热处理工艺对9Ni钢组织和低温韧性的影响  

Effect of heat treatment process on microstructure and cryogenic toughness of 9Ni steel

作　　者：何应玲 何宜柱[1] 杨磊[1] 

机构地区：[1]安徽工业大学材料科学与工程学院,安徽马鞍山243000

出　　处：《金属热处理》2017年第2期119-123,共5页Heat Treatment of Metals

摘　　要：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。Heat treatment processes of 9Ni steel plates such as quenching ＋ reheat quenching ＋ lamellarizing ＋ tempering（ RLT）,quenching＋ lamellarizing ＋ tempering（ QLT）,quenching ＋ tempering（ QT） were carried out,respectively. The microstructure and cryogenic toughness under each process were analyzed by means of optical microscope,X ray diffraction,impact test machine,scanning electron microscope and multifunction internal friction apparatus（ MIFA）. The results show that microstructure of the 9Ni steel quenched and tempered is composed of lath martensite and reversed austenite; After two-phase region heat treatment,the microstructure consist of fine martensitic lath,increased reverse austenite and a certain amount of ferrite. Under the RLT process,the highest impact toughness of the steel is obtained,and the impact energy at- 196 ℃ reaches to 188 J. At the same time,the amount of reversed austenite increases to 8. 90%,this is attributable to the grain refinement,the increase of nucleation sites of reversed austenite,which is helpful to the purification of martensite matrix and the ferrite coarsening.

关 键 词：9NI钢 低温韧性 逆转奥氏体 铁素体 

分 类 号：TG142.1[一般工业技术—材料科学与工程]