置氢对Ti-6Al-4V合金组织和性能的影响

摘要

In order to master the mechanism of hydrogenation improving titanium alloy machinability, microstructure of the hydrogenated Ti-6A1-4V alloy was analyzed by optical microscopy and XRD. Thermal expansion coefficient and thermal conductivity of the alloy were measured by thermal expansion instrument and thermal constant measuring apparatus. Mechanical properties were studied through tensile tests at elevated temperatures. The results show that after hydrogenation β phase ratio increased and δ hydrides formed with increasing the hydrogen content. Compared with the alloy before hydrogenation, thermal expansion coefficient decreased by 60% 0 at 900℃ mostly and thermal conductivity increased by 40% at 500℃ mostly. Tensile strength and elongation of Ti-6A1-4V alloy after hydrogenation decreased by 19% and 74% separately at 800℃.%为掌握置氢改善钛合金切削性能的机理，利用光学显微镜与X射线衍射仪分析了置氢Ti-6Al-4V合金的显微组织，采用热膨胀仪与热常数测试仪测定了该合金的热膨胀系数和导热系数，通过高温拉伸试验研究了该合金的力学性能。结果表明：置氢后，随着氢含量的增加，合金中的β相比例提高，并且生成了δ氢化物；与未置氢钛合金相比，在900℃时的热膨胀系数最大降幅为6％，而导热系数在500℃时的增幅最大，为40％；置氮后的钛合金，在800℃时抗拉强度与伸长率的降幅分别为19％和74％。