6061铝合金搅拌摩擦焊接头组织及性能

对厚度6 mm的6061铝合金进行了搅拌摩擦焊对接焊,采用光学显微镜、扫描电子显微镜、拉伸试验机及电化学工作站等设备对焊接接头的金相组织、断口形貌、拉伸性能和腐蚀性能进行了测试和分析。结果表明,当焊接速度为80 mm/min、旋转速度在600~1 500 r/min之间时,焊接接头的外观良好,无明显缺陷。随着旋转速度的增加,焊核区晶粒呈现出先减小后增大的现象。当旋转速度为1 200 r/min时,焊核区的晶粒最细小,焊接接头的抗拉强度和断后伸长率最高,分别为168 MPa和14.7%,焊缝强度达到了母材的81.9%,焊接接头的断裂形式为以韧性断裂为主的韧-脆混合断裂模式。随着旋转速度增大,搅拌摩擦焊接头的耐腐蚀性能呈现先上升后下降的趋势,当搅拌头旋转速度为1 200 r/min时,焊接接头的耐腐蚀性能最好,其腐蚀电流密度最小为2.4×10^-5A/cm²。

Microstructure and properties of 6061 aluminum alloy welded joint by FSW

Friction stir welding was carried out on 6061 aluminum alloy with a thickness of 6 mm. Metallographic structure, fracture morphology, tensile property and corrosion property of welded joints were tested and analyzed by optical microscope, scanning electron microscope, tensile testing machine and electrochemical workstation, respectively. The results showed that when the welding speed was 80 mm/min and the rotation speed was between 600~1 500 r/min, the welded joint had a good appearance without obvious defects. With the increase of rotation speed, the grain size of the welding nuclear zone decreased first and then increased. When the rotation speed was 1 200 r/min, the grain size of the welded core area was the smallest, and the tensile strength and elongation of the welded joint were the highest, 168 MPa and 14.7%, respectively. The weld strength reached 81.9% of base metal. The fracture mode of the welded joint was ductile-brittle mixed fracture mode, which was mainly ductile fracture. With the increase of rotation speed, the corrosion resistance of FSW joint first increased and then decreased. When the rotation speed of FSW joint was 1 200 r/min, the corrosion resistance of FSW joint was the best, and the minimum self-corrosion current density of FSW joint was 2.4×10^-5A/cm².