金属热处理 ›› 2024, Vol. 49 ›› Issue (8): 88-93.DOI: 10.13251/j.issn.0254-6051.2024.08.014

• 工艺研究 • 上一篇    下一篇

QLT热处理对5.5Ni钢显微组织和拉伸性能的影响

臧岩1,2, 朱莹光1,3, 张弛1,2, 安涛1,2, 刘文月1,2   

  1. 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
  • 收稿日期:2024-01-28 修回日期:2024-06-12 出版日期:2024-08-25 发布日期:2024-09-27
  • 作者简介:臧 岩(1994—),女,工程师,硕士,主要研究方向为金属材料热处理,E-mail:1773275233@qq.com

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

Zang Yan1,2, Zhu Yingguang1,3, Zhang Chi1,2, An Tao1,2, Liu Wenyue1,2   

  1. 1. State Key Laboratory of Metal Materials for Marine Equipment and Application, Anshan Liaoning 114009, China;
    2. Ansteel Beijing Research Institute Co. Ltd., Beijing 102200, China;
    3. Iron and Steel Institute of Angang Group, Anshan Liaoning 114009, China
  • Received:2024-01-28 Revised:2024-06-12 Online:2024-08-25 Published:2024-09-27

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。

关键词: 两相区淬火, 逆转变奥氏体, 屈强比, QLT

Abstract: 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.

Key words: intercritical quenching, reversed austenite, yield ratio, QLT

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