J. Mater. Sci. Technol. ›› 2010, Vol. 26 ›› Issue (12): 1107-1113.

• Research Articles • 上一篇    下一篇

Investigation on Mechanical Properties and Temper Resistance of DIF

郝露菡1,肖纳敏1,郑成武1,李殿中2   

  1. 1. 中国科学院金属研究所
    2. 中国科学院金属研究所材料加工模拟研究部
  • 收稿日期:2009-08-11 修回日期:2010-03-02 出版日期:2010-12-31 发布日期:2010-12-21
  • 通讯作者: 郝露菡
  • 基金资助:

    低碳钢热变形过程中动态相变的同步耦合模拟

Mechanical Properties and Temper Resistance of Deformation Induced Ferrite in a Low Carbon Steel

Luhan Hao, Namin Xiao, Chengwu Zheng, Dianzhong Li   

  1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
  • Received:2009-08-11 Revised:2010-03-02 Online:2010-12-31 Published:2010-12-21
  • Supported by:

    the National Natural Science Foundation of China (NSFC) under Grant No. 50871109

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摘要： The microstructures and mechanical properties of DIF under different deformation temperature have been investigated systematically. Through DIFT, ferrite grain can be refined to 3μm and accounts for above 85% of the overall microstructure. Yield strength of DIF (>500MPa) is increased by up to 100% than conventional low carbon steel. Comparison of DIF and tempered DIF in microstructure and mechanical properties illustrates that the strengthen mechanism of DIF is the combination of grain boundary strengthen and carbon supersaturated strengthen. EBSD analysis and high magnification SEM observation denote that high-angle grain boundary among ultrafine ferrite grain and cementite membrane along ferrite boundary are responsible for the stability of ferrite grain size during tempering process.

关键词: Low carbon steel, DIFT, Grain size, Mechanical properties, Temper resistance

Abstract: The microstructures and mechanical properties of deformation induced ferrite (DIF) in the low carbon steel Q235 under different deformation temperatures have been investigated systematically. Through deformation induced ferrite transformation (DIFT), ferrite grain can be refined to 3 μm and accounts for above 85% of the overall fraction. Yield strength of DIF (>500 MPa) is increased by up to 100% compared with the conventional low carbon steel. Comparison of microstructure and mechanical properties in the Q235 steel with DIF and tempered DIF microstructure illustrates that the strengthening mechanism of DIF microstructure is the com- bination of grain boundary strengthening and carbon supersaturated strengthening. Electron back-scattered diffraction (EBSD) analysis and high magnification scanning electron microscopy (SEM) observation denote that high-angle grain boundary among ultrafine ferrite grain and the transformation product of retain austenite membrane along ferrite boundaries are responsible for the stability of ferrite grain size during tempering process. Transmission electron microscopy (TEM) analysis demonstrates that the transformation product of retained austenite membrane between ferrite grain boundaries is cementite.

Key words: Low carbon steel, Deformation induced ferrite transformation, Grain size, Mechanical properties, Temper resistance