Analysis of oxide layer structure in nitrided grain-oriented silicon steel

Xiao-long Wu; Xia Li; Ping Yang; Zhi-wei Jia; Hai-li Zhang

doi:10.1007/s12613-019-1850-5

Volume 26 Issue 12

Dec. 2019

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Article Navigation > International Journal of Minerals, Metallurgy and Materials > 2019 > 26(12): 1531-1538

Xiao-long Wu, Xia Li, Ping Yang, Zhi-wei Jia, and Hai-li Zhang, Analysis of oxide layer structure in nitrided grain-oriented silicon steel, Int. J. Miner. Metall. Mater., 26(2019), No. 12, pp. 1531-1538. https://doi.org/10.1007/s12613-019-1850-5

Cite this article as:

Xiao-long Wu, Xia Li, Ping Yang, Zhi-wei Jia, and Hai-li Zhang, Analysis of oxide layer structure in nitrided grain-oriented silicon steel, Int. J. Miner. Metall. Mater., 26(2019), No. 12, pp. 1531-1538. https://doi.org/10.1007/s12613-019-1850-5

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Research Article

Analysis of oxide layer structure in nitrided grain-oriented silicon steel

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Corresponding author:
Ping Yang E-mail: yangp@mater.ustb.edu.cn
Received: 3 February 2019; Revised: 4 April 2019; Accepted: 9 April 2019

Abstract

Abstract

The production of low-temperature reheated grain-oriented silicon steel is mainly based on the acquired inhibitor method. Due to the additional nitriding process, a high nitrogen content exists in the oxide layer, which changes the structure of the oxide layer. In this study, the structure of the surface oxide layer after nitriding was analyzed by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), glow discharge spectrometry (GDS), and X-ray diffraction (XRD). The size and orientation of ferritic grains in the oxide layer were characterized, and the distribution characteristics of the key elements along the thickness direction were determined. The results show that the oxide layer of the steel sample mainly comprised particles of Fe₂SiO₄ and spherical and lamellar SiO₂, and Fe₄N and fcc-Fe phases were also detected. Moreover, the size and orientation of ferritic grains in the oxide layer were different from those of coarse matrix ferritic grains beneath the oxide layer; however, some ferritic grains exhibited same orientations as those in the neighboring matrix. Higher nitrogen content was detected in the oxide layer than that in the matrix beneath the oxide layer. The form of nitrogen enrichment in the oxide layer was analyzed, and the growth mechanism of ferritic grains during the oxide layer formation is proposed.
- grain-oriented silicon steel;
- decarburization annealing;
- oxide layer;
- ferritic grains;
- silica

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