Component Assessment Data Requirements from Creep-Fatigue Tests

    Volume 8, Issue 3 (March 2011)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 17 March 2011

    Page Count: 14


    Holdsworth, S. R.
    EMPA: Swiss Federal Laboratories for Materials Science and Technology, Dübendorf,

    (Received 16 November 2010; accepted 14 February 2011)

    Abstract

    Typically, the lifetime assessment of high temperature components, for which both creep and fatigue are principal damage mechanisms, involves (1) the determination of the stress/strain state at critical locations and (2) a numerical evaluation of the consequential damage condition. Until recently, there has not been a standard procedure specifically covering creep-fatigue testing practices. Creep-fatigue tests had been performed for many years, but the reliability and the form of the information generated was dependent on the expertise and specific interests of individual test laboratories. This situation is now resolved by the publication of a new ASTM standard based on an Electrical Power Research Institute (EPRI) led initiative. The way in which the guidance contained in this new standard specifically aims to provide creep-fatigue data requirements for defect-free component assessment is examined. Cyclic/hold tests, usually involving a simple cycle shape representative of the service transients experienced by the target component, are particularly informative in the provision of data to indicate the concurrent influences of cyclic loading on creep deformation characteristics and creep deformation on cyclic plastic response. The crack initiation endurances of such tests also provide the basis of creep-fatigue damage summation representations for a given material. Sequential creep-fatigue testing can be used to quantify the effects of prior cyclic deformation on creep rupture or prior creep deformation on fatigue endurance. The use of such test methods is also considered.


    Paper ID: JAI103583

    DOI: 10.1520/JAI103583

    ASTM International is a member of CrossRef.

    Author
    Title Component Assessment Data Requirements from Creep-Fatigue Tests
    Symposium International Symposium on Creep Fatigue Interactions: Test Methods and Models, 2010-11-17
    Committee E08