Shot peening is a process in which the surface of a part is bombarded with small spherical media (usually hardened steel) called shot. The result of this process is a uniformly dimpled surface, the roughness being determined by the shot size and the peening intensity.
The shot peening process is used to improve the fatigue properties of the part by the introduction of compression forces in the surface layer. The presence of this surface compressive force serves to retard the initiation and growth of fatigue cracks.
