WO2024090727A1 - Hot rolled steel sheet, part for vehicle, and method for manufacturing same - Google Patents

Hot rolled steel sheet, part for vehicle, and method for manufacturing same Download PDF

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WO2024090727A1
WO2024090727A1 PCT/KR2023/010559 KR2023010559W WO2024090727A1 WO 2024090727 A1 WO2024090727 A1 WO 2024090727A1 KR 2023010559 W KR2023010559 W KR 2023010559W WO 2024090727 A1 WO2024090727 A1 WO 2024090727A1
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Prior art keywords
weight
rolled steel
hot rolled
iron
content ratio
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PCT/KR2023/010559
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French (fr)
Korean (ko)
Inventor
강동훈
황성두
권순환
이수민
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현대제철 주식회사
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Publication of WO2024090727A1 publication Critical patent/WO2024090727A1/en

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • 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
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to hot rolled steel sheets, vehicle parts, and methods for manufacturing the same.
  • methods for manufacturing steel include the blast furnace-converter process and the electric furnace process.
  • the blast furnace-converter process is a process of charging iron ore and bituminous coal (e.g., coke) into a blast furnace and melting them with hot air to produce molten iron, and charging molten iron from the blast furnace into a converter to remove impurities such as carbon to produce molten steel. Includes process.
  • iron ore and bituminous coal e.g., coke
  • the electric furnace process includes manufacturing molten steel by melting iron scrap (STEEL SCRAP) in an electric arc furnace (ELECTRIC ARC FURNACE; EAF).
  • Molten steel manufactured by the two methods described above is made into a semi-finished product through a continuous casting process, and the semi-finished product is made into a final product with dimensions suitable for the needs of the consumer through a subsequent rolling process.
  • Carbon dioxide is a representative greenhouse gas.
  • the steel industry is known as an industry with a high proportion of carbon dioxide emissions among other industrial fields.
  • the blast furnace-converter process emits a large amount of carbon dioxide because it uses carbon monoxide (CO) generated by combustion of coke as a reducing agent.
  • CO carbon monoxide
  • Tramp elements refer to impure alloy elements that exist in trace amounts in steel products.
  • tramp elements are not easily dissolved in iron, the base material, and tend to accumulate at the interface. Accordingly, if the tramp element is above the allowable value, cracks may occur on the surface and inside during rolling. Additionally, tramp elements can act as a major factor in hot embrittlement, which significantly reduces ductility at high temperatures.
  • electric furnace products generally have limitations in being applied to high-quality steel materials such as automobile steel plates that require high surface quality characteristics.
  • the purpose of the present invention is to provide a hot rolled steel sheet, vehicle parts, and a method of manufacturing the same that can reduce carbon dioxide emissions generated in the blast furnace-converter process.
  • the purpose of the present invention is to provide a hot rolled steel sheet, vehicle parts, and a method for manufacturing the same using an electric furnace having superior physical properties than existing electric furnace products.
  • the purpose of the present invention is to provide a hot rolled steel sheet, vehicle parts, and a method of manufacturing the same with flexibility in raw material selection by minimizing the impact on the supply and demand of specific raw materials.
  • a method of manufacturing a hot-rolled steel sheet according to an embodiment of the present invention includes manufacturing a molten metal, manufacturing a semi-finished product, and manufacturing a hot-rolled steel sheet.
  • the raw materials of the molten metal include molten pig iron satisfies Equation 1 and Equation 2.
  • Equation 1 a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap.
  • X + Y + Z 100.
  • Equation 1 a1 ⁇ 0.03, a2 ⁇ 0.02, and a3 ⁇ 0.18.
  • the hot rolled steel sheet contains tin (Sn) of K2 wt% or less, and X, Y, Z, and K2 satisfy Equations 3 and 4.
  • Equation 3 b1, b2, and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap.
  • 10 ⁇ Y ⁇ 40 10 ⁇ Y ⁇ 40.
  • the raw material in the step of producing the molten metal, may be melted using an electric furnace.
  • the hot rolled steel sheet contains, on a weight percent basis, carbon: 0.07 to 0.12%, silicon: 0.3 to 0.8%, manganese: 1.5 to 2.0%, phosphorus: 0.02% or less, sulfur: 0.005% or less, Copper: 0.12% or less (excluding 0), Tin: 0.012% or less (excluding 0), including the balance iron (Fe) and inevitable impurities.
