Shot peening involves bombarding the surface of a metal part with small spherical media, typically made of steel, glass, or ceramic (called "shot"). These shots are propelled at high velocity using compressed air or centrifugal force.
As each shot particle hits the surface, it creates a small indentation or dimple. To form this indentation, the surface layer of the metal is plastically deformed, which results in residual compressive stress being imparted into the surface layer.To know more details, read this :https://vibra.com/service/shot-peening/
