目的 通过调控熔覆层的凝固组织，在提升316L激光熔覆层耐磨性的同时，减小添加WC颗粒对冲击韧性的削弱。方法 将316L粉末与WC颗粒球磨混合，采用激光熔覆技术，在316L钢基体表面制备3种质量分数为30%的不同WC粒度(75~150 μm颗粒的WC(L)组，25~45 μm颗粒的WC(S)组，混合粗细粒度颗粒的WC(L/S)组)增强的合金复合涂层。利用扫描电镜(SEM)、X射线衍射仪等对复合涂层的微观组织和物相进行分析，并使用摩擦磨损试验机和冲击韧性试验机测试室温下的摩擦磨损和冲击韧性。结果 混合粒度WC颗粒在316L熔覆层中的使用能有效减少大粒径WC颗粒在凝固过程中的沉降现象，提升了颗粒分布均匀性，平均自由粒子间距离(λ)从WC(L)组的230 μm减至WC(L/S)组的160 μm，降低了30.43%。根据电子背散射衍射(EBSD)结果可知，WC颗粒及其分解产物在凝固过程中能够阻碍晶粒长大，并提供非均质形核点，从而细化晶粒。熔覆层的摩擦磨损性能随着WC颗粒粒度的变化而变化，WC(L/S)组熔覆层的磨损体积仅为无WC组的3.33%，WC(L)组体积损失率的76.60%，WC(S)组体积损失率的73.02%。混合粒度WC的使用降低了WC颗粒对熔覆层韧性的削弱，在相同质量分数下，WC(L/S)组熔覆层的冲击功分别为WC(L)组的104.86%，为WC(S)组的117.97%。结论 在使用微米尺寸WC颗粒且质量分数均为30%时，WC颗粒的粒度配比对熔覆层的摩擦磨损性能和冲击韧性均有显著影响，其中粗、细混合的粒度配比是一种较好的选择。

For laser cladding of tungsten carbide reinforced iron-based layers at low mass fractions, the poor distribution of tungsten carbide results in insufficient strengthening effect. In addition, the impact toughness is weakened significantly and 316L laser cladding layer also has poor wear resistance performance in the current research. In this study, two kinds of spherical tungsten carbide particles with large size difference were used to improve the distribution of tungsten carbide particles in the cladding layer from the principle of the difference of force and motion law of tungsten carbide in the molten pool. The decomposition of tungsten carbide particles in the molten cladding was also explored to control the amount of tungsten carbide decomposition at a level that guaranteed the bond strength without affecting the performance. By ball milling 316L powder with WC particles and using laser cladding technology, three types of alloy composite coatings with 30% WC particles of different sizes (WC(L) group with 75-150 μm particles, WC(S) group with 25-45 μm particles, and WC(L/S) group with mixed coarse and fine particles) were prepared on the surface of a 316L steel substrate. The microstructure and physical phase of the composite coatings were analyzed with an optical microscope, a scanning electron microscope (SEM) and an X-ray diffractometer. The friction and wear properties and the impact toughness at room temperature were tested with a friction and wear tester and an impact toughness tester, and the post-test surface morphology was observed by confocal microscopy and SEM. Experiments showed that the use of mixed particle size WC in the 316L cladding effectively reduced the settling phenomenon of large particles during solidification and improved the uniformity of particle distribution, and the average free inter-particle distance (λ value) was reduced from 230 μm to 160 μm in the WC(L) group, with a reduction of 30.43%. Meanwhile, the WC particles and their decomposition products were found to hinder grain growth and provide non-homogeneous nucleation points to refine the grains during the solidification process after being characterized by EBSD. The friction and abrasion performance of the fused cladding layer varied with the particle size of WC particles, and the friction and wear volume loss of the fused cladding layer in the WC(L/S) group was only 3.33% of that of the group without WC, 76.60% of that in the WC(L) group, and 73.02% of that in the WC(S) group. The use of mixed particle size WC reduced the toughness weakening of the fused cladding layer by WC particles, and the impact work of the fused cladding layer at this mass fraction was 104.86% of that of the WC(L) group and 117.97% of that of the WC(S) group, respectively. When utilizing micron-sized WC particles at 30wt.% WC content, the particle size distribution significantly affects the wear resistance and impact toughness of the cladding layer. A mixed distribution of coarse and fine particles proves to be an optimal choice.