J. Mater. Sci. Technol. ›› 2019, Vol. 35 ›› Issue (9): 1940-1950.DOI: 10.1016/j.jmst.2019.05.009

• Orginal Article • Previous Articles     Next Articles

Microstructure evolution of in-situ nanoparticles and its comprehensive effect on high strength steel

Rongjian Shiac, Zidong Wangb, Lijie Qiaoac*(), Xiaolu Pangab*()   

  1. a Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing 100083, China
    b School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
    c Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083, China
  • Received:2019-01-16 Revised:2019-03-06 Accepted:2019-04-03 Online:2019-09-20 Published:2019-07-26
  • Contact: Qiao Lijie,Pang Xiaolu
  • About author:

    1 These authors contributed equally to this work.

Abstract:

A novel steel strengthened by nanoparticles was investigated in this study. A Fe-based high-strength steel was developed by the trace-element regional supply method during deoxidization to generate in situ nanoparticles with a high number density in the matrix. The results show that the endogenous nanoparticles are aluminum oxide (Al2O3) and titanium oxide (Ti3O5) formed in the liquid melt. Al2O3 functioned as a heterogeneous nucleation site for MnS during solidification; the size of the resultant complex inclusions was approximately 1-2 μm. Furthermore, 13 nm Nb(C,N) precipitates grew with the Ti3O5 during the tempering process. These in situ nanoparticles strongly affected refining of the grain and inclusions. The investigated steel was strengthened more than 200 MPa by precipitation strengthening and more than 265 MPa by grain refinement strengthening according to the Ashby-Orowan mechanism and the Hall-Petch relationship, respectively.

Key words: In situ nanoparticles, Titanium oxide, Aluminum oxide, Strengthening mechanism, HSLA