铝/镀锌钢搅拌摩擦铆焊接头组织与力学性能

Microstructure and mechanical properties of friction stir rivet welding joint between aluminum and galvanized steel

为实现铝钢之间的优质连接,采用搅拌摩擦铆焊新方法对6061铝合金和DP600镀锌钢进行搭接点焊,利用扫描电子显微镜、能谱仪及拉伸试验对接头的微观组织及力学性能进行了研究.结果表明:接头成形平整美观,中心没有匙孔;接头包含铆接区和扩散区,其中在铆接区铝合金以铝柱的形式嵌入到钢板的圆孔中,形成了一个"铝铆钉",底部有富铝的α固溶体偏聚,圆孔四周形成扩散区,铝和钢形成了冶金结合,依靠金属间化合物Fe Al3连接在一起;接头有3种断裂形式,在最佳工艺参数下接头的抗剪力达到8.2 k N;铝柱上断口的微观形貌是被拉长的韧窝,扩散区的断口由灰色基体和白色颗粒组成.

To achieve the high?quality connection between aluminum steel, a novel process of friction stir rivet welding ( FSRW) was carried out for spot joining Al6061 and DP600 galvanized steel. Microstructure and mechanical properties of FSRW joints were investigated using scanning electron microscopy, energy disperse spectroscopy and tensile tests. The results indicated that the beautiful joints without keyhole were achieved. The joint included riveted zone and diffusion zone:aluminum alloy like a rivet inserted the hole of the steel sheet in the riveted zone and there was accumulative rich?aluminum α solid solution at the rivet′s bottom, the metallurgical bonding interface of diffusion zone was mainly composed of FeAl3 which joined aluminum and galvanized steel around the hole. The joints had three fracture modes and the shearing resistance of the joint with the optimum welding parameter could reach 8. 2 kN. The fracture morphology of the aluminum rivet showed elongated dimples, but the fracture of the diffusion zone was composed of gray substrate and white granules.