Creep Behavior of CP-Ti TA2 at Low Temperature and Intermediate Temperature

Abstract:

Significant temperature and stress dependent creep behavior of commercial pure titanium TA2 was observed at low and intermediate temperature. According to the variation of creep strain with applied stress level, the relationship between threshold stress level and the corresponding creep temperature was determined. Based on short time creep tests, the constitutive equation containing steady state creep strain rate was used to extrapolate the minimum creep rate. The existence of steady state creep of commercial pure titanium TA2 was confirmed by subsequent long time creep experiments. Through the minimum creep strain rates, creep stress exponent was obtained which also indicates the accuracy of the extrapolated minimum creep strain rates. The activation energy of primary creep (approximately 60KJ/mol) at different creep strains level was higher than the activation energy for slip controlled creep, which demonstrates the importance of twinning for the development of creep behavior of commercial pure titanium TA2 at low temperature. Moreover, according to the variation of twinning structure with deformed temperature in creep tested specimens, the temperature dependent creep behavior was interpreted and the importance of twinning for creep behavior of TA2 was confirmed.