  • the hot-rolled steel sheet is manufactured by melting molten iron X weight%, direct reduced iron Y weight%, and iron scrap Z weight%, and X, Y, and Z satisfy Equation 1.
  • Equation 1 a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap.
  • X + Y + Z 100.
  • X, Y and Z satisfy Equation 2.
  • Equation 2 b1, b2, and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap.
  • 20 ⁇ X ⁇ 60, 10 ⁇ Y ⁇ 40, and 20 ⁇ Z ⁇ 60 20 ⁇ X ⁇ 60, 10 ⁇ Y ⁇ 40, and 20 ⁇ Z ⁇ 60.
  • the hot rolled steel sheet may further include one or more elements selected from chromium (Cr), niobium (Nb), titanium (Ti), and boron (B).
  • Vehicle parts according to an embodiment of the present invention contain, on a weight percent basis, carbon: 0.07 to 0.12%, silicon: 0.3 to 0.8%, manganese: 1.5 to 2.0%, phosphorus: 0.02% or less, sulfur: 0.005% or less, copper : 0.12% or less (excluding 0), Tin: 0.012% or less (excluding 0), including remaining iron (Fe) and inevitable impurities.
  • the base material of the vehicle parts is manufactured by dissolving molten iron X weight %, direct reduced iron Y weight %, and iron scrap Z weight %, and the
  • Equation 1 a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap, a1 ⁇ 0.03, a2 ⁇ 0.02, a3 ⁇ 0.18.
  • X + Y + Z 100.
  • X, Y, and Z satisfy Equation 2.
  • Equation 2 b1, b2 and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap, b1 ⁇ 0.003, b2 ⁇ 0.002, b3 ⁇ 0.018.
  • 20 ⁇ X ⁇ 60, 10 ⁇ Y ⁇ 40, and 20 ⁇ Z ⁇ 60 20 ⁇ X ⁇ 60, 10 ⁇ Y ⁇ 40, and 20 ⁇ Z ⁇ 60.
  • the amount of carbon dioxide generated during manufacturing steel products can be significantly reduced by significantly reducing the amount of molten iron used compared to the existing blast furnace-converter process.
  • an electric furnace product with excellent physical properties can be produced by controlling the content of tramp elements within an acceptable range compared to existing electric furnace products.
  • the addition content ratio of molten pig iron, direct reduced iron, and iron scrap can be adjusted within a preset range, so that it is possible to flexibly respond even if a problem occurs in the supply and demand of specific raw materials.
  • FIG. 1 is a flowchart showing a method of manufacturing a hot rolled steel sheet according to an embodiment of the present invention.
  • Figure 2 is a flowchart showing in detail the steps for manufacturing molten metal in the flowchart of Figure 1.
  • Figure 3 is a photographic representation showing the bending test evaluation results of Comparative Example 3 and Example 6 shown in Table 2.
  • Figure 4 is a photographic diagram showing the pretreatment characteristic evaluation results of Comparative Example 3 and Example 6 shown in Table 2.
  • Figure 5 is a diagram for explaining a method of evaluating adhesion among the paintability evaluations shown in Table 2.
  • Figure 6 is a diagram instead of a photograph showing the state after impact resistance evaluation of Example 6 shown in Table 2.
  • Figure 7 is a photographic diagram showing the state after weldability evaluation of Comparative Example 1, Comparative Example 3, and Example 6 shown in Table 2.
  • Figure 8 is a diagram instead of a photograph showing the wire processability of Example 6 shown in Table 3 after evaluation.
  • first, second, and third are used to describe various components, regions, parts, or layers, but are not limited thereto. These terms are used to distinguish one component, region, portion or layer from another component, portion or layer.
  • one part is “on” or “on” another part is not limited to the case where there is another part directly above the one part, but also includes the case where there is another part between one part and the other part. will be.
  • the hot rolled steel sheet according to an embodiment of the present invention includes iron (Fe), carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), copper (Cu), and tin (Sn). ) includes.
  • the hot rolled steel sheet according to an embodiment of the present invention may further include one or more of aluminum (Al), chromium (Cr), niobium (Nb), titanium (Ti), boron (B), and nitrogen (N).
