High-Temperature Tribology of Selective Laser-Melted Titanium Alloys: Role of Adhesive Wear

Titanium alloys (Ti6Al4V) are emerging materials used in many engineering applications, especially aerospace, due to their strength-to-weight ratio, corrosion resistance, and high specific strength. The selective laser melting (SLM) process is vividly used to fabricate components with minimum material usage, which reduces the total weight of the product. The hard particles in the atmosphere repeatedly hit the aircraft turbine blades in a rotary motion during aircraft operations. Due to significant sliding action between articulating surfaces, these turbine blades need good wear resistance. With this motivation, rotary wear tests were performed under high vacuum at three different temperatures: room temperature, 400 °C, and 850 °C on as-built and heat-treated titanium alloy fabricated by the SLM process. The parameters like the speed, number of cycles, time, and high vacuum were considered to be constant while performing these high-temperature tribology experiments. As-built and heat-treated samples against the alumina ball resulted in lower coefficient of friction (COF) values at high temperatures compared to room temperature. In addition, adhesive wear was found to be the dominant wear mechanism at high temperatures. From the morphological studies, plowing strips, plowing ridges, and shallow grooves were significantly noticed on the worn-out surfaces of the heat-treated samples. Although low COF values were obtained at high temperatures on tested samples, higher specific wear-rates were seen in these samples due to the continuous removal of soft material.