Research on the Characteristics of Hot Deformation in BT20 Titanium alloy and Its Optimum Spinning Temperature Range

摘要

Hot compression tests were conducted on a Gleeble-1500 simulator to investigate the hot deformation behavior of BT20 Ti alloy (Ti-6Al-2Zr-1Mo-1V) in the temperature range from 550 to 1000 deg C at constant strain rate in the range of 0.01-1 s~(-1), and then the optimum spinning temperature range was determined. Moreover, tube spinning experiments were executed to verify the reasonability of the optimum temperature range. The results show that the flow stress declines gradually with increasing deformation temperature and decreasing strain rate. In alpha + beta phase region the dynamic recrystallization is the main softening mechanism and in beta phase region the hot deformation softening is controlled by dynamic recovery. In alpha + beta phase region with reducing strain rate dynamic recrystallization is fully developed. The optimum temperature of hot spinning is 850-900 deg C and that of warm spinning is 600-650 deg C. Meanwhile, at the temperature above 600 deg C tubular workpieces of BT20 Ti alloy have been spun without surface cracks and microstructure inhomogeneity, which proves that the optimum spinning temperature range obtained through hot compression experiments is reasonable.