Abstract
Low cycle fatigue (LCF) and creep-fatigue testing of Ni-based alloy 617 was carried out at 850 C. Compared with its LCF life, the material's creep-fatigue life decreases to different extents depending on test conditions. To elucidate the microstructure-fatigue property relationship for alloy 617 and the effect of creep and oxidation on its fatigue life, systematic microstructural investigations were carried out using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction (EBSD). In LCF tests, as the total strain range increased, deformations concentrated near high angle grain boundaries (HAGBs). The strain hold period in the creep-fatigue tests introduced additional creep damage to the material, which revealed the detrimental effect of the strain hold time on the material fatigue life in two ways. First, the strain hold time enhanced the localized deformation near HAGBs, resulting in the promotion of intergranular cracking of alloy 617. Second, the strain hold time encouraged grain boundary sliding, which resulted in interior intergranular cracking of the material. Oxidation accelerated the initiation of intergranular cracking in alloy 617. In the crack propagation stage, if oxidation was promoted and the cyclic oxidation damage was greater than the fatigue damage, oxidation-assisted intergranular crack growth resulted in a significant reduction in the material's fatigue life.
| Original language | English |
|---|---|
| Pages (from-to) | 393-403 |
| Number of pages | 11 |
| Journal | Journal of Nuclear Materials |
| Volume | 444 |
| Issue number | 1-3 |
| DOIs | |
| State | Published - 2014 |
Funding
This work was supported by U.S. Department of Energy grants DE-FC07-07ID14819 and NEUP 09-516. Z.Q. Yang was supported partially by NSFC 51171189. The microanalysis was carried out at the Shared Research Equipment User Facility at Oak Ridge National Laboratory, which is supported by the Scientific User Facilities Division of the Office of Science, U.S. Department of Energy. The authors are thankful for Dr. Richard Wright and Dr. Laura Carroll from Idaho National Laboratory for providing test materials. The authors also would like to thank Dr. David Hoelzer from Oak Ridge National Laboratory for providing a critical review of this work. The authors are also grateful for Christopher Stevens and Eric Manneschmidt from Oak Ridge National Laboratory for their technical support. Many thanks to Alan M. Bolind and April J. Novak for the grammar check of the manuscript.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | DE-FC07-07ID14819, NEUP 09-516 |
| Office of Science | |
| Oak Ridge National Laboratory | |
| National Natural Science Foundation of China | 51171189 |