Laser shock processing: an emerging technique for the mechanical and surface properties enhancement of metallic materials

Abstract

Laser Shock Processing (LSP) is as an effective technology for the improvement of surface and mechanical properties of metallic alloys and is an emerging technology in its way to production engineering in direct competence with other well established technologies as, i.e. shot peening. The technique is based on the application of a high intensity pulsed laser beam on a metallic target forcing a sudden vaporization of its surface into a high temperature and density plasma that immediately develops inducing a shock wave propagating into the material. The main advantage
of this technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly, the life improvement under cyclic load connected with improved wear and corrosion resistance.
The laser shock effects achieved by this method are comparable to those of shot-peening: that is, a local material compression linked to the generation and displacement of defects, surface state modification and, most important, a compressing residual stress field whose magnitude and depth into the material is generally associated with large improvements in fatigue resistance. Along with a description of the theoretical/computational and experimental methods developed by the authors for the predictive assessment and experimental implementation of LSP treatments, experimental results on the residual stress profiles and associated surface properties modification successfully reached under different LSP irradiation conditions in typical high strength materials will be presented in this paper.