Study on mechanical properties and microstructure of extrusion weld of 6005A aluminum alloy profiles

6005A铝合金型材挤压焊缝力学性能与显微组织研究 Study on mechanical properties and microstructure of extrusion weld of 6005A aluminum alloy profiles 张海军 ZHANG Haijun 1 first-author 曹春鹏 CAO Chunpeng 1 单清群 SHAN Qingqun 1 吕卫群 LV Weiqun 1 中车青岛四方机车车辆股份有限公司 中车青岛四方机车车辆股份有限公司 CRRC Qingdao Sifang Co.,Ltd. CRRC Qingdao Sifang Co.,Ltd. 通过测试6005A铝合金型材的力学性能以及观察挤压焊缝与母材的显微组织,判断铝合金型材的薄弱位置,研究薄弱位置力学性能与显微组织的差异及其产生原因。结果表明:挤压焊缝与母材显微组织均为Mg 2 Si,均匀分布于铝基体中,但挤压焊缝处Mg 2 Si更粗大,分布更杂乱。挤压焊缝处晶粒形状主要为条状晶粒及细小的等轴晶粒,平均晶粒尺寸为15.5μm。在热挤压过程中,挤压焊缝处晶粒尺寸的不均匀性增大,晶粒间在变形时的协调性变差,在拉伸过程中易产生裂纹导致材料强度降低,成为铝合金型材的薄弱位置。6005A铝合金型材硬度平均值为88.176 HBW,最小值为81.7 HBW且出现在挤压焊缝处。取样位置6断后伸长率最小（4.5%）,判断取样位置6为该型材最薄弱位置。 In this paper,the mechanical properties of 6005A aluminum alloy profiles are tested and the microstructure of extruded weld and base material is observed to determine the weak position of aluminum alloy profiles and discuss the difference between the mechanical properties and microstructure in the weak position and its causes. The results show that the microstructure of the extruded weld and the base material is Mg 2 Si evenly distributed in the aluminum matrix,but the Mg 2 Si in the extruded weld is thicker and more disorderly. The grain shape of the extruded weld is mainly strip grain and fine equiaxed grain,and the average grain size is 15.5 μm.In the process of hot extrusion,the non-uniformity of grain size in the extruded weld increases,and the coordination between grains becomes worse during deformation. Cracks are easy to occur in tensile process,which makes the material strength decrease and becomes the weak position of aluminum alloy profile. The average hardness of 6005A aluminum alloy profile is88.176 HBW,the minimum value is 81.7 HBW,and the minimum value appears in the extruded weld. The sample position 6 has the minimum elongation after fracture（4.5%）,and it is judged that the sample position 6 is the weakest position of the profile. 6005A 挤压焊缝 力学性能 显微组织 EBSD 6005A extruded weld mechanical properties microstructure EBSD U270.41;TG407 2022-03-08 7 51