Surface integrity of machined additively manufactured Ti alloys

Additive manufacturing processes (AM) offer the possibility to easily fabricate three-dimensional parts with high geometrical complexity. However, the additively manufactured components often require finishing operations, such as machining, showing a different machinability than those produced with conventional processes. Thus, it is crucial to study the effect of the manufacturer suggested cutting parameters on the surface integrity of the AM components, since they can behave differently than the correspondent wrought materials. The aim of the present work is to investigate the surface and subsurface modifications induced by turning operations performed on additively manufactured titanium alloys. The material under investigation is the grade 5 titanium alloy (Ti6Al4V) produced by three different methods namely, Electron Beam Melting (EBM), Direct Metal Laser Sintering (DMLS) and conventionally wrought processes. The effect of such processes on machinability and surface integrity is herein extensively studied (nano-hardness, plastically deformed layers, microstructural alterations etc.). In particular, the morphological, chemical and mechanical analyses on the pre- and post-machined samples highlight the influence of the production processes on their surface integrity underlying the need to properly redesign the machining parameters accordingly.