Effect of Hot Cracks on EAC Crack initiation and Growth in Nickel-Base Alloy Weld Metals

Hannu Hänninen, Aki Toivonen, Aki Brederholm, Tapio Saukkonen, Wade Karlsen, Ulla Ehrnstén, Pertti Aaltonen

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

    2 Citations (Scopus)

    Abstract

    The differences in the EAC susceptibility between different weld geometries and weld metals have been distinguished by the doped steam test method. Pure weld metals of Alloy 182 and 82 are clearly more susceptible to EAC than the pure weld metals of Alloy 152 and 52, which did not show any crack initiation. The dissimilar metal welds (DMW) with diluted microstructures are less susceptible than the pure weld metals of Alloy 182 and 82. No crack initiation/extension from hot cracks was observed in any of the studied weld metals. At the hot crack tips no crack growth was observed in any of the studied samples. This is related to the segregated microstructure of the hot crack tips. In accelerated doped steam tests selective dissolution takes place and metallic Ni or NiO forms a continuous layer in the middle of the cracks surrounded by the Cr-rich oxide layer. Selective dissolution typical for EAC was not observed inside the hot cracks or at their crack tips. EAC initiation occurred in the Alloy 600 base metal of the DMWs and selective dissolution inside the EAC cracks in Alloy 600 was extensive. The results are discussed based on the selective dissolution creep model of EAC.
    Original languageEnglish
    Title of host publicationProceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors
    EditorsGabriell Ilevbare, Jeremy Busby, Peter Andersen
    PublisherSpringer
    Pages197-224
    Number of pages26
    ISBN (Electronic)978-3-319-48760-1
    DOIs
    Publication statusPublished - 2011
    MoE publication typeA4 Article in a conference publication
    Event15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors - Colorado Springs, CO, United States
    Duration: 7 Aug 201111 Aug 2011

    Conference

    Conference15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors
    CountryUnited States
    CityColorado Springs, CO
    Period7/08/1111/08/11

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    Keywords

    • nickel-base alloys
    • weld metal
    • hot cracking
    • environment-assisted cracking
    • electron microscopy
    • Laves phase

    Cite this

    Hänninen, H., Toivonen, A., Brederholm, A., Saukkonen, T., Karlsen, W., Ehrnstén, U., & Aaltonen, P. (2011). Effect of Hot Cracks on EAC Crack initiation and Growth in Nickel-Base Alloy Weld Metals. In G. Ilevbare, J. Busby, & P. Andersen (Eds.), Proceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors (pp. 197-224). Springer. https://doi.org/10.1007/978-3-319-48760-1_13