目的 研究激光功率对17-4PH不锈钢丝材激光熔覆组织及硬度的影响，以确定最佳激光熔覆功率，为17-4PH不锈钢丝材激光熔覆的应用提供参考。方法 在27SiMn钢活塞杆表面，对17-4PH不锈钢丝材进行了不同激光功率熔覆试验，利用金相显微镜和扫描电子显微镜表征不同激光功率熔覆层的微观组织，使用硬度计测量不同激光功率熔覆层和基体的硬度。结果 当激光功率分别为1600、1800、2000、2200 W时，熔覆层的高度由1119 μm降低到1006 μm，基体的穿透深度和热影响区宽度都随激光功率的增加而增大，熔覆层的组织主要为较短无方向性的板条马氏体。当激光功率为2400、3000 W时，熔覆层的高度、基体的穿透深度和热影响区宽度均随激光功率的增大而增加，最大值分别达到1119、310、638 μm，熔覆层的组织主要由具有方向取向的板条马氏体组成，靠近基材的位置由晶粒细小而致密的等轴晶组成，随着激光功率的增加，熔覆层弥散析出的沉淀颗粒越来越多。此外，熔覆层和热影响区的显微硬度均高于基体，随着激光功率的增加，熔覆层的显微硬度明显增大，最高可达479.4HV0.2。结论 综合考虑激光功率对17-4PH不锈钢丝材激光熔覆组织及硬度的影响，2600 W为最佳激光熔覆功率。

To study the effect of laser power on laser cladding microstructure and hardness of 17-4PH stainless steel wire, ensure the best laser cladding power, and provide an evidence for 17-4PH stainless steel wire to apply for laser cladding, this paper carries out the laser cladding test for 17-4PH stainless steel wire on the surface of 27SiMn steel piston rod, observes and presents the microstructure of cladding layer under various laser powers by metallographic microscope and scanning electron microscope, and measures the hardness of cladding layer and substrate by hardness tester at different laser powers. It is found that the height of cladding layer is decreased from 1119 μm to 1006 μm, and the penetration depth of the substrate and the width of the heat-affected zone are increased with the increase of the laser power when the laser power is 1600 W, 1800 W, 2000 W and 2200 W, respectively. Its microstructure is mainly composed of shorter lath martensite without directionality. Besides, when the laser power is 2400 W and 3000 W, the height of the cladding layer, the penetration depth of the substrate and the width of the heat-affected zone increase as the laser power is increased, with the maximum up to 1119 μm, 310 μm and 638 μm, respectively. Its microstructure consists of lath martensite with directional orientation, and dense equiaxed crystals close to substrate. Meanwhile, the precipitation particles are increased with the increase of laser power. In addition, micro-hardness of the cladding layer and the heat-affected zone is higher than that of the substrate. Its hardness is up to 479.4HV0.2 as the laser power is increased. Therefore, it is concluded that 2600 W is the best laser cladding power, considering the influence of laser power on laser cladding structure and hardness of 17-4PH stainless steel.