Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld

Matias Ahonen, Roman Mouginot, Sebastian Lindqvist, Teemu Sarikka, Pekka Nevasmaa, Ulla Ehrnstén, Hannu Hänninen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

Dissimilar metal welds (DMWs) have several different microstructural zones in the vicinity of the low-alloy steel - Ni-based weld metal fusion boundary that have an effect on the mechanical and fracture mechanical behaviour of the weld joint. These microstructural zones are especially small when modern narrow-gap (NG) gas tungsten arc welding (GTAW) technique is utilized. Determination of the fracture toughness properties of the microstructural zones of a DMW joint is of utmost importance for successful structural integrity and lifetime analyses. This paper presents the results from fracture resistance (J-R) tests, microhardness measurements and microstructural characterization performed for a DMW mock-up manufactured by Mitsubishi Heavy Industries (MHI). The studied material is fully representative to that of OL3 EPR pressurized water reactor safe-end weld. The results show that the DMW joint is tough at the SA 508 lowalloy steel - Alloy 52 weld metal interface, which typically is the weakest area of a DMW. Fracture surfaces of the J-R test specimens tested in T-L orientation show a wavy appearance that follows the weld bead boundaries. Crack propagation path was studied also using optical 3D profilometry. Microhardness results show that there is a steep hardness gradient at the fusion boundary where the carbon-depleted zone (CDZ) of the SA 508 exhibits the lowest hardness and the narrow zone exhibiting the highest hardness is located right next to the fusion boundary at the Alloy 52 side.
Original languageEnglish
Title of host publicationBaltica X
Subtitle of host publicationInternational Conference on Life Management and Maintenance for Power Plants
EditorsPertti Auerkari
PublisherVTT Technical Research Centre of Finland
Number of pages16
ISBN (Electronic)978-951-38-8436-9, 978-951-38-8435-2
Publication statusPublished - 2016
MoE publication typeA4 Article in a conference publication
EventBALTICA X - International Conference on Life Management and Maintenance for Power Plants - Cruise, Helsinki-Stockholm, Finland
Duration: 7 Jun 20169 Jun 2016

Publication series

SeriesVTT Technology
Volume261

Conference

ConferenceBALTICA X - International Conference on Life Management and Maintenance for Power Plants
Abbreviated titleBaltica X
CountryFinland
CityHelsinki-Stockholm
Period7/06/169/06/16

Fingerprint

Dissimilar metals
Welds
Fusion reactions
Hardness
Microhardness
Fracture toughness
Profilometry
Pressurized water reactors
Electric arc welding
Alloy steel
Structural integrity
Metals
High strength steel
Paramagnetic resonance
Tungsten
Crack propagation

Cite this

Ahonen, M., Mouginot, R., Lindqvist, S., Sarikka, T., Nevasmaa, P., Ehrnstén, U., & Hänninen, H. (2016). Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld. In P. Auerkari (Ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants VTT Technical Research Centre of Finland. VTT Technology, Vol.. 261
Ahonen, Matias ; Mouginot, Roman ; Lindqvist, Sebastian ; Sarikka, Teemu ; Nevasmaa, Pekka ; Ehrnstén, Ulla ; Hänninen, Hannu. / Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld. Baltica X: International Conference on Life Management and Maintenance for Power Plants. editor / Pertti Auerkari. VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).
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title = "Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld",
abstract = "Dissimilar metal welds (DMWs) have several different microstructural zones in the vicinity of the low-alloy steel - Ni-based weld metal fusion boundary that have an effect on the mechanical and fracture mechanical behaviour of the weld joint. These microstructural zones are especially small when modern narrow-gap (NG) gas tungsten arc welding (GTAW) technique is utilized. Determination of the fracture toughness properties of the microstructural zones of a DMW joint is of utmost importance for successful structural integrity and lifetime analyses. This paper presents the results from fracture resistance (J-R) tests, microhardness measurements and microstructural characterization performed for a DMW mock-up manufactured by Mitsubishi Heavy Industries (MHI). The studied material is fully representative to that of OL3 EPR pressurized water reactor safe-end weld. The results show that the DMW joint is tough at the SA 508 lowalloy steel - Alloy 52 weld metal interface, which typically is the weakest area of a DMW. Fracture surfaces of the J-R test specimens tested in T-L orientation show a wavy appearance that follows the weld bead boundaries. Crack propagation path was studied also using optical 3D profilometry. Microhardness results show that there is a steep hardness gradient at the fusion boundary where the carbon-depleted zone (CDZ) of the SA 508 exhibits the lowest hardness and the narrow zone exhibiting the highest hardness is located right next to the fusion boundary at the Alloy 52 side.",
author = "Matias Ahonen and Roman Mouginot and Sebastian Lindqvist and Teemu Sarikka and Pekka Nevasmaa and Ulla Ehrnst{\'e}n and Hannu H{\"a}nninen",
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Ahonen, M, Mouginot, R, Lindqvist, S, Sarikka, T, Nevasmaa, P, Ehrnstén, U & Hänninen, H 2016, Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld. in P Auerkari (ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants. VTT Technical Research Centre of Finland, VTT Technology, vol. 261, BALTICA X - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 7/06/16.

Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld. / Ahonen, Matias; Mouginot, Roman; Lindqvist, Sebastian; Sarikka, Teemu; Nevasmaa, Pekka; Ehrnstén, Ulla; Hänninen, Hannu.

Baltica X: International Conference on Life Management and Maintenance for Power Plants. ed. / Pertti Auerkari. VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

TY - GEN

T1 - Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld

AU - Ahonen, Matias

AU - Mouginot, Roman

AU - Lindqvist, Sebastian

AU - Sarikka, Teemu

AU - Nevasmaa, Pekka

AU - Ehrnstén, Ulla

AU - Hänninen, Hannu

PY - 2016

Y1 - 2016

N2 - Dissimilar metal welds (DMWs) have several different microstructural zones in the vicinity of the low-alloy steel - Ni-based weld metal fusion boundary that have an effect on the mechanical and fracture mechanical behaviour of the weld joint. These microstructural zones are especially small when modern narrow-gap (NG) gas tungsten arc welding (GTAW) technique is utilized. Determination of the fracture toughness properties of the microstructural zones of a DMW joint is of utmost importance for successful structural integrity and lifetime analyses. This paper presents the results from fracture resistance (J-R) tests, microhardness measurements and microstructural characterization performed for a DMW mock-up manufactured by Mitsubishi Heavy Industries (MHI). The studied material is fully representative to that of OL3 EPR pressurized water reactor safe-end weld. The results show that the DMW joint is tough at the SA 508 lowalloy steel - Alloy 52 weld metal interface, which typically is the weakest area of a DMW. Fracture surfaces of the J-R test specimens tested in T-L orientation show a wavy appearance that follows the weld bead boundaries. Crack propagation path was studied also using optical 3D profilometry. Microhardness results show that there is a steep hardness gradient at the fusion boundary where the carbon-depleted zone (CDZ) of the SA 508 exhibits the lowest hardness and the narrow zone exhibiting the highest hardness is located right next to the fusion boundary at the Alloy 52 side.

AB - Dissimilar metal welds (DMWs) have several different microstructural zones in the vicinity of the low-alloy steel - Ni-based weld metal fusion boundary that have an effect on the mechanical and fracture mechanical behaviour of the weld joint. These microstructural zones are especially small when modern narrow-gap (NG) gas tungsten arc welding (GTAW) technique is utilized. Determination of the fracture toughness properties of the microstructural zones of a DMW joint is of utmost importance for successful structural integrity and lifetime analyses. This paper presents the results from fracture resistance (J-R) tests, microhardness measurements and microstructural characterization performed for a DMW mock-up manufactured by Mitsubishi Heavy Industries (MHI). The studied material is fully representative to that of OL3 EPR pressurized water reactor safe-end weld. The results show that the DMW joint is tough at the SA 508 lowalloy steel - Alloy 52 weld metal interface, which typically is the weakest area of a DMW. Fracture surfaces of the J-R test specimens tested in T-L orientation show a wavy appearance that follows the weld bead boundaries. Crack propagation path was studied also using optical 3D profilometry. Microhardness results show that there is a steep hardness gradient at the fusion boundary where the carbon-depleted zone (CDZ) of the SA 508 exhibits the lowest hardness and the narrow zone exhibiting the highest hardness is located right next to the fusion boundary at the Alloy 52 side.

M3 - Conference article in proceedings

T3 - VTT Technology

BT - Baltica X

A2 - Auerkari, Pertti

PB - VTT Technical Research Centre of Finland

ER -

Ahonen M, Mouginot R, Lindqvist S, Sarikka T, Nevasmaa P, Ehrnstén U et al. Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld. In Auerkari P, editor, Baltica X: International Conference on Life Management and Maintenance for Power Plants. VTT Technical Research Centre of Finland. 2016. (VTT Technology, Vol. 261).