东北大学学报（自然科学版）

东北大学学报（自然科学版） ›› 2023, Vol. 44 ›› Issue (11): 1578-1584.DOI: 10.12068/j.issn.1005-3026.2023.11.009

• 材料与冶金 • 上一篇    下一篇

梯度结构中间坯制备超细晶低碳钢的组织特性与强化机理

李慧杰1， 韦浩1， 徐晓宁1， 叶其斌1, 2   

  1. (1． 东北大学 轧制技术及连轧自动化国家重点实验室， 辽宁 沈阳110819； 2． 江苏省(沙钢)钢铁研究院， 江苏 张家港215625)
  • 发布日期:2023-12-05
  • 通讯作者: 李慧杰
  • 作者简介:李慧杰(1995-)， 女，山东菏泽人，东北大学硕士研究生; 叶其斌(1977-)， 男，福建南平人，江苏省(沙钢)研究院研究员.
  • 基金资助:
    辽宁省科技重大专项(2020JH1/1010001).

Microstructure Characteristics and Strengthening Mechanism of Ultrafine-Grain Low-Carbon Steel Prepared by Gradient-Structure Intermediate Billet

LI Hui-jie1， WEI Hao1， XU Xiao-ning1， YE Qi-bin1,2   

  1. 1. State Key Laboratory of Rolling and Automation， Northeastern University， Shenyang 110819， China; 2. Institute of Research of Iron & Steel， Shagang， Jiangsu province， Zhangjiagang 215625， China.
  • Published:2023-12-05
  • Contact: YE Qi-bin
  • About author:-
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摘要： 通过中间坯超快冷工艺，在0.2%C-2%Mn普碳钢中获得表层铁素体和心部马氏体的梯度层状组织，实现了钢板压下量约50%的大变形温轧.大变形马氏体经450℃和530℃退火后，制备出平均晶粒尺寸为0.52μm和0.66μm的超细晶组织.利用扫描电镜(SEM)、电子背散射衍射(EBSD)和准静态拉伸试验等手段，研究了超细晶钢板的微观组织与力学性能.结果表明，相较于610℃退火粗晶钢板，450℃和530℃退火超细晶钢的屈服强度可提升2～3倍，平均屈服强度分别达到了1475MPa和1196MPa，延伸率也显著下降.晶界强化和位错强化是超细晶钢强度提升的主要强化机制，而加工硬化率降低导致了超细晶钢的塑性下降.

关键词: 梯度结构；超细晶钢；微观组织；强度；塑性

Abstract: A gradient structure with ferrite-martensite-ferrite layers was obtained in a 0.2%C-2%Mn plain steel by applying ultra-fast cooling during intermediate passes of hot rolling. The large deformation and warm rolling of steel plate with reduction of about 50% is realized， which provides heavily deformed martensite to form ultrafine-grained ferrite with average grain sizes of 0.52μm and 0.66μm by annealing at 450℃ and 530℃， respectively. The microstructure and mechanical properties of the ultrafine-grain steel sheets were studied by scanning electron microscopy(SEM)， electron backscatter diffraction(EBSD)， and quasi-static tensile tests. The results show that the yield strength of the ultrafine-grained steel is 2~3times higher than that of coarse-grain steel annealed at 610℃， arriving at 1475 MPa and 1196 MPa respectively by annealing at 450℃ and 530℃， but the elongation is significantly reduced. Grain boundaries strengthening and dislocations strengthening are the major strengthening mechanisms for improving the strength of ultrofine-grained steel， while the decrease of work hardening rate leads to the decrease of plasticity of ultrafine grained steel.

Key words: gradient structure; ultrafine-grained steel; microstructure; strength; plasticity

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