Hot deformation behavior of near α titanium alloy Ti-1100 prepared by TiH2-based powder metallurgy

Abstract:

Hot deformation behavior of TiH₂-based PM near α titanium alloy Ti-1100 alloys has been investigated at temperature range of 973–1173K and strain rate range of 0.01–1.0s^_-1 by hot compression tests. The Arrhenius constitutive equation was developed and the hot deformation activation energy was calculated to be 334.76 kJ/mol. The temperature sensitivities (θ) were calculated by a modified function and the strain rate sensitivities (m) were determined. Based on the results of temperature sensitivity and strain rate sensitivity together with microstucture at strain rate of 0.5, the hot working condition was analyzed. It was found that the instability regions is mostly appeared at strain rate of 0.01s^_-1 and 1s^_-1 over whole temperature range, while the optimal hot working conditions are obtained in the range of 1135K 0.29s^_-1 to 1173K 0.76s^_-1, and 1040 0.33 s^_-1 to 1096K 0.6s^_-1. Besides, the microstucture analysis reveals that the dynamic recrystallization (DRX) occurs at strain rate of 0.01–0.1s^_-1, while the formation of micro-voids is the dominant mechanism of flow softening at strain rate of 1s^_-1.

Key words:Ti-1100 alloy, TiH₂-based;Powder metallurgy, Hot;compression test, Arrhenius;constitutive model, Strain;rate sensitivity, Temperature;sensitivity, Hot;workability