The extensive use of light metal material such as aluminum has brought about problems in its joining with steel. However, the weak metallurgical bonding between the dissimilar materials and the formation of hard and brittle intermetallic compounds (IMCs) lead to unsatisfactory joint strength. Aiming at achieving high-quality joining of aluminum and steel, 6061-T6 aluminum and 301L steel alloys were lap joined by ultrasonic assisted friction stir lap welding (UaFSLW) in this study. The UaFSLW joints were well formed with uniform flashes and even arc lines. The strong plastic flow of the aluminum material driven by the dual effects of mechanical stirring and ultrasonic vibration inhibited the excessive growth of the Al–Fe IMCs at the lap interface. Thanks to the enhanced metallurgical bonding and the effective control of the layer thickness of IMCs, the tensile load of the UaFSLW joint under 1,800 rpm reached 16.5 kN, which was an increase of 27.9% compared to that of the conventional FSLW joint.

中文翻译：

---

铝/钢异种合金的超声辅助摩擦搅拌焊接研究

铝等轻金属材料的广泛使用在与钢的连接方面带来了问题。但是，异种材料之间的较弱的冶金结合以及硬而脆的金属间化合物（IMC）的形成导致接头强度不令人满意。为了实现铝和钢的高质量连接，本研究中通过超声辅助摩擦搅拌搭焊（UaFSLW）搭接6061-T6铝和301L合金钢。UaFSLW接头的成型良好，具有均匀的闪光和均匀的弧线。机械搅拌和超声振动的双重作用驱使铝材料产生强大的塑性流动，从而抑制了Al-Fe IMC在搭接界面处的过度生长。得益于增强的冶金结合和对IMC层厚度的有效控制，