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利用传统拉伸试验机和霍普金森(Hopkinson)拉杆实验装置研究电子束焊接的Ti-6Al-4V合金在应变率为10-3和103s-1时的准静态和动态拉伸行为,利用光学显微镜和扫描电子显微镜观察基体材料和焊缝材料的微观组织,研究基体材料和焊接材料在拉伸实验后的断裂特征。结果表明:在应变率分别为10-3和103s-1的条件下,焊缝材料的强度明显高于基体材料,焊缝材料的伸长率低于基体材料。同时,焊缝材料和基体材料均为应变率敏感材料;当应变率从10-3上升到103s-1时,焊缝材料的伸长率明显提高,而基体材料的伸长率基本没有变化;焊缝材料的断裂模式由脆性断裂转向韧性断裂,造成从准静态加载条件到动态加载条件下焊缝材料伸长率的提高。
The quasi-static and dynamic tensile behavior of electron beam welded Ti-6Al-4V alloy at strain rates of 10-3 and 103s-1 were studied by using conventional tensile testing machine and Hopkinson rod testing device. The microstructure of the base material and the weld material was observed under a microscope and a scanning electron microscope to investigate the fracture characteristics of the base material and the welding material after the tensile test. The results show that under the conditions of strain rates of 10-3 and 103s-1 respectively, the strength of the weld material is obviously higher than that of the base material, and the elongation of the weld material is lower than that of the base material. At the same time, the weld material and the matrix material are all strain rate sensitive materials. When the strain rate increases from 10-3 to 103s-1, the elongation of the weld material increases obviously while the elongation of the matrix material does not change basically. The fracture mode of weld material changes from brittle fracture to ductile fracture, which results in the increase of the elongation of weld material from quasi-static loading condition to dynamic loading condition.