Performance of micro-dent array fabricated by laser shock peening on the surface of A304 stainless steel

A technology called net mask laser shock peening (NMLSP) is presented in this paper. A metallic mesh grid was used as a mask. When a high energy laser beam travels through the mask, it is divided into several beams of a micrometer-scale spot size. Shock waves induced by these micrometer-scale laser beams, were used to fabricate micro-dent arrays on the surface of a A304 stainless steel. Due to the interference of shock wave released by adjacent surfaces, surface topography, microhardness and residual stress distribution of the as-fabricated surface were different from the distribution of the surfaces fabricated by a single laser beam. Moreover, the friction wear experiments indicated that the wear performance of as-fabricated surfaces was remarkably improved when the load was low. As load and sliding speed increased, the untreated samples wear was altered from abrasive to adhesive, whereas the NMLSP treated samples still exhibited abrasive wear. Therefore, NMLSP can substantially improve friction and wear performance of the A304 stainless steel.