35CrMo钢表面铁基激光熔覆层的组织和耐磨性能

采用CO2激光熔覆装置将LC3530铁基粉熔覆在35CrMo钢基体表面,研究了熔覆层的显微组织、硬度和耐磨性能,并与基体的进行对比。结果表明:基体组织为回火索氏体,晶粒尺寸在20μm左右,而熔覆层的组织为均匀细小的等轴晶,晶粒尺寸大多在8μm;基体的平均硬度为254.1HV,而熔覆层的平均硬度为640.5HV,且硬度分布更加均匀;在相同试验条件下,熔覆层试样的磨损量仅为基体试样的1/7,磨损系数是基体试样的1/5,且磨损后熔覆层试样的表面粗糙度较磨损前的大幅下降,表明激光熔覆后35CrMo钢的耐磨性能得到显著提高;基体试样的磨损机制为犁削磨损,而熔覆层试样的磨损机制为微观切削,其优异的耐磨性能与含有铁、铬、钼和碳等元素的高硬度合金碳化物的形成有关。

Microstructure and Wear Resistance of Iron-Based Laser Cladding Layer on Surface of 35CrMo Steel

LC3530 iron-based powder was cladded on the surface of 35 CrMo steel substrate by CO2 laser cladding device.The microstructure,hardness and wear resistance of cladding layer were studied and compared with those of substrate.The results show that the microstructure of the substrate was tempered sorbite,and the grain size was about 20μm;the microstructure of the cladding layer was uniform and fine equiaxed grains,and the grain size was mostly 8μm.The average hardness of substrate was 254.1 HV,while that of cladding layer was 640.5 HV and the distribution of hardness was more uniform.Under the same test conditions,the wear loss and wear coefficient of the cladding layer sample were only 1/7 and 1/5 of those of the substrate,respectively;the roughness of the cladding layer sample after wear was significantly lower than that before wear,indicating that the wear resistance of 35 CrMo steel was significantly improved after laser cladding.The wear mechanism of the substrate was plough wear;the wear mechanism of the cladding layer was microscopic cutting,and its excellent wear resistance was related to the formation of high hardness alloy carbides containing iron,chromium,molybdenum and carbon.