Creep strain, damage and life prediction for welded 0.5CMV steel

Juhani Rantala, Pertti Auerkari, Stefan Holmström, Jorma Salonen, Anssi Laukkanen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

Abstract

Creep damage as cavitation and cracking has historically occurred somewhat earlier in the inspections of steam lines made of 0.5CMV steel, when compared to other low alloy steels. The difference has been attributed to modest creep ductility of 0.5CMV steel, and has resulted in attention paid to inspection and maintenance. As the steel is still being used in vintage plants, it is of interest for users while also serving as a model material that can show some essential features of long term creep in much shorter laboratory testing. Particularly challenging service can combine welded thick-wall components with pre-existing fabrication defects, resulting in an unfavorable combination of high stresses, multi-axial loading, and locally weak material. Examples are shown of the observed damage evolution in welded 0.5CMV steam line material in front of a crack-like defect. Long-term multi-axial loading does not necessarily result in type IV failure of welds, but can also induce creep damage and cracking close to the fusion line. This particularly applies to welds with undermatching weld metal such as those made with consumables corresponding to 2.25Cr-1Mo steel. With the LICON approach, it has been shown that this IIIa type of damage can be reproduced in about 5 000 h of multi-axial creep testing, while in plant such damage may require more than 100 000 h of service. The microstructural features of the observed damage and a comparison of uniaxial and CT test data suggest that the LICON approach of life prediction could be applied also for welded components where the location of maximum damage deviates from the type IV position.
Original languageEnglish
Title of host publicationBaltica VIII
Subtitle of host publicationLife Management and Maintenance for Power Plants
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages176-192
Volume2
ISBN (Electronic)978-951-38-7594-7
ISBN (Print)978-951-38-7593-2
Publication statusPublished - 2010
MoE publication typeB3 Non-refereed article in conference proceedings
EventBALTICA VIII - International Conference on Life Management and Maintenance for Power Plants - Helsinki-Stockholm, Finland
Duration: 18 May 201020 May 2010

Publication series

NameVTT Symposium
PublisherVTT
Number265
ISSN (Print)0357–9387
ISSN (Electronic)1455–0873

Conference

ConferenceBALTICA VIII - International Conference on Life Management and Maintenance for Power Plants
CountryFinland
CityHelsinki-Stockholm
Period18/05/1020/05/10

Fingerprint

Creep
Steam piping systems
Welds
Steel
Inspection
Creep testing
Defects
High strength steel
Cavitation
Ductility
Fusion reactions
Cracks
Fabrication
Testing
Metals

Cite this

Rantala, J., Auerkari, P., Holmström, S., Salonen, J., & Laukkanen, A. (2010). Creep strain, damage and life prediction for welded 0.5CMV steel. In Baltica VIII: Life Management and Maintenance for Power Plants (Vol. 2, pp. 176-192). Espoo: VTT Technical Research Centre of Finland. VTT Symposium, No. 265
Rantala, Juhani ; Auerkari, Pertti ; Holmström, Stefan ; Salonen, Jorma ; Laukkanen, Anssi. / Creep strain, damage and life prediction for welded 0.5CMV steel. Baltica VIII: Life Management and Maintenance for Power Plants. Vol. 2 Espoo : VTT Technical Research Centre of Finland, 2010. pp. 176-192 (VTT Symposium; No. 265).
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title = "Creep strain, damage and life prediction for welded 0.5CMV steel",
abstract = "Creep damage as cavitation and cracking has historically occurred somewhat earlier in the inspections of steam lines made of 0.5CMV steel, when compared to other low alloy steels. The difference has been attributed to modest creep ductility of 0.5CMV steel, and has resulted in attention paid to inspection and maintenance. As the steel is still being used in vintage plants, it is of interest for users while also serving as a model material that can show some essential features of long term creep in much shorter laboratory testing. Particularly challenging service can combine welded thick-wall components with pre-existing fabrication defects, resulting in an unfavorable combination of high stresses, multi-axial loading, and locally weak material. Examples are shown of the observed damage evolution in welded 0.5CMV steam line material in front of a crack-like defect. Long-term multi-axial loading does not necessarily result in type IV failure of welds, but can also induce creep damage and cracking close to the fusion line. This particularly applies to welds with undermatching weld metal such as those made with consumables corresponding to 2.25Cr-1Mo steel. With the LICON approach, it has been shown that this IIIa type of damage can be reproduced in about 5 000 h of multi-axial creep testing, while in plant such damage may require more than 100 000 h of service. The microstructural features of the observed damage and a comparison of uniaxial and CT test data suggest that the LICON approach of life prediction could be applied also for welded components where the location of maximum damage deviates from the type IV position.",
author = "Juhani Rantala and Pertti Auerkari and Stefan Holmstr{\"o}m and Jorma Salonen and Anssi Laukkanen",
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Rantala, J, Auerkari, P, Holmström, S, Salonen, J & Laukkanen, A 2010, Creep strain, damage and life prediction for welded 0.5CMV steel. in Baltica VIII: Life Management and Maintenance for Power Plants. vol. 2, VTT Technical Research Centre of Finland, Espoo, VTT Symposium, no. 265, pp. 176-192, BALTICA VIII - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 18/05/10.

