Fundamental understanding of the mechanism of solid-state weld formation in dissimilar metal welds using ultrasonic additive manufacturing

摘要

Welding metals in the solid state always involves plastic deformation of the metals that need to be welded. Plastic deformation serves to remove the oxide layers and collapse asperities bringing nascent materials in contact [1]. However some underlying fundamental mechanisms are yet to be resolved. One of the areas where a fundamental gap exists is if co deformation is necessary to initiate a solid state weld in a dissimilar metal combination. To address this question attempts were made to weld aluminum to titanium and characterize the interfaces. Al and Ti were chosen primarily for the difference in hardness. In addition to the above objective aluminum and titanium were chosen due to their industrial relevance. Solid state welds are necessary to fabricate Al-Ti welds due to the formation of intermetallic compounds at the interface during fusion welding [2]. UAM is an important additive manufacturing technique that has gained significant importance in the present times to fabricate complex geometries using dissimilar metals for a wide gamut of applications. Though UAM has been used to successfully join Al 3003 and CP Ti [3] there is a fundamental gap in understanding the actual bonding mechanism due to the lack of characterization. Hence to address the exact mechanism of bonding a detailed multiscale characterization coupled with mechanical testing is performed in this work.