铸铁表面Cr合金化层的微观结构及耐磨性能

采用聚焦光束重熔预涂单质Cr粉的方法对灰铸铁进行了表面改性处理,用SEM,EDS,Xray等分析了合金化层的微观组织特点及其物相组成,用环块摩擦试验测试了合金化层的耐磨性能。试验结果表明,聚焦光束重熔Cr粉合金化层的耐磨性较灰铸铁基体明显提高,合金化层的耐磨性随着Cr粉预涂量的增加而提高,表面磨损机制由犁沟和划伤转变为表面塑性变形。其原因在于,随Cr粉预涂量的增加,合金化层微观组织中的富铁α(Fe,Cr)+Cr7C3共晶体基底依次被富铁的α(Fe,Cr)+Cr23C6共晶体和富铬的α(Fe,Cr)铁素体取代。

Microstructure and wear resistance of Cr powder alloying layers on cast iron

The grey cast iron was alloyed by light beam remelting the preplacing layer of Cr powder. The microstructure and phase of alloying layers were analyzed by SEM,EDS and X-ray diffraction. The ring-block wear test was use to evaluate the wear resistance of alloying layers. The results show that the wear resistance of Cr powder alloying layer is greatly higher than that of grey cast iron. The wear resistance is heightened with the increases of preplacing mass of Cr powder,and the wear mechanism changes from furrow and scratch to surface plastic deformation. The reason is that with the increases of preplacing mass of Cr powder,the eutectic matrix of α-(Fe,Cr) rich in Fe+Cr₇C₃ in alloying layer is replaced by the eutectic of α-(Fe,Cr) rich in Fe+Cr₂₃C₆,then replaced by α-(Fe,Cr) ferrite rich in Cr.