Effect of solution temperature and cooling rate on microstructure and mechanical properties of laser solid forming Ti-6A1-4V alloy

The effect of solution temperature and cooling rate on microstructure and mechanical properties of laser solid forming (LSF) Ti-6A1-4V alloy is investigated. The samples are solutions treated at 900, 950, and 1000°C, followed by water quenching, air cooling, and furnace cooling, respectively. It is found that the cooling rate of solution treatment has a more important effect on the microstructure in comparison with the solution temperature. The martensite α' formed during water quenching results in the higher hardness and tensile strength but lower ductility of samples. With decreasing the cooling rate and increasing the solution temperature, the width of primary α laths increases, and the aspect ratio and volume fraction decrease, which make the hardness and tensile strength decrease and the ductility increase.