40Cr曲面基体激光熔覆W6Mo5Cr4V2性能

Performance of W6Mo5Cr4V2 laser cladding on 40Cr curved substrate

为了利用激光熔覆技术实现模切机刀辊刀刃的增材制造,以曲率半径、熔覆轨迹、搭接率等为影响因素,在40Cr曲面基体上进行W6Mo5Cr4V2粉末的多道激光熔覆正交试验研究,并对熔覆层的残余应力、显微硬度以及显微组织结构进行分析。结果表明,保护气流量对残余应力变化影响显著,当工艺参数为激光功率1 800 W、扫描速度10 m/s、保护气流量400 g/min、曲率半径60 mm、搭接率30%、周向熔覆时,残余应力达到最小值。当残余应力满足成形要求时,显微组织的结晶形态从熔覆层顶部到结合区由平面晶向树状晶发展,熔覆层没有缺陷且与基体实现了良好的冶金结合。同时,显微硬度值从基体到熔覆层顶部呈阶梯状增长式分布,熔覆层的显微硬度平均值均在60HRC以上,满足模切机刀辊刀刃的硬度要求。

In order to realize the additive manufactured on the blade edges of die-cutting machines by using laser cladding technology,o rthogonal tests of multi-pass laser cladding with high-speed steel powder W6Mo5Cr4V2 on the curved substrate 40Cr were carried out. Process parameters which included the radius of curvature, cladding trajectory and the lap-over ratio,etc. were taken as the influencing factors. The residual stress,micro-hardness and microstructure of the cladding layer were analyzed. The results showed that the flow of protective gas had a significant effect on the residual stress. The minimum residual stresses were obtained under the laser power of 1 800 W, the scanning velocity of 10 m/s, the protective gas flow of 400 g/min, the curvature radius of 60 mm and the lap-over ratio of 30% with a circumferential cladding direction. The crystal morphology from the top of the cladding layer to the bonding zone was developed from the plane crystal to the dendrite. Besides,no defects in the cladding layer were observed and a metallurgical bonding between powders and substrate was achieved. In addition,the micro-hardness value experienced a stair-step increase from the substrate to the top of cladding layer. The average micro-hardness was more than 60 HRC,which could meet the hardness requirements of blade edges on die-cutting machines.