稀土氧化物及合金元素对堆焊金属显微组织的影响

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

采用金相显微镜对堆焊金属的显微组织进行了观察,用X射线衍射仪(XRD)对堆焊金属中相结构进行了分析,用扫描电镜(SEM)及能谱仪(EDS)对断口形貌及夹杂物进行了观察分析.结果表明,在含有Cr,Mn,Mo,N i等合金元素的焊条药皮中添加稀土氧化物,其堆焊金属组织为细针状铁素体,断口为细韧窝状,且分布均匀.而未添加稀土氧化物的堆焊金属组织为粗针状铁素体及少量珠光体,断口中存在准解理断裂形貌.添加稀土氧化物后,堆焊金属中夹杂物类型发生改变,形状近似球形,尺寸均在6μm以下,且弥散分布于堆焊金属中.

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.