CN115488301A - Continuous casting covering slag for ultra-low carbon high-aluminum steel - Google Patents

Continuous casting covering slag for ultra-low carbon high-aluminum steel Download PDF

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Publication number
CN115488301A
CN115488301A CN202211101278.9A CN202211101278A CN115488301A CN 115488301 A CN115488301 A CN 115488301A CN 202211101278 A CN202211101278 A CN 202211101278A CN 115488301 A CN115488301 A CN 115488301A
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China
Prior art keywords
slag
continuous casting
covering slag
sio
bao
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CN202211101278.9A
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Chinese (zh)
Inventor
周建川
韩健
贾改风
李红俊
张继永
张志强
裴庆涛
柳风林
张宇
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Handan Iron and Steel Group Co Ltd
HBIS Co Ltd Handan Branch
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Handan Iron and Steel Group Co Ltd
HBIS Co Ltd Handan Branch
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Priority to CN202211101278.9A priority Critical patent/CN115488301A/en
Publication of CN115488301A publication Critical patent/CN115488301A/en
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/111—Treating the molten metal by using protecting powders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Continuous Casting (AREA)

Abstract

The invention discloses a continuous casting covering slag for ultra-low carbon high-aluminum steel, which comprises the following chemical components in percentage by mass: caO 28-40%, baO 10-16%, siO 2 5%～10%，Al 2 O 3 10%～20%，MgO 2%～5%，Na 2 O+CaF 2 6%～12%，K 2 O+B 2 O 3 3%～10%，C 2%～4%，Li 2 O and the balance impurities; and satisfies (CaO + BaO)/SiO 2 =5～10，(K 2 O+B 2 O 3 )/Li 2 O =1.6 to 2.5. The covering slag adopts CaO-BaO-Al 2 O 3 The non-reaction slag system avoids the violent change of the components of the covering slag caused by the reaction of slag and metal, and ensures the stability of the lubricating and heat transfer performances of the covering slag in the crystallizer in the continuous casting process; the high-alkalinity slag is adopted to reduce SiO in the slag 2 Content, reducing slag-metal reaction, and adopting K to reduce melting point of casting powder 2 O、B 2 O 3 With Li 2 And the fluxing effect is obviously improved by the matching use of O. The covering slag can effectively inhibit SiO in the covering slag 2 The reaction with active element Al in steel avoids great change of the components and performance of the casting powder, can effectively avoid the phenomenon of deterioration of the casting powder, and ensures the stability of the performance of the casting powder in the continuous casting process.

