Effect of gamma prime depletion on creep behaviour of a nickel base superalloy (Inconel alloy X-750)

Abstract

Specimens of a nickel base superalloy were exposed to air at 1423 K to study the effect of gamma prime depletion in the near-surface region on the creep behaviour of the alloy. The results showed that the gamma prime depletion in the air-exposed specimens caused a weakening effect, leading to enhanced creep rate. Kachanov's damage parameter ∫ was determined and was found to be 0.5 indicating that the near-surface region, comprising of surface oxide, grain boundary oxide and gamma prime depleted region, carried a small fraction of the applied stress. It is further shown that the damaging effect is more pronounced in thinner specimens.