2606 電磁超音波共鳴法によるマルテンサイト系ステンレス鋼のクリープ損傷評価(S22-2 非破壊評価とモニタリング(2),S22 非破壊評価とモニタリング)

概要

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Electromagnetic acoustic resonance (EMAR) is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method is free from extra energy losses, resulting in the measurement of intrinsic ultrasonic attenuation in solids. In this study, the EMAR was applied to detect the creep damage of a martensite stainless steel (JIS-SUS403). The material was exposed to the temperature of 873K at 120MPa. We measured ultrasonic attenuation for 1-7-MHz frequency range as the creep advanced. The attenuation coefficient exhibits much larger sensitivity to the damage accumulation than the velocity. It shows a maximum around 20% of the whole life, which is interpreted as resulting from microstructure changes, especially, dislocation mobility. This is supported by TEM observations for dislocation structure. This technique has a potential to assess the damage advance and to predict the creep life of metals.
2007-09-07