Rare earth modified high-strength corrosion-resistant steel bar and preparation method thereof

Abstract

The invention discloses a rare earth modified high-strength corrosion-resistant steel bar and a preparation method thereof. The rare earth modified high-strength corrosion-resistant steel bar comprises the following components: C, Si, Mn, Cr, P, S, 0.008-0.010 wt% of composite rare earth alloy and the balance of Fe and inevitable impurities. The composite rare earth alloy comprises the following components: RE, Al, Si and Ca; the RE component in the composite rare earth alloy comprises the following components: Ce, La and Y; fe is composed of iron ore and waste steel, the iron ore accounts for 20-55 wt% of the total mass of Fe, and the balance is the waste steel. The composite rare earth alloy (especially rare earth elements such as yttrium, cerium and lanthanum) is added into the steel bar, so that the corrosion resistance of the steel bar can be remarkably improved, and the corrosion of chloride ions can be effectively resisted especially in a marine environment. The addition of the rare earth elements can improve the microstructure of the steel bar and enhance the strength and toughness of the material, so that the steel bar is less prone to fracture or fatigue failure when bearing external force.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion-resistant steel bars, and in particular to a rare earth modified high-strength corrosion-resistant steel bar and a preparation method thereof. Background Art

[0002] The cost of repairing, reinforcing and replacing corroded components caused by corrosion of reinforced concrete structures accounts for about 3% to 5% of the total cost of the building each year. In coastal areas, this proportion is even higher, reaching more than 10%. Taking bridge engineering as an example, the maintenance costs caused by corrosion account for 27% to 32% of the life cycle cost of the bridge. In addition, the indirect economic losses such as structural safety accidents and loss of use functions caused by corrosion are even more difficult to estimate. Especially in major projects such as marine engineering and nuclear power plants, once steel bar corrosion failure occurs, it will not only cause huge maintenance costs, but may also trigger a chain reaction, leading to serious consequences such as project delays and suspension of production for rectification, highlighting the importance and urgency of developing high-performance corrosion-resistant steel bars.

[0003] Statistics show that steel bar corrosion causes more than 50% of reinforced concrete structure failures, among which local corrosion and stress corrosion caused by non-metallic inclusions are particularly significant, which not only affects the strength and bonding properties of the steel bars, but also endangers the bearing capacity and service life of the entire structure, causing huge economic losses. Therefore, it is urgent to carry out systematic research in terms of material design, inclusion control and modification, and corrosion resistance optimization, in order to develop new corrosion-resistant steel bars through low-cost and high-efficiency technical means to meet the requirements of green, safety, and long life engineering construction.

[0004] In the prior art, steel bars usually face the following problems: Insufficient corrosion resistance: Steel bars are susceptible to corrosion in complex environments, especially in hot and humid environments, atmospheric and seawater environments, which can lead to structural performance degradation and shorten service life. The optimization of corrosion-resistant elements (such as Cr) in existing steel materials is not sufficient, and the passive film of steel bars has poor stability in harsh environments, making pitting and other forms of corrosion more likely to occur.

[0005] It is difficult to balance strength and plasticity: In order to improve the strength of steel bars, the carbon content or alloy element content is usually increased, but this will lead to a decrease in the plasticity and toughness of the material, affecting its actual performance and safety. In addition, excessive grain size and uneven inclusion morphology will also affect the strength and ductility of the material.

[0006] Inclusions and grain refinement have limited effects: Inclusions and coarse grains in steel often lead to uneven mechanical properties and reduce the overall performance of steel. Existing methods have limited effects on inclusion control and grain refinement, making it difficult to significantly improve the strength and corrosion resistance of materials.

[0007] In order to overcome the above technical problems, the present invention proposes to optimize the alloy composition of steel by adding rare earth elements and chromium elements, and adopt multiple strengthening mechanisms to improve the performance of steel bars. Summary of the invention

[0008] In view of the deficiencies of existing steel bar materials in terms of strength and corrosion resistance, the present invention proposes a rare earth modified high-strength corrosion-resistant steel bar and a preparation method thereof, which improves the steel bar performance through multiple strengthening mechanisms.

