Predicting weld creep strength reduction for 9% Cr steels

Stefan Holmström (Corresponding Author), Pertti Auerkari

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)

Abstract

In design standards and in post-service life assessment, the cross-weld (CW) creep strength of ferritic steels is nearly universally assumed to be 80% of the corresponding value for the parent material (PH). However, CW data assessment of some 9% Cr steels such as E911 and P91 suggests that this would not hold at least at the high temperature end of the testing range. The resulting weld creep strength factor (WSF) is then attaining values well below 0.8 when extrapolated to typical design life of 100 000 h or more. Under such conditions the conventional value of 0.8 would result in non-conservative (too long) predicted life for structures subjected to CW loading in the creep regime.

To accommodate the CW strength data for realistic values of WSF requires appropriate correction based on actual data. For this purpose, an alternative assessment approach, rigidity parameter correction (RPC), is proposed. This approach can be used to predict CW rupture strength from the PM master curves, with any PM rupture model optimized to correspond to the welded materials data.
Original languageEnglish
Pages (from-to)803-808
Number of pages6
JournalInternational Journal of Pressure Vessels and Piping
Volume83
Issue number11-12
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

Fingerprint

Steel
Creep
Welds
Ferritic steel
Service life
Rigidity
Testing

Keywords

  • creep
  • welds
  • modeling
  • extrapolation
  • 9% Cr
  • ferritic steel
  • ECCC

Cite this

@article{4fedec12a9c94b24a87ace2175e396c2,
title = "Predicting weld creep strength reduction for 9{\%} Cr steels",
abstract = "In design standards and in post-service life assessment, the cross-weld (CW) creep strength of ferritic steels is nearly universally assumed to be 80{\%} of the corresponding value for the parent material (PH). However, CW data assessment of some 9{\%} Cr steels such as E911 and P91 suggests that this would not hold at least at the high temperature end of the testing range. The resulting weld creep strength factor (WSF) is then attaining values well below 0.8 when extrapolated to typical design life of 100 000 h or more. Under such conditions the conventional value of 0.8 would result in non-conservative (too long) predicted life for structures subjected to CW loading in the creep regime.To accommodate the CW strength data for realistic values of WSF requires appropriate correction based on actual data. For this purpose, an alternative assessment approach, rigidity parameter correction (RPC), is proposed. This approach can be used to predict CW rupture strength from the PM master curves, with any PM rupture model optimized to correspond to the welded materials data.",
keywords = "creep, welds, modeling, extrapolation, 9{\%} Cr, ferritic steel, ECCC",
author = "Stefan Holmstr{\"o}m and Pertti Auerkari",
year = "2006",
doi = "10.1016/j.ijpvp.2006.08.007",
language = "English",
volume = "83",
pages = "803--808",
journal = "International Journal of Pressure Vessels and Piping",
issn = "0308-0161",
publisher = "Elsevier",
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}

Predicting weld creep strength reduction for 9% Cr steels. / Holmström, Stefan (Corresponding Author); Auerkari, Pertti.

In: International Journal of Pressure Vessels and Piping, Vol. 83, No. 11-12, 2006, p. 803-808.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Predicting weld creep strength reduction for 9% Cr steels

AU - Holmström, Stefan

AU - Auerkari, Pertti

PY - 2006

Y1 - 2006

N2 - In design standards and in post-service life assessment, the cross-weld (CW) creep strength of ferritic steels is nearly universally assumed to be 80% of the corresponding value for the parent material (PH). However, CW data assessment of some 9% Cr steels such as E911 and P91 suggests that this would not hold at least at the high temperature end of the testing range. The resulting weld creep strength factor (WSF) is then attaining values well below 0.8 when extrapolated to typical design life of 100 000 h or more. Under such conditions the conventional value of 0.8 would result in non-conservative (too long) predicted life for structures subjected to CW loading in the creep regime.To accommodate the CW strength data for realistic values of WSF requires appropriate correction based on actual data. For this purpose, an alternative assessment approach, rigidity parameter correction (RPC), is proposed. This approach can be used to predict CW rupture strength from the PM master curves, with any PM rupture model optimized to correspond to the welded materials data.

AB - In design standards and in post-service life assessment, the cross-weld (CW) creep strength of ferritic steels is nearly universally assumed to be 80% of the corresponding value for the parent material (PH). However, CW data assessment of some 9% Cr steels such as E911 and P91 suggests that this would not hold at least at the high temperature end of the testing range. The resulting weld creep strength factor (WSF) is then attaining values well below 0.8 when extrapolated to typical design life of 100 000 h or more. Under such conditions the conventional value of 0.8 would result in non-conservative (too long) predicted life for structures subjected to CW loading in the creep regime.To accommodate the CW strength data for realistic values of WSF requires appropriate correction based on actual data. For this purpose, an alternative assessment approach, rigidity parameter correction (RPC), is proposed. This approach can be used to predict CW rupture strength from the PM master curves, with any PM rupture model optimized to correspond to the welded materials data.

KW - creep

KW - welds

KW - modeling

KW - extrapolation

KW - 9% Cr

KW - ferritic steel

KW - ECCC

U2 - 10.1016/j.ijpvp.2006.08.007

DO - 10.1016/j.ijpvp.2006.08.007

M3 - Article

VL - 83

SP - 803

EP - 808

JO - International Journal of Pressure Vessels and Piping

JF - International Journal of Pressure Vessels and Piping

SN - 0308-0161

IS - 11-12

ER -