【摘要】 随着轻量化技术的发展，镀锌钢板与铝合金等异种金属连接在现代汽车工业中的应用越来越多，回抽式无匙孔搅拌摩擦点焊具有热输入低、焊缝晶粒细小、接头力学性能高等优点，在铝合金等轻金属焊接领域具有很大的优势。本工作使用回抽式搅拌摩擦点焊技术，成功实现了0.7 mm厚的镀锌钢板与2 mm厚的铝合金板的无匙孔搅拌摩擦点焊连接。在不同的焊接转速下，对铝钢异种金属进行无匙孔搅拌摩擦点焊实验研究，分析了无匙孔搅拌摩擦点焊接头的剪切性能、断口形貌、各区微观组织、界面区特征及连接机理。研究结果表明，转速为1 200 r/min、压入量为0.2 mm、焊接时间为15 s时焊接接头最佳，具有最好的力学拉伸性能，断裂位置为热机影响区；通过扫描电镜（SEM）和能谱分析（EDS）对接头的微观形貌以及断口形貌进行观察分析发现，在搅拌区接头界面形成了约6μm厚的金属间化合物，为AlFe₃、Al₁₃Fe₄、AlFe；各位置处金属间化物的形貌与厚度不同，断裂方式为混合断裂机制，界面处的连接为机械结合和冶金结合两种接合方式。更多还原

【Abstract】 With the development of lightweight technology, the applications of the dissimilar metals joints between steel and aluminum become more and more widely in modern automobile industry. The keyhole can be eliminated by retracting FSSW process, and it also has low heat input, more refined grain and higher strength. In this work, the dissimilar metals keyhole-free FSSW joints between 0.7 mm steel and 2 mm aluminium alloy were successfully realized. Experimental study friction stir spot welding without keyholes of aluminum and steel dissimilar metals at different welding rotation speed, the effect of the rotation on tensile-shear strength of the speed, the fracture mechanism, the microstructure of different weld zones and the interface behaviour were analysed. In this paper, the author used the friction stir welding machine which was indepen-dently researched and successfully realized the lap connection between 0.7 mm steel plate and 2 mm aluminium alloy plate with different rotating speeds. The results show that the welding speed is 1 200 r/min, the pressing amount is 0.2 mm, and the welding time is 15 s. The welding surface joint has the best mechanical tensile properties, and the fracture location is in the heat mechanical affected zone. Intermetallic compounds(AlFe₃, Al₁₃Fe₄,AlFe) with a thickness of about 6μm were formed at the lap interface. The microstructure and fracture morphology of the joint were observed and analyzed by scanning electron microscopy（SEM） and energy spectrum analysis（EDS）, and it was found that the fracture mode was mixed fracture mechanism. The connection at the interface is a mechanical and metallurgical bonding.更多还原