A mechanism study on characteristic curve of residual stress field in Ti–6Al–4V induced by wet peening treatment

Highlights: • We systematically analyzed the micro-structure evolution of peening process. • The modified layer was divided into 3 regimes based on the micro-structure. • We proposed a residual stress formation mechanism model in peened samples. • The wet peening residual stress curve was explained by the dislocation activities. - Abstract: The microstructure evolution of Ti–6Al–4V alloy induced by wet peening treatment was studied in this work. The results show that the dislocation interaction dominates the grain refinement process. The modified layer could be divided into reconfiguration regime, unstable regime and metastable regime with depth. Corresponding to the characteristic curve of residual stress field, the maximum of compressive residual stress locates in the unstable regime and the dislocation annihilation and rearrangement lead to the decrease of the compressive residual stress in the near surface layer.