Laser Peening of Metallic Materials

Abstract

Laser peening is a good candidate for the surface treatment industry because of its localized operation, very fast processing, and ability to use multiple types of radiation; therefore, it has recently become a process used for industrial production. The mechanical recoil impulse that arises from rapidly expanding vapor generates high pulse pressure, and the structure of the workpiece changes. In the laser peening process, no melting takes place and a shock wave is generated; compressive residual stresses are induced in the material surface. It is used primarily to increase the fatigue life and improve cracking resistance of engineering materials. Compared with the traditional shot peening process, laser peening creates a higher magnitude of deeper compressive residual stresses in component surfaces, therefore creating high fatigue resistance in metallic materials because these compressive residual stresses inhibit fatigue crack initiation and propagation. Laser peening also has a significant role in improving microstructure, surface morphology, hardness, strength, fatigue life, and corrosion resistance. Laser peening can be applied to a finished surface of a part or before the finishing step, and the process is applicable to a wide range of metals and alloys of titanium, aluminum, nickel, and steels.