液压支架材料表面激光熔覆Ni60高硬耐磨涂层的性能

Performance of Ni60 high hardness wear-resistant layer prepared by laser cladding on hydraulic support materials surface

为实现损伤液压支架立柱的再制造修复,采用激光熔覆技术在液压支架立柱材料27SiMn钢表面制备Ni60合金涂层。通过正交试验法研究激光工艺参数对涂层稀释率的影响规律并确定最优工艺参数。利用超景深显微镜、显微硬度计及摩擦磨损试验机等分析了涂层的显微组织、硬度及耐磨性能。结果表明,影响熔覆层稀释率的因素由大到小依次为:激光功率>扫描速度>送粉速度>离焦量。以稀释率为指标的最佳工艺参数组合为A_(1)B_(3)C_(3)D_(3),即激光功率为1500 W、扫描速度为22 mm/s、离焦量为+1 mm、送粉速度为12 g/min。熔覆层整体晶粒细小均匀,涂层上部主要由等轴晶组成,中部主要由等轴晶和树枝晶组成,下部则主要由沿熔合界面生长的胞状晶及柱状晶组成。熔覆层的平均硬度值为729.5 HV0.5,是基体硬度的2.32倍,最高硬度出现在熔覆层顶部的等轴晶区,为756.9 HV0.5。熔覆层的显微硬度压痕棱边平直、四角光滑无裂纹,具有良好的韧性。熔覆层的摩擦系数明显低于基材,且稳定性好于基材,磨损量仅为基材的58%,熔覆层的磨损机制为磨粒磨损和轻微的黏着磨损。

To achieve remanufacturing and repair of damaged and failed hydraulic support columns,a Ni60 alloy layer was prepared on the surface of 27SiMn steel material for hydraulic support columns using laser cladding technology.The influence of laser process parameters on dilution rate of the cladding layer was studied through orthogonal experimental method,and the optimal process parameters were determined.Microstructure,hardness and wear resistance of the cladding layer were analyzed by means of ultra depth-of-field microscopy,microhardness tester and friction and wear testing machine.The results show that the factors that affect the dilution rate of the cladding layer,in a descending order by influence,are:laser power>scanning speed>powder feeding speed>defocusing distance.The optimal process parameter combination based on dilution ratio is A1B3C3D3,which includes a laser power of 1500 W,a scanning speed of 22 mm/s,a defocusing distance of+1 mm,and a powder feeding speed of 12 g/min.The overall grain size of the cladding layer is fine and uniform.The upper part of the cladding layer is mainly composed of equiaxed crystals,the middle part is mainly composed of equiaxed crystals and dendrites,and the lower part is mainly composed of cellular and columnar crystals growing along the fusion interface.The average hardness of the cladding layer is 729.5 HV0.5,which is 2.32 times of the substrate,and the highest hardness occurs in the equiaxed grain zone at the top of the cladding layer,which is 756.9 HV0.5.The micro hardness indentation of the cladding layer has straight edges,smooth corners and no cracks,and the cladding layer has good toughness.The friction coefficient of the cladding layer is significantly lower than that of the substrate,and the stability is better.The wear mass loss of the cladding layer is only 58% of the substrate,and the wear mechanism is abrasive wear and slight adhesive wear.