Abstract
Electromagnetic acoustic resonance (EMAR) is a contactless resonance method using an electromagnetic acoustic transducer (EMAT). In this study, EMAR was applied to detect the creep damage process in Cr–Mo–V steel, which is an important structural material for thermal energy plants. The material was exposed to temperatures up to 923 K at various stresses. Two types of EMAT were used: bulk-wave EMAT for plate samples and axial-shear-wave EMAT for cylindrical samples. We measured ultrasonic attenuation in the frequency range between 1 and 7 MHz as creep progressed. Attenuation coefficient exhibits a much larger sensitivity to damage accumulation than velocity. It shows a maximum peak at approximately 30% and a minimum peak at 50% of the creep life, independent of the applied stress and the type of EMAT used. EMAR has the potential for assessing damage progress and for predicting the creep life of metals.