In the present study, laser shock peening (LSP) was employed to enhance the rotating bending fatigue life of 1Cr12Ni3Mo2VN martensitic stainless steel used in steam turbine blades, addressing the issue of insufficient fatigue performance in these components. The aim of this study was to investigate the effect of LSP on the microhardness, residual stress, and rotating bending fatigue life of 1Cr12Ni3Mo2VN steel samples. The microhardness of LSP-treated samples was increased by 10.5% (LSP-3J sample) and 15.3% (LSP-4J sample), respectively, compared to high-frequency hardening samples. The residual compressive stress of the LSP-4J sample was the largest, reaching −689 MPa, and the affected layer depth was about 800 μm. Fatigue tests showed that the number of cycles at the fracture point for the LSP-3J and LSP-4J samples increased by 163% and 233%, respectively. The fatigue fracture morphology of the four samples showed that the microhardness and residual compressive stress distribution introduced by LSP could effectively inhibit the initiation of surface cracks, slow down the crack growth rate, and improve the rotating bending fatigue life of 1Cr12Ni3Mo2VN.

In the service process of gears, premature fatigue failure or fracture of gears is often caused by poor surface performance. 20CrNiMo steel is a commonly used material for gears. Laser-shock peening (LSP), carburizing treatment (CT), and hybrid modification of carburizing treatment and laser-shock peening (LSP + CT) were carried out to improve the performance of 20CrNiMo steel. The hardness, residual stress, microstructure, subgrain size, and toughness of the samples were analyzed following various modification methods. It was observed that the properties of the composite-modified gradient structure materials achieved through carburizing and laser-shock peening were superior to those modified using single methods. After the composite treatment of carburizing and laser shocking, the samples exhibited the most significant increase in hardness, up to 916HV0.1, with a surface layer experiencing residual compressive stress as low as −635 MPa. Simultaneously, a gradient microstructure was formed on the surface layer, with 80% of the crystallites being in the nanoscale range. Furthermore, the toughness was notably enhanced. Experimental results confirm the improvement in the properties of 20CrNiMo samples, resulting in the creation of a functionally graded material through the composite treatment of carburizing and laser shocking.