  • Al aluminum
  • Cr chromium
  • Nb niobium
  • Ti titanium
  • B boron
  • N nitrogen
  • the hot rolled steel sheet according to this embodiment has, on a weight percent basis, carbon (C): 0.07 to 0.12, silicon (Si): 0.3 to 0.8, manganese (Mn): 1.5 to 2.0, and phosphorus (P): 0.02 or less.
  • S Sulfur
  • Aluminum Al: 0.2 to 0.5
  • Copper Cu
  • Tin Sn
  • Chromium Cr
  • Niobium Nb
  • Ti Titanium
  • B Boron
  • Nitrogen N: 0.006 or less, including the balance iron (Fe) and other unavoidably added impurities. can do.
  • Carbon (C) is an essential element for securing the necessary strength.
  • carbon (C) can be added to secure the strength of the bainite structure.
  • carbon (C) can be added to ensure the balance of precipitates.
  • the carbon (C) content may be 0.07% by weight to 0.12% by weight.
  • the carbon (C) content may be about 0.07% by weight to 0.12% by weight, preferably about 0.09% by weight to 0.10% by weight.
  • Silicon (Si) is a solid solution strengthening element.
  • silicon (Si) is a ferrite stabilizing element dissolved in ferrite and can increase strength without deteriorating ductility.
  • Silicon (Si) can improve the elongation of steel sheets by suppressing the formation of carbides.
  • the silicon content may be 0.3% by weight to 0.8% by weight. According to one embodiment of the present invention, the silicon content may be about 0.3% by weight to 0.8% by weight.
  • Manganese improves the strength of steel through strengthening solid solution and improving hardenability. Manganese is an essential ingredient to suppress pearlite transformation and obtain bainite structure.
  • the content of manganese (Mn) may be 1.5% by weight to 2.0% by weight. According to one embodiment of the present invention, the content of manganese (Mn) may be about 1.5% by weight to 2.0% by weight.
  • Sulfur (S) can impair toughness and weldability and increase non-metallic inclusions (sulfur compounds) during hot rolling, thereby impairing the workability of steel. Therefore, in one embodiment of the present invention, the content of sulfur (S) may be 0.005% by weight or less. According to one embodiment of the present invention, the sulfur (S) content may be about 0.005% by weight or less.
  • Phosphorus (P) is an impurity element that promotes grain boundary segregation and high-temperature cracking. Accordingly, in one embodiment of the present invention, the content of phosphorus (P) may be 0.02% by weight or less. According to one embodiment of the present invention, the phosphorus (P) content may be about 0.02% by weight or less.
  • Aluminum (Al) is a representative deoxidizing agent. Aluminum (Al) is added to the converter before or during steel tapping to suppress the generation of pinholes or non-metallic inclusions. Aluminum (Al) combines with nitrogen in steel to form nitride (AlN).
  • AlN, a nitride precipitates at grain boundaries and is effective in refining the grains of steel, thereby improving the toughness of steel.
  • AIN effectively prevents high-temperature oxidation and can prevent cracks when manufacturing slabs.
  • the content of aluminum (Al) may be 0.02% by weight to 0.5% by weight. According to one embodiment of the present invention, the content of aluminum (Al) may be about 0.02% by weight to 0.5% by weight.
  • Copper (Cu) and tin (Sn) can be mixed from iron scrap. Copper (Cu) and tin (Sn) are elements that can hardly be removed during the steelmaking process and correspond to tramp elements. Tramp elements can cause cracks on the surface and inside during rolling. Additionally, tramp elements can act as a major factor in hot embrittlement, which significantly reduces ductility at high temperatures.
  • tin (Sn) inhibits the unevenness of the size of phosphate and the stability of the amount of phosphate adhesion when forming a phosphate film on steel.
  • the content of copper (Cu) and tin (Sn) may be 0.12% by weight or less (excluding 0) and 0.012% by weight or less (excluding 0), respectively. According to one embodiment of the present invention, the content of copper (Cu) and tin (Sn) may be about 0.12% by weight or less (excluding 0) and about 0.012% by weight or less (excluding 0), respectively.
  • Chromium (Cr) is a solid solution strengthening element. Chromium (Cr) can help the formation of martensite and bainite by delaying ferrite transformation.
