Austenitic S30408 stainless steel exhibits good low-temperature resistance and good welding performance. This steel is often used in liquefied natural gas stainless steel storage tanks. During the construction process, the tank wall is primarily connected by butt weld joints. Because welded joints are easily affected by temperature, low-temperature weld cracking can reduce the safety of structures. To study the cryogenic mechanical properties of austenitic S30408 stainless steel welded joints at low temperatures, the low-temperature mechanical properties of austenitic S30408 stainless steel base metal and welded joint components were studied by tensile tests from − 60 to 20 °C and scanning electron microscopy analysis of fractures at various temperatures. The results show that when the temperature decreases, the stress–strain curve of base metal components changes from a power function type to an inverted "s" type; in addition, secondary hardening occurs. The yield strength and tensile strength of the welded joint and base metal increased with decreasing temperature, and the elongation and reduction of area decreased. The plastic deformation capacity of the welded joint was significantly lower than that of the base metal, and there were obvious inclusions in the microstructure.

奥氏体S30408不锈钢表现出良好的耐低温性和良好的焊接性能。这种钢常用于液化天然气不锈钢储罐。施工过程中，罐壁主要采用对接焊缝连接。由于焊接接头易受温度影响，低温焊缝裂纹会降低结构的安全性。为了研究奥氏体S30408不锈钢焊接接头在低温下的低温力学性能，通过-60~20℃拉伸试验和扫描电镜研究了奥氏体S30408不锈钢母材和焊接接头部件的低温力学性能。不同温度下的断裂分析。结果表明，当温度降低时，母材构件的应力-应变曲线由幂函数型转变为倒“s”型；此外，还会发生二次硬化。焊接接头和母材的屈服强度和抗拉强度随温度降低而增加，伸长率和断面收缩率降低。焊接接头的塑性变形能力明显低于母材，显微组织中存在明显的夹杂物。