Reaction mechanisms between molten CaF2-based slags and molten 9CrMoCoB steel

In the electroslag remelting (ESR) process, low‐frequency power supply can significantly reduce power consumption and achieve three‐phase balance of power supply. Therefore, a transient coupling model of fluid flow, heat transfer, and component transport in the ESR process, which is coupled to the electromagnetic field calculated using Maxwell 3D software, is established to study the influence of low‐frequency power supply on desulfurization. When a 50 Hz power supply is used, a skin effect is observed in the metal, and the direction of the Lorentz force at the slag/metal interface changes. However, this effect becomes less pronounced with decreasing current frequency. Sulfur is mainly transferred at the electrode tip, and the desulfurization rate is approximately 50%. Electrochemical reactions mainly occur at the electrode tip/slag interface and the metal pool/slag interface. The removal rate of sulfur using direct current (DC) power supply is less than that using an alternating current power supply. The DC reverse polarity power supply leads to higher desulfurization rate than DC straight polarity, which is 74% and 31%, respectively. The sulfur removal rate increases from 81.37% to 84.59% as the frequency decreases from 50 to 2 Hz because of the longer electrochemical reaction time at this lower frequency.

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“…}$ is the activity of oxygen, which is determined by Equation (10). [ 38 ]

k_{\text{ss}} = 0.4 \gamma_{\text{ss}}^{0.5} \left(\left(\right. \frac{\epsilon}{\nu} \left.\right)\right)^{0.25}

$$C_{S^{2 -}} = 9.852 \times \left(10\right)^{- 6} w \left(\right.

…”

Section: Model Descriptionmentioning

confidence: 99%

“…a ½O is the activity of oxygen, which is determined by Equation (10). [38] k ss ¼ 0.4γ 0.5 ss ε ν 0.25 and k sm ¼ 0.4γ 0.5 sm ε ν 0.25 (7)…”

Section: Governing Equations Symbolsmentioning

confidence: 99%

Numerical Study on the Effect of Low‐Frequency Power Supply on Desulfurization in the Electroslag Remelting Process

Duan

Liu

et al. 2023

steel research int.

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Active element variation of G115 heat-resistant steel and its dependence on slag composition during electroslag remelting

Wang

Shi

Liu

et al. 2023

Journal of Materials Research and Technology

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Research on the reaction mechanism and control of aluminium enhancement for electroslag remelting high-quality turbine blade steel

Yan,

Geng,

Jiang

et al. 2024

Ironmaking & Steelmaking: Processes, Products and Applicati

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Based on laboratory experiments and thermodynamic analysis, this article reveals the reaction mechanism behind the increase in aluminium content during the electroslag remelting (ESR) process in a protective atmosphere. It investigates the effects of slag composition, steel composition, reaction temperature, and reaction atmosphere on the aluminium content in ingots to inhibit the increase of aluminium during the remelting process. The results indicate that the increase in aluminium content is accompanied by significant silicon loss in the steel and an increase in silicon dioxide in the slag. The aluminium content in the ingots is controlled by the thermodynamic reaction equilibrium between [Si] in the steel and (Al2O3) in the slag. The high-temperature conditions during the ESR process promote the occurrence of the aluminium addition reaction. In the ESR process without a protective atmosphere, the oxidation of the consumable electrode in air forms a ferrous oxide, leading to a decrease in silicon activity. Consequently, the trend of aluminium increase in ingots remelted in a nonprotective atmosphere is lower than that in ingots remelted in a protective atmosphere. Increasing the silicon dioxide content in the slag to 1.96%–7.62% is an effective approach to inhibit aluminium addition in the ingot. However, excessive addition of silicon dioxide can cause the burning loss of alloy elements and increase the content of silicate inclusions. Additionally, reducing the initial silicon content in the electrode from 0.55% to 0.40% further reduces the aluminium content in the ingot. Industrial experiments were conducted using the optimised S2 slag system (68.63% CaF2–19.61% Al2O3–4.90% CaO–4.90% MgO–1.96% SiO2). The results were consistent with laboratory experiments, and the aluminium content in the ingots met the standard requirements.

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Reaction mechanisms between molten CaF2-based slags and molten 9CrMoCoB steel

Cited by 4 publications

References 21 publications

Numerical Study on the Effect of Low‐Frequency Power Supply on Desulfurization in the Electroslag Remelting Process

Numerical Study on the Effect of Low‐Frequency Power Supply on Desulfurization in the Electroslag Remelting Process

Active element variation of G115 heat-resistant steel and its dependence on slag composition during electroslag remelting

Research on the reaction mechanism and control of aluminium enhancement for electroslag remelting high-quality turbine blade steel

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