1. EBSD analysis of cyclic load effect on final misorientation distribution of post-mortem low alloy steel: A new method for fatigue crack tip driving force prediction
- Author
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Yue Su, Wenhui Qiu, Shao-Shi Rui, Yasuharu Chuman, Shunsaku Matsumoto, Yi-Bo Shang, Li-Sha Niu, and Hui-Ji Shi
- Subjects
Diffraction ,Materials science ,Misorientation ,Mechanical Engineering ,Alloy steel ,02 engineering and technology ,engineering.material ,Plasticity ,021001 nanoscience & nanotechnology ,Power law ,Industrial and Manufacturing Engineering ,020303 mechanical engineering & transports ,Distribution function ,0203 mechanical engineering ,Mechanics of Materials ,Modeling and Simulation ,engineering ,Range (statistics) ,General Materials Science ,Composite material ,0210 nano-technology ,Electron backscatter diffraction - Abstract
The effect of applied cyclic load, including the maximum plastic strain e max p and the plastic strain amplitude e a p on final misorientation level of post-mortem low alloy steel after low cycle fatigue (LCF) test, was analyzed by Electron Back-Scattered Diffraction (EBSD) in this research at first. Two misorientation parameters widely used in EBSD analysis, Kernel Average Misorientation (KAM) and Grain Reference Orientation Deviation (GROD), are compared in terms of accumulated plasticity characterization after LCF failure, where a bilinear function is found between final KAM and applied cyclic load e max p & e a p . Then the cyclic load effect on final misorientation distribution of post-mortem low alloy steel after fatigue crack propagation (FCP) test was further analyzed by EBSD based on the above bilinear function between final KAM and e max p & e a p , as well as the equivalent e ¯ max p & Δ e ¯ p distribution functions given by HRR field. −1/2 power law is established to describe final KAM distribution near crack path. The area SKAM between final KAM distribution curve and undeformed KAM0 base line within a certain range, rather than SGROD, is proposed as a better measurement of fatigue crack tip driving force ΔK in constant load ratio R condition. Meanwhile, the influence of load ratio R on final misorientation distribution is also discussed.
- Published
- 2018
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