Microstructural characterization of alloy 52 narrow-gap dissimilar metal weld after aging

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

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

    2 Citations (Scopus)

    Abstract

    The safe-end dissimilar metal weld (DMW) joining the reactor pressure vessel to the main coolant piping is one of the most critical DMWs in a nuclear power plant (NPP). DMWs have varying microstructures at a short distance across the ferritic-austenitic fusion boundary (FB) region. This microstructural variation affects the mechanical properties and fracture behavior and may evolve as a result of thermal aging during long-term operation of an NPP. This paper presents microstructural characterization performed for as-manufactured and 5000 h and 10,000 h thermally aged narrow-gap DMW representing a safe-end DMW of a modern pressurized water reactor (PWR) NPP. The most significant result of the study is that the thermal aging leads to a significant decrease in a hardness gradient observed across the ferritic-austenitic FB of the as-manufactured DMW.
    Original languageEnglish
    Title of host publicationProceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems
    Subtitle of host publicationWater Reactors
    EditorsJohn H. Jackson, Denise Paraventi, Michael Wright
    Place of PublicationCham
    PublisherSpringer
    Pages1979-1993
    ISBN (Electronic)978-3-030-04639-2
    ISBN (Print)978-3-030-04638-5
    DOIs
    Publication statusPublished - 2 Apr 2019
    MoE publication typeA4 Article in a conference publication
    Event18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors 2019 - Boston, United States
    Duration: 18 Aug 201922 Aug 2019

    Publication series

    SeriesMinerals, Metals and Materials Series
    NumberPart F11
    ISSN2367-1181

    Conference

    Conference18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors 2019
    Country/TerritoryUnited States
    CityBoston
    Period18/08/1922/08/19

    Funding

    This study, carried out in parallel with that presented by Ahonen et al. on mechanical behavior, has been made in collaboration between Aalto University School of Engineering and VTT Technical Research Centre of Finland Ltd within the Nickel-base Alloy Welding Forum (NIWEL)-research project funded by TEKES, Finnish (Teollisuuden Voima Oyj and Fortum Oyj) and Swedish (Vattenfall AB and OKG AB) energy industry. The authors wish to express their gratitude for the funding and participation to the project.

    Keywords

    • Aging
    • Dissimilar metal weld
    • Microstructural characterization
    • Ni-base alloy

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