介绍了国内外9Ni钢的发展概况。分析了9Ni钢的化学成分，组织结构和性能特点，并对其焊接性进行了系统的阐述。分析结果表明，9Ni钢以其强度高、易于加工和焊接性优良等优势适于在超低温条件下的LNG储罐设备中安全使用。9Ni钢的冷裂敏感性不大，当焊接材料、焊接工艺措施配合适当时，可防止焊接热裂纹和其他焊接缺陷的产生，以及低温韧性的降低。9Ni钢焊接时，宜采用小线能量，多层多道焊，焊前不需预热，但需控制层间温度在100℃以下。%In this article, it introduced the development of 9Ni steel at home and abroad, analyzed its chemical composition, microstructure, properties characteristics, and systematically expatiated weldability. The analysis results showed that 9Ni steel is with some advantages, such as high strength, easy to be processed, good weldability and so on, which is suitable for usage in LNG tank under ultra-low temperature conditions. 9Ni steel is with little cold crack sensitivity, when matching welding materials with welding process is applicable, the welding hot cracking and other welding defects can be avoided, as well as the decrease of low temperature toughness. In practical welding, it should adopt low heat input and multi-layer, multi-pass welding. The preheating before welding is not necessary, but the interlayer temperature should be controlled lower than 100℃.
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