Influence of forging process on microstructure and mechanical properties of large section Ti-6.5Al-1Mo-1V-2Zr alloy bars

The mechanical properties, microstructure and tensile fracture of Ti-6.5Al-1Mo-1V-2Zr large section bars produced by three diffrent forging processes were investigated. The results show that when billet forging and finish forging were conducted by means of fullering at high and low temperature of β-region, respectively; the microstructure of forged bar is coarse Widmanstaten structure; the mechanical properties, especially the reduction of cross-sectional area, are poor, and the room temperature tensile fracture presents a brittle feature. While billet forging was carried out by upset-fullering at high temperature of the β-region, and finish forging was proceeded through fullering at (α+β)-region, the microstructure of forged bar was a duplex structure, the bar has better comprehensive mechanical properties, and the room temperature tensile fracture reveals a ductile feature. In order to obtain qualified Ti-6.5Al-1Mo-1V-2Zr alloy bar, it is the key that as-cast microstructure should be completely broken during billet forging, and the forging temperature and deformation are also well controlled upon finishing forging.