[0009] The technical solution of the present invention to solve the above technical problems is as follows: A rare earth modified high-strength corrosion-resistant steel bar comprises the following components in percentage by mass: C: 0.07wt%~0.10wt%, Si: 0.30wt%~0.55wt%, Mn: 1.25wt%~1.36wt%, Cr: 1.05wt%~1.65wt%, P≤0.035wt%, S≤0.035wt%, composite rare earth alloy 0.008wt%-0.010wt%, the balance is Fe and unavoidable impurities; The composite rare earth alloy comprises the following components in percentage by weight: RE: 70-82wt%, Al: 7-12wt%, Si: 5-8wt%, Ca: 6-10wt%; The RE component in the composite rare earth alloy includes the following components in percentage by mass: 45wt%~55wt% Ce, 25wt%~30wt% La, 15wt%~30wt% Y; The Fe is composed of iron ore and scrap steel, wherein the iron ore accounts for 20-55wt% of the total mass of Fe, and the rest is scrap steel.

[0010] The present invention adds yttrium (Y) to the steel bar. The addition of yttrium can improve the strength and hardness of the steel bar and enhance its bearing capacity. Yttrium has good corrosion resistance. The addition of yttrium can improve the durability of the steel bar in a moist or corrosive environment and extend the service life. Yttrium compounds have good oxidation resistance, which helps to reduce oxidation damage to the steel bar in a high temperature environment. The addition of yttrium can improve the toughness of the steel bar, reduce brittleness, and improve the performance of the material under dynamic loads. Yttrium can improve the welding performance of steel, reduce cracks and defects during welding, and make the welded joints stronger. Under high temperature conditions, the presence of yttrium can improve the stability and strength of the steel bar, which is suitable for structures used in high temperature applications.

[0011] Cerium (Ce) added to steel bars can refine grains and optimize inclusion morphology, thereby improving the plasticity and toughness of steel. Cerium can also form a dense protective film on the steel surface, significantly improving the corrosion resistance of steel in high temperature and acidic environments.

[0012] Lanthanum (La) can inhibit grain growth. Adding lanthanum to steel bars makes the structure more uniform, which helps improve the overall performance of steel. Lanthanum can also improve the morphology of inclusions, thereby improving plasticity and toughness, while forming a protective film to enhance corrosion resistance, especially in acidic and seawater environments.

[0013] The present invention also provides a method for preparing rare earth modified high-strength corrosion-resistant steel bars, comprising the following steps: S1. Smelting process: mixing raw materials according to mass percentage; smelting the raw materials in an electric furnace, supplying oxygen and adding slag-forming agent during the smelting process; adding a composite deoxidizer at the beginning of steel tapping; tapping when there is no slag at the eccentric furnace bottom, and then alloying; when the tapping amount reaches 1 / 5 of the total mass of the molten steel, starting to add the composite rare earth alloy, when the tapping amount reaches 2 / 3 of the total mass of the molten steel, all the composite rare earth alloys are added; controlling the temperature of the molten steel at the time of tapping to be 1630~1650℃, the carbon content in the molten steel to be 0.07wt%~0.10wt%, and the phosphorus content ≤0.030wt%; S2. Refining and reduction: LF furnace refining is adopted, the binary basicity CaO / SiO2 ratio of slag is 3.5~5.0, T.Fe in slag is ≤0.5wt%; the tapping temperature of LF furnace is 1650℃~1690℃, the sulfur content in the final molten steel is 0.002wt%~0.004wt%, and the oxygen content is 0.003wt%~0.005wt%; S3, continuous casting: using a continuous casting furnace to pour molten metal into a continuous casting mold, and using an arc-shaped billet continuous casting machine to produce steel billets; S4, heating treatment: using a walking beam heating furnace to heat the continuous casting billet in three stages, the heating temperature of the first stage is lower than that of the second stage, and the heating temperature of the second stage is lower than that of the third stage; and S5. Rolling process.

[0014] Based on the above technical solution, the present invention can also be improved as follows.

