This study aims to examine the crack growth behavior of turbine disc GH4169 superalloy under creepfatigue loading. Crack growth experiments were performed on compact tension specimens using trapezoidal waveform with d...This study aims to examine the crack growth behavior of turbine disc GH4169 superalloy under creepfatigue loading. Crack growth experiments were performed on compact tension specimens using trapezoidal waveform with dwell time at the maximum load at 650℃. The crack growth rate of GH4169 superalloy significantly increased with dwell time. The grain boundaries oxidize during the dwell process, thereby inducing an intergranular creep-fhtigue fracture mode. In addition, testing data under the same dwell time showed scattering at the crack growth rate. Consequently, a modified model based on the Saxena equation was proposed by introducing a distribution factor for the crack growth rate. Microstructural observation confirmed that the small grain size and high volume fraction of the δ phase led to a fast creep-fatigue crack growth rate at 650℃, thus indicating that two factors, namely, fine grain and presence of the δ phase at the grain boundary, increased the amount of weakened interface at high temperature, in which intergranular cracks may form and propagate.展开更多
基金National Natural Science Foundation of China (Grant Nos. 51675024, 51305012, and 51375031).
文摘This study aims to examine the crack growth behavior of turbine disc GH4169 superalloy under creepfatigue loading. Crack growth experiments were performed on compact tension specimens using trapezoidal waveform with dwell time at the maximum load at 650℃. The crack growth rate of GH4169 superalloy significantly increased with dwell time. The grain boundaries oxidize during the dwell process, thereby inducing an intergranular creep-fhtigue fracture mode. In addition, testing data under the same dwell time showed scattering at the crack growth rate. Consequently, a modified model based on the Saxena equation was proposed by introducing a distribution factor for the crack growth rate. Microstructural observation confirmed that the small grain size and high volume fraction of the δ phase led to a fast creep-fatigue crack growth rate at 650℃, thus indicating that two factors, namely, fine grain and presence of the δ phase at the grain boundary, increased the amount of weakened interface at high temperature, in which intergranular cracks may form and propagate.
