东北大学学报:自然科学版 ›› 2019, Vol. 40 ›› Issue (11): 1561-1567.DOI: 10.12068/j.issn.1005-3026.2019.11.008

• 材料与冶金 • 上一篇    下一篇

QT工艺对一种B-Nb低碳贝氏体钢组织及强韧性的影响

任家宽, 阎冬, 陈俊, 刘振宇   

  1. (东北大学 材料科学与工程学院, 辽宁 沈阳110819)
  • 收稿日期:2019-02-15 修回日期:2019-02-15 出版日期:2019-11-15 发布日期:2019-11-05
  • 通讯作者: 任家宽
  • 作者简介:任家宽(1993-), 男, 山东潍坊人, 东北大学博士研究生; 刘振宇(1968-), 男, 内蒙古赤峰人, 东北大学教授, 博士生导师.
  • 基金资助:
    中央高校基本科研业务费专项资金资助项目(N170708018); 国家自然科学基金资助项目(U1660117).

Effect of QT Treatment on Microstructure and Obdurability of a B-Nb Low Carbon Bainite Steel

REN Jia-kuan, YAN Dong, CHEN Jun, LIU Zhen-yu   

  1. School of Material Science & Engineering, Northeastern University, Shenyang 110819, China.
  • Received:2019-02-15 Revised:2019-02-15 Online:2019-11-15 Published:2019-11-05
  • Contact: LIU Zhen-yu
  • About author:-
  • Supported by:
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摘要: 通过室温拉伸、摆锤冲击、光学及扫描电镜研究了QT(淬火+回火)工艺对实验钢晶界比例、晶粒尺寸、碳化物析出情况及强韧性的影响,并对其变体的分布及组合方式进行了分析.结果表明:随着回火温度的升高,实验钢强度逐渐降低,塑性逐渐提高;450T和500T钢断口为准解理型断裂,贝氏体板条间析出的碳化物及较低比例的大角度晶界使得冲击韧性较差;而600T和650T钢断口为韧窝断裂,组织中大角度晶界的比例增加,有效地阻碍了裂纹的扩展.变体分析表明,450T钢变体组合方式介于Bain group和CP(close packed)group之间,而600T钢变体之间呈现较明显的CP组合方式,同一CP group内的变体取向差较大,偏折了裂纹传播路径,提高了低温韧性.

关键词: B-Nb钢, 热轧, 回火, 强韧性, 变体

Abstract: Effects of QT (quenching+tempering) treatment on the proportion of grain boundary, grain size, carbide precipitation, strength and toughness of the tested steels were studied by room-temperature tensile test, pendulum impact test, optical and scanning electron microscopy, and the distribution and combination of the variants were also analyzed. The results show that when the tempering temperature increases, the strength of the tested steels gradually decreases with an increase of plasticity. The fracture modes of 450T and 500T steels are quasi-cleavage fracture, where the impact toughness becomes worse due to the carbides precipitated from bainite laths and the smaller proportion of high-angle grain boundary. The fracture modes of 600T and 650T steels are dimple fracture, where the increased proportion of the high-angle grain boundary hinders the crack propagation more effectively. The variant analysis shows that the variant combination mode of 450T steel is between Bain group and CP (close-packed) group, while that of 600T one tends to be a CP combination mode. The larger misorientation between the variants in the same CP group can deflect the path of crack propagation, which improves the low-temperature toughness.

Key words: B-Nb steel, hot rolling, tempering, strength and toughness, variant

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