Creep properties of V–4Cr–4Ti strengthened by cold working and aging

A study on uniaxial creep properties of V–4Cr–4Ti alloy (NIFS-HEAT-2) is carried out at 700 °C and 750 °C in a vacuum better than 1 × 10−6 Torr. The alloy is thermomechanically treated by cold working and aging for strengthening. The treatment introduces high density dislocations and fine precipitates. The pinning by precipitates is considered to suppress the glide of dislocations, causing significantly low creep rate at high stress levels. Power-law dependence of the minimum creep rate on applied stress was found. The predominant mechanism of creep deformation for the alloy with the strengthening is most likely to be dislocation climbing, because the creep activation energy is near the diffusion activation energy of vanadium.