Contribution à la prédiction des conséquences mécaniques des transformations structurales.

Abstract

The phenomenon of structural changes materials caused by procedures such as welding and heat treatment, involves complex interaction between various aspects: mechanical, thermal and metallurgical into the material. Therefore, experimental and theoretical studies were conducted to predict these mechanical impacts in order to optimize the choice of materials to use. In This work we adopt The Ganghoffer approach usually used in this domain. This work represents a contribution to the prediction of plasticity of transformation (TRIP) for a martensitic transformation of the Fe-Ni-C steel. In this regard, a criterion for selecting transformation into martensite platelets based on the shear mechanical force (SMF). Another originality of this work, is the development of two numerical models; the first focuses on mono-grain of non regular shape and the second one concerns the multi-grain scale formed by a set of five grains of different non regular (nonidentical) shapes with a surrounding medium. To validate these models, many numerical simulations were carried out by imposing more uniaxial and biaxial loads to predict the kinetics and the final value of the TRIP.