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一引言高温工作条件下金属部件同时承受动应力和静应力时会发生疲劳和蠕变现象。例如燃汽轮机的轴、叶片等部件,由于蠕变疲劳的交互作用,造成高温部件的过早损坏。高温下使用的结构材料承受机器启动-停止时,由于受力变化的交变负荷和稳定运转时的静负荷同时作用,使用条件恶劣,在设计高温结构材料的安全性及使用条件下估算构件寿命时,都要考虑蠕变疲劳交互作用。然而蠕变疲劳交互作用的现象还未能充分说明,还未确立有关此问题的试验方法和寿命预测。已有文献研究蠕变疲劳交互作用下裂纹扩展问题,但研究甚少。本文主要研究钛合金在蠕变疲劳交互作用下的裂纹扩展。 Ti-6Al-4V钛合金是含有稳定β相的α+β型合金,它比重小、强度高,在400℃还有较好的强度,广泛应用于宇航、造船、化工等方面。
I. INTRODUCTION Fatigue and creep occur when metal parts are subjected to both dynamic and static stresses under high temperature operating conditions. For example, the gas turbine shaft, blades and other components, due to the interaction of creep fatigue, resulting in premature damage to high temperature components. Structural materials used at high temperatures withstand the start-stop of the machine, due to the alternating load of the force change and the static load of the stable operation at the same time, the use of harsh conditions, the design of high temperature structural material safety and use conditions to estimate component life When, should consider the creep fatigue interaction. However, the phenomenon of creep fatigue interaction has not yet been fully elucidated. Test methods and life prediction for this problem have not yet been established. There are literature studies of crack propagation under creep-fatigue interaction, but few studies have been done. In this paper, we mainly study the crack growth of titanium alloy under the interaction of creep fatigue. Ti-6Al-4V titanium alloy is an α + β type alloy with stable β phase. It has the advantages of small specific gravity, high strength and good strength at 400 ℃. It is widely used in aerospace, shipbuilding and chemical industries.