A physically-based method for predicting high temperature fatigue crack initiation in P91 welded steel
Zhou, Jinbiao Barrett, Richard A. Leen, Sean B.
Zhou, Jinbiao
Barrett, Richard A.
Leen, Sean B.
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Publication Date
2021-08-27
Type
Article
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Zhou, Jinbiao, Barrett, Richard A., & Leen, Sean B. (2021). A physically-based method for predicting high temperature fatigue crack initiation in P91 welded steel. International Journal of Fatigue, 153, 106480. doi: https://doi.org/10.1016/j.ijfatigue.2021.106480
Abstract
A methodology is presented for physically-based prediction of high temperature fatigue crack initiation in 9Cr steels, with a focus on material inhomogeneity due to welding-induced metallurgical transformations. A modified form of the Tanaka-Mura model for slip band formation under cyclically-softening conditions is implemented in conjunction with a physically-based unified cyclic viscoplasticity constitutive model. The physically-based constitutive model accounts for the key strengthening mechanisms, including precipitate hardening and hierarchical grain boundary strengthening, successfully predicting cyclic softening in 9Cr steels. A five-material, finite element model of a P91 cross-weld test specimen, calibrated using the physically-based yield strength and constitutive models, successfully predicts the measured detrimental effect of welding on high temperature low-cycle fatigue crack initiation for P91 cross weld tests, via the modified Tanaka-Mura model. A key finding of the current work is the requirement to adopt an energy-based Tanaka-Mura method to account for cyclic softening in 9Cr steels, with packet size as the critical length-scale for slip band formation. The work demonstrates the significant effect of highly flexible operation on the service life of welded connections.
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Publisher
Elsevier
Publisher DOI
10.1016/j.ijfatigue.2021.106480
Rights
Attribution 4.0 International (CC BY 4.0)