EAGER: Feasibility Study of Hybrid Friction-Stir Riveting of Mg Alloys

这项探索性研究（EAGER）早期概念补助金为开发一种新的搅拌摩擦铆接技术提供了资金，用于连接难以焊接的材料，如镁、铝合金和异种金属。在这种方法中，固体铆钉被用作搅拌摩擦焊头，用于连接两个材料，可以是板材或大块金属。旋转和压合的作用将铆钉压入金属中。在达到预定深度后，动作停止，铆钉留在金属中，形成理想的机械连接。在接触面处也形成了一个坚固的键合环。对接头的锁紧机制、缺陷形成以及影响物理属性与重要强度指标之间的关系进行了研究。将这种连接方法与其他连接方法（如自穿孔铆接和电阻点焊）进行直接比较，以验证这种新的连接方法。本研究的成功完成将为今后提出更大规模、更深入的研究和优化这种连接方法铺平道路。对包括母材和铆钉在内的材料影响的基本理解，以及所获得的设计和工艺变量，将为该技术的进一步发展提供关键信息。将连接质量与易于测量的连接几何属性之间的关系用于质量检测，并将某些关键工艺参数（如铆接过程中的扭矩和推力轮廓）用作实时质量控制的手段。本研究的最终目标是开发一种坚固、经济和工业化的连接工艺，使先进材料在钣金工业中的使用节能减排成为可能。

This EArly-concept Grants for Exploratory Research (EAGER) grant provides funding for the development of a new friction-stir riveting technique for joining hard-to-weld materials such as Mg and Al alloys, and dissimilar metals. In this method, a solid rivet is used as a friction-stir welding head for joining two pieces of materials which can be either sheets or bulk metals. An action of combined rotation and pressing pushes the rivet into the metals. After a predetermined depth is reached, the action stops and the rivet is left in the metals, forming a desirable mechanical joint. A solid bonding ring is also created at the faying interface. The locking mechanism, defect formation, and relationship between influential physical attributes and important strength measures of a joint will be investigated. A direct comparison between this and other joining methods such as self-piercing riveting and resistance spot welding will be conducted to validate this new joining method.The successful completion of this research will pave the way for a future proposal for a larger scale, in-depth study and optimization of this joining method. The basic understanding of the effects of materials including the base metal(s) and rivet, and design and process variables obtained will provide critical information for further development of this technique. A relationship linking the quality of a joint to easily measurable geometric attributes of the joint will be developed for quality inspection, and certain critical process parameters such as the profiles of torque and thrust during riveting may be used as a means for real time quality control. The ultimate goal of this research is to develop a robust, economical and industrial joining process to enable the use of advanced materials in sheet metal industry for energy saving and emission reduction.