Metal Additive Manufacturing Conference - MAMC 2023

Powder bed Electron Beam Melting of Ti-6Al-4V possesses better ultimate tensile strength than the conventional mill annealed Ti-6Al-4V. The changes in microstructure, tensile and fatigue crack growth rates were observed in the heat-treated samples below and above β transus temperature for one hour residence time followed by water and furnace cooling. Heat treatment below β transus temperature do not erase the signature of epitaxial growth during the re-melting of subsequent layers in EBM process. Whereas, the heat treatment above β transus temperature erases the footprint of additive manufacturing and epitaxial columnar grain growth of prior β grans is converted into coarse α+β phase and the structure is homogenous normal to building and transverse directions and hence the structure is similar to conventional Ti-6Al-4V. Very fine grains decorated with nano-size β phase in as build microstructure possess better mechanical strength, ductility and fatigue crack growth resistance than heat-treated samples.