利用扫描电镜、冲击试验机和拉伸试验机等研究了630 ℃长时时效对G112钢组织和力学性能的影响; 并用X射线衍射仪及扫描电镜的背散射电子系统分析了经不同时间时效后G112钢中的析出相及其含量。结果表明: 630 ℃时效态试验钢中存在Laves相、M23C6相和M(C,N)相; 随着时效时间的延长, 各析出相含量不断增多, 其中Laves相的析出速度和析出量都比M23C6相高, 平均尺寸比M23C6相小, 对强化的作用较大; 630 ℃时效3 000 h后G112钢的高温强度下降了约12.0%, 室温冲击功下降了约52.2%; G112钢力学性能的变化是马氏体板条回复和析出相强化共同作用的结果。

Effects of long-term aging at 630 ℃ on the microstructure and mechanical properties of G112 steel were investigated using SEM, impact testing machine and tensile testing machine. The precipitates and their contents in G112 steel for different aging times were studied using XRD and BSE of scanning electron microscope. The results show that there were Laves, M23C6, M(C,N) phases in the test steel aged at 630 ℃. As the aging time increased, the amount of precipitates increased. The growth rate and precipitates′ amount of the Laves phase were all larger than those of the M23C6 phase, and the average size of the Laves was smaller than that of the M23C6 phase, so the Laves phase had better strengthening effect than the M23C6 phase. During the aging process, the high temperature strength of the G112 steel aged at 630 ℃ for 3 000 h decreased by about 12%, impact toughness at room temperature decreased by about 52.2%. The change of mechanical properties of the test steel was the result of martensite lath recovery and precipitation strengthening.