Effect of elastic follow-up and ageing on the creep of an austenitic stainless steel

Y. Q. Wang*, H. E. Coules, C. E. Truman, D. J. Smith

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)
235 Downloads (Pure)

Abstract

Elastic follow-up is a mechanical boundary condition lying between constant load and constant strain control. It exists in many engineering components operating at high temperature and can result in dramatically different creep stress relaxation and strain accumulation rates in a localized region of a component. We have performed creep tests under constant load, constant strain and elastic follow-up control on an aged (additional 22,000 h) 316H austenitic stainless steel after service in a nuclear power station for 65,000 h. Primary and secondary forward creep models with parameters derived from the constant-load data were able to describe constant-load creep adequately, but not able to predict stress relaxation and elastic follow-up. We show that this is because ageing has increased the constant-load creep strain rate significantly but has no effect on stress relaxation creep strain rate. Ageing promotes the formation of ferrite/chi phase at grain boundaries which are preferential sites for creep cavitation under load control. However, creep cavitation is less likely under constant strain and elastic follow-up control because a high creep strain rate, large creep strain and stress cannot coexist under these boundary conditions.

Original languageEnglish
Pages (from-to)219-232
Number of pages14
JournalInternational Journal of Solids and Structures
Volume135
Early online date2 Dec 2017
DOIs
Publication statusPublished - 15 Mar 2018

Keywords

  • Ageing
  • Austenitic stainless steel
  • Constitutive equations
  • Creep stress relaxation
  • Elastic follow-up

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