Abrasive wear resistance of Ti-6AL-4V obtained by the conventional manufacturing process and by electron beam melting (EBM)

Ti–6Al–4V is one of the most used commercial titanium alloys, in part due to properties that are desirable in high value sectors such as the aerospace industry, such as good strength-to-weight ratio and corrosion resistance. These are of importance in gas turbine engines and structural components, where titanium alloys complement heavier steel or nickel alloys. It is also a good candidate to be used in the manufacturing of prostheses, since it has good biocompatibility, but applications in other areas are limited due to its poor bulk wear resistance. Conventionally processed Ti-6AL-4V is typically used, however additive manufacturing (AM) techniques such as electron beam melting (EBM) can also be applied to this alloy. These techniques are increasingly attractive across many industries because of geometrical freedom and control of mechanical properties, both key, for example, to the successful production of highly personalised prostheses and complex thermofluids channels in aerospace and automotive components. Parts produced by EBM are typically denser than those obtained by other AM processes, but still experience increased wear over their traditionally obtained equivalents, particularly in sliding, thus surface treatment is common. This work compares the wear observed when specimens manufactured by either conventionally or EBM were subjected to abrasion via means of a dry sand-rubber wheel tribometer capable of testing to the ASTM G65 test method. The specimens and resulting wear scars were characterised (hardness, grain size, roughness) and details of the wear mechanism(s) identified. The EBM specimens exhibited much greater wear, over twice that of the conventionally obtained specimens, and feature significantly more scratches. Although there are several studies variously considering two-body sliding wear and the efficacy of surface treatments of this type of alloy, this work addresses the paucity of information about the comparative abrasive wear performance of the alloy obtained via the two process routes.