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为研究合金钢稀土渗氮层硬度增强机理,采用扫描电镜、透射电镜和显微硬度计等测试方法,对3种常用合金钢的常规渗氮和稀土渗氮的显微组织和渗层硬度进行分析。结果表明:稀土原子的渗入导致钢表层晶粒缺陷密度增加,在缺陷处生成气团,使晶粒内氮原子偏聚区增多,晶粒亚结构细化,导致硬度提高;同时稀土原子沿晶界渗入和扩散,会诱导晶界迁移,使晶界表面突壁和扭折密度发生变化,可以使常规渗氮中容易析出的网状ε氮化物减少,降低了沿晶界断裂的可能性,强化了晶界。这些作用的叠加,提高了渗氮层的硬度和材料的力学性能。
In order to study the hardness enhancement mechanism of RE-nitrided layer in alloy steel, the microstructures and the hardness of nitrided layer in conventional nitriding and nitriding of three kinds of alloy steel were studied by scanning electron microscopy, transmission electron microscopy and microhardness tester analysis. The results show that the infiltration of rare earth atoms leads to the increase of the density of grain defects in the steel surface and the generation of air masses in the defects, which increases the segregation of nitrogen atoms in the grain and the refinement of the grain structure, resulting in the increase of hardness. Meanwhile, Infiltration and diffusion, will induce grain boundary migration, so that the grain boundary surface wall and kink distorted density changes, the conventional nitriding can easily precipitate out of the network epsilon nitride reduced, along the grain boundaries to reduce the possibility of fracture, strengthen The grain boundary. The superposition of these effects increases the hardness of the nitrided layer and the mechanical properties of the material.