Characterization of 420 martensitic steel after nanosecond laser peening

Abstract

Laser shock peening has been established as a surface enhancement technique capable of altering mechanical properties of materials. The shock waves from laser peening generate compressive residual stresses that increase the resistance of materials to surface-related failures. By varying the process parameters, a range of distribution profiles can be attained. The aim of the current work is to investigate the effects of peak power density on the resulting residual stress distribution, characterized by hardness and the integral compressive stress area over specimen depth. A series of measurements were carried out on laser peened AISI 420 martensitic stainless steel for the comparative study. Results indicate that the surface engineering process is capable of inducing the beneficial residual stresses substantially, whereas the effects on hardness is not relatively significant. More importantly, peak power densities are found to have a positive correlation with the depth of influence of the compressive residual stresses.