Mechanical Properties Variation of Ti-6Al-4V Alloy by Microstructural Control

The mechanical properties of Ti-6Al-4V can be improved by microstructural control through the heat treatment in α+β region. The heat treatment was carried out with a variety of heat treatment temperatures and holding times to find the optimized heat treatment conditions and it was analyzed by linking the microstructural characteristics and mechanical properties. The part of β phase with 10±2wt% vanadium was transformed into α^ martensite phase after quenched, so the hardness and tensile properties were decreased below 900∘C . The higher the heat treatment temperature is, the smaller is the vanadium-rich region, which leads to transformation into hcp α^ martensite above 900∘C . The hardness and tensile properties were improved due to the hard α^ martensite. As the holding times were longer, the hardness and tensile properties decreased below 900∘C because of the softening effect by the grain growth. When varying the holding times above 900∘C , the change of mechanical properties was slight because the softening effect of grain growth and the strengthening effect of α^ phase were counteractive. Therefore, the best conditions of heat treatment, which is in the range of 920~960∘C , 40 min, WQ, can effectively improve the mechanical properties of Ti-6Al-4V.