Effects of microstructure on high temperature dwell fatigue crack growth in a coarse grain PM nickel based superalloy
By Hangyue Li, Ji-feng Sun, M. Hardy, H. Evans, S. Williams, T. Doel, P. Bowen. 2015
155 citations recorded by the source corpus.
Abstract The influence of microstructure on the dwell fatigue crack growth behaviour of an advanced nickel-based superalloy was investigated at a temperature of 700 °C. Microstructural variations were induced by heat treatment variables: different cooling rates of quenching from super-solvus solution heat treatment, 0.7 and 1.8 °C s −1 , and an addition of a high temperature stabilisation heat treatment (2 h at 857 °C) between the solution treatment and the final ageing treatment. With a one hour dwell introduced at the peak load of the fatigue cycle, such different microstructural conditions can lead to a difference of up to two orders of magnitude in crack growth rates in air, when compared to those obtained under baseline fatigue loading. By performing such dwell fatigue and baseline fatigue tests in vacuum, it is confirmed that such increases in crack growth rates under dwell fatigue loading in air are mainly environmentally related. Transmission electron microscopy (TEM) was utilised to analyse both crack tip oxides and associated deformation mechanisms in the matrix. A novel mechanism taking into account competing interactions of crack tip oxidation (leading to increases in crack growth rates) and stress relaxation (leading to decreases in crack growth rates) is outlined.
Subfields: Aerospace Engineering, Mechanical Engineering, Mechanics of Materials
View Paper: https://www.semanticscholar.org/paper/077d283cf4ed05d2e94457118d464e3a9781ff1d
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In Aerospace Engineering
In Mechanical Engineering
In Mechanics of Materials
Citations in the corpus
- Environmentally-assisted grain boundary attack as a mechanism of embrittlement in a nickel-based superalloy (2017, methodology): “EDX mapping showed that the cracked grain boundaries and the incoherent primary g0-interfaces are decorated with oxidation products.”