Sliding wear of selective laser melting processed Ti6Al4V under boundary lubrication conditions

The titanium alloy Ti6Al4V is widely used in industry due to its high strength-to-mass ratio and good performance at high temperature. However, it exhibits poor tribological performance. The selective laser melting (SLM) process increases the application range of Ti6Al4V because of its flexibility for prototyping any part and its low material waste. In the present paper, three types of Ti6Al4V samples (a conventionally processed (CP) sample, an as prepared SLM sample, and a heat treated SLM sample) were analyzed. Material properties analysis was conducted in terms of microstructural observations, hardness, and Young׳s modulus. The wear behaviors were evaluated in contact with soft and hard materials using a ring-on-disc rig under boundary lubrication conditions. The results indicate that the three sample types have different microstructures. The wear for Ti6Al4V in contact with brass is characterized as mild wear. Adhesive wear was observed due to the failure of the lubricant. The tribo-layer is thin and contains a trace of oxygen. Oxidative wear, abrasion, and delamination were observed on the Ti6Al4V surface in contact with hardened 38CrMoAl. Only the heat treated SLM sample presented a protective tribo-oxide and no plastic deformation was found, which has the lowest wear rate.