METHOD AND APPARATUS FOR EVALUATING CREEP DAMAGE OF FERROMAGNETIC STRUCTURE USING AC MAGNETIZATION

PROBLEM TO BE SOLVED: To provide a method and apparatus for evaluating the creep damage of a ferromagnetic structure in a non-destructive manner. SOLUTION: The AC magnetization waveform of a test object 10 magnetized by AC is detected by an AC magnetizing probe 12. The intensity ratio to a fundament...

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Bibliographische Detailangaben
Hauptverfasser: SHIBA MITSUHARU, YAMAGUCHI ATSUNORI
Format: Patent
Sprache:eng
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Zusammenfassung:PROBLEM TO BE SOLVED: To provide a method and apparatus for evaluating the creep damage of a ferromagnetic structure in a non-destructive manner. SOLUTION: The AC magnetization waveform of a test object 10 magnetized by AC is detected by an AC magnetizing probe 12. The intensity ratio to a fundamental wave of the third higher harmonic contained in the detected AC magnetization waveform is calculated outside a Rayleigh's loop limit. The obtained intensity ratio is compared with a preliminarily formed master curve of creep damage and an intensity ratio to estimate a creep time and residual life can be evaluated on the basis of the creep time. Histeresis loss is calculated within the Rayleigh's loop limit to perform evaluation in the same way.