Effect of small temperature variations on the tensile behaviour of Ti-6Al-4V

Although the effect of high and low temperatures on the mechanical properties of Ti-6Al-4V has already been extensively studied, extreme temperatures are usually considered in these investigations. Instead, the present work focuses on a range of temperatures not far from room conditions. This particular range of temperatures is important not only because it is commonly found in service, but also because it corresponds with the temperatures reached by plastic work heating when the material is plastically deformed. Isothermal tensile tests show that relatively low temperatures (of less than 100 degrees C) already have a non-negligible effect on the plastic flow of the material. Numerical simulations of the heat generation in the test samples and the heat transfer to the surrounding environment show that there is a significant temperature increment in samples loaded at low strain rates. As is confirmed by experiments at these speeds, thermal softening, together with the strain rate effect, is playing an important role, even at strain rates at which isothermal conditions are often assumed. Finally, the suitability of the Johnson-Cook plasticity model to describe the observed behaviour is discussed. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11