[0015] Furthermore, in step S5, the starting rolling temperature is 1050-1200°C, 6 rolling passes are adopted, the deformation of the first four rolling passes is >40%, the final rolling temperature is 980-1150°C, and the rolled steel bars are air-cooled after rolling is completed.

[0016] Furthermore, the main components of the slag-forming agent are lime and light-burned dolomite, or / and the main components of the composite deoxidizer are composite rare earth alloy and calcium-aluminum alloy.

[0017] Furthermore, the calcium aluminum alloy includes metal calcium powder, metal aluminum powder and core material, the metal calcium powder accounts for 55wt%-65wt% of the weight of the calcium aluminum alloy, and the metal aluminum powder accounts for 45wt%-35wt% of the weight of the core material.

[0018] Furthermore, in step S2, during LF refining, argon gas is blown into the bottom of the LF furnace, with an argon gas flow rate of 12-20 NL / min and a blowing time of 10-18 minutes.

[0019] Furthermore, in step S3, the superheat degree of the casting process is 1632° C., and / or the continuous casting speed is controlled to be 2.0-2.6 m / min.

[0020] Furthermore, in step S3, an argon sealing protection casting technology is adopted in combination with an argon blowing process, and the argon flow rate is 7-22 NL / min.

[0021] Furthermore, in step S3, the temperature of the continuous casting furnace is 1570-1620° C., or / and the continuous casting furnace adopts electromagnetic stirring and automatic control of the crystallizer liquid level.

[0022] Furthermore, the crystallizer water flow rate is controlled to be 135~150m 3 / h; or / and adopt secondary cooling dynamic water distribution and aerosol cooling process, the water volume of the secondary cooling zone is 14~16m 3 / h, one roller water volume is 9.5~11m 3 / h, the water volume of the second roller is 17.5~19m 3 / h, three-roller water volume is 4~6m 3 / h.

[0023] Furthermore, in step S4, the heating temperature of the first stage is 830°C to 930°C; the heating temperature of the second stage is 1080°C to 1180°C, and the heating temperature of the third stage is 1150°C to 1250°C.

[0024] Furthermore, in step S4, the first heating period is 45 to 100 minutes, the second heating period is 45 to 70 minutes, and the third heating period is 30 to 80 minutes.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects: The present invention adds a composite rare earth alloy (especially rare earth elements such as yttrium, cerium and lanthanum) to the steel bar, which can significantly improve the corrosion resistance of the steel bar, especially in the marine environment, and can effectively resist the erosion of chloride ions. The addition of rare earth elements can improve the microstructure of the steel bar, enhance the strength and toughness of the material, and make the steel bar less prone to fracture or fatigue damage when subjected to external forces. Rare earth elements can improve the weldability of steel, reduce defects and brittleness in welded joints, and improve the reliability of the overall structure. Aluminum and calcium in the composite rare earth alloy can improve the oxidation resistance of the steel bar, especially in high temperature and humid environments, and extend the service life. By using a combination of scrap steel and iron ore, the waste of resources in the production process can be effectively reduced, which meets the needs of sustainable development.

[0026] By adding trace rare earth elements (such as cerium, lanthanum, etc.), the morphology of inclusions in steel is improved, and harmful long strip inclusions are transformed into spherical ones, thereby effectively refining the grains and improving the plasticity and toughness of steel. In addition, rare earth elements can form a dense oxide film on the surface of steel to enhance the corrosion resistance of the material. Chromium is the key to improving the corrosion resistance of steel. By adding an appropriate amount of chromium (1.5wt%), a stable passivation film can be formed on the surface of steel, significantly improving the corrosion resistance of steel bars in corrosive environments. At the same time, the solid solution strengthening, precipitation strengthening and fine grain strengthening effects of chromium can effectively improve the strength of steel. Appropriate amounts of carbon, silicon, manganese and other elements are introduced into the alloy composition to ensure the strength and toughness of the steel bars. Among them, the carbon content is controlled within 0.10wt% to avoid the decrease in plasticity and corrosion resistance due to excessive carbon content; the introduction of manganese (1.36wt%) and silicon (0.55wt%) helps to improve the strength and deoxidation effect of steel and ensure the comprehensive performance of steel. DETAILED DESCRIPTION

