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对LNG储罐用9Ni钢板进行超低温CTOD试验;采用手工电弧焊、埋弧焊分别对9Ni钢板进行焊接,通过接头拉伸、弯曲和冲击试验,光学显微镜、扫描电镜等试验仪器对焊缝组织、热影响区组织观察,研究9Ni在两种不同焊接方法下所得到的焊接接头的微观组织及性能。结果表明:LNG储罐用9Ni钢在-196℃具有较好的强度、伸长率和韧性;焊缝组织主要由奥氏体和析出相组成,焊接热影响区组织主要由板条马氏体和板条间的残余奥氏体组成;LNG储罐用9Ni钢板焊缝的化学成分与母材匹配良好,接头强度大、低温冲击性能和弯曲性能良好。
Cryogenic CTOD tests were carried out on 9Ni steel plates for LNG storage tanks. 9Ni steel plates were welded respectively by hand electric arc welding and submerged arc welding. Tensile test, bending and impact test, optical microscope and scanning electron microscope The microstructure and properties of the welded joint obtained by 9Ni under two different welding methods were investigated by microstructure observation in the heat affected zone. The results show that 9Ni steel for LNG storage tank has good strength, elongation and toughness at -196 ℃. The microstructure of the weld consists mainly of austenite and precipitated phase. The microstructure of HAZ is mainly composed of lath martensite And retained austenite between slats. The chemical composition of 9Ni steel welds in LNG storage tank matched well with the base metal, the strength of joint was good, the impact performance at low temperature and the bending property were good.