等离子熔覆铁基涂层组织结构及热影响区特点

采用等离子束作为热源,在16Mn钢上熔覆一层铁基合金涂层.分析了涂层的组织结构;并通过对等离子熔覆热循环的特点和冶金过程的探讨,着重对钢基体的热影响区进行了测试分析;将热影响区划分为过热区、完全相变区和不完全相变区.过热区显微组织粗大,有魏氏体产生,硬度下降;完全相变区晶粒细化,硬度较高;不完全相变区组织只有部分发生转变,晶粒大小不均匀.过热区魏氏体组织的产生,使热影响区有脆化的倾向.

Microstructure of the Fe-based coating by plasma cladding and characteristics of its heat-affected zone

With plasma as heat source, Fe-based alloy powder was cladded on the surface of 16Mn steel and the microstructure and phases of the clad coating were analyzed. The thermal cycle characteristics of plasma cladding and the cladding process were discussed. The heat-affected zone was studied and divided into three zones, i.e., overheated zone, perfect phase transformation zone and imperfect phase transformation zone. In the overheated zone, the microstructure was coarse, Widmanstaten structure generated and the hardness fell down. In the perfect phase transformation zone, the microstructure was refined, and hardness was higher. In the imperfect phase transformation zone, part phase transformation generated, and the microstructure was nonhomogeneous. The Widmanstaten structure in the overheated zone made the heat-affected zone brittle.