An improved constitutive description of tensile behavior for CP-Ti at ambient and intermediate temperatures

摘要

The tensile behavior of commercially pure titanium (CP-Ti) was investigated at temperatures ranging from 283 K to 573 K and strain rates ranging from 5 × 10~(-5) s~(-1) to 5 × 10~(-3) s~(-1). In this temperature range, the apparent activation energy (Q) is temperature dependent causing by the competing process of deformation mechanisms. In order to quantitatively describe the evolutionary process of the deformation mechanism with temperature, a quantitative index is proposed based on the variation of Q with temperature. The threshold temperature 438 K is determined by the quantitative index of deformation mechanism, and this threshold temperature indicates the transition from the low temperature deformation mechanism dominated regime to the high temperature deformation mechanism dominated regime. Since the deformation mechanism is changing in the concerned temperature range, the classical Arrhenius type model is inappropriate to describe the tensile behavior of CP-Ti. To extend the application scope of the Arrhenius type model to a wider temperature range, the Arrhenius type model is improved by considering the competing process of deformation mechanisms.