Creep Behavior and Fracture of Ultra-Fine Grained Commercial Purity Zirconium at Ambient Temperature

Creep tests were carried out on ultra-fine grained commercial purity zirconium under the stresses of 0.875Rp0.2, 0.9Rp0.2, 0.9125Rp0.2, 0.925Rp0.2, 0.9375Rp0.2 and 0.95Rp0.2 at ambient temperature. Steady state creep rate was calculated. The creep fracture of the UFG CP Zr was investigated by SEM. A new expression was proposed which fitted the creep of UFG CP Zr better. It is found that the creep saturation phenomenon happens under the creep stress of 0.875Rp0.2; the steady state creep rate increases with the increase of creep stress and thus the steady state creep stage shortens; the creep resistance of UFG CP Zr is better than that of CG CP Zr at ambient temperature; the maximum of steady state creep rate is 3.140×10-6 s-1 under 0.95Rp0.2. According to the calculated creep stress exponent, the creep mechanism can be categorized into the dislocation motion. The creep fracture of UFG CP Zr is ductile fracture. © 2019, Science Press. All right reserved.