Effect of solution treatment on the microstructure and mechanical properties of Ti-6Al-6Mo hot-rolled alloy

Abstract

Titanium and its alloys are widely used in biomedical applications due to their unique combination of good hot workability, high specific strength and good corrosion resistance. In this study, elastic modulus, hardness and the effects of solution treatment on microstructures and mechanical properties of Ti-6Al-6Mo hot-treated alloy were investigated using OM (optical microscopy), XRD (X-ray diffractometry), SEM (Scanning electron microscopy), Ultrasonic testing and hardness testing. Previously, the sampels were hot-rolled at 900oC for 1 h with a total reduction of 50%,and then followed by air cooling. The samples were carried out solution treatment for 1 h at 850oC and 950oC, followed by water cooling and at temperature of 1050oC with water and air cooling. The results indicate that the hardness of the Ti-6Al-6Mo alloy increased with the increasing of solution treatment temperature on the water cooling, while the elastic modulus was decreased. The lowest elasticity modulus value and the highest hardness, 125.4 GPa and 46.3 RC were obtained at 1050oC with equiaxed micro structure and β' precipitate. XRD analysis exhibited the presence of α and β phases in Ti-6Al-6Mo alloys after solution treatment. Based on the relative intensity of XRD strongest peak analysis, the α phase intensity decreases with the increasing of solution treatment temperature, this phenomenon causes the decreasing of elasticity modulus value with the increasing of solution treatment temperature on water cooling medium.