[0027] In order to facilitate understanding of the present application, the present application will be described more comprehensively below. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] A rare earth modified high-strength corrosion-resistant steel bar comprises the following components in percentage by mass: C: 0.07wt%~0.10wt%, Si: 0.30wt%~0.55wt%, Mn: 1.25wt%~1.36wt%, Cr: 1.05wt%~1.65wt%, P≤0.035wt%, S≤0.035wt%, composite rare earth alloy 0.008wt%-0.010wt%, the balance is Fe and unavoidable impurities; The composite rare earth alloy comprises the following components in percentage by weight: RE: 70-82wt%, Al: 7-12wt%, Si: 5-8wt%, Ca: 6-10wt%; The RE component in the composite rare earth alloy includes the following components in percentage by mass: 45wt%~55wt% Ce, 25wt%~30wt% La, 15wt%~30wt% Y; The Fe is composed of iron ore and scrap steel, wherein the iron ore accounts for 20-55wt% of the total mass of Fe, and the rest is scrap steel.

[0030] The present invention also provides a method for preparing rare earth modified high-strength corrosion-resistant steel bars, comprising the following steps: S1. Smelting process: mixing raw materials according to mass percentage; smelting the raw materials in an electric furnace, supplying oxygen and adding slag-forming agent during the smelting process; adding a composite deoxidizer at the beginning of steel tapping; tapping when there is no slag at the eccentric furnace bottom, and then alloying; when the tapping amount reaches 1 / 5 of the total mass of the molten steel, starting to add the composite rare earth alloy, when the tapping amount reaches 2 / 3 of the total mass of the molten steel, all the composite rare earth alloys are added; controlling the temperature of the molten steel at the time of tapping to be 1630~1650℃, the carbon content in the molten steel to be 0.07wt%~0.10wt%, and the phosphorus content ≤0.030wt%; S2. Refining and reduction: LF furnace refining is adopted, the binary basicity CaO / SiO2 ratio of slag is 3.5~5.0, T.Fe in slag is ≤0.5wt%; the tapping temperature of LF furnace is 1650℃~1690℃, the sulfur content in the final molten steel is 0.002wt%~0.004wt%, and the oxygen content is 0.003wt%~0.005wt%; S3, continuous casting: using a continuous casting furnace to pour molten metal into a continuous casting mold, and using an arc-shaped billet continuous casting machine to produce steel billets; S4, heating treatment: using a walking beam heating furnace to heat the continuous casting billet in three stages, the heating temperature of the first stage is lower than that of the second stage, and the heating temperature of the second stage is lower than that of the third stage; and S5. Rolling process.

[0031] Based on the above technical solution, the present invention can also be improved as follows.

[0032] Furthermore, in step S5, the starting rolling temperature is 1050-1200°C, 6 rolling passes are adopted, the deformation of the first four rolling passes is >40%, the final rolling temperature is 980-1150°C, and the rolled steel bars are air-cooled after rolling is completed.

[0033] Furthermore, the main components of the slag-forming agent are lime and light-burned dolomite, or / and the main components of the composite deoxidizer are composite rare earth alloy and calcium-aluminum alloy.

[0034] Furthermore, the calcium aluminum alloy includes metal calcium powder, metal aluminum powder and core material, the metal calcium powder accounts for 55wt%-65wt% of the weight of the calcium aluminum alloy, and the metal aluminum powder accounts for 45wt%-35wt% of the weight of the core material.

[0035] Furthermore, in step S2, during LF refining, argon gas is blown into the bottom of the LF furnace, with an argon gas flow rate of 12-20 NL / min and a blowing time of 10-18 minutes.

[0036] Furthermore, in step S3, the superheat degree of the casting process is 1632° C., and / or the continuous casting speed is controlled to be 2.0-2.6 m / min.

[0037] Furthermore, in step S3, an argon sealing protection casting technology is adopted in combination with an argon blowing process, and the argon flow rate is 7-22 NL / min.

