Cyclic viscoplasticity testing and modeling of a service-aged P91 steel

Hyde, Christopher J.; Sun, Wei; Hyde, T.H.; Rouse, J.P.; Farragher, T.; O'Dowd, Noel P.; Leen, S.B.

Abstract

A service-aged P91 steel was used to perform an experimental program of cyclic mechanical testing in the temperature range of 400 °C–600 °C, under isothermal conditions, using both saw-tooth and dwell (inclusion of a constant strain dwell period at the maximum (tensile) strain within the cycle) waveforms. The results of this testing were used to identify the material constants for a modified Chaboche, unified viscoplasticity model, which can deal with rate-dependant cyclic effects, such as combined isotropic and kinematic hardening, and time-dependent effects, such as creep, associated with viscoplasticity. The model has been modified in order that the two-stage (nonlinear primary and linear secondary) softening which occurs within the cyclic response of the service-aged P91 material is accounted for and accurately predicted. The characterization of the cyclic viscoplasticity behavior of the service-aged P91 material at 500 °C is presented and compared to experimental stress–strain loops, cyclic softening and creep relaxation, obtained from the cyclic isothermal tests.

• Journal Article Type: Article
• Acceptance Date: Feb 14, 2014
• Online Publication Date: Apr 16, 2014
• Publication Date: Aug 1, 2014
• Deposit Date: Sep 19, 2017
• Journal: Journal of Pressure Vessel Technology
• Print ISSN: 0094-9930
• Electronic ISSN: 1528-8978
• Publisher: American Society of Mechanical Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 136
• Issue: 4
• Article Number: 044501
• DOI: https://doi.org/10.1115/1.4026865
• Public URL: https://nottingham-repository.worktribe.com/output/994764
• Publisher URL: http://pressurevesseltech.asmedigitalcollection.asme.org/article.aspx?articleid=1832496
• Additional Information: Paper No: PVT-12-1136. Copyright © 2014 by ASME