Study on surface nanocrystallization and dislocation configuration of E690 steel strengthened by laser shock peening

Abstract

Through the combination of simulation and experiment, this paper explored the direct relationship between laser energy and surface nanocrystallization of E690 steel, and analyzed the indirect relationship between surface residual compressive stress and surface nanocrystallization. The experimental and simulation results showed that when the laser energy reached 10J, grain refinement occurred on the surface of E690 steel, and the maximum residual compressive stress appeared on the sub surface of the material. At the same time, with the increase of laser energy, violent vibration and extrusion occurred between lattices, resulting in a certain micro thermal effect and inducing the climbing of screw dislocations. Therefore, there was a qualitative relationship between the surface nanocrystallization of E690 steel after laser shock peening and the distribution of residual stress, that was, when the maximum residual stress appeared on the sub surface, the surface of material appeared nanocrystallization. This was because surface nanocrystallization consumed a lot of energy, which reduced the surface residual stress. This study was of great significance to predict the dislocation configuration changes of E690 steel after laser shock peening.