Evaluation of creep damage of high Cr ferritic steel by non-linear eddy current testing focusing on dynamic magnetization process

本研究探讨了利用结构的蠕变损伤对结构变化进行无损评价的可能性。9Cr-1Mo钢是日本JSFR示范堆的结构材料。为此，对蠕变样品的位错密度和析出物进行了定量分析，并通过磁光Kerr效应测量和电磁场有限元分析评价了动态磁化过程的频率响应。通过这些研究，整理了蠕变试件的结构变化与磁化动态响应之间的关系，并对其机理进行了探讨。根据测量原理，给出了弹性体蠕变试件。用非线性涡流法对9Cr-1Mo钢进行了评价，论证了用蠕变损伤评价组织变化的可行性。

This study investigates the possibility of nondestructive evaluation of structural changes by creep damage of Mod. 9Cr-1Mo steel which is used for structural material of the Japanese demonstration reactor of fast breeder, JSFR. For the purpose, dislocation density and precipitations of creep specimens were quantitatively analyzed, and frequency response of dynamic magnetization process were evaluated by the magneto-optical Kerr effect measurements and the FEM analysis of electromagnetic field. Through these investigations, the relation between structural change of creep specimens and dynamic response of magnetization were organized and the mechanism was discussed. Based on the measuring principle, the creep specimens of Mod. 9Cr-1Mo steel were evaluated by the non-linear eddy current method and the feasibility of evaluating structural change by creep damage was demonstrated.