Modelling of Grain Refinement Induced by SMAT Process, Using a Complete Numerical Chaining Methodology

Abstract : Surface Mechanical Attrition Treatment (SMAT) is a recent process that enables to nanocrystallise the surface of metallic alloys. It can thus enhance mechanical properties of the treated material by inducing a grain refinement down to the nanometre scale, in the top surface layer. This nanocrystallisation process leads to different effects that were successively studied on several metallic materials. In the present work, investigations are carried out on the modelling of SMAT. A simulation of the shot dynamics is performed using different process parameters, with the aim to obtain the impact velocity field on the treated surface. This field is then used as an input for a finite element model to predict the induced grain refinement. The evolution of the micro and nanostructures are then calculated using a micromechanical approach, which takes into account the dislocations and their interactions. Coupled with a finite element analysis, this approach enables to deduce the influence of the process on the macroscopic material properties, whatever the geometry of the sample.