가동이력 FM강의 열노화가 재료 강도 및 파괴인성에 미치는 영향 분석

초록

In this study, the effects of thermal aging on the material strength, ductility, and fracture behavior of Mod.9Cr-1Mo (ASME Grade 91) and 9Cr-2W (ASME Grade 92) steels were investigated through tensile and J-R tests. Specimens of aged Gr.91 (73,716 h) and Gr.92 (88,046 h) steels sampled from the reheat steam piping system of a supercritical plant in Korea were used for tensile tests. The test data of service-exposed material specimens were compared with the test results of the virgin Gr.91 steel specimens. In addition, the material properties provided in the elevated temperature design (ETD) rules were compared and analyzed. The material properties of the ETD rules were confirmed to be nonconservative values; hence, additional testing was deemed necessary. A series of J-R tests, which are not codified in the ETD rules, were performed on virgin and aged ferritic-martensitic steels. The fracture toughness properties were determined, and effects of thermal aging on the fracture toughness were investigated.

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