Microstructures and hardness of Ti-6Al-4V alloy staging castings under centrifugal field

By means of induction melting technology, Ti-6Al-4V alloy staging casting was made with the same rotation velocity and centrifugal radius. The effects of casting modulus on the grain size, the thickness of lamellar α+β phase, and the Vickers hardness, as well as the relationships between Vickers hardness, grain size and thickness of lamellar α+β phase were investigated. The results show that the greater the modulus, the larger the grain size and the thickness of lamellar α+β phase, and the less the Vickers hardness. The relationship between Vickers hardness and grain size meets the Hall-Petch equation: Hv=353.45+74.17d_G^-1/2. The relationship between the Vickers hardness and the thickness of lamellar α+β phase is expressed as Hv=2.45d_{α + β}² - 35.96d_{α + β} + 476.84.