Research Progress in Dwell Fatigue Service Reliability of Titanium Alloys for Pressure Shell of Deep-Sea Submersible

Service reliability of deep-sea submersible pressure shells is critical for ensuring the safety of the submersibles. To manufacture pressure shells for deep-sea submersibles, titanium alloys have emerged as key materials owing to their exceptional service performances in the deep-sea environment. Herein, use of titanium alloys in deep submersibles is introduced. Then, the latest research on the primary failure modes of titanium alloys, including creep at room temperature, low cycle fatigue, and dwell fatigue, based on the types of titanium alloys used in deep-sea submersibles is reviewed. Additionally, the main factors that affect dwell fatigue, including the micromechanism of dwell fatigue damage and dwell fatigue model, are summarized. This work can serve as a reference for the development of new titanium alloys with high strength and low dwell effect. Finally, specific issues related to the service reliability evaluation of titanium alloy components used in the deep sea are outlined, and future research focuses are presented.