Long-Term Thermal Stability of Reduced Activation Ferritic/Martensitic Steels as Structural Materials of Fusion Blanket

Abstract

In this work, the effects of thermal ageing on mechanical properties of JLF-1 and CLAM steels have been studied at temperatures in a 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 used for predicting the long-term creep performance based on the shortterm experiments at higher temperature with higher stress including the pre-ageing effects. By extrapolation to the typical blanket condition, 823 K for 100 000 h, the rupture stress was estimated to be about 140 MPa for the both steels. The present thermal ageing treatments influence the estimated rupture stress for about ±10 MPa for both steels. c © 2010 The Japan Society of Plasma Science and Nuclear Fusion Research