激光熔覆滑靴材料基体熔覆层裂纹的产生机理

Formation Mechanism of Crack in Cladding Layer of Slipper Materials Matrix Prepared by Laser Cladding

采用两层熔覆方式的激光熔覆技术在27SiMn钢表面熔覆铁基合金粉末,其激光工艺参数为:激光功率2300 W、熔覆速度16 mm/s、搭接率0.5。借助于光学显微镜和扫描电镜,从熔覆层厚度、组织形貌、析出相、元素偏析及裂纹扩展等方面,研究了裂纹产生机理。结果表明:元素偏析在熔覆层与基体的过渡区较为明显;熔覆层与基体的过渡区厚度大于第一层熔覆层与第二层熔覆层的过渡区的;激光熔覆过程中第一层熔覆层底部产生有较强取向性的粗大枝晶组织,裂纹易于在其上产生扩展且断裂类型为穿晶断裂。

Fe-based alloy powder was cladded on the surface of 27SiMn steel by laser cladding technique with two layer cladding methods.The laser technology parameters are that,the laser power is 2300 W,the cladding speed is 16 mm/s and the lap rate is 0.5.The formation mechanism of the crack was studied by optical microscope and scanning electron microscope from the aspects of cladding layer thickness,microstructure morphology,precipitated phase,segregation of elements and the crack propagation.The results show that obvious element segregation appears in the transition zone of the cladding layer and the matrix.The thickness of the transition zone between cladding layer and matrix is greater than that of the first layer cladding layer and the second layer cladding layer.The coarse dendritic structure with strong orientation appears at the bottom of the first layer of the laser cladding.The crack is easy to be extended and the propagation of the crack is dominated by transgranular fracture.