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CN-121992171-A - Preparation method of ultralow-sulfur low-manganese titanium-containing steel for electrode

CN121992171ACN 121992171 ACN121992171 ACN 121992171ACN-121992171-A

Abstract

The invention provides a preparation method of ultralow-sulfur low-manganese titanium-containing electrode steel, which comprises the steps of adding a first slag-making material into a converter for dephosphorization and demanganization, pouring part of converter slag, adding a second slag-making material into the converter for decarburization, tapping steel from the converter and fully leaving slag, adding active lime and cryolite in an LF (ladle furnace) in a station for removing manganese in molten steel, heating to a target outlet temperature, adding a ladle slag modifier into a ladle slag surface, carrying out soft argon blowing, adding carbon powder for RH vacuum deoxidation, adding titanium sponge for RH alloying, adding a desulfurization modifier composite ball for RH deep desulfurization and inclusion modification, adopting a sealing ring and argon blowing whole-course protection casting for a large ladle long water gap, adopting a covering agent for tundish and supplementing the covering agent according to the condition of the tundish covering in the continuous casting process. The method utilizes thermodynamic and kinetic conditions of each working procedure and combines the ladle slag modifier and the desulfurization modifier composite sphere to realize the steps of demanganization, desulfurization and ladle slag modification, thereby preparing the ultralow-sulfur low-manganese titanium-containing steel for the electrode.

Inventors

  • YANG XINGDI
  • HUANG GUANGJIE

Assignees

  • 重庆大学
  • 攀钢集团研究院有限公司

Dates

Publication Date
20260508
Application Date
20260210

Claims (10)

