采用对接焊方法，以NiCrMo-6焊条作为填充材料，对板厚9 mm的9Ni钢母材进行了焊接试验.通过光学显微镜(OM)、扫描电子显微镜(SEM)和能谱分析(EDS)等方法对熔焊接头组织进行观察分析.采用纳米压痕技术对熔焊接头中母材(BM)、粗晶热影响区(CGHAZ)、熔合区(FB)和焊缝中心区域(WM)各微区之间的微观组织与力学性能的关系进行表征.辅以接头原位拉伸试验，确定焊接薄弱区.结果表明，焊缝柱状组织中，Fe-Cr，Ni-Cr-Fe等主要析出相在奥氏体基体上弥散分布，热影响区组织以粗板条马氏体及贝氏体为主，板条间逆变奥氏体相已基本消失.纳米压痕试验结果显示，熔焊接头具有突出的抗塑性流变变形能力，粗晶热影响区强度最高，而熔合区强度最低.拉伸断口观察试验进一步显示熔合线区域受撕裂应力影响易发生断裂，为接头薄弱区.
Adopting the butt welding method and using NiCrMo-6 electrode as the filler material, the welding experiment of the 9 mm thickness 9Ni steel base metal was carried out. Through optical microscope (OM), scanning electron microscope (SEM) and energy spectrum analysis (EDS), etc. Method Observe and analyze the structure of fusion welded joint. Nanoindentation technology is used to improve the microstructure and mechanical properties of the base metal (BM), coarse-grain heat affected zone (CGHAZ), fusion zone (FB) and weld center area (WM) in the fusion welded joint. The relationship is characterized. Supplemented by the joint in-situ tensile test to determine the weakened area. The results show that: in the columnar structure of the weld, Fe-Cr, Ni-Cr-Fe and other main precipitation phases are dispersed on the austenite matrix, and the heat-affected zone is mainly composed of coarse lath martensite and bainite. The inverted austenite phase between the bars has basically disappeared. The nanoindentation test results show that the welded joint has outstanding resistance to plastic rheological deformation. The coarse-grain heat-affected zone has the highest strength, while the fusion zone has the lowest strength. The tensile fracture observation test further shows that the fusion line area is prone to tearing stress. Fracture is the weak area of the joint.
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