Study On The Dislocation Density And Grain Size Of Metal Surface By Laser Shock Peening

The microstructure of the metal surface is very important to its wear resistance, corrosion resistance and fatigue resistance. LSP can change the surface microstructure of the metal, LSP is used to induce the effect of shock wave on the surface of the material to produce dislocations on the surface of the material, which can improve the wear resistance, corrosion resistance and fatigue resistance of the material. LSP can be used to strengthen the surface of the metal material, the lightweight of the structure and the wear resistance of the surface. At present, the research on LSP are used in test methods, but the simulation of the surface microstructure evolution is lack of.This paper aims to study the evolution of dislocation density and grain size of LY2 aluminum, the establishment of finite element model is based on the ABAQUS software, the material subroutine based on the dislocation theory is written in VISUAL STUDIO. And the prediction of dislocation density and grain size of metal surface was realized. The simulation results were in good agreement with the experimental results. Using the model to study the microstructure evolution under a variety of conditions, and obtained the relationship between the parameters and grain size, which has laid an important foundation for the system to optimize the laser shock parameters. The main contents and conclusions are as follows:Firstly, the finite element model of LY2 aluminum alloy was established by using ABAQUS software. By using appropriate material model and the finite element modeling method and microstructure evolution model to describe the evolution of dislocation density and grain size of the metal after LSP. The microstructure prediction model is embedded in the form of user subroutine in the finite element model.Secondly, by adjusting the microstructure evolution of the parameters in the model, the simulation results of single laser shock and muti-times laser shock strengthening of dislocation density and grain size of metal surface results were compared with previous experimental results, verify the accuracy of the simulation model.In the end, the model based on dislocation theory is proposed to study the effect of LSP. Including with the change of the impact times of LSP, the variation of dislocation density and grain size and severe plastic deformation depth, the change trend of dislocation density and grain size of different materials. The results show that with the increase of the impact times, the increase rate of the depth of the plastic deformation is very low, especially the fourth shock and the fifth impact; with the increase of shock wave pressure, grain size decreases, the dislocation density increases; The change trends of grain size and dislocation density of different materials under the same conditions are consistent.