电子束焊接Ti-6Al-4V合金的准静态和动态拉伸行为

摘要

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103 s-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103 s-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103 s-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 behaviors in electron beam welded (EBW) Ti-6Al-4V alloy were investigated at strain rates of 10-3 and 103 s-1, respectively, by materials test system (MTS) and reconstructive Hopkinson bars apparatus. The microstructures of the base metal (BM) and the welded metal (WM) were observed with optical microscope. The fracture characteristics of the BM and WM were characterized with scanning electronic microscope. In Ti-6Al-4V alloy joint, the flow stress of WM is higher than that of BM, while the fracture strain of WM is less than that of BM at strain rates of 103 and 10-3 s-1, respectively. The fracture strain of WM has apparent improvement when the strain rate rises from 10-3 to 103 s-1, while the fracture strain of BM almost has no change. At the same time, the fracture mode of WM alters from brittle to ductile fracture, which causes improvement of the fracture strain of WM.