Fusion Science and Technology / Volume 56 / Number 1 / July 2009 / Pages 323-327
Fusion Materials / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 1)
The effects of thermal aging at a temperature range of 823 to 973 K on the mechanical properties and microstructure of JLF-1 and CLAM steels were investigated. The results showed that the hardness increased slightly and the creep properties improved after aging at 823 K for 2000 h, suggesting that strengthening occurred. However, softening took place by aging at 973 K for 100 h. The microstructural observation showed that there was no remarkable growth of lath width and grain size for the aged specimens. According to the microstructure and the model analyses, the increase in the density of precipitates, especially fine Ta-rich particles, are considered to be the main reason for the strengthening due to aging at 823 K for 2000 h. On the other hand, fine TaC precipitates were deduced to be dissolved due to aging at 973 K for 100 h. However, the change in precipitates alone cannot account for the softening occurred due to the aging.