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The size and distribution of TiN particles have a great influence on the properties of industrial pure iron. It is necessary to understand TiN precipitation behavior in bloom. Herein, inclusions in industrial pure iron cast billets are observed. The temperatures and conditions for TiN precipitation are calculated using thermodynamics and kinetics. The results show a large number of TiN inclusions in the bloom, and the quantity density is the largest at the inner arc of the bloom. This is caused by the large cooling rate at the inner arc and the homogeneous nucleation of inclusions. According to the thermodynamic calculations, during the solidification of industrial pure iron, TiN begins to precipitate at a solidification fraction greater than 0.82. The amount of TiN precipitated during solidification is 93%, with TiN continuing to precipitate from the solid phase after the solidification is complete. The results of TiN particle growth kinetics reveal that MgO is the most effective in promoting TiN nucleation, followed by δ‐Fe, CaS, and MgAl2O4, the effectiveness of Al2O3 as a heterogeneous nucleation core is relatively poor. The radius of the TiN particles decreases with a decrease in the N and Ti content and an increase in the cooling rate. [ABSTRACT FROM AUTHOR]

With the reduction of raw material quality and the improvement of user requirements, the cost of dephosphorization increases. Steel plants urgently need an efficient and economic dephosphorization process to support the production. To address this issue, first, the migration and distribution of phosphorus in the converter smelting process are described quantitatively. Based on the regular solution model, the influence of slag components and temperature on the dephosphorization capacity of steel slag is explored. Afterward, considering the phosphorus distribution ratio, melting point, and phosphorus capacity of slag, the advantages of the slag‐forming route with higher FeO content in rapid slag formation and dephosphorization are expounded. Based on the guidance of the slag‐forming route, the scheme of controlling oxygen lance position and charging is optimized, and a novel blowing control mode is proposed. Finally, industrial tests on a 120 t converter show that the optimized smelting mode significantly reduces the cost and improves the efficiency. As a result, the lime consumption used to smelt a ton of steel is reduced by 3.67 kg t−1, and the dephosphorization rate is still increased by about 3.07%. [ABSTRACT FROM AUTHOR]

Industrial trials and thermodynamic calculations are performed to investigate the effect of Al content on the evolution of non-metallic inclusions in Si-Mn deoxidized spring steel by using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS) and FactSage thermodynamic software. Sulfide type inclusions and CaO-Al2O3-SiO2-MgO type complex inclusions are two major non-metallic inclusions. The effect of Al content on the evolution of CaO-Al2O3-SiO2-MgO system inclusions is discussed. The stability diagram of Fe-Mn-Si-Al-Mg-O system inclusions is calculated in liquid steel at 1873 K. In practice, to achieve the liquid inclusions in molten steel, both the amount of magnesium and aluminum should be considered simultaneously. [ABSTRACT FROM AUTHOR]