ラウンドロビン試験によるクリープ損傷をうけたCr-Mo-V鋼の非破壊評価とミクロ損傷解析

概要

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We studied the evolution of microstructure in a Cr-Mo-V (JIS-SNB16) during creep by three kinds of nondestructive evaluations (NDEs). After a series of creep samples with various strains was obtained under a tensile stress of 25 and 35MPa at 923K, small samples were removed from the creep samples. Round-robin NDEs were carried out with the small samples. Internal friction with electromagnetic acoustic resonance (EMAR), parameters in magnetic minor hysteresis loops and thermoelectric power (TEP) were measured. Furthermore, the evolution of microstructure was observed with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The results by these NDE techniques have good correlations with microstructural observations. The combination of these techniques would utilize the advantages of the different methods and compensate for the weaknesses. This study suggests the importance of the combined usage in establishing reliable NDE procedures for the determination of creep damage.