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

通过引入涉及不同材料类别组合的设计，如钢、钛、镁和铝合金、金属板和铸件以及更高效混合结构中的层压板，运输行业有明显的驱动力来降低燃料消耗和二氧化碳排放。因此，运输行业的未来发展方向无疑将基于多材料解决方案。这种转变的设计理念已经过去的萌芽阶段，引进铝前端钢车身外壳（宝马5系）以及铝合金车身中铝板和镁合金高压压铸件的集成（例如Jaguar XK）。这种材料组合目前通过紧固件连接，这是昂贵且低效的，因为它们很难通过常规技术如电阻点焊、电弧焊和激光焊接来焊接。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，因为它们降低了整体热输入并且不会熔化材料。这大大降低了由于界面反应和固化开裂导致的粘结强度差的趋势，以及对汽车车身中使用的层压板和铝合金等热敏材料的损坏，这些材料旨在在烤漆过程中硬化。摩擦连接技术也更加高效，相对于电阻点焊和激光焊接，可节省90%以上的能源，是更稳健的工艺，并且可随时与粘合剂结合使用。（例如Jaguar-Land Rover、Airbus、Corus、Meridian、Novelis、TWI，Sonobond）将研究与优化混合动力、更大质量效率结构的摩擦连接相关的材料和工艺问题，重点是摩擦搅拌、摩擦搅拌点焊和高功率超声点焊。这项工作将得到新方法的支持，以开发这些令人兴奋的新工艺的模型，并详细分析和建模关键材料的相互作用，如界面结合/反应和焊接微观结构的形成。

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.