In powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While... Show moreIn powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While numerous studies have
evaluated 3D-printing of spherical powder, very limited research has been carried out on
the processing of the non-spherical feedstock. This study is targeted specifically to the use
of non-spherical Ti-6Al-4V powders in the laser powder bed fusion (L-PBF) process. Two
different post-heat-treatments including hot isostatic pressing and solution treatment are
applied. The microstructure evaluation, potentiodynamic polarization, and electrochemical
impedance spectroscopy methods are used to characterize L-PBF processed and post-
treated specimens. Though as-built part exhibits anisotropic microstructure containing
acicular α′ martensite with trace amount of β phase, the heat-treated parts are composed of
α+β in which length and thickness of the α-lath depends on the treatment. The below β
transus heat treatment leads to the formation of a homogenized grain structures composed
of α+β. Electrochemical results show that the below β transus heat-treatment had a slight
positive effect on the improvement of corrosion resistivity (corrosion rate of 4.2×10-6 mmy-
1
, which is classified as an excellent ) compared to other conditions, which would be associated to the natural excellent corrosion resistance of Ti-6Al-4V alloy. This slight improvement can be ascribed by the slightly faster formation of a passive layer and its enhanced efficiency because of the presence of the fine-structured β phase in post heat- treated L-PBF processed Ti-6Al-4V alloy. Show less
