Title: In-situ and ex-situ microstructure studies and dislocation-based modelling for primary creep regeneration response of 316H stainless steel

Abstract

The emergence of renewable energy sources with their variable and unpredictable nature demands for flexible operation of thermal power plants, and hence alters the typical steady creep loading of their high-temperature components to a stress-varying or cyclic creep conditions. The introduced load transients have been found to affect the strain hardening memory of the creeping alloys and might lead to multiple regenerations of primary creep stage and therefore considerably increase creep strain accumulation. Consideration of the primary creep regeneration (PCR) phenomenon is beyond the capability of conventional creep constitutive models which are based on strain- or time-hardening assumptions. The present study conducted in-situ and ex-situ experiments for 316H stainless steel and employed various microstructural examination techniques such as synchrotron high energy X-ray and neutron diffractions, backscattered and transmission electron microscopies for characterising the evolution of dislocation structure and internal lattice strain/stress state of the alloy during stress-varying and cyclic creep conditions. Formation/annihilation of dislocation pileups and bowing/unbowing of dislocation-lines were identified as the responsible mechanisms for PCR. A dislocation-based model was then formulated according to the proposed mechanisms which could well represent the measured microstructure evolution and mechanical response of the steel during the conducted experiments at 650°C.

Authors:

Li, X.; Holdsworth, S. R.; Kalácska, S. ;

• Search DOE PAGES for author "Kalácska, S."
• Search DOE PAGES for ORCID "0000-0001-5601-5859"

Balogh, L. ;

• Search DOE PAGES for author "Balogh, L."
• Search DOE PAGES for ORCID "0000-0003-3448-7833"

Park, J. -S.; Dasilva, Y. Arroyo Rojas; Maeder, X.; Cocks, A. ;

• Search DOE PAGES for author "Cocks, A."
• Search DOE PAGES for ORCID "0000-0002-6245-3406"

Mazza, E.; Hosseini, E.

Publication Date:

Wed Sep 01 00:00:00 EDT 2021

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC); Swiss National Science Foundation (SNSF); European Research Council (ERC)

OSTI Identifier:

1798908

Alternate Identifier(s):

OSTI ID: 1840528

Grant/Contract Number:  

AC02-06CH11357; 169877; 754364

Resource Type:

Published Article

Journal Name:

Acta Materialia

Additional Journal Information:

Journal Name: Acta Materialia Journal Volume: 216 Journal Issue: C; Journal ID: ISSN 1359-6454

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 316H austenitic steel; Dislocation-based model; EBSD; In-situ synchrotron XRD; Neutron diffraction; Primary creep regeneration; TEM