From conventional to severe shot peening to generate nanostructured surface layer: A numerical study

Surface nanocrystallization (SNC) was shown to be an effective approach to bypass the challenges of synthesizing bulk nanocrystalline material (NC) and yet to harvest its potential advantages. In this study unusual coverage (high number of impacts) was simulated for air blast shot peening process to induce SNC. The process is called severe shot peening. While the body of knowledge is mainly experimental in similar processes such as ultrasonic shot peening or surface mechanical attrition, a multi-scale scheme was developed to discuss the possibility of refinement from micro to nano-regime. The numerical framework combines finite element simulation of peening process with the dislocation density model. The result affirms the possibility of adopting air blast shot peening to induce surface nanocrystallization using typical media size, typical impact velocity and high coverage. This is an attempt to move from conventional shot peening toward severe shot peening to obtain surface nanocrystallization.