Effect of LASER shock peening on microstructure, mechanical properties and corrosion behavior of interstitial free steel

LASER shock peening (LSP) is an effective process of surface modification. This work is concerned with the effect of LSP on the modification of microstructure, hardness, microhardness profile, residual stress, tensile properties and corrosion behavior of interstitial free (IF) steel. In order to study the effect of pulse energy on hardness, samples were subjected to LSP at pulse energy of 170, 230, 290 and 340 mJ respectively. The effect of LSP time on hardness, microhardness profile and tensile properties was investigated by processing the samples for 5, 10, 15 and 20 min at pulse energy of 230 mJ and there was found to be significant increase in tensile strength. There was grain refinement to nano level in the surface region due to LSP. Hardness was observed to increase by LSP up to 10 min and tensile strength increased up to LSP of 5 min. However with the increase in LSP time beyond 10 min there was prominent ablation and melting. The effect of overlapped (OV) LASER shocks was also studied by comparing their behavior with that of single shock. The potentiodynamic polarization study showed significant increase in corrosion resistance of the LSPed IF steel.