Laser Shock Peening of Al 6061- T6 Alloy, a theoretical and experimental study

Inducing compressive residual stress is one of the methods of improving fatigue life in metallic components. There are numerous and various methods for inducing compressive residual stress, such as shot peening and deep rolling. One of the most recent and most advanced methods for inducing compressive residual stress in industrial components is Laser Shock Peening (LSP). LSP is a relatively new and complex process, therefore, vast experimental investigations are needed for better understanding the process. For this purpose in the present work, an Nd: YAG Laser with 1200mJ of energy per pulse was used to investigate the LSP process experimentally on Al 6061- T6 alloy. The effect of process on the hardness beneath the surface, the microstructure, and the surface roughness was studied. In addition, in order to investigate the effect of the LSP process on a notch, a notched sample was treated using the LSP process. The results showed that the process could increase the hardness of the material up to 1000μm below the surface. Furthermore, the results showed that the surface roughness would slightly get increased, while this increase could be limited by properly selecting the process parameters. The LSP process of the notched sample showed that this process could lead to the growth of cracks in such samples.