The Formation of the Metal Structure of Titanium Alloys Additively Manufactured by Direct Energy Deposition Using Hollow Conical Electron Beam with Coaxial Wire Feeding

The metal structure formed in any metallurgical process is determined by many phenomena and factors accompanying the transition of the metal from the liquid phase to the solid state. Metallurgical technologies suitable for industrial applications should provide the best controllability of the main process parameters that affect the formation of the metal structure of the product, and hence the mechanical properties and performance characteristics of the product.

The additive manufacturing technologies are essentially micro-metallurgical processes, where fundamentally the same factors and phenomena work as in the processes of melting and casting, but with a much greater influence of gravity, surface tension forces and various boundary effects. Therefore, the analysis of the conditions for the formation of the metal structure should be carried out with special care, and practically no factors can be neglected.

The report will analyze the characteristics of the formation of the metal structure of titanium alloys, produced by the technology of additive manufacturing famous as the xBeam 3D Metal Printing. The main difference of this technology is the usage of a hollow conical electron beam generated by a low-voltage (<20kV) electron gun, and a coaxial feed of the consumable wire to the deposition zone. These features provide the best opportunities for flexible and precise control of the thermal and hydrodynamic conditions of deposition of the added material on the substrate (previous layer) with the formation of accurate and repeatable layers.

Up to date, the xBeam 3D Metal Printing technology has already demonstrated the ability to form an isotropic metal structure with practically equiaxed grains, which ensured the uniformity of mechanical properties regardless of the orientation of the samples for testing. Possibilities for further improving the structure in “as built” state by applying appropriate deposition strategies, control methods and on-line adjustment of process parameters will be analyzed.