TIME-DEPENDENT FATIGUE AND ITS MICROMECHANISM OF SUPERALLOY GH169 UNDER OXIDATION

The time-dependent fatigue and its micromechanism of superalloy GH169 at 650℃ have beenstudied.Under the same stress and duration,its cyclic life in Ar is shorter than that in air.Thedamage mechanism is mainly of the interaction between high temperature oxidation and fa-tigue.The fracture surface of GH169 specimen oxidized at 650℃ in air is revealed to be cov-ered with a dense and even oxide film,but in Ar,with uncontinuous oxide particles.As thetime prolonged,the Cr_2O_3 content in the surface oxides increases in air and decreases in Ar.