热轧辊等离子束表面合金化层的显微组织及性能

Microstructure and Properties of Plasma Surface Alloying Layer of Hot Roller

传统的热处理不能很好地解决热轧辊在服役期内的失效问题。采用等离子束表面合金化技术对热轧辊表面进行了强化,利用SEM,X射线衍射仪和显微硬度计对合金化层的显微组织、成分、物相和截面显微硬度分布进行了分析。结果表明:合金化层由合金化区、热影响区组成,合金化区域表面较平整,与热影响区以及热影响区与基体之间都形成了良好的冶金结合;由于晶粒细化形成的细晶强化、合金元素固溶于非平衡相形成的固溶强化及合金碳化物析出形成的硬质相弥散强化的综合作用,使合金化层的硬度能够达到685～794 HV2 N,是基材的1.2～1.4倍;合金化处理后抗回火性能良好。

The surface of hot rollers was strengthened by making use of plasma surface alloying technology. The microstructure and phase composition of the surface alloying layer were analyzed by means of scanning electron microscopy and X-ray diffraction, and its cross-sectional hardness distribution was determined with a microhardness meter.It was found that the surface alloying layer consisted of alloyed zone and heat-affected zone. The alloyed zone was relatively smoother.Metallurgical bonding was formed between the alloyed zone and heat-affected zone as well as between the heat-affected zone and substrate. Due to the fine-grain strengthening induced by refining of grains,solid solution strengthening induced by dissolving of alloying elements in unbalanced phases,and dispersion strengthening induced by precipitation of hard carbides, the hardness of the alloying layer could reach as high as 685～794 HV2N, which was 1.2～1.4 times as much as that of the hot roller substrate. In the meantime, the hot rollers after surface alloying treatments possessed good resistance to tempering.