Processing Map of Powder Metallurgy TA15 Titanium Alloy for High Temperature Plastic Deformation

Abstract:

Hot compressing tests on powder metallurgy (P/M) TA15 titanium alloy have been conducted by a Gleeble-1500 simulator. A processing map for P/M TA15 titanium alloy in the temperature range of 850~1050 oC and the strain rate range of 0.001~10 s-1 was developed on the basis of a dynamic materials model and interpreted by microstructure observation. The results show that the alloy possesses superplasticity at the peak of power dissipation efficiency when deformed at T=1000 oC/=0.001 ~0.01 s-1. The alloy exhibits instability regime at T=850 oC/=0.001~0.01 s-1, T=900 oC/=1~10 s-1, T=950 oC/=0.01~1 s-1 and T=1050 oC/=1~10 s-1 with the power dissipation efficiency lower than 30%. Surface cracks and coarse β grains are observed. The deformation characteristics of P/M TA15 alloy at T=900 ~950 oC/=0.001~0.01 s-1, T=950 ~1000 oC/=1~10 s-1 and T=1000~1050 oC/=0.01~0.1 s-1, are recrystallization with the power dissipation efficiency of 30%~60%. Dynamic recrystallization or dynamic recovery can be observed in these domains.

Key words:powder metallurgy TA15 alloy; processing map; superplasticity; dynamic recrystallization; flow instability