  • the content of chromium (Cr) may be 0.5% by weight to 1.1% by weight. According to one embodiment of the present invention, the content of chromium (Cr) may be about 0.5% by weight to 1.1% by weight.
  • Niobium (Nb) is effective in improving strength and impact toughness by refining crystal grains.
  • the content of niobium (Nb) may be 0.05% by weight to 0.1% by weight. According to one embodiment of the present invention, the content of niobium (Nb) may be about 0.05% by weight to 0.1% by weight.
  • Titanium (Ti) combines with nitrogen in steel to form nitride (TiN), which can suppress the growth of crystal grains and the production of free nitrogen.
  • TiN nitride
  • TiN nitride
  • the amount of titanium (Ti) added is excessive, excessive precipitates may be formed, which may reduce impact toughness.
  • the amount of titanium (Ti) added is insufficient, the above-described addition effect may be insignificant.
  • the content of titanium (Ti) may be 0.06% by weight to 1.1% by weight. According to one embodiment of the present invention, the content of titanium (Ti) may be about 0.06% by weight to 1.1% by weight.
  • Boron (B) improves strength by suppressing ferrite transformation. However, if the amount of boron (B) added is excessive, weldability and processability may be reduced. Conversely, if the amount of boron (B) added is insufficient, the above-described addition effect may be insufficient.
  • the content of boron (B) may be 0.001% by weight to 0.0035% by weight. According to one embodiment of the present invention, the content of boron (B) may be about 0.001% by weight to 0.0035% by weight.
  • Nitrogen (N) can have a significant impact on the mechanical properties of steel.
  • nitrogen (N) can increase tensile strength and yield strength while decreasing elongation. Additionally, free nitrogen can cause strain aging.
  • the nitrogen (N) content may be 0.006% by weight or less. According to one embodiment of the present invention, the nitrogen (N) content may be 0.006% by weight or less.
  • the balance includes Fe and inevitable impurities.
  • unavoidable impurities they are impurities mixed in during the manufacturing process of hot rolled steel sheets, and since these are widely known in the field, detailed descriptions will be omitted.
  • the addition of elements other than the above-described alloy components is not excluded, and various elements may be included within a range that does not impair the technical spirit of the present invention. If additional elements are included, they are included by replacing the remaining Fe.
  • FIG. 1 is a flowchart showing a method of manufacturing steel according to an embodiment of the present invention.
  • the method of manufacturing steel includes manufacturing a molten metal (S10), manufacturing a semi-finished product (S20), and manufacturing a hot rolled steel sheet (S30).
  • the step of manufacturing molten metal (S10) refers to the step of making molten metal (eg, molten steel) by dissolving raw materials.
  • Raw materials may include ore-based materials and iron scrap.
  • Ore-based materials may include molten iron and direct reduced iron.
  • Molten iron can be manufactured by charging iron ore and coke into a blast furnace and blowing hot air to reduce and melt the iron ore.
  • Directly reduced iron can be manufactured by reducing solid iron ore using a reducing gas (carbon monoxide, hydrogen, etc.).
  • a reducing gas carbon monoxide, hydrogen, etc.
  • direct reduced iron may be Direct Reduction Iron (DRI) or Hot Briquetted Iron (HBI).
  • Directly reduced iron can be processed into pellet form.
  • Steel scrap can be obtained from steelmaking or from unusable steel products.
  • molten iron has a low content of impurities and is suitable for producing high-quality steel products, but there is a problem in that a large amount of carbon dioxide is emitted during the molten iron manufacturing process.
  • the amount of carbon dioxide emitted when producing 1 ton of molten iron is about 2 tons.
  • Electric furnace molten steel is manufactured by melting iron scrap in an electric furnace. Electric furnace molten steel emits less carbon dioxide during the manufacturing process than the blast furnace process. For example, the carbon dioxide emissions of molten steel are about 1/4 of that of molten iron.
  • steel products produced from electric furnace molten steel have a high content of impurities such as tramp elements, making it difficult to satisfy the physical properties required for high-quality steel products such as automobile parts.
  • the step (S10) of manufacturing molten metal according to an embodiment of the present invention is to charge molten iron, direct reduced iron, and iron scrap, which are ore-based materials, into an electric furnace and melt them to manufacture molten metal. do.
  • Figure 2 is a flowchart showing in detail the steps for manufacturing molten metal in the flowchart of Figure 1.
