Friction Joining - Low Energy Manufacturing for Hybrid Structures in Fuel Efficient Transport Applications

通过引入不同材料类别的组合设计，例如钢、钛、镁和铝合金、金属板和铸件，以及更高效的混合结构中的层压板，运输行业有明显的驱动因素，以降低燃油消耗和二氧化碳排放。因此，运输业的未来方向无疑将基于多种材料的解决方案。这种设计理念的转变已经过了萌芽阶段，随着铝制前端钢制车身外壳(宝马5系列)的引入以及铝板和镁高压铸件在铝制车身中的集成(例如捷豹XK)。这种材料组合目前通过紧固件连接，这些紧固件昂贵且效率低下，因为它们很难通过传统技术进行焊接，如电阻点焊、MIG电弧和激光焊接。新的先进固态摩擦焊接技术可以潜在地克服与连接不同材料组合相关的许多问题，因为它们降低了总体热输入，并且不会熔化材料。这极大地减少了由于界面反应和固化开裂造成的粘合强度差的倾向，以及对热敏性材料的损害，如汽车车身中使用的层压板和铝合金，这些材料旨在在油漆烘烤过程中硬化。摩擦连接技术的效率也高得多，与电阻点焊和激光焊接相比，节省了90%的能源，工艺更加稳健，可以很容易地与粘接结合使用。该项目与业界(如捷豹-路虎、空中客车、Corus、子午线、Novelis、TWI、Sonobond)密切合作，将研究与优化混合、质量效率更高的结构的摩擦连接相关的材料和工艺问题，重点是摩擦搅拌、摩擦点焊和高功率超声波点焊。这项工作将以开发这些令人兴奋的新工艺模型的新方法为基础，并对关键材料相互作用进行详细分析和建模，如界面结合/反应和焊接微结构形成。

There are clear drivers in the transport industry towards lower fuel consumption and CO2 emissions through the introduction of designs involving combinations of different material classes, such as steel, titanium, magnesium and aluminium alloys, metal sheet and castings, and laminates in more efficient hybrid structures. The future direction of the transport industry will thus undoubtedly be based on multi-material solutions. This shift in design philosophy is already past the embryonic stage, with the introduction of aluminium front end steel body shells (BMW 5 series) and the integration of aluminium sheet and magnesium high pressure die castings in aluminium car bodies (e.g. Jaguar XK).Such material combinations are currently joined by fasteners, which are expensive and inefficient, as they are very difficult to weld by conventional technologies like electrical resistance spot, MIG arc, and laser welding. New advanced solid state friction based welding techniques can potentially overcome many of the issues associated with joining dissimilar material combinations, as they lower the overall heat input and do not melt the materials. This greatly reduces the tendency for poor bond strengths, due to interfacial reaction and solidification cracking, as well as damage to thermally sensitive materials like laminates and aluminium alloys used in automotive bodies, which are designed to harden during paint baking. Friction joining techniques are also far more efficient, resulting in energy savings of > 90% relative to resistance spot and laser welding, are more robust processes, and can be readily used in combination with adhesive bonding.This project, in close collaboration with industry (e.g. Jaguar - Land Rover, Airbus, Corus, Meridian, Novelis, TWI, Sonobond) will investigate materials and process issues associated with optimising friction joining of hybrid, more mass efficient structures, focusing on; Friction Stir, Friction Stir Spot, and High Power Ultrasonic Spot welding. The work will be underpinned by novel approaches to developing models of these exciting new processes and detailed analysis and modelling of key material interactions, such as interfacial bonding / reaction and weld microstructure formation.