Laser Shock Processing as a Method for the Improvement of Metallic Materials Surface Properties: A Discussion on the Influence of Combined Mechanical and Thermal Effects

Abstract

Laser shock processing (LSP) has been presented as an effective technology for improving surface mechanical and corrosion properties of metals, and is being developed as a practical process amenable to production engineering. The main acknowledged advantages of the laser shock processing technique consist 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 of the treated specimens against wear, crack growth and stress corrosion cracking. In the present paper, practical results at laboratory scale on the application of Laser Shock Processing are presented showing the obtained tensile residual stresses relaxation along with corresponding preliminary results about the resulting mechanical properties improvement induced by the treatment. Additionally, the influence of different irradiation parameters will be presented along with a physical interpretation of the mechanical effects induced in the materials by the characteristic fast laser-plasma interaction regime occurring in the process and model based assessments on the real possibilities of the technique as a substitutive of traditional techniques as, for example, shot peening. From a specific point of view, a critical analysis of the relative influences of coupled thermal and mechanical stress and deformation effects during LSP is presented.