采用金属粉型药芯焊丝自保护明弧焊制备 Cr9Mn6Nb2WVSiTi 奥氏体耐磨堆焊合金，借助 XRD，SEM， EDS及光学显微镜研究外加WC颗粒对其显微组织及耐磨性的影响。结果表明，随焊丝药芯中WC增加，奥氏体晶粒细化，沿晶分布的多元合金化碳化物数量增加。初生γ-Fe相原位析出了(Nb,Ti,V)C相和残留WCx颗粒，起到晶内弥散强化作用，沿晶分布的(Nb,Ti,V)C和M6C(M=Fe,Cr,Mn,V,W)相隔断了网状或树枝状的沿晶M7C3相，使其细化、断续分布而提高合金韧性，减轻沿晶碳化物数量增加的不利影响。硬度和磨损测试结果显示，明弧堆焊奥氏体合金洛氏硬度仅为40～47，但其磨损质量损失低于高铬铸铁合金，具有良好耐磨性；随外加WC含量提高，奥氏体合金晶内和晶界显微硬度差异显著减小，合金表面趋于均匀磨损而改善耐磨性。该奥氏体合金的磨损机制主要是磨粒显微切削，适用于带有一定冲击载荷磨粒磨损的工况下使用。%Cr9Mn6Nb2WVSiTi austenitic wear-resisting hardfacing alloys were deposited by metal-cored wire self-shielded open arc welding. The effects of WC addition on the microstructure and the wear resistance were investigated by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer(EDS) together with optical microscopy(OM). The results show that with increasing WC content in metal-cored wire, the size of austenitic grain decreases, and the volume fraction of intergranular complex carbides increases. The in-situ (Nb,Ti,V)C grains precipitated from primaryγ-Fe phase as well as the residual WCx grains play a role in dispersion strengthening on the intra-crystalline. (Nb,Ti,V)C and M6C (M=Fe,Cr,Mn,V,W) grains in the cellularγ-Fe intergranular colonies intercept intergranular M7C3 phases in reticular or dendritic shape, and make them finer and discontinuous, which can improve the toughness of hardfacing alloys, and decrease the effect of intergranular carbide increasing. The results of hardness measurement and abrasion testing show that the wear mass loss of these austenitic hardfacing alloys with the bulk hardness of only 40−47 HRC are lower than those of high-chromium cast irons. With increasing WC addition, the microhardness gap between intra-austenitic grains and inter-austenitic grains decrease markedly, and tends to uniformly wear on surface, which can improve the wear resistance. The dominating wear mechanism of austenitic hardfacing alloys is micro-cutting, and it adapts to be used in the abrasive particle working condition with certain impact load.
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