Texture and Crystal Orientation in Ti-6Al-4V Builds Fabricated by Shaped Metal Deposition

The texture and crystal orientation of Ti-6Al-4V components, manufactured by shaped metal deposition (SMD), is investigated. SMD is a novel rapid prototyping tungsten inert gas (TIG) welding technique leading to near-net-shape components. This involves sequential layer by layer deposition with repeated partial melting and heat treatment, which results in epitaxial growth of large elongated prior beta grains. This leads to a directionally solidified texture, where the prior beta grains exhibit only a small misorientation with each other. The beta grains grow in < 100 > direction with a second < 100 > direction perpendicular to the wall surface. During cooling, the alpha phase transformation follows the Burgers orientation relationship leading to a Widmanstatten structure, with orientation relations between most of the alpha lamellae and also of the residual beta phase. The directionally solidi. cation and the transformation into the alpha phase following the Burgers relationship results in a texture, where the hcp pole figures look similar to bcc pole figures.