【摘要】 利用等离子束送丝熔覆技术在50Mn2合金结构钢表面制备耐磨熔覆层,研究主弧电流和扫描速度等工艺参数对熔覆层宏观形貌、显微组织及显微硬度影响。研究表明:主弧电流和扫描速度是影响熔覆层质量主要因素。随主弧电流增大,熔覆层焊道更连续且熔宽增大、余高先减后增,熔覆层中部组织形貌由胞状晶向树枝晶和等轴晶转变,组织以马氏体和铁铬碳共晶化合物为主,显微硬度较基体提高2~3倍;扫描速度越高,熔覆层焊道越不连续且易出现凹陷,熔宽和余高减小,显微组织形貌由胞状晶向树枝晶转变,其相组织仍以马氏体和铁铬碳共晶化合物为主,显微硬度随着扫描速度增大而增大,比基体硬度有很大提高。更多还原

【Abstract】 A wear resistant coating was produced on the surface of 50Mn2 alloy structural steel by wire cladding of plasma. The effects of different working currents and scanning speeds on the morphology,microstructure and microhardness of the cladded hard facing layer were investigated. The results show that the working current and scanning speed are the major factors that influence the quality of plasma cladded layer. With increasing working currents, the trace and width of the cladded layer becomes more continuous and wider while the height firstly decreases and then subsequently increases. The microstructure in middle zone of the cladded layer evolves from cellular dendrite to dendrite and equiaxed grain and is mainly composed of martensite and Fe-Cr-C eutectics. The microhardness of the cladded layer is 2-3 times as that of the substrate. The increase in scanning speed leads to discontinuous trace and narrower width of the cladded layer and also some pit defects. The microstructure in the cladded middle zone primarily changes from cellular dendrite to dendrite and still consists of martensite and Fe-Cr-C eutectics. Rising scanning speed results in higher microhardness in the cladded layer,which is more than the substrate.更多还原