激光冲击对K403合金激光熔覆修复微观组织和性能的影响

针对激光熔覆修复K403镍基高温合金构件组织粗大和力学性能下降的问题，提出采用激光冲击强化技术对修复区进行表面强化。利用SEM观察不同区域微观组织，利用显微硬度、残余应力和高温拉伸强度测试研究其力学性能。结果表明，激光冲击强化细化试样表层晶粒；强化后，试样基体区和熔覆区表面硬度分别提高21%和8%，影响深度约0.8 mm；激光冲击在试样表层引入约610 MPa且均匀分布的残余压应力，影响深度层达1.2 mm，经保温处理后，应力释放约18%，但在表面仍残留较大的残余压应力；激光冲击提高了材料高温拉伸强度约15%，解决了激光熔覆修复K403镍基构件力学性能下降的问题。

Effect of laser shock processing on microstructure and properties of K403 alloy repaired by laser cladding

Aiming at bulky grains and declination of mechanical properties of K403 nickel-alloy repaired by laser cladding, the laser shock processing(LSP) technology was applied to strengthen the surface of repaired region. The microstructuree was observed through SEM and the mechanical properties were represented by testing microhardness, residual stress and high temperature tensile strength. The results show that the LSP refines crystalline grain of the surface of the specimen. After LSP, the surface hardness of matrix region and cladding zone were improved by 21% and 8% respectively. The hardness affected depth of the LSP was about 0.8 mm. Besides, about 610 MPa and equally distributed residual compressed stress was generated and the affected depth was about 1.2 mm. After thermal retardation, the residual compressed stress was released by about 18%, but high residual compressed stress also existed on surface. The high temperature tensile strength was increased by about 15% after LSP. The problem of mechanical properties decrease of K403 nickel-alloy repaired by laser cladding was solved.