研究了CLAM钢在600 ℃时效1100 和3000 h后的显微组织与力学性能变化. 结果表明, 随着时效时间的延长, CLAM钢中析出相的数量逐渐增多, 尺寸增大. 时效1100 h时, CLAM钢的强度略有提高; 时效至3000 h时, CLAM钢强度又有所降低. 与原始热处理态相比, 时效1100 h后CLAM钢的韧脆转变温度升高, 但时效时间延长到3000 h时, 韧脆转变温度又降低到原始热处理态水平. 根据钢中析出相在时效过程中的析出和粗化行为, 解释了CLAM钢时效不同时间后强度、冲击韧性和韧脆转变温度的变化, 同时还指出钢中较低的W含量可以有效延缓钢中Laves相的析出.
China low activation martensitic (CLAM) steel is a new reduced activation ferritic/martensitic steel developed in China to use for blanket/first-wall structures of the D-T fusion reactor. The microstructures and mechanical properties of the CLAM steel after aging at 600 ℃ for 1100 and 3000 h were investigated by SEM and TEM. The results showed that the prior austenite grain size did not increase with increasing aging time, while the precipitates at grain boundaries and inside grains were increased. The strength of CLAM steel was slightly increased after aging for 1100 h. When the aging time was prolonged to 3000 h, the strength of CLAM steel was decreased due to coarsening of precipitates. The ductile-brittle transition temperature (DBTT) was increased after aging for 1100 h. However, when the aging time increased to 3000 h, the DBTT lowered to the as heat-treated level. The changes of strength, toughness and DBTT after aging were interpreted from the view points of precipitation and coarsening behaviors of precipitates. It was also noticed that the low W content in the CLAM steel can effectively postpone the formation of Laves phase.