Long-term thermal stability of reduced activation ferritic/martensitic steels as structure materials of fusion blanket

摘要

In this work, the effect of thermal ageing on mechanical properties of JLF-1 (JOYO-II HEAT) and CLAM (HEAT 0603) steels have been studied at temperatures in the range of 823 - 973 K. The results showed that the hardness increased slightly and the creep properties improved after ageing at 823 K for 2000 h for the both steels. On the other hand, the hardness decreased after ageing above 823 K, especially at 973 K for 100 h, and the creep property degraded at 973 K for 100 h. The Larson-Miller parameter was shown to be appropriate for predicting the long-term creep properties from the short-term experiments at higher temperature with higher stress. By extrapolation to the typical design limit for the blanket, 823 K for 100 000h, the rupture stress was estimated to be about 135 MPa for the both steels. The present thermal aging treatments influenced the rupture stress by –15 MPa