[0038] Furthermore, in step S3, the temperature of the continuous casting furnace is 1570-1620° C., or / and the continuous casting furnace adopts electromagnetic stirring and automatic control of the crystallizer liquid level.

[0039] Furthermore, the crystallizer water flow rate is controlled to be 135~150m 3 / h; or / and adopt secondary cooling dynamic water distribution and aerosol cooling process, the water volume of the secondary cooling zone is 14~16m 3 / h, one roller water volume is 9.5~11m 3 / h, the water volume of the second roller is 17.5~19m 3 / h, three-roller water volume is 4~6m 3 / h.

[0040] Furthermore, in step S4, the heating temperature of the first stage is 830°C to 930°C; the heating temperature of the second stage is 1080°C to 1180°C, and the heating temperature of the third stage is 1150°C to 1250°C.

[0041] Furthermore, in step S4, the first heating period is 45 to 100 minutes, the second heating period is 45 to 70 minutes, and the third heating period is 30 to 80 minutes.

[0042] Example 1 A rare earth modified high-strength corrosion-resistant steel bar comprises the following components in percentage by mass: C: 0.07wt%, Si: 0.30wt%, Mn: 1.25wt%, Cr: 1.05wt%, P≤0.035wt%, S≤0.035wt%, composite rare earth alloy 0.008wt%, the balance is Fe and unavoidable impurities; The composite rare earth alloy comprises the following components in percentage by weight: RE: 82wt%, Al: 7wt%, Si: 5wt%, Ca: 6wt%; The RE component in the composite rare earth alloy includes the following components in percentage by mass: 55wt% Ce, 25wt% La, and 20wt% Y; The Fe is composed of iron ore and scrap steel, wherein the iron ore accounts for 20wt% of the total mass of Fe, and the rest is scrap steel.

[0043] The present invention also provides a method for preparing rare earth modified high-strength corrosion-resistant steel bars, comprising the following steps: S1, smelting process: the raw materials are mixed according to the mass percentage; the raw materials are smelted in an electric furnace, oxygen is supplied and slag-making agent is added during the smelting process; a composite deoxidizer is added at the beginning of steel tapping; steel is tapped when there is no slag at the eccentric furnace bottom, and then alloying treatment is performed; when the amount of steel tapped reaches 1 / 5 of the total mass of the molten steel, the composite rare earth alloy is added, and when the amount of steel tapped reaches 2 / 3 of the total mass of the molten steel, all the composite rare earth alloys are added; the temperature of the molten steel during steel tapping is controlled to be 1630°C, the carbon content in the molten steel is 0.07wt%, and the phosphorus content is ≤0.030wt%; the main components of the slag-making agent are lime and light-burned dolomite, and the main components of the composite deoxidizer are composite rare earth alloy and calcium-aluminum alloy. The calcium-aluminum alloy includes metal calcium powder, metal aluminum powder and core material, the metal calcium powder accounts for 55wt% of the weight percentage of the calcium-aluminum alloy, and the metal aluminum powder accounts for 45wt% of the weight percentage of the core material.

[0044] S2. Refining and reduction: LF furnace refining is adopted, argon is blown into the bottom of LF furnace, the argon flow rate is 12NL / min, and the blowing time is 10 minutes. The binary basicity CaO / SiO2 ratio of slag is 3.5, and T.Fe in slag is ≤0.5wt%; the tapping temperature of LF furnace is 1650℃, and the sulfur content in the final molten steel is 0.002wt%, and the oxygen content is 0.003wt%.

[0045] S3, continuous casting: the molten metal is poured into a continuous casting mold by a continuous casting furnace, and the billet is produced by an arc-shaped billet continuous casting machine. The superheat degree of the casting process is 1632°C, or / and the continuous casting speed is controlled at 2.0m / min, and the argon sealing protection casting technology is adopted, with the argon blowing process, and the argon flow rate is 7NL / min. The temperature of the continuous casting furnace is 1570°C, or / and the continuous casting furnace adopts electromagnetic stirring and automatic control of the crystallizer liquid level.

