As-Built EBM and DMLS Ti-6Al-4V Parts: Topography–Corrosion Resistance Relationship in a Simulated Body Fluid

Abstract

Machined devices made of titanium or titanium alloys are widely used in biomedical applications. Recently, additive manufacturing technologies (AM) were proposed to reduce the cost of parts and customise their shape. While several researchers have studied the characterisation of the machined surfaces of AM products, less attention has been focused on the study of the surfaces of as-produced parts. The aim of this study was to compare the surface and bulk properties of Ti-6Al-4V alloy products obtained using two types of AM—i.e., electron beam melting and direct metal laser sintering—in comparison to the wrought material and analyse their metallographic, crystallographic, topographic, and electrochemical properties. The metallographic and crystallographic, as well as topographic, analysis showed different microstructures and surface area extensions between the tested specimens. Potentiodynamic polarisation tests highlighted the complex electrochemical behaviour of additively manufactured parts if compared to that of the traditionally fabricated ones. The tests performed on mechanically polished parts underlined similar electrochemical performance between them, even if the additive manufactured ones exhibited a certain instability. Although the as-produced additive manufactured parts present exciting surface shapes, useful in the biomedical field, significant drawbacks remain. A more in-depth study of the device surface modifications, to improve their electrochemical behaviour, is needed.