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本文在Ti-5Al-4V合金的WOL试样裂纹尖端前13mm外的区域引入氢,结果表明,20个月后试样发生了滞后开裂。离子探针断口分析表明,在裂纹前端三向应力最大的区域,氢的聚集系数远高于Li等人的热力学理论预言值exp((V_Hσ_h)/(RT))。金相和电子显微镜研究表明,在α/β相界面及α小片间界面上生成了fct和fcc结构的氢化钛沉淀。断裂正是沿着这些界面发生的。断裂力学分析表明K_(IH)≤0.46K_(IC)。基于这些实验事实,本文讨论了钛合金中氢在非均匀应力场下再分布所能达到的程度及其动力学特征;并讨论了同类实验中一些可能导致假象的因素。
In this paper, hydrogen is introduced into the region 13 mm before the crack tip of WOL specimen of Ti-5Al-4V alloy. The results show that the specimen lags and cracks after 20 months. The ion probe fracture analysis shows that the hydrogen accumulation coefficient is much higher than that predicted by Li et al. In thermodynamic theory exp (exp (V_Hσ_h) / (RT)) where the three-axial stress is the largest at the front of the crack. Metallographic and electron microscopy studies showed that the titanium hydride precipitates of fct and fcc structures were formed on the interface between α / β phase and α-platelet. Fracture happens to happen along these interfaces. Fracture mechanics analysis shows K_ (IH) ≤0.46K_ (IC). Based on these experimental facts, this paper discusses the degree of re-distribution of hydrogen in titanium alloy under inhomogeneous stress field and its dynamic characteristics; and discusses some possible causes of artifacts in similar experiments.