增材制造成形方向对冲蚀磨损性能的影响*

增材制造的零部件由于逐层制造而具有各向异性,为研究成形方向对冲蚀磨损性能的影响,采用激光同轴送粉工艺制备逐层堆积的铁基合金熔覆层,并对其显微硬度、金相组织、微观组织及冲蚀后表面形貌进行分析。水平表面(XY)、横截面(YZ)和纵截面(XZ)的显微观察表明:各方向的微观组织结构与热流方向、熔合线密切相关,进而显著影响了细晶区的分布和数量;堆积熔覆层水平上表面的平均显微硬度最大,横截面的平均显微硬度次之,纵截面的平均显微硬度最低;由于冲蚀过程中的加工硬化,弱化了各成形方向之间冲蚀磨损性能的差异,进而导致各成形方向上相似的冲蚀磨损形貌。冲蚀磨损试验表明,堆积熔覆层的冲蚀机制以微切削和犁削为主,堆积熔覆层水平表面的抗冲蚀磨损性能最好,纵截面的抗冲蚀磨损性能最差。

Effect of Additive Manufactured Building Direction on the Erosion Wear Resistance

Parts made of additive are anisotropic due to layer by layer manufacturing.In order to study the effect of building direction on the erosion wear performance,the laser coaxial powder feeding process was used to prepare the Fe-based alloy cladding layer by layer,and the microhardness,metallographic structure,microstructure of the Fe-based cladding layer and the surface morphology after erosion were analyzed.The results of microscopic observation on horizontal surface (XY),cross section (YZ) and longitudinal section (XZ) show that the microstructure of each direction is closely related to the direction of heat flow and fusion line,and thus significantly affects the distribution and size of fine grain areas.The average microhardness of the horizontal surface of the deposited clad layer is the largest,the average microhardness of the cross section is the second,and the average microhardness of the longitudinal section is the lowest.Due to the work hardening in the process of erosion,the difference of erosion wear performance between different building directions is weakened,which leads to similar erosion wear morphology in each building direction.The results of erosion wear test show that the erosion mechanism of the deposited clad layer is mainly micro cutting and ploughing.The horizontal surface of the deposited clad layer has the best erosion wear resistance,and the longitudinal section has the worst erosion wear resistance.