采用波长为1064 nm、脉冲宽度约为10 ns的激光束对304不锈钢进行双面冲击强化处理(LSP), 利用三维形貌仪观察LSP试样的表面形貌, 采用X射线应力仪测量试样表面的残余应力; 采用伺服液压疲劳试验机对试样进行疲劳试验, 以得到疲劳裂纹扩展速率曲线; 采用扫描电子显微镜观察试样裂纹扩展不同阶段的断口形貌。结果表明：激光冲击强化处理可使试样表面产生最大变形量约为25 μm的塑性变形, 形成最大值为-218 MPa的残余压应力, 并可使裂纹源向试样内部转移; 激光冲击强化能显著降低冲击区域处的裂纹扩展速率。基于疲劳裂纹扩展速率曲线再次验证了激光冲击处理可显著提高304不锈钢的抗疲劳性能。

The 304 stainless steel plates are double-sided shocked by laser beam with a wavelength of 1064 nm and the pulse width of 10 ns, the surface morphology of sample treated by laser shock processing (LSP) is observed by a three-dimensional profilometer, and the residual stress of the specimen surface is measured by an X-ray diffractometer, respectively. And a servo-hydraulic fatigue test machine is employed to implement the fatigue experiments on samples without and with LSP to obtain the fatigue crack growth rate curves. In addition, a scanning electron microscope (SEM) is applied to detect the fracture morphology at different crack growth stages. The experimental results indicate that LSP can not only cause plastic deformation to a maximum value of 25 μm and form compressive residual stress with a maximum value of -218 MPa on the sample surface, bust also transfer the crack source to the inside of the sample. And the crack growth rate at the shocked region is significantly retarded by LSP. The validity of utilizing LSP to improve the fatigue resistance of 304 stainless steel can be verified according to the fatigue crack growth rate curves.