Effect of annealing treatment and aging on the microstructure and tensile properties of Ti-6242

The effect of variation in annealing heat treatment parameters such as temperature and cooling rate and subsequent aging temperature on the microstructure and tensile properties of Ti-6Al-2Sn-4Zr-2Mo alloy is the purpose of this study. In order to clarify the effect of annealing temperature, heat treatment carried out in the temperature range of 940-990°C (with 15°C steps) followed by air cooling. The effect of cooling rate was also examined in one specimen annealed at 955°C by cooling in oil. The response of this alloy to aging temperature was evaluated by aging annealed specimens at 955°C at various temperatures of 570, 600 and 630°C. Microstructural analysis showed that increasing the annealing temperature led to a decrease in volume fraction of primary alpha and increase in secondary alpha thickness and alpha colony size. In addition, the most important microstructural difference in various cooling rate after annealing treatment is the decrease in secondary alpha thickness that causes an increase in strength and decrease in ductility. Increasing the aging temperature led to an increase in alpha colony size and secondary alpha thickness while negligible variation in ductility was detected. The best tensile properties of the alloy resulted by annealing at 955°C, cooling in air and aging at 600°C.