Thread Content
This post was last edited by goldliyang on 2019-11-14 at 11:35. Oxygen poses a significant threat in steelmaking; therefore, deoxidizers are needed to remove it. However, not all deoxidizers are effective in this regard. Thus, experts offer the following suggestions: The following deoxidizers are commonly used in steelmaking converters: Fe-Mn, Fe-Si, Mn-Si alloys, Ca-Si alloys, aluminum, Fe-Al, and composite deoxidizers. The use of deoxidizers should aim to reduce the cost of steel by employing inexpensive ferroalloys, while ensuring the quality of the steel. (1) Deoxidation with Si/Mn can result in pure SiO2 in the solid phase ； MnO•SiO2 in the liquid phase ； MnO-FeO in the solid solution. By controlling an appropriate ω/ω ratio, a liquid-phase MnO·SiO2 product can be obtained, and inclusions can be easily removed by flotation. (2) Deoxidation is carried out using S + Mn-rich aluminum, and the deoxidation products may contain calcium nicotinate (2MnO•Al2O3•5SiO2) ； Garnet (3MnO•Al2O3•3SiO2); Al2O3 (ω 30%). The composition of the inclusions should be kept within a low-melting-point range, with ωIAl] in the steel being ≤0.006%, and this value can reach 0.0020% (20 ppm) without the formation of Al2O3. Such inclusions can be added to the molten steel without blocking the taphole, and no subsurface pores will form in the cast billet. (3) Deoxidize with excess aluminum. For low-carbon aluminum-killed steel, the content of acid-soluble aluminum, denoted as s, in the steel ranges from 0.02% to 0.04%, and the deoxidation products are all Al2O3. Al2O3 has a melting point as high as 2050°C and remains in a solid state within molten steel. If the poly203 content in the molten steel is low, its pourability is poor, and it tends to clog the taphole. Furthermore, Al2O3 is an indented inclusions that affect the properties of steel. Al2O3 is accelerated by argon blowing, or Si-Ca and Ca wires are treated with calcium to change the state of Al2O3. With a low S content, calcium treatment can produce a low-melting-point 2CaO•Al2O3•SiO2. For low-carbon aluminum-killed steel, this product can be easily floated through calcium treatment, thereby removing slag and improving pourability. Photos of the deoxidizer are shown below: