Microstructure and residual stresses issued from the bonding of an austenitic onto a ferritic steel by solid diffusion

a thermo-metallurgical-mechanical analysis has been developed to simulate the welding of a ferritic steel onto an austenitic stainless steel by solid state diffusion bonding. The simulation of the process requires to take into account microstructural evolutions such as the growth of austenite grain size, carbon diffusion and phase transformations and their coupling to the usual thermo-mechanical analysis. The complete model has been implemented in a finite element code. The residual stresses issued from the welding of a cylinder 316LN/Inco/16MND5 followed by a subsequent heat treatment cycle have been calculated. The influence of the transformation induced plasticity has been emphasized.