Guo Jizhi, Wang Jianfeng, Cheng Lihong, Duan Yuhang, Zhan Xiaohong
College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China.
College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China.
Ultrasonics. 2024 Jul;141:107342. doi: 10.1016/j.ultras.2024.107342. Epub 2024 May 11.
In this study, the microstructural evolution and mechanical properties of Ti6Al4V titanium alloy welded joints subjected to ultrasonic assisted laser welding were scrutinized, while numerical simulations were employed to explicate the grain refinement mechanism. The simulations indicate that the ultrasonic vibration significantly improves the overall fluidity and temperature of the molten pool. Under the identical condition of laser power and welding speed (1500 W, 1.3 m/min), the presence of 0.2A ultrasonic current yields a more uniform refinement of columnar grains, along with a denser arrangement of acicular martensite. The refinement mechanism can be attributed to the small temperature gradient, cavitation effects, and stress induced by ultrasonic vibration. Notably, the welded joint attains a peak tensile strength of 945.2 MPa under the aforementioned 0.2A condition, distinctly demonstrating the characteristics of ductile fracture. This research further reveals the underlying mechanism of grain refinement in Ti6Al4V alloy laser-welded joints induced by ultrasonic vibration, providing valuable references for optimizing process parameters and improving the quality of such welded joints.
在本研究中，对经超声辅助激光焊接的Ti6Al4V钛合金焊接接头的微观结构演变和力学性能进行了研究，同时采用数值模拟来解释晶粒细化机制。模拟结果表明，超声振动显著提高了熔池的整体流动性和温度。在相同的激光功率和焊接速度（1500W，1.3m/min）条件下，0.2A超声电流的存在使柱状晶粒得到更均匀的细化，同时针状马氏体的排列更密集。细化机制可归因于小温度梯度、空化效应以及超声振动引起的应力。值得注意的是，在上述0.2A条件下，焊接接头的峰值抗拉强度达到945.2MPa，明显呈现出韧性断裂的特征。本研究进一步揭示了超声振动诱导Ti6Al4V合金激光焊接接头晶粒细化的潜在机制，为优化工艺参数和提高此类焊接接头的质量提供了有价值的参考。
