SGER: Improved and Efficient Solid State Joining Process

这项SGER研究的目的是调查是否可以设计一种改进的金属固态焊接工艺，以节能的方式连接高温合金，这些合金在传统的搅拌摩擦焊接操作中由于其高抗变形性和焊接工具的过度磨损而无法实际连接。该研究方法是基于在旋转刀具之前使用多销刀具来提高变形体积的局部软化速率，从而使加工区域的局部剪切速率增加数倍。这个新概念以前没有被研究过。通过对剪切速率的分析，期望通过降低多销刀具的转速和修改刀具轨迹的结合，可以减小刀具表面的变形力，同时在接合界面处进行有效的传质。设计并制造了一个多针焊接头，并通过不同的工艺参数对其工作进行了研究。预计NSF资金将用于工具设计和工艺理论分析，而操作物理和优化研究将在额外的工业支持下进行。参与该项目的研究生将被训练在常规实验和分析之外，沿着具有挑战性和创新性的方向思考。这将使学生处于技术所有权的地位，并在以后的行业中占据主导地位。改进的工艺可以延长刀具寿命，简化操作，这可能成为工业的首选方法。该技术的增加和广泛使用将创造更多与该技术相关的制造业就业机会。行业管理者认为，这项技术未来的增长潜力很大。这项技术的知识将被纳入密歇根大学的工程课程。

The objective of this SGER research is to investigate if an improved solid-state welding process for metals could be designed to operate in an energy-efficient manner to join high temperature alloys that cannot be joined practicably because of their high deformation resistance and excessive wear of weld tooling in conventional friction stir welding operation. The research approach is based on increasing the local softening rate of the deforming volume ahead of the rotating tool by using a multi-pin tool capable of intensifying local rate of shear in the process zone many-fold. This novel concept has not been examined previously. Through analysis of shear rate, it is expected that a combination of reduced rotational speed of multiple pin tool and modification of the tool path would lead to reduced deformation forces on the tool surface while performing efficient mass transfer at the joining interface. A multi-pin welding head would be designed and built and its operation studied by varying process parameters. It is anticipated that NSF funds would be used for design of tooling and theoretical analysis of the process, while operational physics and optimization studies would be conducted with additional industrial support.Graduate student involved in the project would be trained to think along challenging and innovative directions in addition to routine experiments and analysis. This would place the student in a position of ownership of technology, and commanding position in industry later. Improved process could lead to longer tool life and simpler operation, which could become a preferred approach for industry. Increased and widespread use of this technology would create more manufacturing jobs tied to this technology. Industry mangers believe that future growth potential of this technology is major. The knowledge of this technology will be incorporated into engineering courses at the University of Michigan.