[0046] S4, heating treatment: the continuous casting billet is heated in three stages by a walking beam heating furnace, the heating temperature of the first stage is lower than that of the second stage, and the heating temperature of the second stage is lower than that of the third stage; the heating temperature of the first stage is 830°C; the heating temperature of the second stage is 1080°C, and the heating temperature of the third stage is 1150°C. The heating time of the first stage is 45 minutes, the second stage is 45 minutes, and the third stage is 30 minutes.

[0047] S5, rolling process, starting rolling temperature 1050 ℃, 6-pass rolling, the first four rolling deformation > 40%, final rolling temperature 980 ℃, after rolling is completed, the rolled steel bars are air-cooled.

[0048] Example 2 A rare earth modified high-strength corrosion-resistant steel bar comprises the following components in percentage by mass: C: 0.09wt%, Si: 0.45wt%, Mn: 1.31wt%, Cr: 1.35wt%, P≤0.035wt%, S≤0.035wt%, composite rare earth alloy 0.009wt%, the balance is Fe and unavoidable impurities; The composite rare earth alloy comprises the following components in percentage by weight: RE: 77wt%, Al: 7wt%, Si: 8wt%, Ca: 8wt%; The RE component in the composite rare earth alloy includes the following components in percentage by mass: 50wt% Ce, 30wt% La, and 20wt% Y; The Fe is composed of iron ore and scrap steel, wherein the iron ore accounts for 35wt% of the total mass of Fe, and the rest is scrap steel.

[0049] The present invention also provides a method for preparing rare earth modified high-strength corrosion-resistant steel bars, comprising the following steps: S1, smelting process: the raw materials are mixed according to the mass percentage; the raw materials are smelted in an electric furnace, oxygen is supplied and slag-forming agent is added during the smelting process; a composite deoxidizer is added at the beginning of steel tapping; steel is tapped when there is no slag at the eccentric furnace bottom, and then alloying treatment is performed; when the amount of steel tapped reaches 1 / 5 of the total mass of the molten steel, the composite rare earth alloy is added, and when the amount of steel tapped reaches 2 / 3 of the total mass of the molten steel, all the composite rare earth alloys are added; the temperature of the molten steel during steel tapping is controlled to be 1640°C, the carbon content in the molten steel is 0.09wt%, and the phosphorus content is ≤0.030wt%; the main components of the slag-forming agent are lime and light-burned dolomite, or / and the main components of the composite deoxidizer are composite rare earth alloy and calcium-aluminum alloy. The calcium-aluminum alloy includes metal calcium powder, metal aluminum powder and core material, the metal calcium powder accounts for 60wt% of the weight percentage of the calcium-aluminum alloy, and the metal aluminum powder accounts for 40wt% of the weight percentage of the core material.

[0050] S2. Refining and reduction: LF furnace refining is adopted, argon is blown into the bottom of LF furnace, the argon flow rate is 16NL / min, and the blowing time is 13 minutes. The binary basicity CaO / SiO2 ratio of slag is 4.0, and T.Fe in slag is ≤0.5wt%; the tapping temperature of LF furnace is 1670℃, and the sulfur content in the final molten steel is 0.003wt%, and the oxygen content is 0.004wt%.

[0051] S3, continuous casting: a continuous casting furnace is used to pour the molten metal into a continuous casting mold, and an arc-shaped billet continuous casting machine is used to produce steel billets. The superheat degree of the casting process is 1632°C, or / and the continuous casting speed is controlled at 2.4m / min, and the argon sealing protection casting technology is used, combined with the argon blowing process, and the argon flow rate is 16NL / min. The temperature of the continuous casting furnace is 1600°C, or / and the continuous casting furnace adopts electromagnetic stirring and automatic control of the crystallizer liquid level.

[0052] S4, heating treatment: the continuous casting billet is heated in three stages by a walking beam heating furnace, the heating temperature of the first stage is lower than that of the second stage, and the heating temperature of the second stage is lower than that of the third stage; the heating temperature of the first stage is 900°C; the heating temperature of the second stage is 1150°C, and the heating temperature of the third stage is 1200°C. The heating time of the first stage is 65 minutes, the second stage is 60 minutes, and the third stage is 60 minutes.

