Effects of RE oxide and alloy elements on microstructure of hardfacing metal

The microstructures of the hardfacing specimens for large gear were observed by optical microscopy(OM) and the matrix phase of the hardfacing metals was determined by X-ray diffraction(XRD).Meanwhile,the fractographs and inclusions were analyzed by scanning electron microscopy(SEM) with energy dispersive spectrum(EDS).The results show that,the microstructure of the hardfacing metal is mainly composed of the fine acicular ferrite.The fractograph of the specimen with addition rare earth(RE) oxide(Ce₂O₃) and Cr,Mo,Ni element in electrode coating is uniform and fine dimple addition.However,the microstructure is composed of coarse acicular ferrite and pearlite and the fractograph is composed with dimple and quasi-cleavage in the specimen without RE oxide.The inclusions become spherical and distribute in hardfacing metal dispersively by adding RE oxide in electrode coating,their sizes are smaller than 6 μm.