Process Development of the MELD Process for the Fabrication of Large Scale Titanium Alloy Components

Additive manufacturing (AM) is of high interest to manufacturers looking to “print” complex components on-demand. The ability to print their components on-demand enables shortened product delivery lead times, reduced financial investment associated with initial fixturing, and the ability to rapidly adjust designs to meet changes in applications and/or requirements. However, spatially restrictive deposition chambers, slower than desired production rates, and suboptimal physical properties are the some of the main hurdles AM technologies face as these processes look for more wide-spread adoption throughout industry for large-scale applications. The Additive Friction Stir (AFS) process is a novel solid-state AM technology that creates fully-dense products with near wrought properties, reduced distortion, and high deposition rates. The process principle is simple and is similar to Friction Stir Welding (FSW) with the exception of the use of filler material, either in solid or powder form. In this work, the fabrication of Ti-6Al-4V (Ti64) via the AFS process is presented. Ti64 finds applications in many industries including aerospace, marine, turbo machinery, and medical due to its high strength to weight ratio and corrosion resistance properties at high temperatures. The ability to use this material in additive manufacturing is in high demand by manufacturers within these industries as the cost of the material is significant, meaning that the scrap associated with traditional subtractive machining can be very costly, especially for the manufacture of large-scale complex parts. Ti64 deposited via the AFS process is fully dense with uniform grain structure and refinement (~5µm). The effect of the AFS process on the Ti64 deposited material including yield strength, elongation, hardness, microstructure, etc., will be presented. The content of this presentation will focus on the development efforts required to achieve excellent material properties (strength, microstructure, grain refinement) that are now exhibited by Ti64 material deposited by the AFS process.