Effects of ferrosilicon alloy, Si content of steel, and slag basicity on compositions of inclusions during ladle furnace
- PDF / 762,395 Bytes
- 7 Pages / 595.276 x 790.866 pts Page_size
- 67 Downloads / 170 Views
ORIGINAL PAPER
Effects of ferrosilicon alloy, Si content of steel, and slag basicity on compositions of inclusions during ladle furnace refining of Al‑killed steel Jian‑fei Xu1 · Kun‑peng Wang1 · Ying Wang1 · Zhi‑dong Qu1 · Xing‑kuang Tu1 Received: 15 August 2019 / Revised: 6 November 2019 / Accepted: 19 November 2019 © China Iron and Steel Research Institute Group 2020
Abstract To obtain solid A l 2O 3 or MgO·Al 2O 3 inclusions in ladle furnace (LF) refining process and achieve ultra-low total oxygen content in steel through subsequent Ruhrstahl Heraeus degassing, the effects of ferrosilicon alloy, Si content of steel, and slag basicity on the compositions of inclusions during LF refining were investigated in Al-killed steel. Al2O3 inclusions could be transformed into CaO–Al2O3–MgO–CaS inclusions after adding ferrosilicon alloy in the LF refining process as this alloy contains some CaSi alloy impurities. The addition of all ferrosilicon alloys required for the steel in the tapping process could eliminate the influence of Ca in ferrosilicon alloy on the compositions of inclusions. Si in liquid steel had a significant influence on the compositions of inclusions during LF refining when CaO–Al2O3–SiO2–MgO slag with high basicity of 7.0 was used. This was because [Ca] produced by the reaction of CaO and [Al] could be consumed more readily by SiO2 in Si-free steel than in Si-containing steel, which was confirmed by the difference of total calcium content between Si-free and Si-containing steels. As a result, Al2O3 and MgO·Al2O3 inclusions were retained in Si-free steel, whereas calcium aluminate inclusions were found in Si-containing steel. For CaO–Al2O3–SiO2–MgO slag with low basicity of 2.8, A l2O3 and MgO·Al2O3 inclusions were obtained after LF refining in Si-containing steel when all ferrosilicon alloys required for the steel were added in the tapping process. This was because the reaction of CaO and [Al] was weak, and residual [Ca] in the steel could be rapidly consumed by SiO2 in low-basicity slag owing to the low activity of CaO and high activity of SiO2, leading to a low total calcium content of 0.0003% in Si-containing steel. Keywords Inclusion · Ferrosilicon alloy · Si content · Basicity · LF refining
1 Introduction With development in steelmaking technology, the demand for high-cleanliness liquid steel has increased. To achieve ultra-low total oxygen (TO) content in liquid steel, the effect of inclusion compositions on its removal was discussed, and it was found that solid inclusions were easier to be removed through Ruhrstahl Heraeus (RH) degassing than liquid
* Jian‑fei Xu [email protected] * Kun‑peng Wang [email protected] 1
Zenith Steel Group Co., Ltd., Changzhou 213000, Jiangsu, China
inclusions due to a higher contact angle between inclusions and molten steel [1–6]. Therefore, a basic oxygen furnace (BOF)–RH–continuous casting (CC) process was proposed as solid Al2O3 inclusions formed in the tapping process were easy to transform into liquid CaO–Al2O3–MgO inclusions in ladle
Data Loading...
