Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals

Pekka Nevasmaa, Jorma Salonen, Stefan Holmström

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

Abstract

In comparison with conventional creep resisting grade T/P22, the modified 2%Cr steels T/P23 and T/P24 show nearly twice the creep strength at typical service temperatures of about 520-570°C. The possibility of welding thin-wall boiler tubes without preheating or PWHT has promoted the use of T23 and T24 in practical boiler service. For thick-wall applications and multipass welds, welding consumables still require further development to improve creep strength and ductility. Susceptibility to reheat cracking and hydrogen cracking increase with the wall-thickness and structural rigidity of the component. Consequently, thick-wall sections generally require the use of PWHT and sometimes preheating as well. This paper is concerned with weldability of P23 pipe steel, with particular emphasis on reheat cracking sensitivity of simulated HAZ microstructures and thick-section multipass welds made using closely matching and mis-matching filler metals. The results demonstrate that the weld metal is far more critical than the parent steel HAZ, both in terms of reheat cracking sensitivity and ductility & toughness. In the as-welded condition, the weld metal exhibited excessive hardness of 380 HV and only diminutive Charpy toughness at room temperature. Adoption of the PWHT (760°C/2h) enhanced the weldment toughness; however, it also inevitably raises risk to reheat cracking in the weld metal that showed values of reduction of area (RA) no more than 2-3% in the BWI cracking test. The results imply that thick-section multipass welds made using filler metal with the chemical composition closer to P24 grade material are much less susceptible to reheat cracking than 'matching' P23 grade welds.
Original languageEnglish
Title of host publicationBALTICA VII - Life Management and Maintenance for Power Plants. Vol. 1
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages128-142
ISBN (Electronic)978-951-38-6316-6
ISBN (Print)978-951-38-6315-9
Publication statusPublished - 2007
MoE publication typeB3 Non-refereed article in conference proceedings
EventBALTICA VII - International Conference on Life Management and Main-tenance for Power Plants - Helsinki-Stockholm, Finland
Duration: 12 Jun 200714 Jun 2007

Publication series

SeriesVTT Symposium
Number246
ISSN0357-9387

Conference

ConferenceBALTICA VII - International Conference on Life Management and Main-tenance for Power Plants
CountryFinland
CityHelsinki-Stockholm
Period12/06/0714/06/07

Fingerprint

Filler metals
Welds
Steel
Toughness
Creep
Preheating
Boilers
Ductility
Welding
Metals
Weldability
Steel pipe
Heat affected zone
Rigidity
Hardness
Hydrogen
Temperature
Microstructure
Chemical analysis

Cite this

Nevasmaa, P., Salonen, J., & Holmström, S. (2007). Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals. In BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 1 (pp. 128-142). Espoo: VTT Technical Research Centre of Finland. VTT Symposium, No. 246
Nevasmaa, Pekka ; Salonen, Jorma ; Holmström, Stefan. / Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals. BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 1. Espoo : VTT Technical Research Centre of Finland, 2007. pp. 128-142 (VTT Symposium; No. 246).
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title = "Reheat cracking susceptibility of new generation 2{\%}CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals",
abstract = "In comparison with conventional creep resisting grade T/P22, the modified 2{\%}Cr steels T/P23 and T/P24 show nearly twice the creep strength at typical service temperatures of about 520-570°C. The possibility of welding thin-wall boiler tubes without preheating or PWHT has promoted the use of T23 and T24 in practical boiler service. For thick-wall applications and multipass welds, welding consumables still require further development to improve creep strength and ductility. Susceptibility to reheat cracking and hydrogen cracking increase with the wall-thickness and structural rigidity of the component. Consequently, thick-wall sections generally require the use of PWHT and sometimes preheating as well. This paper is concerned with weldability of P23 pipe steel, with particular emphasis on reheat cracking sensitivity of simulated HAZ microstructures and thick-section multipass welds made using closely matching and mis-matching filler metals. The results demonstrate that the weld metal is far more critical than the parent steel HAZ, both in terms of reheat cracking sensitivity and ductility & toughness. In the as-welded condition, the weld metal exhibited excessive hardness of 380 HV and only diminutive Charpy toughness at room temperature. Adoption of the PWHT (760°C/2h) enhanced the weldment toughness; however, it also inevitably raises risk to reheat cracking in the weld metal that showed values of reduction of area (RA) no more than 2-3{\%} in the BWI cracking test. The results imply that thick-section multipass welds made using filler metal with the chemical composition closer to P24 grade material are much less susceptible to reheat cracking than 'matching' P23 grade welds.",
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Nevasmaa, P, Salonen, J & Holmström, S 2007, Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals. in BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 1. VTT Technical Research Centre of Finland, Espoo, VTT Symposium, no. 246, pp. 128-142, BALTICA VII - International Conference on Life Management and Main-tenance for Power Plants, Helsinki-Stockholm, Finland, 12/06/07.

Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals. / Nevasmaa, Pekka; Salonen, Jorma; Holmström, Stefan.

BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 1. Espoo : VTT Technical Research Centre of Finland, 2007. p. 128-142 (VTT Symposium; No. 246).

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

TY - GEN

T1 - Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals

AU - Nevasmaa, Pekka

AU - Salonen, Jorma

AU - Holmström, Stefan

PY - 2007

Y1 - 2007

N2 - In comparison with conventional creep resisting grade T/P22, the modified 2%Cr steels T/P23 and T/P24 show nearly twice the creep strength at typical service temperatures of about 520-570°C. The possibility of welding thin-wall boiler tubes without preheating or PWHT has promoted the use of T23 and T24 in practical boiler service. For thick-wall applications and multipass welds, welding consumables still require further development to improve creep strength and ductility. Susceptibility to reheat cracking and hydrogen cracking increase with the wall-thickness and structural rigidity of the component. Consequently, thick-wall sections generally require the use of PWHT and sometimes preheating as well. This paper is concerned with weldability of P23 pipe steel, with particular emphasis on reheat cracking sensitivity of simulated HAZ microstructures and thick-section multipass welds made using closely matching and mis-matching filler metals. The results demonstrate that the weld metal is far more critical than the parent steel HAZ, both in terms of reheat cracking sensitivity and ductility & toughness. In the as-welded condition, the weld metal exhibited excessive hardness of 380 HV and only diminutive Charpy toughness at room temperature. Adoption of the PWHT (760°C/2h) enhanced the weldment toughness; however, it also inevitably raises risk to reheat cracking in the weld metal that showed values of reduction of area (RA) no more than 2-3% in the BWI cracking test. The results imply that thick-section multipass welds made using filler metal with the chemical composition closer to P24 grade material are much less susceptible to reheat cracking than 'matching' P23 grade welds.

AB - In comparison with conventional creep resisting grade T/P22, the modified 2%Cr steels T/P23 and T/P24 show nearly twice the creep strength at typical service temperatures of about 520-570°C. The possibility of welding thin-wall boiler tubes without preheating or PWHT has promoted the use of T23 and T24 in practical boiler service. For thick-wall applications and multipass welds, welding consumables still require further development to improve creep strength and ductility. Susceptibility to reheat cracking and hydrogen cracking increase with the wall-thickness and structural rigidity of the component. Consequently, thick-wall sections generally require the use of PWHT and sometimes preheating as well. This paper is concerned with weldability of P23 pipe steel, with particular emphasis on reheat cracking sensitivity of simulated HAZ microstructures and thick-section multipass welds made using closely matching and mis-matching filler metals. The results demonstrate that the weld metal is far more critical than the parent steel HAZ, both in terms of reheat cracking sensitivity and ductility & toughness. In the as-welded condition, the weld metal exhibited excessive hardness of 380 HV and only diminutive Charpy toughness at room temperature. Adoption of the PWHT (760°C/2h) enhanced the weldment toughness; however, it also inevitably raises risk to reheat cracking in the weld metal that showed values of reduction of area (RA) no more than 2-3% in the BWI cracking test. The results imply that thick-section multipass welds made using filler metal with the chemical composition closer to P24 grade material are much less susceptible to reheat cracking than 'matching' P23 grade welds.

M3 - Conference article in proceedings

SN - 978-951-38-6315-9

T3 - VTT Symposium

SP - 128

EP - 142

BT - BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 1

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Nevasmaa P, Salonen J, Holmström S. Reheat cracking susceptibility of new generation 2%CrMo(W)V P23 steel multipass welds made using matching and mis-matching filler metals. In BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 1. Espoo: VTT Technical Research Centre of Finland. 2007. p. 128-142. (VTT Symposium; No. 246).