Journal of Northeastern University Natural Science ›› 2015, Vol. 36 ›› Issue (5): 641-645.DOI: 10.12068/j.issn.1005-3026.2015.05.008

• Materials & Metallurgy • Previous Articles     Next Articles

Non-metallic Inclusions and Its Effect on Microstructure of Zr Deoxidized Steel

WANG Chao, WANG Guo-dong   

  1. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China.
  • Received:2014-03-31 Revised:2014-03-31 Online:2015-05-15 Published:2014-11-07
  • Contact: WANG Chao
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Abstract: Transformation behaviors of a Zr deoxidized and Ti microalloyed low C-Mn steel under continuous cooling and isothermal treatment were studied. The precipitation of non-metallic inclusions and its influence on the microstructure were analyzed. Statistical results showed that the inclusions are mainly ZrO2·MnS and ZrO2·MnS·TiN composites, which are in accordance with thermodynamic analysis. The size of inclusions is in the range of 0.2~1μm and the number density of inclusions is high. Intragranular acicular ferrite is obtained under both conditions of continuous cooling with 1℃/s and isothermal treatment at 500℃. Inclusions, which can promote ferrite nucleation, are mostly ZrO2·MnS·TiN type. Formation of Mn-depletion zone with MnS precipitation on the ZrO2 core is an important factor in ferrite nucleation. Composite precipitation of TiN can reduce the interface energy of ferrite nucleation, which can further promote acicular ferrite transformation.

Key words: Zr deoxidized steel, non-metallic inclusion, acicular ferrite, Mn-depletion zone, ZrO2

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