutive equations have been implemented into the F.E. code ZeBuLoN and we briefly present a thermo-metallurgical and mechanical simulation with hardening couplings.