On the creep resistance in cast Ni-base superalloys

In this paper, we attempt to apply the modified hardening theory to estimate the creep resistance, which is considered as a key factor for controlling the creep deformation mechanism in cast nickel-base superalloys. It is suggested that, when the applied stress is high enough for the dislocations to cut into the γ′ particles, the creep resistance is almost a constant and independent of applied stress. At low applied stress, creep deformation is mainly controlled by dislocations climb, where the creep resistance has two components of a threshold stress and a friction stress. The model is verified for two cast nickel-base superalloys DZ17G and IN738. The results of detailed calculations are in good agreement with the experimental data.