電磁超音波共鳴法による低炭素鋼の疲労進行中の超音波減衰のモニタリング

概要

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We studied microstructure evolution in low carbon steels, containing C:0.15 mass%, subjected to tensioncompressionfatigue through in situ monitoring of axial shear wave attenuation and velocity with the electromagneticacoustic resonance (EMAR)which is a combination of the resonant technique and a non-contacting electromagneticacoustic transduce(r EMAT). This transducer based on the magnetostrictive effect is key to establish a continuousmonitoring for microstructural change in the surface of the materials with high sensitivity. We find that the attenuationis highly sensitive to the accumulated fatigue damage, showing a minimum around 20 percent of the whole life. Thisnovel phenomenon is interpreted in terms of drastic change in dislocation mobility and rearrangement, which issupported by TEM observation for dislocation structure. This technique has a potential to assess the damage advanceand to predict the fatigue life of metals.
2010-07-14