Abstract The phase balance, interface boundaries, and grain types were characterized in the local dry underwater welded DSS metals. The results showed that the austenite content of the weld metals decreased first, then increased and then decreased with the increase in the simulated water depth from 0.1 m to 75 m. The fractions of Σ3 austenite twin grain boundaries and recrystallized ferrite and austenite grains had a similar trend with the austenite content, while the change in the proportion of special ferrite-austenite interphase boundaries showed an opposite trend. The microstructure changes in the weld metal from 15 m to 45 m were more dramatic than those from 45 m to 75 m. The resultant mechanical performance was in good agreement with the microstructure evolution. More austenite content, Σ3 austenite twin grain boundaries and recrystallized grains made the plasticity and toughness of the weld metals better at 45 m and 75 m. The best plasticity and toughness performance was obtained in the weld metal at 45 m.

中文翻译：

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不同模拟水深下水下局部干焊DSS金属的显微组织演变和力学性能

摘要 表征了局部干式水下焊接DSS金属的相平衡、界面边界和晶粒类型。结果表明，随着模拟水深从0.1 m增加到75 m，焊缝金属的奥氏体含量先降低，然后增加再降低。Σ3奥氏体孪晶界和再结晶铁素体和奥氏体晶粒的比例与奥氏体含量的变化趋势相似，而特殊铁素体-奥氏体相界的比例变化则呈现相反的趋势。焊缝金属从 15 m 到 45 m 的显微组织变化比从 45 m 到 75 m 更显着。所得机械性能与微观结构演变非常一致。更多的奥氏体含量，Σ3奥氏体孪晶界和再结晶晶粒使45m和75m焊缝金属的塑性和韧性更好。焊缝金属在 45 m 处获得了最好的塑性和韧性性能。