  1. 1. The preparation method of the ultralow-sulfur low-manganese titanium-containing electrode steel is characterized by comprising the steps of sequentially carrying out a converter process, an LF refining process, an RH refining process and a billet continuous casting process, so as to prepare the ultralow-sulfur low-manganese titanium-containing electrode steel, wherein: the converter process comprises the steps of adding semisteel or molten iron into a converter, performing top blowing oxygen, adding a first slag-making material into the converter for dephosphorization and demanganization, blowing for a first time, pouring out part of converter slag, adding a second slag-making material into the converter for blowing decarburization, and finishing the blowing when the blowing is ended, wherein the converter is tapped and the slag is left; The LF refining process comprises the steps of adding active lime and cryolite at an LF inlet station, removing manganese in molten steel, heating to a target outlet temperature, adding ladle slag modifier into the ladle slag surface, and performing soft argon blowing for a second time; The RH refining process comprises vacuum deoxidation of RH treatment, RH alloying by adding titanium sponge, RH deep desulfurization by adding desulfurization modifier composite balls, and inclusion modification; The continuous casting process of the square billets comprises the steps of adopting a sealing ring and argon blowing whole-process protection casting for a long water gap of a large ladle, blowing argon by a stopper rod, wherein the weight of the large ladle molten steel is not less than 25 tons in the casting process, adopting a covering agent for a middle ladle, and supplementing the covering agent according to the condition of the middle ladle covering in the continuous casting process.
  2. 2. The method for preparing the ultralow-sulfur low-manganese titanium-containing electrode steel according to claim 1, wherein the step of adding a first slag-making material into the converter for dephosphorization and demanganization comprises the step of adding the first slag-making material into the converter, wherein the alkalinity of converter slag is controlled to be 1.6-2.1, dephosphorization and demanganization are carried out, the first slag-making material comprises active lime, high-magnesium lime and an acidic composite slag former, and the addition amount of the first slag-making material is 2.5-3.5 kg/t of the active lime, 2.1-3.1 kg/t of the high-magnesium lime and 6-9 kg/t of the acidic composite slag former.
  3. 3. The method for preparing the ultralow-sulfur low-manganese titanium-containing electrode steel, which is characterized by comprising the step of adding a second slag forming material into a converter to carry out blowing decarburization, wherein the step of adding the second slag forming material into the converter to control the alkalinity of converter slag to be 4.1-4.5, and the step of carrying out blowing decarburization comprises the steps of adding active lime and high-magnesium lime, wherein the addition amount of the second slag forming material is 11-15 kg/t of steel and 3-5 kg/t of high-magnesium lime.
  4. 4. The preparation method of the ultralow-sulfur low-manganese titanium-containing electrode steel is characterized in that the tapping temperature is controlled to be 1640-1660 ℃ when a converter is tapped, deoxidization alloying is not performed when tapping is performed, active lime and cryolite are added to adjust slag of ladle slag when the converter is tapped for 1/5~2/5, the addition amount of the active lime is 3.0-3.5 kg/t of steel, and the addition amount of the cryolite is 0.7-1.2 kg/t of steel.
  5. 5. The method for preparing the ultralow-sulfur low-manganese titanium-containing electrode steel according to claim 1, wherein a first slag-making material is added into the converter to carry out dephosphorization and demanganization, and after a first time of blowing, the temperature of molten steel reaches a first temperature, part of converter slag is poured out, the pouring amount of the converter slag is 75-85wt% of the total amount of the converter slag, the first time is 2.5-3.5 min, and the first temperature is 1390-1400 ℃.
  6. 6. The method for preparing the steel for the ultralow-sulfur low-manganese titanium-containing electrode, according to claim 1, wherein when active lime and cryolite are added at an LF station, the addition amount of the active lime is 3.0-4.0 kg/t of steel, the addition amount of the cryolite is 0.7-1.2 kg/t of steel, the addition amount of the ladle slag modifier is 2.1-2.9 kg/t of steel, and the second time is 3-5 min.
  7. 7. The method according to claim 1, wherein the RH refining step comprises detecting aO Measuring and [ C ] Measuring in molten steel before RH treatment and calculating aO Meter with a meter body by using the detected [ C ] Measuring , and adding carbon powder to the molten steel to remove redundant aO in the molten steel by using carbon if the detected aO Measuring in the molten steel is more than 25 ppm.
  8. 8. The method for preparing the ultralow-sulfur low-manganese titanium-containing electrode steel according to claim 1, wherein the RH-treated vacuum deoxidation comprises the steps of reaching a vacuum degree of less than or equal to 300Pa within 3min after the vacuum treatment is started, reaching a vacuum degree of less than or equal to 100Pa within 4min after the vacuum treatment is started, and keeping the vacuum degree of less than or equal to 100Pa for more than 4min, wherein the RH-treated vacuum deoxidation time is 8-10 min.
  9. 9. The preparation method of the ultralow-sulfur low-manganese titanium-containing electrode steel, which is characterized by comprising the steps of adding a desulfurization modifier composite ball for RH deep desulfurization and inclusion modification, wherein after the titanium sponge is added for a third time, adding the desulfurization modifier composite ball from a high-level bin of a vacuum chamber, and performing vacuum treatment for a fourth time after the addition of the desulfurization modifier composite ball, wherein the addition amount of the desulfurization modifier composite ball is 2.5-3.6 kg/t steel, the third time is 2-4 min, and the fourth time is 6-8 min.
  10. 10. The method for preparing the ultralow-sulfur low-manganese titanium-containing electrode steel according to claim 9, wherein the desulfurization modifier composite ball comprises an inner layer and an outer layer, the outer layer is positioned outside the inner layer, the mass ratio of the outer layer to the inner layer is 3.1-3.9:1, the outer layer comprises a desulfurizing agent and a titanium-containing oxide modifier, and the inner layer comprises a metal deep desulfurizing agent and a sulfide inclusion modifier.