Description

Continuous casting covering slag for ultra-low carbon high-aluminum steel
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to continuous casting covering slag for ultra-low carbon high-aluminum steel.
Background
With the development of industrial technology, the requirement on the specificity of steel materials is more and more, and high-aluminum steel has a series of advantages of light weight, oxidation resistance, electromagnetic property improvement and the like, and can be widely applied to the industrial fields of automobiles, electrics, aviation and the like. But when the high-aluminum steel is produced in continuous casting, because of SiO in the continuous casting covering slag 2 Will react with active element Al in steel violently to result in Al in the protecting slag 2 O 3 Rapidly increased content of SiO 2 The content is sharply reduced, the fluidity and the heat transfer property of the covering slag are changed, good lubrication and heat transfer effects cannot be achieved in the crystallizer, so that the quality problems of casting blank depression, longitudinal crack, slag inclusion and the like are increased, the steel leakage risk is increased, and the smooth continuous casting cannot be ensured.
Disclosure of Invention
The invention aims to provide the continuous casting covering slag for the ultra-low carbon high-aluminum steel so as to improve the quality of a casting blank.
In order to solve the technical problems, the casting powder provided by the invention comprises the following chemical components in percentage by mass: caO 28%～40%，BaO 10%～16%，SiO 2 5%～10%，Al 2 O 3 10%～20%，MgO 2%～5%，Na 2 O+CaF 2 6%～12%，K 2 O+B 2 O 3 3 to 10 percent of carbon, 2 to 4 percent of carbon and the balance of Li 2 O and unavoidable impurities; and satisfies (CaO + BaO)/SiO 2 =5～10，(K 2 O+B 2 O 3 )/Li 2 O=1.6～2.5。
Preferably, the chemical components of the casting slag comprise 30-36% of CaO, 12-16% of BaO, and Al 2 O 3 10%～15%。
Preferably, in the chemical composition of the protective slag, na 2 O+CaF 2 7%～10%。
Preferably, in the chemical composition of the casting powder, K 2 O+B 2 O 3 5～8%。
The casting powder is suitable for steel grades with less than or equal to 0.03 percent of C and 0.2 to 0.5 percent of Al.
The design principle of the invention is as follows: the covering slag adopts CaO-BaO-Al to avoid violent slag-metal reaction 2 O 3 A slag system; by properly increasing Al in the mold flux 2 O 3 Content, reduction of SiO 2 Content of SiO in slag 2 Reaction with Al in steel; meanwhile, in order to ensure that the viscosity of the covering slag is proper, a certain amount of BaO is added to reduce the melting point of the covering slag and improve the fluidity of the slag; therefore, it is required that (CaO + BaO)/SiO be used 2 And (5) = 10 to 5. The MgO content in the covering slag can reduce the viscosity and the melting point of the covering slag. CaF in the covering slag 2 And Na 2 O promotes the migration and diffusion of ions in the molten slag, enhances the fluidity of the molten mold flux, and improves the lubricating property in the continuous casting process, but excess CaF 2 And Na 2 O can promote nepheline to be separated out, is not beneficial to vitrification of the covering slag and influences heat transfer stability of the covering slag in the crystallizer. Li in the mold flux 2 The addition of O can lead Al in the casting powder 2 O 3 The melting temperature does not change much after the content is increased by a small amount, so that the fluidity of the casting powder is ensured; at the same time K 2 O and B 2 O 3 The fluxing action of (A) has a certain particularity inWith Li 2 The strong fluxing effect is shown only when the O is used in combination. The covering slag is suitable for ultra-low carbon steel, so the control range of the C content in the covering slag is 2-4%.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: the invention adopts CaO-BaO-Al 2 O 3 The non-reaction slag system avoids the violent change of the components of the covering slag caused by the reaction of slag and metal, and ensures the stability of the lubricating and heat transfer performances of the covering slag in the crystallizer in the continuous casting process. The invention adopts high-alkalinity slag to reduce SiO in the slag 2 Content, reducing slag-metal reaction, and adopting K to reduce melting point of casting powder 2 O、B 2 O 3 With Li 2 And the fluxing effect is obviously improved by matching the O with the alloy. The invention can effectively inhibit SiO in the covering slag 2 The protective slag has the advantages that the protective slag reacts with active element Al in steel, so that the components and the performance of the protective slag are prevented from being greatly changed, the phenomenon of deterioration of the protective slag can be effectively avoided, and the stability of the performance of the protective slag in the continuous casting process is ensured, so that the protective slag has stable lubricating and heat transferring effects in a crystallizer, continuous casting can be carried out smoothly, and the quality problem of casting blanks is reduced.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments.
Examples 1 to 8: the continuous casting mold flux for the ultra-low carbon high aluminum steel adopts the following component proportions.
(1) The casting powder comprises the following chemical components in percentage by mass: caO 28-40%, baO 10-16%, siO 2 5%～10%，Al 2 O 3 10%～20%，MgO 2%～5%，Na 2 O+CaF 2 6%～12%，K 2 O+B 2 O 3 3 to 10 percent of carbon, 2 to 4 percent of carbon and the balance of Li 2 O and unavoidable impurities; and satisfies (CaO + BaO)/SiO 2 =5～10，(K 2 O+B 2 O 3 )/Li 2 O =1.6 to 2.5. The preferable composition of the components is as follows: 30-36 percent of CaO, 12-16 percent of BaO and Al 2 O 3 10%～15%，Na 2 O+CaF 2 7%～10%，K 2 O+B 2 O 3 5 to 8 percent. Each implementationThe composition ratios of the mold flux are shown in Table 1.
Table 1: the compositions of the covering slag in each example are proportioned
Figure DEST_PATH_IMAGE002
(2) The covering slag is suitable for continuous casting production of steel grades with less than or equal to 0.03wt% of C and 0.2-0.5 wt% of Al; in the continuous casting production process, the melting point of the covering slag is 997-1138 ℃, the viscosity is 0.192-0.397 Pa.s, the drawing speed of continuous casting is 1.2-1.4 m/min, the slag consumption is 0.33-0.43 kg/t, and the thickness of a molten slag layer on molten steel in a crystallizer is 9.4-15.8 mm. The stability of the components and the performance of the casting powder in the continuous casting process is ensured, the melting and the absorption inclusion of the casting powder are better, the casting powder is uniformly spread on the surface of molten steel in a crystallizer, and better lubricating and heat transfer effects can be achieved; the defects of longitudinal cracks, depressions and the like on the surface of the continuous casting billet are obviously reduced, and the incidence of the defects of the continuous casting billet is reduced to be within 2.5 percent from about 10 percent by low-power inspection statistics on the surface of the continuous casting billet. The performance of the covering slag meets the continuous casting requirement of the steel grade.
Comparative example 1: the comparative example covering slag comprises the following components in percentage by mass: caO 7%, baO 14.5%, al 2 O 3 31%、B 2 O 3 8%、SiO 2 5%、CaF 2 11.3%、Na 2 O 12.8%、Li 2 1.5% of O, 2.5% of MnO and 5% of C, and its melting temperature is 988 deg.C and viscosity is 0.24 pas. When the covering slag is adopted for continuous casting, the bonding breakout alarm appears for 1 time, but the breakout alarm does not appear in the covering slag of the embodiment, because the covering slag adopts high Al 2 O 3 Low content of SiO 2 The content components are designed to inhibit SiO in the slag 2 Reacting with Al in steel, and adding a large amount of cosolvent CaF to reduce the melting point of the casting powder 2 And Na 2 O, but a large amount of CaF 2 And Na 2 O promotes the precipitation of nepheline and Na-Al-O crystals, so that the heat transfer uniformity of the mold flux is poor, and the risk of bonding breakout is increased. The comparison of the application effects of the comparative example and the examples is shown in Table 2.
Comparative example 2: the comparative example still adoptedSystematic CaO-SiO 2 The protective slag comprises the following components in percentage by mass: caO 25.41%, siO 2 33.15%、Al 2 O 3 9.9%、Na 2 O 6.6%、Li 2 O 4.97%、MnO 5.5%、MgO 5.4%、F - 8.8 percent, the melting temperature range is 1157 to 1266 ℃, and the viscosity is 0.19 +/-0.05 Pa.s. MnO is added into the casting powder to ensure that the casting powder is mixed with SiO 2 Preferential reaction to slow down the reaction with Al in the steel, but due to SiO in the slag 2 The high content of Al can still react with Al in steel, so that the composition change of the casting powder is still more violent after the casting powder is added into a crystallizer, and the Al in the powder 2 O 3 The content rapidly increases with Al 2 O 3 The accumulation of slag results in poor adsorption conditions for inclusions, which easily causes defects such as the inclusion of slag under the slab, and therefore, the slag is not suitable for a long continuous casting time. The comparison of the application effects of the comparative example and the examples is shown in Table 2.
Table 2: application effects of examples and comparative examples
Figure DEST_PATH_IMAGE004
。

