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).
    @inproceedings{7c9bfa7c160c4a94a328ffdcb41a49d6,
    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",
    year = "2016",
    language = "English",
    series = "VTT Technology",
    publisher = "VTT Technical Research Centre of Finland",
    editor = "Pertti Auerkari",
    booktitle = "Baltica X",
    address = "Finland",

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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).