Description

Preparation method of ultralow-sulfur low-manganese titanium-containing steel for electrode Technical Field The invention relates to the technical field of steel smelting, in particular to a preparation method of ultralow-sulfur low-manganese titanium-containing steel for an electrode. Background In order to avoid problems such as an increase in resistivity, an increase in pressure drop, and a decrease in strength, a low and stable carbon content is often required for the steel for an electrode for electrolytic aluminum. Carbon is the main strengthening element in steel, but too high a carbon content increases the resistivity of steel (e.g., resistivity increases significantly at 0.06% carbon content), resulting in increased electrical energy loss during electrolysis. The low carbon content (less than or equal to 0.06%) is beneficial to reducing the resistivity and the electricity consumption. However, too low a carbon content (e.g., < 0.01%) may result in insufficient strength of the steel, failing to withstand the mechanical stresses (e.g., lifting, thermal expansion) of the anode, and being subject to deformation or fracture. Therefore, the lower the carbon content is, the better the carbon content is, but the accurate control of carbon is performed, and the stability of the comprehensive properties such as conductivity, strength, corrosion resistance, processability and the like is realized. Manganese is a ferromagnetic element and can significantly reduce the electrical conductivity of the steel. In the electrolysis of aluminium, the anode steel is subjected to a high current density (typically in excess of 350A/m 2), and the high manganese content causes an increase in the anode resistance, which causes additional joule heat losses. Studies show that the conductivity of the steel decreases by about 2% for every 0.1% increase in manganese content. Manganese is easy to react with elements such as oxygen, sulfur and the like in a high-temperature electrolysis environment to form a passivation layer such as MnO 2 and the like. The passivation layer may prevent uniform dissolution of the anode surface active material, resulting in excessive local current density, accelerating anode corrosion and breakage. Sulfur is a typical conductivity-disrupting element that reduces the conductivity and toughness of the steel. Sulfur is easy to form sulfide inclusions such as MnS, feS and the like in steel, the resistivity of the steel is obviously increased, and researches show that the conductivity of the steel is reduced by about 3 percent when the sulfur content is increased by 0.1 percent. And in the strongly corrosive electrolyte of electrolytic aluminum (such as cryolite molten salt), mnS inclusions accelerate the formation and expansion of pitting. Therefore, by reducing sulfide inclusions, the pitting resistance can be significantly improved and the risk of anode failure can be reduced. CN 117127092A discloses a production method of steel for low-carbon electrode, the chemical composition mass percentage of steel is C=0.02%～0.04%,Si≤0.01%,Mn≤0.03%,P≤0.05%,S≤0.005%,Al≤0.02%,V=0.03%～0.07%,N=0.008～0.014%,Cr+Ni+Mo+Cu≤0.08,As+Sn+Pb+Bi+Sb≤0.015%,, and the balance is Fe and unavoidable impurities. According to the prior art, the contents of Mn, si and other residual elements in steel types are reduced as much as possible, the carbon content, the vanadium content and the N content in the steel are controlled, so that V and C are combined to generate VC and VN, and the toughness of the steel is effectively improved. In the prior art, LF is refined twice, after the first refining, ladle slag containing MnO is completely scraped off, aluminum wire is fed to deoxidize molten steel, lime is added for 0.5t, and slag formation, deoxidization and desulfurization are carried out on refined synthetic slag for 0.3 t. In addition, the ladle slag for the first time has high TFe content due to non-deoxidization in the slag, so that slag skimming not only takes away a large amount of iron in the slag but also can cause unavoidable part of molten steel to be scraped off, so that the loss of steel materials is large, the large-scale application is not facilitated, and aluminum deoxidization can cause a large amount of alumina inclusion in the steel, so that the control of steel cleanliness is not facilitated. In the production method of the steel for the low-carbon electrode disclosed by CN 114892066A, oxidizing slag is adopted for demanganizing in the LF refining process, the molten steel is ensured to be discharged out of an LF furnace for active oxygen of 400-500 ppm, and a carbon powder deoxidizing method is adopted in the vacuum process, wherein the mass percentage of chemical components of the prepared steel is C=0.03%～0.06%,Si≤0.01%,Mn≤0.05%,P≤0.01%,S≤0.01%,Al≤0.01%,Ti=0.05%～0.10%,N≤0.005%,As+Sn+Pb+Bi+Sb≤0.015%,, and the balance is Fe and unavoidable impurities. In order to inhibit manganese return, the prior art does not modify