能量密度对激光熔覆钼层组织及性能的影响

Effect of Energy Density on Structure and Properties of a Laser Cladding Molybdenum Layer

为了提高铌合金的综合性能,利用激光熔覆技术,通过预置粉末成功制备了钼熔覆层,采用金相显微镜、扫描电子显微镜、X射线衍射仪、显微硬度计、摩擦磨损试验机分析了不同能量密度获得的激光熔覆层微观组织、裂纹率、硬度及耐磨性。结果表明,当能量密度为6.67 J/mm^(2)时,熔覆层表面平整,熔道规则连续。当能量密度从5.56 J/mm^(2)上升到8.90 J/mm^(2)时,熔覆层硬度从420 HV_(0.05)提高到480 HV_(0.05),磨损率从12.24×10^(-3) mg/m下降至7.59×10^(-3) mg/m,降低了38%;熔覆层物相主要为Nb-Mo固溶体,其中Mo质量分数达到22.3%;经10%的HF酸腐蚀5 h,没有腐蚀出熔覆层晶界,耐HF酸腐蚀性明显提高。综上所述,激光熔覆制备钼熔覆层可以提高铌合金的综合性能。

A molybdenum cladding layer was prepared by laser cladding technology with a preset powder to improve the comprehensive properties of Nb alloy.The microstructure,crack rate,hardness,and wear resistance of the laser cladding layer with different energy densities were analyzed using a metallographic microscope,scanning electron microscope,X-ray diffraction,microhardness tester,and friction and wear tester.The findings show that when the energy density was 6.67 J/mm^(2),the surface of the cladding layer was smooth and the weld path was regular and continuous.The hardness of the cladding layer increased from 420 HV_(0.05) to 480 HV_(0.05) when the energy density was increased from 5.56 J/mm^(2) to 8.90 J/mm^(2),while the wear rate decreased from 12.24×10^(-3) mg/m to 7.59×10^(-3) mg/m,showing a 38%decrease.The phase of the cladding layer was mainly a Nb-Mo solid solution,with a Mo content of up to 22.3%.After 5 h of corrosion with 10%HF acid,no grain boundaries of the cladding layer were found,and the corrosion resistance of the cladding layer to HF acid showed significant improvement.In conclusion,the comprehensive performance of the niobium alloy can be improved by preparing a molybdenum cladding layer by laser cladding.