Linear friction welding (LFW), an emerging automated technology, has potential for solid-state joining of dissimilar materials (bi-metals) to enable tailoring of the mechanical performance, whilst limiting the assembly weight for increased fuel efficiency. However, bi-metallic welds are quite difficult to manufacture, especially when the material combinations can lead to the formation of intermetallic (brittle) phases at the interface, such as the case with assembly of Ti base alloys with Ni base superalloys. The intermetallic phase, once formed, lowers the performance of the as-manufactured properties and its growth during elevated temperature service can lead to unreliable performance. In this project, it was demonstrated that linear friction welding can be applied to join Ti-6%Al-4%V (workhorse Ti alloy) to INCONEL® 718 (workhorse Ni-base superalloy) with minimized interaction at the interface. Of particular merit is that no intermediate layer (between the Ti alloy and Ni-base superalloy) was needed for bonding. Characterization of the bi-metallic weld included macro-and microstructural examination of the flash and interface regions and evaluation of the hardness.
On Liquation and Liquid Phase Oxidation during Linear Friction Welding of Nickel-base IN 738 and CMSX 486 Superalloys
