Zhang Wenyan, Mao Yuqing, Yang Ping, Li Ning, Ke Liming, Chen Yu
National Defence Key Discipline Laboratory of Light Alloy Processing Science and Technology, Nanchang Hangkong University, Nanchang 330063, China.
Materials (Basel). 2022 Jan 27;15(3):969. doi: 10.3390/ma15030969.
In the present study, 2198 Al-Cu-Li alloys were successfully friction stir welded by using various welding speed ranges of 90~180 mm/min with an invariable rotation speed of 950 r/min. The effect of welding speed on microstructure evolution and mechanical properties of the joints was investigated. The results show that, with the welding speed decreasing, the size of the nugget zone (NZ) first increases and then decreases due to different welding temperatures. At a welding speed of 150 mm/min, the size of the NZ in all joints is the biggest and the "S" curve disappears. The equiaxed grains are finer, attributed to a higher degree of dynamic recrystallization, and a larger number of fine reprecipitated phase (δ', β' phases) particles are dispersively distributed in the NZ. Correspondingly, the joints have the highest tensile properties, and the tensile strength, yield strength and elongation are, respectively, 406 MPa, 289 MPa and 7.2%. However, compared to the base material, the tensile properties of all joints are reduced because a greater amount of δ' and β' phases particles are dissolved in the NZ. Only the joints produced at 150 mm/min are fractured in the TMAZ with detected deep dimples and tearing ridges, and a significant necking phenomenon is observed, which indicates a complete ductile fracture mode.
在本研究中，通过使用90~180mm/min的各种焊接速度范围以及950r/min的恒定转速，成功地对2198铝铜锂合金进行了搅拌摩擦焊接。研究了焊接速度对接头微观结构演变和力学性能的影响。结果表明，随着焊接速度降低，由于焊接温度不同， nugget区（NZ）的尺寸先增大后减小。在150mm/min的焊接速度下，所有接头中NZ的尺寸最大，且“S”曲线消失。等轴晶粒更细小，这归因于更高程度的动态再结晶，并且大量细小的再沉淀相（δ'、β'相）颗粒分散分布在NZ中。相应地，接头具有最高的拉伸性能，抗拉强度、屈服强度和伸长率分别为406MPa、289MPa和7.2%。然而，与母材相比，所有接头的拉伸性能都有所降低，因为大量的δ'和β'相颗粒溶解在NZ中。只有在150mm/min下生产的接头在热机械影响区（TMAZ）发生断裂，观察到深韧窝和撕裂棱，并且出现明显的颈缩现象，这表明是完全的韧性断裂模式。
