Refill friction stir spot welding (RFSSW) is a highly flexible and promising solid-state joining method for aluminium alloys. Alternatively, resistance spot welding (RSW) can be stated as an appropriate joining method which can be automated and used within a high-volume production due to short process times. Both processes do not need any additional elements and a flat surface on both sides of the joints can be realised. In order to meet the modern requirements for crash safety and structural stiffness, thermal and mechanical joining methods are mainly combined by using single-component epoxy resin adhesives. Due to an insufficient knowledge about the application of both thermal joining methods for the abovementioned material combinations combined with additional adhesives, deeper investigations were done regarding the interactions of the polymers and the joining processes. Starting with a brief presentation of the boundary conditions of the investigations and the refill friction stir spot welding and resistance spot welding of high-strength aluminium alloys with sheet thicknesses bigger than 5.8 mm, the paper introduces the process-related joint properties of friction-based and resistance-based welded joints. Afterwards, the paper discusses the influences of the process parameter on the metallographic joint formation and load-bearing capacities for a selected two-sheet and four-sheet material combination. When combining the spot welding technologies with adhesives, the process parameters of the RFSSW process have to be adapted for the two-sheet combination by adding a squeeze-out step, while for RSW, just the preholding time has to be increased. Different challenges for both joining methods are shown. For RFSSW, the gap formation has to be considered when welding big total sheet thicknesses, while for RSW, the shape of the weld nugget is more important for an appropriate joint performance. Additionally, process optimisations for less adhesive incineration will be discussed for both joining processes, and the influences of the adhesive on the joint formation will be addressed with the help of load-bearing capacity evaluations. The paper closes with specific recommendations for the realisation of refill friction stir and resistance spot-welded joints with and without adhesive in the field of Al joints with big total sheet thicknesses which meet the quality demands and an outlook for further research steps will be given.

中文翻译：

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总厚度较大的铝制接头的补充搅拌摩擦点焊和电阻点焊（III-1965-19）

补充摩擦搅拌点焊（RFSSW）是铝合金的一种高度灵活且有希望的固态连接方法。替代地，电阻点焊（RSW）可以说是一种合适的连接方法，由于工艺时间短，因此可以自动化并在大批量生产中使用。这两个过程都不​​需要任何其他元素，并且可以在接头的两侧实现平坦的表面。为了满足现代对碰撞安全性和结构刚度的要求，主要通过使用单组分环氧树脂粘合剂来组合热和机械连接方法。由于对上述两种材料结合其他粘合剂的热连接方法的应用知识不足，关于聚合物的相互作用和连接过程进行了更深入的研究。首先简要介绍了研究的边界条件，并对片材厚度大于5.8 mm的高强度铝合金进行了补充摩擦搅拌点焊和电阻点焊，然后介绍了基于过程的基于摩擦的接头性能。和基于电阻的焊接接头。然后，本文讨论了工艺参数对所选的两层和四层材料组合的金相接头形成和承载能力的影响。当将点焊技术与粘合剂结合使用时，必须通过增加挤出步骤将RFSSW工艺的工艺参数调整为两片组合，而对于RSW，只是保留时间必须增加。显示了两种连接方法的不同挑战。对于RFSSW，在焊接较大的总板厚时必须考虑间隙的形成，而对于RSW，对于合适的接头性能，熔核的形状更为重要。此外，将在两种连接工艺中讨论减少粘合剂焚烧的工艺优化方法，并借助承载能力评估解决粘合剂对接缝形成的影响。最后，针对在总厚度较大，满足质量要求的铝制接头领域中实现或不采用粘合剂的补充摩擦搅拌和电阻点焊接头的实现提出了具体建议，并给出了进一步研究的前景。