The evaluation of high-stress creep ductility for 316 stainless steel at 550 °C by extrapolation of constitutive equations derived for lower stress levels

Qiang Xu, David Hayhurst

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13 Citations (Scopus)

Abstract

The CDM-based constitutive equations for the creep of 316 Stainless Steel at 550 °C are reviewed. During creep tests carried out under these conditions, it has been observed that as time elapses inelastic straining takes place due to time independent plasticity and to creep. It has been recognised that at high stress levels the time dependent plastic strain accumulated during constant load creep tests forms a major part of the inelastic strain and dominates over the creep strain. Hence, due to the plastic strain the true stress level is not constant during the test. The time independent plastic strain has been evaluated using a stress–strain curve obtained at a high strain rate, and the creep strains have been evaluated for the relevant stress history by integration of the constitutive equations. Minimum creep rates and lifetimes have been extrapolated from low stresses to higher stresses using linear stress versus logarithmic plots. In this way, the creep strain–time history, the minimum creep rates, lifetimes and ductilities have been evaluated. In the stress range 325–450 MPa a lower shelf ductility of 1.1% has been found. The model is also shown to predict the isochronous rupture locus determined from multi-axial test data obtained from a range of different sources.
Original languageEnglish
Pages (from-to)689-694
Number of pages6
JournalInternational Journal of Pressure Vessels and Piping
Volume80
Issue number10
DOIs
Publication statusPublished - 1 Oct 2003
Externally publishedYes

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Stainless Steel
Constitutive equations
Extrapolation
Ductility
Creep
Stainless steel
Plastic deformation
Plasticity
Strain rate

Cite this

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title = "The evaluation of high-stress creep ductility for 316 stainless steel at 550 °C by extrapolation of constitutive equations derived for lower stress levels",
abstract = "The CDM-based constitutive equations for the creep of 316 Stainless Steel at 550 °C are reviewed. During creep tests carried out under these conditions, it has been observed that as time elapses inelastic straining takes place due to time independent plasticity and to creep. It has been recognised that at high stress levels the time dependent plastic strain accumulated during constant load creep tests forms a major part of the inelastic strain and dominates over the creep strain. Hence, due to the plastic strain the true stress level is not constant during the test. The time independent plastic strain has been evaluated using a stress–strain curve obtained at a high strain rate, and the creep strains have been evaluated for the relevant stress history by integration of the constitutive equations. Minimum creep rates and lifetimes have been extrapolated from low stresses to higher stresses using linear stress versus logarithmic plots. In this way, the creep strain–time history, the minimum creep rates, lifetimes and ductilities have been evaluated. In the stress range 325–450 MPa a lower shelf ductility of 1.1{\%} has been found. The model is also shown to predict the isochronous rupture locus determined from multi-axial test data obtained from a range of different sources.",
keywords = "High-temperature creep, Continuum damage mechanics, Finite element method, Time-independent plasticity and creep, Creep damage, Austenitic stainless steel AISI 316, Uni-axial constitutive equations",
author = "Qiang Xu and David Hayhurst",
year = "2003",
month = "10",
day = "1",
doi = "10.1016/j.ijpvp.2003.08.005",
language = "English",
volume = "80",
pages = "689--694",
journal = "International Journal of Pressure Vessels and Piping",
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TY - JOUR

T1 - The evaluation of high-stress creep ductility for 316 stainless steel at 550 °C by extrapolation of constitutive equations derived for lower stress levels

AU - Xu, Qiang

AU - Hayhurst, David

PY - 2003/10/1

Y1 - 2003/10/1

N2 - The CDM-based constitutive equations for the creep of 316 Stainless Steel at 550 °C are reviewed. During creep tests carried out under these conditions, it has been observed that as time elapses inelastic straining takes place due to time independent plasticity and to creep. It has been recognised that at high stress levels the time dependent plastic strain accumulated during constant load creep tests forms a major part of the inelastic strain and dominates over the creep strain. Hence, due to the plastic strain the true stress level is not constant during the test. The time independent plastic strain has been evaluated using a stress–strain curve obtained at a high strain rate, and the creep strains have been evaluated for the relevant stress history by integration of the constitutive equations. Minimum creep rates and lifetimes have been extrapolated from low stresses to higher stresses using linear stress versus logarithmic plots. In this way, the creep strain–time history, the minimum creep rates, lifetimes and ductilities have been evaluated. In the stress range 325–450 MPa a lower shelf ductility of 1.1% has been found. The model is also shown to predict the isochronous rupture locus determined from multi-axial test data obtained from a range of different sources.

AB - The CDM-based constitutive equations for the creep of 316 Stainless Steel at 550 °C are reviewed. During creep tests carried out under these conditions, it has been observed that as time elapses inelastic straining takes place due to time independent plasticity and to creep. It has been recognised that at high stress levels the time dependent plastic strain accumulated during constant load creep tests forms a major part of the inelastic strain and dominates over the creep strain. Hence, due to the plastic strain the true stress level is not constant during the test. The time independent plastic strain has been evaluated using a stress–strain curve obtained at a high strain rate, and the creep strains have been evaluated for the relevant stress history by integration of the constitutive equations. Minimum creep rates and lifetimes have been extrapolated from low stresses to higher stresses using linear stress versus logarithmic plots. In this way, the creep strain–time history, the minimum creep rates, lifetimes and ductilities have been evaluated. In the stress range 325–450 MPa a lower shelf ductility of 1.1% has been found. The model is also shown to predict the isochronous rupture locus determined from multi-axial test data obtained from a range of different sources.

KW - High-temperature creep

KW - Continuum damage mechanics

KW - Finite element method

KW - Time-independent plasticity and creep

KW - Creep damage

KW - Austenitic stainless steel AISI 316

KW - Uni-axial constitutive equations

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JO - International Journal of Pressure Vessels and Piping

JF - International Journal of Pressure Vessels and Piping

SN - 0308-0161

IS - 10

ER -