Shot peening is a cold working metal treatment process.
Shot peening increases the resistance to fatigue and stress corrosion failures, thus preventing premature fatigue failures in metal parts. The process parameters are closely controlled by specially designed machines. Shot peening is a surface treatment process, and most fatigue failures propagate from a focal point at the surface. These focal points, commonly called stress raisers, emanate from a variety of sources that result in concentrations of residual surface tensile stresses. Shot peening negates residual surface tensile stresses by the introduction of compressive stresses.