Practical application of impression creep data to power plant

S.J. Brett, Juhani Rantala, Stefan Holmström

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

    Abstract

    The measured "minimum" creep rate in the impression creep (IC) test is currently obtained from a "stabilized" deflection rate, and the time to "stabilization" is somewhat arbitrarily chosen at durations up to 500 h, regardless of the applied load. Nevertheless, IC tests have been successfully utilized for aged ½CrMoV and P91 steam line components by conducting tests at the same load so that the deflection rates can directly be compared and used for ranking. By this experience, the IC test is an excellent tool for material ranking and lifing of service exposed material. However, further development in the IC data assessment procedures and the translation between IC and uniaxial test is still needed for determination of the lower stress range material creep properties from the IC test. It is suggested that the deflection rate should be correlated to a Monkman-Grant type relation with the calculated deflection rate at specified "strain/deflection" against the corresponding uniaxial strain rate at the same specified strain. The modified MG relationship should correct the increasing error expected at IC test conducted at decreasing loads. To be able to do this the strain rate as a function of time (or strain) should be available for primary creep of the uniaxial test. The corrective impact of the modified MG has to be verified by further analysis and testing.
    Original languageEnglish
    Title of host publicationBaltica IX. International Conference on Life Management and Maintenance for Power Plants
    EditorsPertti Auerkari, Juha Veivo
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages553-566
    ISBN (Electronic)978-951-38-8025-5, 978-951-38-8026-2
    Publication statusPublished - 2013
    MoE publication typeA4 Article in a conference publication
    EventBALTICA IX - International Conference on Life Management and Maintenance for Power Plants - Helsinki-Stockholm, Finland
    Duration: 11 Jun 201313 Jun 2013

    Publication series

    SeriesVTT Technology
    Number106
    ISSN2242-1211

    Conference

    ConferenceBALTICA IX - International Conference on Life Management and Maintenance for Power Plants
    CountryFinland
    CityHelsinki-Stockholm
    Period11/06/1313/06/13

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  • Cite this

    Brett, S. J., Rantala, J., & Holmström, S. (2013). Practical application of impression creep data to power plant. In P. Auerkari, & J. Veivo (Eds.), Baltica IX. International Conference on Life Management and Maintenance for Power Plants (pp. 553-566). VTT Technical Research Centre of Finland. VTT Technology, No. 106 https://www.vtt.fi/inf/pdf/technology/2013/T106.pdf