Effects of annealing temperature and quenching medium on microstructure, mechanical properties as well as fatigue behavior of Ti-6Al-4V alloy

In this research, the effects of annealing temperature and quenching medium on microstructure, mechanical properties as well as high cycle and low cycle fatigue behavior of Ti-6Al-4V were investigated. Four types of different heat treatments consisting annealing at 930‌°C and 970 °C followed by air cooling or water quenching were considered. Microstructural and mechanical evolutions were evaluated using optical microscope (OM), hardness and tensile tests. According to S-N curves, fatigue behavior followed up the same trend in both high and low cycle fatigue regimes in a way that the higher the annealing temperature and more intense the quenching medium, the better fatigue resistance. SEM fractography of fatigue surfaces indicated cleavage ductile fracture mode in all kinds of applied heat treatments.