采用手工非熔化极惰性气体钨极保护焊将ERNiCrMo-3镍基合金焊丝堆焊于X70管线钢表面，分析了堆焊层/母材界面处的显微组织、元素分布和硬度分布，并采用电解充氢方法研究了氢致裂纹萌生位置和扩展方式。结果表明：X70管线钢表面镍基合金堆焊层/母材界面热影响区中细晶区的组织为细小铁素体和少量珠光体，靠近熔合线粗晶区的组织为粗大的铁素体，熔合区的组织为马氏体，堆焊层的组织为树枝状奥氏体；堆焊层冲击断口呈韧性断裂特征，母材断口呈解理或准解理脆性断裂特征，熔合区断口呈由浅韧窝+准解理组成的具有变形特征的混合过渡特征；堆焊层和熔合区的硬度均高于母材的；堆焊层表面氢致裂纹萌生于Al₂O₃和单质硅夹杂物处，扩展方式为沿晶和穿晶扩展。

ERNiCrMo-3 nickel-based alloy welding wire was deposited on the surface of X70 pipeline steel by manual tungsten inert gas welding. The microstructure, element distribution and hardness distribution of the interface between the surfacing layer and base metal were analyzed. The initiation and propagation mode of hydrogen induced cracks were studied by electrochemical hydrogen charging method. The results show that the microstructure of fine grained region in heat affected zone of the interface between nickel-based alloy surfacing layer on X70 pipeline steel and base metal was fine ferrite and a small amount of pearlite. The microstructure of coarse grained region near fusion line was coarse ferrite. The microstructures of the fusion zone and surfacing layer were martensite and dendritic austenite, respectively. The impact fracture of surfacing layer showed a ductile fracture feature, the base metal showed a cleavage or quasi-cleavage brittle fracture feature, and fusion zone showed a mixture transition feature with deformation characteristics composed of shallow dimples and quasi-cleavage. The hardness of both the surfacing layer and fusion zone was higher than that of the base metal. The hydrogen induced cracks of the surfacing layer originated around the inclusions of Al₂O₃ and monatomic silicon, and propagation mode was intergranular and transgranular propagation.