Abstract: The carbide phase in grain and at grain boundary, microstructure and mechanical properties of heat resistant steel 5Cr21Mn9Ni4Nb2WN of status forged, status solution-treated at 1200 °C for 120 min water cooled, + at 1030 °C for 20 ~ 240 min water cooled, and status solution-treated again at 1220 °C for 20 -240 min water cooled have been studied by scanning electron microscope ( SEM) , transmission electron microscope (TEM) , electron diffraction analysis ( EDA) and energy dispersive X-ray diffraction analysis (EDAX) etc techniques. Results show that with solid-solution-treated at 1030 °C , not only the granular (CN)₆ precipitates in grain and at grain boundary of steel 5Cr21Mn9Ni4Nb2WN, but also as a addition of carbon resource the M(CN) degenerates into (CN)₆ , the ambient impact energy of steel markedly decreases but the change of yield strength of steel is minor； with again solid-solution-treated at 1220 °C the reverse precipitation reaction from M₂₃(CN)₆ to M(CN) occurs once more, and the higher ambient energy impact of steel shows again.

Key words: Heat Resistant Steel 5Ci21Mn9Ni4Nb2WN, Reversible Precipitation Reaction, Solid-Solution Treatment, M (CN ), M₂₃(CN)₆, Mechanical Properties

摘要： 通过扫描电镜(SEM)、透射电镜(TEM)和选区电子衍射分析(EDA)、能量色散X-射线衍射分析(EDAX)等技术研究了5Cr21Mn9Ni4Nb2WN耐热钢锻态,1200℃ 120 min水冷固溶,+1030℃ 20~240 min水冷固溶状态,再经1220℃ 20~240 min水冷固溶状态的晶内和晶界面上碳化物相、显微组织和力学性能。结果表明,5Cr21Mn9Ni4Nb2WN钢在1030℃固溶时晶界晶内不但有粒状M₂₃(CN)₆析出,同时M(CN)块作为补充碳源发生了向M₂₃(CN)₆的退化反应,其室温冲击功急剧下降,但对钢的屈服强度影响不大;再经在1220℃固溶处理时出现M₂₃(CN)₆向M(CN)的逆析出反应,该钢又显示出较高的室温冲击功。

关键词: 5Cr21Mn9Ni4Nb2WN耐热钢, 可逆析出反应, 固溶工艺, M(CN), M₂₃(CN)₆, 力学性能