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对9Ni钢进行三种热处理工艺试验,分别为两次淬火+双相区淬火+回火(RLT)、淬火+双相区淬火+回火(QLT)、淬火+回火(QT)。采用X射线衍射仪、扫描电镜及多功能内耗仪等对不同工艺下9Ni钢的组织和低温韧性进行分析研究。结果表明,9Ni钢经QT处理后组织为马氏体+逆转变奥氏体;经RLT和QLT处理后,组织中的马氏体变得细小,逆转变奥氏体含量增加,并有23%左右的铁素体生成。RLT工艺下试验钢在-196℃下的低温冲击吸收能量最高,达到188 J,此时测得的逆转奥氏体含量也最多,为8.90%。RLT工艺下增韧归因于:晶粒细化;增加了逆转变奥氏体形核点,逆转变奥氏体含量增加,马氏体基体得到净化;铁素体组织粗化。
Three heat treatment tests were carried out on 9Ni steel, which were quenching + two-phase quenching and tempering (RLT), quenching + QLT and quenching + tempering (QT) respectively. The microstructure and low temperature toughness of 9Ni steel under different technological processes were analyzed by X-ray diffraction, scanning electron microscopy and multi-function internal friction meter. The results showed that the microstructure of 9Ni steel was transformed into martensite + retrotransformed austenite by QT treatment. The martensite in the microstructure became fine and the content of retrograded austenite increased after treatment with RLT and QLT, and 23% About ferrite generation. Under the RLT process, the impact energy of the test steel at -196 ℃ is the highest, reaching 188 J, and the reverse austenite content measured at this time is also the highest at 8.90%. RLT process toughening due to: grain refinement; increase the retrograde austenite nucleation point, reverse austenite content increases, the martensite matrix to be purified; ferrite coarse.