Crystal plasticity modelling of stability of residual stresses induced by shot peening

Gas turbine components are often shot-peened to improve surface integrity and fatigue capability. Compressive Residual Stress (CRS) and increased surface hardness are the key outcomes of shot peening. But the CRS is observed to relax during the service life, and its stability depends on the amount of cold work during the shot peening process and the applied load during service life. This study develops a numerical framework capable of accurately estimating the amount of cold work using a dislocation density-based crystal plasticity model. The proposed framework captures the evolution of microstructure during the shot peening process, incorporating the effects of grain size, orientation, and strain rate. The simulation methodology is used to investigate the influence of loading conditions on work hardening and relaxation. The numerical predictions are shown to agree with available experimental observations. The proposed method demonstrates the capability to optimize microstructure and shot peening parameters to reduce the relaxation of CRS during service life.