Fatigue induced deformation and thermodynamics evolution in a nano particle strengthened nickel base superalloy

Abstract

In‐situ neutron‐diffraction and temperature measurements were simultaneously applied to investigate low‐cycle‐fatigue behaviour of a nano‐precipitate strengthened nickel‐based superalloy. Two transitions in the temperature‐evolution are observed subjected to cyclic loading. Two models are compared with the measured temperature evolution. One is based on bulk stress, and the other is based on lattice‐strain evolution. The calculated thermoelastic responses in both models qualitatively agree with the measured bulk‐temperature evolution for the first transition. The in‐situ neutron‐diffraction results reveal that the first transition is associated with the cyclic hardening/softening dislocation‐structural transformation. However, the second transition, which is observed at larger number of fatigue cycles during the steady cycles, does not correlate with the dislocation evolution. A phenomenological model is applied to describe the second temperature‐transition stages. The energy dissipation evolutions in the second fatigue stage indicate the initiation and the growth activities of fatigue microcrack. The data reported here may be useful for cohesive zone model.

Comparing Cyclic Tension-Compression Effects on CoCrFeMnNi High-Entropy Alloy and Ni-Based Superalloy

“…The nickel-based superalloy HASTELLOY C22™ (Ni-21Cr-17Mo in weight percentage) was annealed to dissolve most precipitates into the fcc matrix structure. C22™ has been chosen as a reference because this Ni-based superalloy has been extensively studied using neutron diffraction and other complimentary experiments [11][12][13][14][15][16][17]. Several correlations from diffraction-data characteristics, microscopic images and underneath deformation mechanisms have been found as benchmarks and references.…”

“…Hence, we follow the same protocol and experimental design performed on the C22™ to apply to the current CoCrFeMnNi HEA examinations. In addition, the LCF experiments and cyclic-loading deformation mechanisms of the C22™ are clarified and cited in many articles [11][12][13][14][15][16].…”

“…The cyclic frequency was 1 Hz. The neutron diffraction profiles were analyzed by applying pseudo-Voigt function for single peak fitting with the General Structure Analysis Software (GSAS, Los Alamos National Laboratory, version 1, Los Alamos County, New Mexico, United States) [21] and Convolutional Multiple Whole Profile (CMWP) [22] software, following the previously used protocol [13,15].…”

On the Evidence of Thermodynamic Self-Organization during Fatigue: A Review

“…Similar to stored energy measurement, non-destructive techniques such as acoustic signals and temperature are useful macroscale indicators to evidence patterning and self-organization occurrence in fatigue-induced structural transformations [ 98 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 ]. Among abundant and compelling works concerning measuring the degree of degradation through acoustic emission and thermography, a few selective of them are of interest here to elaborate the rationale between the appearance of patterning and macroscale measurement tools [ 98 , 154 , 155 ]. However self-organization was not directly addressed in some of the aforementioned references, the patterning occurrence can be justified by analogy among dislocations activities, acoustic sound, and temperature evolution in the course of fatigue.…”

Fatigue‐Crack‐Growth Behavior of Two Pipeline Steels

“…Fatigue studies are the key aspects of the present work . The FCGR properties are of vital importance for the structural‐reliability assessment, when a structural component is subjected to cyclic loading .…”