Claims (5)

1. The continuous casting covering slag for the ultra-low carbon high-aluminum steel is characterized by comprising the following chemical components in percentage by mass: 28-40% of CaO, 10-16% of BaO and SiO 2 5%～10%，Al 2 O 3 10%～20%，MgO 2%～5%，Na 2 O+CaF 2 6%～12%，K 2 O+B 2 O 3 3 to 10 percent of carbon, 2 to 4 percent of carbon and the balance of Li 2 O and unavoidable impurities; and satisfies (CaO + BaO)/SiO 2 =5～10，(K 2 O+B 2 O 3 )/Li 2 O=1.6～2.5。
2. The continuous casting mold flux for ultra-low carbon high aluminum steel according to claim 1, wherein: the chemical components of the casting powder comprise 30-36% of CaO, 12-16% of BaO and Al 2 O 3 10%～15%。
3. The continuous casting mold flux for ultra-low carbon high aluminum steel according to claim 1, wherein: in the chemical composition of the protective slag, na 2 O+CaF 2 7%～10%。
4. The continuous casting mold flux for ultra-low carbon high aluminum steel according to claim 1, wherein: in the chemical composition of the casting powder, K 2 O+B 2 O 3 5～8%。
5. The continuous casting mold flux for ultra-low carbon high aluminum steel according to any one of claims 1 to 4, wherein: the covering slag is suitable for steel grades with less than or equal to 0.03 percent of C and 0.2 to 0.5 percent of Al.
CN202211101278.9A 2022-09-09 2022-09-09 Continuous casting covering slag for ultra-low carbon high-aluminum steel Pending CN115488301A (en)

Priority Applications (1)

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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211101278.9A CN115488301A (en) 2022-09-09 2022-09-09 Continuous casting covering slag for ultra-low carbon high-aluminum steel

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