农业拖拉机主轴激光熔覆再制造修复研究

Laser CladdingRemanufacturingand Repair of Agricultural Tractor Spindle

为了实现拖拉机主轴的激光熔覆再制造修复,采用激光熔覆技术在主轴材料40Cr轴面上制备Ni60A合金涂层。通过光学显微镜、显微硬度计、摩擦磨损试验机对比分析离焦量对熔覆层宏观形貌、微观组织、显微硬度及耐磨性的影响。试验结果表明:离焦量为8mm时,熔覆层表面光滑、平整,结合面无气孔、裂纹及夹渣等缺陷,熔覆层与基体间形成了良好的冶金结合;熔覆层中部为细小的等轴晶,两侧为树枝晶和柱状晶,底部为沿基体表面生长的平面晶组织;最高硬度出现在熔覆层中部,其显微硬度达660HV,是基体硬度的2倍;在相同磨损条件下,熔覆层的磨损失重仅为基体材料的33%。随着离焦量增大,熔覆层表面粗糙度增加,硬度不均匀性增大,耐磨性能随之降低。

In order to realize the laser cladding remanufacturing and repair of tractor spindle,Ni60 Aalloy coating was prepared by laser cladding technology on spindle material 40 Cr axial surface.The effects of defocusing amount on the macromorphology,microstructure,microhardness,and wear resistance of the cladding layer were analyzed by optical microscope,microhardness tester,and friction wear tester.The results show that when the defocusing amount is 8 mm,the surface of the cladding layer is smooth and flat,and there are no defects such as pores,cracks,and slag inclusion on the bonding surface.In the middle of the cladding layer,there are fine equiaxial crystals,dendrites and columnar crystals on both sides,and planar crystal structures growing along the surface of the substrate at the bottom.The highest hardness was found in the middle of the cladding layer,and its microhardness was up to 660 HV,twice that of the substrate.Under the same wear condition,the wear weight of cladding layer is only 33% of that of matrix material.As the amount of defocusing increases,the surface roughness of cladding layer increases,the hardness non-uniformity increases,and the wear resistance decreases.