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.
