Multiscale mechanical fatigue damage of stainless steel investigated by neutron diffraction and X-ray microdiffraction
[1];
[7]
- Univ. of Science and Technology Beijing, Beijing (China); Northern Illinois Univ., DeKalb, IL (United States)
- Univ. of Science and Technology Beijing, Beijing (China); Northeastern Univ., Shenyang (China)
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Northeastern Univ., Shenyang (China)
- Univ. of Science and Technology Beijing, Beijing (China)
- Northern Illinois Univ., DeKalb, IL (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Mechanical fatigue behavior of AL6XN stainless steel as a typical type of planar slip alloy was investigated by in situ neutron diffraction and synchrotron-based X-ray microdiffraction methods. Under cyclic loading at a high strain amplitude (+/- 0.8%), the fatigue damage originated mainly from the accumulation of statistical stored dislocations, as clearly evidenced from a continuous increase in diffraction peak width with increasing the number of load cycles. However, under cyclic loading at a low strain amplitude (+/- 0.3%), the density of statistical stored dislocations became saturated just after a hundred loading cycles and the fatigue damage was mainly dominated by the accumulation of persistent [Alders bands (PLBs) and the complex interactions among various PLBs as evidenced through X-ray microdiffraction measurements. It was further found that there exists obvious grain-orientation-dependent local damage in the low-strain-amplitude fatigued sample. In particular, fatigued grains orientated with [001] paralleling the loading direction are subjected to compressive stress and contain a large number of broad PLBs in boundaries arraying the edge dislocation pile-ups, which generate a large stress gradient leading to local plastic instability. As a result, the highly localized stress field at PLBs in the cyclically-deformed sample at a low strain amplitude may explain the obvious cyclic stress softening.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC05-00OR2272; AC02-06CH11357; 2017YFA0403804; 51471032; 51527801; 06111020; 2018Z-13; AC05-00OR22725
- OSTI ID:
- 1507001
- Alternate ID(s):
- OSTI ID: 1636994
- Journal Information:
- Acta Materialia, Vol. 165, Issue C; ISSN 1359-6454
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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