Residual Stress Distribution, Phase Transformation, and Wettability Characteristics of Laser Peened Austenitic Stainless Steel

Laser peening without protective coating (LPwC) has been performed on austenitic stainless steel (SS304) with a power density of 9 GW cm(-2) and peening passes of one, three and five. Effect of single and multiple laser peening on the residual stress distribution, work-hardening, surface roughness, phase transformation, and wettability has been studied using XRD, EBSD, surface profilometer and goniometer. A maximum compressive residual stress of - 581 MPa and work hardening depth that extended beyond 500 mu m were observed with 5 peening passes. Further, an increase in austenite to martensite transformation (gamma -> alpha ') from 9.4 (unpeened) to 18.5% was observed for 5 peening passes. The average grain size reduced to 11.53% for five-time peened samples compared to single-time peened samples. Wettability studies revealed hydrophilic to hydrophobic transformation after laser peening.

Automated summary

In this study, laser peening without protective coating was performed on stainless steel to investigate the effects on residual stress distribution, work hardening, surface roughness, phase transformation, and wettability. The results showed that multiple peening passes led to higher compressive residual stress, deeper work hardening depth, smaller grain size, and a transformation from hydrophilic to hydrophobic behavior.