[0053] S5, rolling process, starting rolling temperature 1150 ℃, 6 rolling passes, the first four rolling deformation > 40%, final rolling temperature 1100 ℃, after rolling is completed, the rolled steel bars are air-cooled.

[0054] Example 3 A rare earth modified high-strength corrosion-resistant steel bar comprises the following components in percentage by mass: C: 0.10wt%, Si: 0.55wt%, Mn: 1.36wt%, Cr: 1.65wt%, P≤0.035wt%, S≤0.035wt%, composite rare earth alloy 0.010wt%, the balance is Fe and unavoidable impurities; The composite rare earth alloy comprises the following components in percentage by weight: RE: 70wt%, Al: 12wt%, Si: 8wt%, Ca: 10wt%; The RE component in the composite rare earth alloy includes the following components in mass percentage: 45 wt% Ce, 30 wt% La, and 25 wt% Y; The Fe is composed of iron ore and scrap steel, wherein the iron ore accounts for 55wt% of the total mass of Fe, and the rest is scrap steel.

[0055] The present invention also provides a method for preparing rare earth modified high-strength corrosion-resistant steel bars, comprising the following steps: S1, smelting process: the raw materials are mixed according to the mass percentage; the raw materials are smelted in an electric furnace, oxygen is supplied and slag-forming agent is added during the smelting process; a composite deoxidizer is added at the beginning of steel tapping; steel is tapped when there is no slag at the eccentric furnace bottom, and then alloying treatment is performed; when the amount of steel tapped reaches 1 / 5 of the total mass of the molten steel, the composite rare earth alloy is added, and when the amount of steel tapped reaches 2 / 3 of the total mass of the molten steel, all the composite rare earth alloys are added; the temperature of the molten steel during steel tapping is controlled to be 1650°C, the carbon content in the molten steel is 0.10wt%, and the phosphorus content is ≤0.030wt%; the main components of the slag-forming agent are lime and light-burned dolomite, or / and the main components of the composite deoxidizer are composite rare earth alloy and calcium-aluminum alloy. The calcium-aluminum alloy includes metal calcium powder, metal aluminum powder and core material, the metal calcium powder accounts for 65wt% of the weight percentage of the calcium-aluminum alloy, and the metal aluminum powder accounts for 35wt% of the weight percentage of the core material.

[0056] S2. Refining and reduction: LF furnace refining is adopted, argon is blown into the bottom of LF furnace, the argon flow rate is 20NL / min, and the blowing time is 18 minutes. The binary basicity CaO / SiO2 ratio of slag is 5.0, and T.Fe in slag is ≤0.5wt%; the tapping temperature of LF furnace is 1690℃, and the sulfur content in the final molten steel is 0.004wt%, and the oxygen content is 0.005wt%.

[0057] S3, continuous casting: the molten metal is poured into a continuous casting mold by a continuous casting furnace, and the billet is produced by an arc-shaped billet continuous casting machine. The superheat degree of the casting process is 1632℃, or / and the continuous casting speed is controlled at 2.6m / min, and the argon sealing protection casting technology is adopted, combined with the argon blowing process, and the argon flow rate is 22NL / min. The temperature of the continuous casting furnace is 1620℃, or / and the continuous casting furnace adopts electromagnetic stirring and automatic control of the crystallizer liquid level.

[0058] S4, heating treatment: the continuous casting billet is heated in three stages by a walking beam heating furnace, the heating temperature of the first stage is lower than that of the second stage, and the heating temperature of the second stage is lower than that of the third stage; the heating temperature of the first stage is 930°C; the heating temperature of the second stage is 1180°C, and the heating temperature of the third stage is 1250°C. The heating time of the first stage is 100 minutes, the second stage is 70 minutes, and the third stage is 80 minutes.

