General view of an engineer operating shot peening equipment at the Naval Air Material Center's Aeronautical Materials Laboratory. Shot peening is a cold work process used to finish metal parts to prevent fatigue and stress corrosion failures and prolong the life of the part. In shot peening, a small spherical shot bombards the surface of the part to be finished, dimpling the surface and causing compression stresses under the dimple. As multiple overlapping dimples form throughout the metal surface, the compression stress strengthens the metal and ensures that the finished part will resist fatigue failures, corrosion, and cracking.