Creep strain, damage and life prediction for welded 0.5CMV steel. / Rantala, Juhani; Auerkari, Pertti; Holmström, Stefan; Salonen, Jorma; Laukkanen, Anssi.

Baltica VIII: Life Management and Maintenance for Power Plants. Vol. 2 Espoo : VTT Technical Research Centre of Finland, 2010. p. 176-192 (VTT Symposium; No. 265).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

TY - GEN

T1 - Creep strain, damage and life prediction for welded 0.5CMV steel

AU - Rantala, Juhani

AU - Auerkari, Pertti

AU - Holmström, Stefan

AU - Salonen, Jorma

AU - Laukkanen, Anssi

PY - 2010

Y1 - 2010

N2 - Creep damage as cavitation and cracking has historically occurred somewhat earlier in the inspections of steam lines made of 0.5CMV steel, when compared to other low alloy steels. The difference has been attributed to modest creep ductility of 0.5CMV steel, and has resulted in attention paid to inspection and maintenance. As the steel is still being used in vintage plants, it is of interest for users while also serving as a model material that can show some essential features of long term creep in much shorter laboratory testing. Particularly challenging service can combine welded thick-wall components with pre-existing fabrication defects, resulting in an unfavorable combination of high stresses, multi-axial loading, and locally weak material. Examples are shown of the observed damage evolution in welded 0.5CMV steam line material in front of a crack-like defect. Long-term multi-axial loading does not necessarily result in type IV failure of welds, but can also induce creep damage and cracking close to the fusion line. This particularly applies to welds with undermatching weld metal such as those made with consumables corresponding to 2.25Cr-1Mo steel. With the LICON approach, it has been shown that this IIIa type of damage can be reproduced in about 5 000 h of multi-axial creep testing, while in plant such damage may require more than 100 000 h of service. The microstructural features of the observed damage and a comparison of uniaxial and CT test data suggest that the LICON approach of life prediction could be applied also for welded components where the location of maximum damage deviates from the type IV position.

AB - Creep damage as cavitation and cracking has historically occurred somewhat earlier in the inspections of steam lines made of 0.5CMV steel, when compared to other low alloy steels. The difference has been attributed to modest creep ductility of 0.5CMV steel, and has resulted in attention paid to inspection and maintenance. As the steel is still being used in vintage plants, it is of interest for users while also serving as a model material that can show some essential features of long term creep in much shorter laboratory testing. Particularly challenging service can combine welded thick-wall components with pre-existing fabrication defects, resulting in an unfavorable combination of high stresses, multi-axial loading, and locally weak material. Examples are shown of the observed damage evolution in welded 0.5CMV steam line material in front of a crack-like defect. Long-term multi-axial loading does not necessarily result in type IV failure of welds, but can also induce creep damage and cracking close to the fusion line. This particularly applies to welds with undermatching weld metal such as those made with consumables corresponding to 2.25Cr-1Mo steel. With the LICON approach, it has been shown that this IIIa type of damage can be reproduced in about 5 000 h of multi-axial creep testing, while in plant such damage may require more than 100 000 h of service. The microstructural features of the observed damage and a comparison of uniaxial and CT test data suggest that the LICON approach of life prediction could be applied also for welded components where the location of maximum damage deviates from the type IV position.

M3 - Conference article in proceedings

SN - 978-951-38-7593-2

VL - 2

T3 - VTT Symposium

SP - 176

EP - 192

BT - Baltica VIII

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Rantala J, Auerkari P, Holmström S, Salonen J, Laukkanen A. Creep strain, damage and life prediction for welded 0.5CMV steel. In Baltica VIII: Life Management and Maintenance for Power Plants. Vol. 2. Espoo: VTT Technical Research Centre of Finland. 2010. p. 176-192. (VTT Symposium; No. 265).