Prediction of residual mechanical fields using multi-impact model and eigenstrain reconstruction method: Application to TRIP780 steel containing an artificial surface defect

Shot-peening is an effective cold surface treatment process widely used to enhance the fatigue behavior of many critically loaded metallic components by generating compressive residual stresses beneath the shot-peened surface. However, surface or subsurface geometrical defects may be present in these components, which can negatively impact their fatigue life. Knowing the residual mechanical fields induced by shot-peening in the vicinity of these defects is highly important for accurate fatigue life prediction. The aim of this work is to propose two predictive approaches to evaluate the residual mechanical fields around an artificial hole as well the associated edge-hole distortion in shot-peened TRIP780 steel. For this purpose, a multi-impact shot-peening model and an eigenstrain reconstruction method based on finite element framework were employed. It was concluded that the multi-impact shot-peening model successfully captured the localized plastic deformation adjacent to the hole and simulated edge-hole distortion. The eigenstrain method provided accurate residual stress predictions thanks to input from the multi-impact model; it was, however, unable to simulate the edge-hole distortion.

Keywords: Shot-peening; Finite element modeling; Multi-impact shot-peening model; Eigenstrain reconstruction method; Residual mechanical field; TRIP 780