高速钢表面激光熔覆高硬涂层的组织性能

Microstructure and properties of surface coating on a high speed steel by laser cladding

为实现高硬焊丝激光熔覆修复高速钢刀具的目的,采用Nd:YAG脉冲激光器,利用966T高硬度焊丝在M2高速钢基材表面进行激光熔覆试验获得高硬涂层。采用光学显微镜、显微硬度计、洛氏硬度计和高速往复磨损摩擦试验机等试验设备,对熔覆涂层的成分、显微组织、显微硬度、常温硬度、红硬性和耐磨性能进行了研究。结果表明,熔覆涂层化学成分与基材的化学成分相近;熔覆涂层上层由等轴晶和树枝晶组成,下层以柱状树枝状晶为主,无晶粒粗大现象;熔覆涂层硬度在60 HRC以上、熔覆层涂层的耐磨性与基材相近,满足高速钢刀具的修复要求。

In order to repair high speed steel（HSS） tools by laser cladding with welding wire,high hardness 966 T welding wire was used to fabricate high hard coatings on the surface of a M2 HSS.Composition,microstructure,microhardness,rockwell hardness,red hardness and wear resistance of the cladding coatings were examined by optical microscope,microhardness,rockwell hardness and friction-wear tests.The results show that the chemical composition of the coatings is similar to the chemical composition of the substrate.The microstructure of the upper layer in the coatings consists of equiaxed grains and dendritic crystals while that of the bottom layer is mainly composed of dendrites,and no coarsened grains are observed in the laser cladding coatings.The hardness of the coatings is higher than 60 HRC.The base metal and the cladding coatings exhibit similar wear resistance,and the laser cladding coatings can be used for the repairing of the high speed steel cutting tools.