Effect of Heat Treatment on the Oxidation and High Temperature Wear Performance of Alloy Ti-6Al-4V Manufactured by Direct Metal Laser Sintering

In this work, alloy Ti-6Al-4V was fabricated using direct metal laser sintering (DMLS) approach and studied the effect of heat treatment (solution treatment 950 degrees C/2h-furnace cooling and aging 550 degrees C/6h-air cooling) on the oxidation and wear performance at elevated temperature. The microstructural investigation revealed that as- built alloy consists of a fine-grained martensitic needle shape structure with columnar grains. In the solution treatment aging (STA) treated alloy, the rod-shaped beta with different lengths of a was observed. As-built and STA-treated alloy Ti-6Al-4V were subjected to a cyclic oxidation test at 650 degrees C for 50 h in air. The reaction products developed on the sample's surface are evaluated by scanning electron microscope (SEM) and X-ray diffraction (XRD). A thick TiO2 layer was formed on the alloy surface, and some cracks were noticed due to thermal stress. The high-temperature wear test was carried out on the Ti-6Al-4V alloy at room temperature (30 degrees C), 200, and 400 degrees C using a reciprocating pin-on-disc tribometer in dry conditions. The abrasive wear mechanism was found at RT, whereas oxidation and the adhesive mechanism were noticed at 200 and 400 degrees C. Results exhibited that STA alloy had a higher wear resistance than that of as-built alloy.