QLT热处理对5.5Ni钢显微组织和拉伸性能的影响  

Effect of QLT heat treatment on microstructure and tensile properties of 5.5Ni steel

作　　者：臧岩 朱莹光 张弛 安涛 刘文月 Zang Yan;Zhu Yingguang;Zhang Chi;An Tao;Liu Wenyue(State Key Laboratory of Metal Materials for Marine Equipment and Application,Anshan Liaoning 114009,China;Ansteel Beijing Research Institute Co.Ltd.,Beijing 102200,China;Iron and Steel Institute of Angang Group,Anshan Liaoning 114009,China)

机构地区：[1]海洋装备用金属材料及其应用国家重点实验室,辽宁鞍山114009 [2]鞍钢集团北京研究院有限公司,北京昌平102200 [3]鞍钢集团钢铁研究院,辽宁鞍山114009

出　　处：《金属热处理》2024年第8期88-93,共6页Heat Treatment of Metals

摘　　要：利用扫描电镜(SEM)、电子背散射衍射(EBSD)、透射电镜(TEM)、X射线衍射(XRD)试验方法,研究了5.5Ni钢经过淬火+两相区淬火+回火(QLT)热处理后的组织形貌、逆转变奥氏体含量及拉伸性能,分析两相区淬火温度对5.5Ni钢组织和拉伸性能的影响。结果表明,QLT热处理后,试验钢显微组织为回火马氏体+临界铁素体+逆转变奥氏体。两相区淬火温度对逆转变奥氏体含量、屈服强度和屈强比有较大影响,淬火和回火温度的影响不明显。随着两相区淬火温度升高,逆转变奥氏体含量增多,抗拉强度基本不变,屈服强度和屈强比同时下降。三叉晶界处块状逆转变奥氏体在拉伸过程中发生应力诱导马氏体相变,是造成不同温度两相区淬火后5.5Ni钢屈强比存在差异的主要原因。Microstructure,reversed austenite content and tensile properties of 5.5Ni steel after quenching+intercritical quenching+tempering(QLT)heat treatment were studied by means of scanning electron microscope(SEM),electron backscatter diffraction(EBSD),transmission electron microscope(TEM)and X⁃ray diffraction(XRD).The effect of quenching temperature in two⁃phase region on the microstructure and tensile properties of the 5.5Ni steel was analyzed.The results show that the microstructure of the tested steel after QLT heat treatment is tempered martensite+critical ferrite+reversed austenite.The quenching temperature in the two⁃phase region has great influence on the content of reversed austenite,yield strength and yield ratio,but the quenching and tempering temperature have a little influence.With the increase of quenching temperature in the two⁃phase region,the content of reversed austenite increases,the tensile strength is basically unchanged,and the yield strength and yield ratio decrease at the same time.The stress⁃induced transformation of bulk reversed austenite at the triple junction into martensite during the tensile process is the main reason for the difference in yield ratio of the 5.5Ni steel quenched in the two⁃phase region at different temperatures.

关 键 词：两相区淬火 逆转变奥氏体 屈强比 QLT 

分 类 号：TG156.1[金属学及工艺—热处理]