高铬钢轧辊激光熔凝层组织及性能

Structure and Properties of High-Cr Steel Roller by Laser Surface Melting

利用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射(XRD)等手段对高铬钢轧辊激光熔凝层的显微组织、相结构,回火稳定性及高温耐磨性能进行了分析。结果表明,高铬钢激光熔凝处理后剖面区山熔凝区、热影响区(HAZ)和基体组成。基体组织为回火马氏体和网状M7C3型碳化物,激光熔凝处理使基体中脆性碳化物完全溶解,表面熔凝区组织得到高度细化,呈现组织梯度,生成奥氏体和M23C6型碳化物,热影响区由隐晶马氏体、残余奥氏体和弥散的碳化物组成。激光熔凝区由于细晶强化、固溶强化和位错强化的共同作用,回火稳定性明显提高,560℃回火后出现二次硬化,峰值硬度达到672 HV。高温滑动磨损条件下激光熔凝层具有优良的耐磨性能。

Microstructure, phase structure, tempering stability and high-temperature wear resistance of laser melted layer of high-Cr steel roller are analysed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The tests show that after laser treatment the cross section of melted surface is divided into melted zone, heat affected zone （HAZ） and the matrix. The matrix consists of martensite and reticular M7C3 carbides. Laser surface melting leads to the complete dissolution of brittle carbides, and the structure of the melted zone is refined highly consisting of austenite and M23C6 carbide particles. The HAZ consists of crypto-crystal martensite, retained austenite and dispersed carbides. Combined effects of grain refining strengthening, solution strengthening and dislocation strengthening lead to the obvious enhancement of tempering stability of laser melted zone and the hardness reaches a peak of 672 HV at 560 ℃ due to secondary hardening. Laser melted layer has excellent high-temperature wear resistance under high-temperature sliding wear test condition.