TC4ELI 钛合金疲劳裂纹路径偏折与寿命提升机制

As the optimal material for deep-sea manned equipment structure, TC4ELI(Extra-low-interstitial) titanium alloy's anti fatigue crack growth performance is crucial. In this work, the fatigue crack growth behavior of TC4ELI is systematically tested and observed in situ, and the traditional TC4 titanium alloy is selected for comparative experiments. The results show that TC4ELI has a higher fatigue crack growth life than TC4; At the same time, in situ observation found that the fatigue crack growth of TC4ELI is obviously deflected, resulting in a more tortuous crack path than TC4. Furthermore, TC4ELI fatigue fracture surface, material composition and microstructure of crack path region were systematically analyzed by means of microscopic characterization. On this basis, the variation of crack growth driving force with deflection angle is calculated by finite element simulation, and the influence mechanism of crack deflection on TC4ELI fatigue growth life is analyzed. This study provides a reference for the damage tolerance design of TC4ELI deep-sea equipment structure.