Analysis of inclusions in whole smelting process of non-oriented silicon steel DG47A
CAO Jian-qi1, CHEN Chao1, XUE Li-qiang1,2, LI Zhou3,4, ZHAO Jian1, LIN Wan-ming1,5
1. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China; 2. No.2 Steelmaking Plant, Shanxi Taigang Stainless Steel Co., Ltd.,Taiyuan 030030, Shanxi, China; 3. College of Artificial Intelligence and Big Data for Medical Sciences,Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, Shandong, China; 4. Department of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen 518055, Guangdong, China; 5. College of New Energy and Materials Engineering, Shanxi Electronic Science and Technology Institute, Linfen 041075, Shanxi, China
Abstract：For a high grade non-oriented silicon steel DG47A(Fe-2%Si-0.36%Al-0.26%Mn),clustered Al2O3-MgO spinel inclusion with a length of 50 μm, which may influence the product property in the sequent process, is found in a hot rolled sheet produced by a steelmaking plant. By analyzing the samples taken from the BOF→RH→tundish→continuous casting slab production process and thermodynamic calculation, the evolution of inclusions in the smelting process of this steel grade are studied. The morphology, size and type of inclusions were analyzed by scanning electron microscope and energy dispersive spectrometer analysis (SEM-EDS). The formation condition of Mg-Al spinel inclusion was calculated by thermodynamics. In addition,the mechanism of precipitation phase during solidification process was calculated by PANDAT software. The results show that SiO2 is the main inclusion after RH decarburization. There are Al2O3 and a small amount of SiO2 inclusions after 3 minutes of adding aluminum in RH. Afterwards, Al2O3-MgO and MnS-containing composite inclusions are formed after adding alloys of ferro-silicon and manganese in RH treatment. CaS-containing composite inclusions are formed after adding desulfurizers. There are no single Al2O3 inclusions before the content of CaS and MnS in the composite inclusions tended to increase, and MgO remained at about 25%. CaS and AlN inclusions are wrapped around the outer edge of Al2O3-MgO inclusions. The AlN and MnS inclusions were found in slab. After adding aluminum in RH, the average size of the inclusions is about 20-25 μm, and decreased to about 2-5 μm before tapping of RH. In the tundish and the slab, with the cooling of the molten steel,the second phase precipitated on the surface of the inclusions, and the average size of the inclusions slightly increased to around 3-6 μm. The thermodynamic calculation results show that, at 1 873 K, when the Mg content in the molten steel is greater than 0.000 26%, Al2O3-MgO inclusions are formed. During the cooling process of molten steel, AlN and MnS inclusions precipitated successively with the decrease of temperature.
曹建其, 陈超, 薛利强, 栗周, 赵健, 林万明. 无取向硅钢DG47A冶炼全流程夹杂物分析[J]. 钢铁, 2023, 58(2): 61-71.
CAO Jian-qi, CHEN Chao, XUE Li-qiang, LI Zhou, ZHAO Jian, LIN Wan-ming. Analysis of inclusions in whole smelting process of non-oriented silicon steel DG47A[J]. Iron and Steel, 2023, 58(2): 61-71.
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