Investigating the effect of distance of carbon steel particles from the impacted surface on mechanical properties in SMAT process of AZ31 using molecular dynamics

In the surface mechanical attrition treatment (SMAT) process, the material surface layer is peened with a high-velocity number of carbon steel shot particles. Various parameters such as the distance of the peening gun to the impacted surface can affect the material's surface mechanical properties in the SMAT process. In this paper, the molecular dynamics (MD) approach has been used to study the effect of particle distance from the impacted surface on mechanical and physical behavior of AZ31 after the SMAT process. For this purpose, Universal Force Field (UFF) and Embedded Atom Model (EAM) force field have been utilized for atomic interactions. Based on the molecular simulation results, residual stress, hardness, and temperature of the atomic surface layer have been obtained for various distances. The simulation results demonstrated that reducing the particle distance in the SMAT process increases residual stress and surface layer hardness. Numerically, the maximum residual stress value of 268 MPa has been obtained for a distance of 5 nm in the SMAT molecular simulation results.