Molecular dynamics simulation of microstructural evolution and mechanical behavior of titanium alloy subjected to laser shock peening

In this study, the main purpose was to investigate the microstructural evolution and mechanical behavior of titanium alloy treated by laser shock peening using the piston impact method. The molecular dynamics model was established utilizing the Atomsk software. Based on the large-scale atomic/molecular massively parallel simulator, the simulation process of laser shock peening on polycrystalline titanium alloy was performed using the semi empirical embedded-atom method. The visualization software with ovito was utilized to analyze the microstructural evolution process, residual stress distribution and intrinsic mechanism of improving tensile properties of titanium alloys. Laser shock peening promoted HCP → BCC → FCC phase transition in titanium alloy and generated high-density of dislocations. Meanwhile, a large number of stacking faults, subgrains and twinning structures were also generated. Furthermore, laser shock peening induced the generation of compressive residual stress on the surface of titanium alloy model. Uniaxial tension was also carried out, and the tensile strength gradually increased with increasing the shock velocity. The strengthening mechanism of microstructure and compressive residual stress induced by laser shock peening on tensile strength has also been explored.