Creep-fatigue crack growth behavior in GH4169 superalloy
Dianyin HU , Xiyuan WANG , Jianxing MAO , Rongqiao WANG
Front. Mech. Eng. ›› 2019, Vol. 14 ›› Issue (3) : 369 -376.
Creep-fatigue crack growth behavior in GH4169 superalloy
This study aims to examine the crack growth behavior of turbine disc GH4169 superalloy under creep-fatigue loading. Crack growth experiments were performed on compact tension specimens using trapezoidal waveform with dwell time at the maximum load at 650 °C. 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-fatigue 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 d phase led to a fast creep-fatigue crack growth rate at 650 °C, thus indicating that two factors, namely, fine grain and presence of the d phase at the grain boundary, increased the amount of weakened interface at high temperature, in which intergranular cracks may form and propagate.
crack growth rate / creep-fatigue / GH4169 superalloy / CT specimen / dwell time
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Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature
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