This study aims to investigate the effect of laser peening with (LP) and without coating (LPwC) process on subsurface microstructural evolution, mechanical properties, and stress corrosion cracking (SCC) of laser-welded samples fabricated using 304 stainless steel. SCC behavior of this steel has been studied by the slow strain rate test in air and 3.5wt pct NaCl + 0.5 mol/L H₂SO₄ solution. Microhardness profiles and metallographic microstructures of the peened and unpeened samples presented and compared. Martensitic transformation is observed by XRD on the surface layer of the peened and unpeened samples. These improvements correlate with the formation of dense deformation bands and work hardening effects resulting from high strain plastic deformation. In unpeened specimens, tensile-type residual stresses arising from the welding process occur. In addition, the LPwC process also induces tensile-type residual stress on the surface. The tensile-type residual stresses on the weld metal and base metal surface as a result of thermal effect are not disruptive for SCC performance because the mechanical effect of LPwC produces an extremely strong work hardening layer just below the surface. As a result, although LPwC offers a combined effect of thermal and mechanical effects on the material, it is an effective and useful method in terms of both mechanical performance and corrosive behavior.

本研究旨在研究激光喷丸 (LP) 和无涂层 (LPwC) 工艺对使用 304 不锈钢制造的激光焊接样品的亚表面微观结构演变、机械性能和应力腐蚀开裂 (SCC) 的影响。通过在空气和 3.5wt pct NaCl + 0.5 mol/LH ₂ SO _{4 中}的慢应变速率试验研究了这种钢的 SCC 行为解决方案。展示并比较了喷丸和未喷丸样品的显微硬度分布和金相微观结构。通过 XRD 在喷丸和未喷丸样品的表面层上观察到马氏体转变。这些改进与致密变形带的形成和高应变塑性变形导致的加工硬化效应有关。在未喷丸的试样中，会出现焊接过程中产生的拉伸型残余应力。此外，LPwC 工艺还会在表面引起拉伸型残余应力。由于热效应在焊缝金属和母材表面产生的拉伸型残余应力不会破坏 SCC 性能，因为 LPwC 的机械效应会在表面下方产生极强的加工硬化层。因此，