[0059] S5, rolling process, starting rolling temperature 1200 ℃, 6 rolling passes, the first four rolling deformation > 40%, final rolling temperature 1150 ℃, after rolling is completed, the rolled steel bars are air-cooled. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A rare earth modified high strength corrosion resistant steel bar, characterized in that: Includes the following components in percentage by mass: C: 0.07wt%~0.10wt%, Si: 0.30wt%~0.55wt%, Mn: 1.25wt%~1.36wt%, Cr: 1.05wt%~1.65wt%, P≤0.035wt%, S≤0.035wt%, composite rare earth alloy 0.008wt%-0.010wt%, the balance is Fe and unavoidable impurities; The composite rare earth alloy comprises the following components in percentage by weight: RE: 70-82wt%, Al: 7-12wt%, Si: 5-8wt%, Ca: 6-10wt%; The RE component in the composite rare earth alloy includes the following components in percentage by mass: 45wt%~55wt% Ce, 25wt%~30wt% La, 15wt%~30wt% Y; The Fe is composed of iron ore and scrap steel, wherein the iron ore accounts for 20-55wt% of the total mass of Fe, and the rest is scrap steel.

2. The method for preparing a rare earth modified high-strength corrosion-resistant steel bar according to claim 1, characterized in that: The following steps are included: S1. Smelting process: mixing raw materials according to mass percentage; smelting the raw materials in an electric furnace, supplying oxygen and adding slag-forming agent during the smelting process; adding a composite deoxidizer at the beginning of steel tapping; tapping when there is no slag at the eccentric furnace bottom, and then alloying; when the tapping amount reaches 1 / 5 of the total mass of the molten steel, starting to add the composite rare earth alloy, when the tapping amount reaches 2 / 3 of the total mass of the molten steel, all the composite rare earth alloys are added; controlling the temperature of the molten steel at the time of tapping to be 1630~1650℃, the carbon content in the molten steel to be 0.07wt%~0.10wt%, and the phosphorus content ≤0.030wt%; S2. Refining and reduction: LF furnace refining is adopted, the binary basicity CaO / SiO2 ratio of slag is 3.5~5.0, T.Fe in slag is ≤0.5wt%; the tapping temperature of LF furnace is 1650℃~1690℃, the sulfur content in the final molten steel is 0.002wt%~0.004wt%, and the oxygen content is 0.003wt%~0.005wt%; S3, continuous casting: using a continuous casting furnace to pour molten metal into a continuous casting mold, and using an arc-shaped billet continuous casting machine to produce steel billets; S4, heating treatment: using a walking beam heating furnace to heat the continuous casting billet in three stages, the heating temperature of the first stage is lower than that of the second stage, and the heating temperature of the second stage is lower than that of the third stage; and S5. Rolling process.

3. The preparation method according to claim 2, characterized in that: In step S5, the starting rolling temperature is 1050-1200°C, 6 rolling passes are adopted, the deformation of the first four rolling passes is >40wt%, the final rolling temperature is 980-1150°C, and the rolled steel bars are air-cooled after rolling is completed.

4. The preparation method according to claim 2, characterized in that: The main components of the slag-forming agent are lime and light-burned dolomite, or / and the main components of the composite deoxidizer are composite rare earth alloy and calcium-aluminum alloy.

5. The preparation method according to claim 4, characterized in that: The calcium aluminum alloy comprises metal calcium powder, metal aluminum powder and core material, wherein the metal calcium powder accounts for 55wt%-65wt% of the weight of the calcium aluminum alloy, and the metal aluminum powder accounts for 45wt%-35wt% of the weight of the core material.

6. The preparation method according to claim 2, characterized in that: In step S2, during LF refining, argon gas is blown into the bottom of the LF furnace at a flow rate of 12 to 20 NL / min for a blowing time of 10 to 18 minutes.

7. The preparation method according to claim 3, characterized in that: In step S3, the superheat degree of the casting process is 1632° C., and / or the continuous casting speed is controlled to be 2.0-2.6 m / min.

8. The preparation method according to claim 3, characterized in that: In step S3, an argon sealing protection casting technology is adopted, in combination with an argon blowing process, with an argon gas flow rate of 7-22 NL / min.

9. The preparation method according to claim 3, characterized in that: In step S3, the temperature of the continuous casting furnace is 1570-1620° C., or / and the continuous casting furnace adopts electromagnetic stirring and automatic control of the crystallizer liquid level.