| 摘要 |
PURPOSE: To obtain a remaining-life evaluation method in which a creep rupture life (hysteresis time/creep rupture life) can be determined and evaluated quickly and objectively by measuring a slenderized change (rafting) in aγ' phase by long-time use at a high temp. and using the Larson-Miller parameter(LMP). CONSTITUTION: Regarding a material whose temperature and time hysteresis is know, a change in aγ' phase is measured in advance, a calibration curve regarding the mean value and the LMP of a common equivalent diameter is prepared, theγ' phase of an object to be evaluated is applied, and a metal use temperature is estimated. In addition, the mean value of a circle equivalent diameter at theγ' phase in a perpendicular face and a parallel face in the stress load direction of theγ' phase is found, and the change is put in order, and a metal temperature is estimated. Then, the ratio (aspect ratio) of the long diameter to the short diameter of theγ' phase is found by an image processor, and the ratio of a stress application face to a no-load face is found as a rafting ratio. Then, on the basis of the relationship between the rafting ratio at every temperature and every time and the LMP, a creep rupture life ratio is estimated.
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