Tailoring titanium alloys to additive manufacturingWednesday (26.09.2018) 14:30 - 15:00 S1/03 - 221 Part of:
Metal-based additive manufacturing (AM) permits fabrication of near net-shape metallic components with complex geometries providing -for instance- inner channels for cooling fluids, or bionic and load-optimized structures of minimal weight not achievable with conventional production methods (e.g. casting or machining). For titanium based components, these advantages account estimated production savings up to 50% by missing out in major part, exorbitant machining costs and material loss. A critical issue for certification of AM parts is the degree of isotropy of their microstructure, derived from the solidification conditions during AM and eventual post-treatments. A deep-rooted drawback during AM of titanium alloys is the steep and directional thermal gradient in the molten metal pool, provoking epitaxial growth of coarse columnar prior β-grains with strong <100>β orientation along the building direction. The investigations presented, aim at triggering alternative paths of α formation other than direct transformation from the parent β phase, which leads to inheritance of texture and usually, to brittle microstructures with unsuitable martensite for structural applications. Remarkable texture reductions are obtained by slightly altering chemical composition and exploiting the metastability of the AM process.