Metallurgical evaluation of laser additive manufactured Ti6Al4V components

Abstract

Ti6Al4V laser manufactured samples were analysed using optical and scanning electron microscopy equipped with X-ray micro-analyser. The presence of a, a(sub2), ß, a', and a'' phases were determined using differential scanning calorimetry. The angle of contact between single deposited layer and Ti6Al4V base as well as the tensile properties of the component were evaluated. Powdered metal globularization, size segregation, un-melted or semi-melted particles and chemical surface contamination were revealed. Very few globules were in perfect contact with the Ti6Al4V base. The lack of wettability, between the Ti6Al4V base and molten Ti6Al4V powder, and the partial immiscibility evidently is the result of relatively higher interfacial energy between the solid and liquid compared to the surrounding atmosphere-liquid and solid-gas interfacial energies. The produced surface finish was relatively rougher. A mixture of columnar grains, layer bands and fully martensitic structure was developed during the laser additive manufacturing due to fast cooling and heat input localization. Ultimate and yielding strength were relatively higher in the as manufactured and polished parts, however lower tensile properties were revealed mil-annealed.