在试验的基础上 ,探讨了镧基轻稀土、钇基重稀土对镍铁型铸铁焊缝的石墨化及石墨形态的影响。结果显示 ,镧具有较强的石墨化效果 ,能减少或消除焊缝组织中的晶间共晶组织 ,所获焊缝硬度较低 ;钇基重稀土具有较弱的石墨化效果和较强的石墨球化效果 ,所获石墨球细小均匀 ,但易形成晶间共晶组织 ,使焊缝硬度增高。用气泡理论对实验结果进行了较好的解释 Based on the experiments, the effects of lanthanum-based light rare earths and yttrium-based heavy rare earths on graphitization and graphite morphology of Ni-Fe-based cast iron welds were discussed. The results show that lanthanum has a strong graphitization effect, which can reduce or eliminate the intergranular eutectic structure in the weld microstructure, and the hardness of the obtained weld is low. The yttrium-based heavy rare earth has a weak graphitization effect and strong Graphite ball effect, graphite balls obtained small and uniform, but easy to form intergranular eutectic structure, the weld hardness increases. The experimental results are well explained by bubble theory