Heat Treatment Distortions and Residual Stresses Simulations: Influence of Heat Transfer and Phase Transformations

Numerical simulation is today a necessary tool in order to better optimize heat treatments as far as microstructures, mechanical properties and residual stresses and deformations in a workpiece are concerned. These simulations need the modelling of the material behaviour (thermophysical behaviour, kinetics of phase transformations, thermomechanical behaviour), the « process » modelling (heating, cooling…) and to take into account the couplings between the different phenomena in numerical tools. This approach has been largely developed for steels and extended to other metallic alloys (aluminium alloys, titanium alloys…). Today, it can be considered that the modelling of the « material » is well advanced for applications, at least for steels, but one key issue remains the prediction of the heat transfer between the solid and its environment particularly during quenching. In this presentation, an overview of the present models and necessary data will be given. Simulation examples that highlight the respective effects of thermal gradients and phase transformations on deformations and their experimental validation through in situ measurements will also be presented.