Biaxial thermal creep of V–4Cr–4Ti at 700°C and 800°C

A study of the thermal creep properties of V–4Cr–4Ti were performed using pressurized tube specimens. Creep tubes nominally 4.57 mm OD by 0.25 mm wall thickness were pressurized with high-purity helium gas to mid-wall effective stresses below the uniaxial yield strength. Specimens were heated to 700°C and 800°C in an ultra-high vacuum furnace and periodically removed to measure the change in OD with a high-precision laser profilometer. The secondary creep rate was found to be power-law dependent on the applied stress with a stress exponent of 3.7 at 700°C and 2.7 at 800°C. The average activation energy for creep of V–4Cr–4Ti was 299 kJ/mol, which is quite close to the activation energy for self-diffusion in pure vanadium in this temperature regime. The predominant mechanism of creep deformation for the conditions employed in this study is most likely climb-assisted dislocation motion.