Wang Chunxia, Cui Hongbo, Tang Xin, He Kezhun
Key Laboratory of New Processing Technology for Nonferrous Metals & Materials, Ministry of Education, Guilin University of Technology, Guilin 541004, China.
College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China.
Materials (Basel). 2020 Feb 14;13(4):861. doi: 10.3390/ma13040861.
A wrought Al-11.3Si-0.6Mg alloy under hot extrusion (T1), solution treatment (T4), and solution treatment + artificial aging (T6) states were friction stir welded at welding speed of 100 mm/min and rotation rate of 800 rpm. The effect of prior heat-treatment on the microstructure and mechanical properties of the welds were investigated. The results show that the microstructures of the nugget zones have little dependence on the initial states of the base material. In the nugget zones, complete recrystallized structures with equaxied grains in the Al matrix were formed under all conditions. The Si particles in the nugget zones are almost unchanged compared with those of their base materials (BMs) in the three states. In contrast, the joint efficiency of the obtained welds was very sensitive to the initial material condition. The joint efficiency under the T1 state is more than 90% due to the fact that the microstructure is almost unchanged, except for the slight coarsening of the Al matrix grains and some of the MgSi phases during the friction stir welding process. However, the joint efficiency in the T4 and T6 conditions is only 77.22% and 62.03%, respectively. The relatively low weld strength in the T4 and T6 conditions is due to the elimination of the solid solution strengthening and age hardening effects during friction stir welding. The hardness distributions along the cross section of joints are all W-shaped under T1, T4, and T6 conditions.
对处于热挤压（T1）、固溶处理（T4）和固溶处理+人工时效（T6）状态的变形Al-11.3Si-0.6Mg合金，以100mm/min的焊接速度和800rpm的转速进行搅拌摩擦焊。研究了预先热处理对焊缝微观结构和力学性能的影响。结果表明，焊核区的微观结构对母材的初始状态几乎没有依赖性。在所有条件下，焊核区均形成了Al基体中具有等轴晶粒的完全再结晶组织。焊核区的Si颗粒与三种状态下母材中的Si颗粒相比几乎没有变化。相比之下，所得焊缝的接头效率对初始材料状态非常敏感。T1状态下的接头效率超过90%，这是因为在搅拌摩擦焊过程中，除了Al基体晶粒和一些MgSi相略有粗化外，微观结构几乎没有变化。然而，T4和T6状态下的接头效率分别仅为77.22%和62.03%。T4和T6状态下焊缝强度相对较低是由于搅拌摩擦焊过程中固溶强化和时效硬化效果的消除。在T1、T4和T6条件下，沿接头横截面的硬度分布均为W形。