  • the step of manufacturing molten metal (S10) may include preparing raw materials (S11), charging the raw materials (S12), and dissolving the raw materials (S13).
  • molten iron, direct reduced iron, and iron scrap are each prepared according to a preset content ratio.
  • the content ratio of molten pig iron is defined as X, the content ratio of direct reduced iron as Y, and the content ratio of iron scrap as Z.
  • the maximum value of the copper (Cu) content of the hot rolled steel sheet produced in the hot rolling step described later is defined as K1
  • the maximum value of the tin (Sn) content is defined as K2.
  • Each content ratio is based on weight percent.
  • the sum of X + Y + Z may be 100.
  • X, Y, Z, K1, and K2 satisfy Equations 1 to 4 below.
  • Equation 1 a1, a2, and a3 each mean the copper content ratio of molten iron, the copper content ratio of direct reduced iron, and the copper content ratio of iron scrap.
  • Equation 3 b1, b2, and b3 each refer to the tin content ratio of molten iron, the tin content ratio of direct reduced iron, and the tin content ratio of iron scrap.
  • the copper content ratio (a1) of molten iron may be 0.03% by weight (excluding 0) or less.
  • the copper content ratio (a2) of direct reduced iron may be 0.02% by weight (excluding 0) or less.
  • the copper content ratio (a3) of iron scrap may be 0.18% by weight (excluding 0) or less.
  • the copper content ratio (a1) of molten iron may be about 0.03% by weight (excluding 0) or less.
  • the copper content ratio (a2) of direct reduced iron may be about 0.02% by weight (excluding 0) or less.
  • the copper content ratio (a3) of the iron scrap may be about 0.18% by weight (excluding 0) or less.
  • the tin content ratio (b2) of direct reduced iron may be 0.002% by weight (excluding 0) or less.
  • the tin content ratio (b3) of iron scrap may be 0.018% by weight (excluding 0) or less.
  • the tin content ratio (b1) of molten iron may be 0.003% by weight (excluding 0) or less.
  • the tin content ratio (b2) of direct reduced iron may be about 0.002% by weight (excluding 0) or less.
  • the tin content ratio (b3) of iron scrap may be about 0.018% by weight (excluding 0) or less.
  • the tin content ratio (b1) of molten iron may be less than about 0.003% by weight (excluding 0).
  • the copper content ratio (a1, a2, a3) and tin content ratio (b1, b2, b3) depend on the quality of each raw material, It may increase or decrease within a certain range depending on the degree of processing, etc.
  • the effect of reducing carbon dioxide emissions may be insufficient. Conversely, if the molten iron content ratio (X) of molten iron exceeds a preset range, the effect of reducing carbon dioxide emissions may be insufficient. Conversely, if the molten iron content ratio (X) of molten iron exceeds a preset range, the effect of reducing carbon dioxide emissions may be insufficient. Conversely, if the molten iron content ratio (X) of molten iron exceeds a preset range, the effect of reducing carbon dioxide emissions may be insufficient. Conversely, if the molten iron content ratio (X) of molten iron exceeds a preset range, the effect of reducing carbon dioxide emissions may be insufficient. Conversely, if the molten iron content ratio (X) of molten iron exceeds a preset range, the effect of reducing carbon dioxide emissions may be insufficient. Conversely, if the molten iron content ratio (X) of molten iron exceeds a preset range, the effect of reducing carbon dioxide emissions
  • the content ratio (X) of molten iron may be 20% by weight to 60% by weight. According to one embodiment of the present invention, the content ratio (X) of molten iron may be about 20% by weight to 60% by weight.
  • the electric furnace process temperature when the content ratio (Y) of direct reduced iron exceeds a preset range, the electric furnace process temperature must be maintained high as the amount of gangue in the molten metal increases, thereby reducing energy efficiency. In addition, it results in a decrease in refining ability, so a separate design is required to correct slag making during the dephosphorization process.
  • the content ratio (Y) of direct reduced iron is below the preset range, the content ratio of molten iron or iron scrap inevitably increases to replace it.
  • the content ratio of molten iron or iron scrap increases instead of direct reduced iron, it may cause the problem of an increase in the content ratio of tramp elements (i.e., copper or tin).
  • the content ratio (Z) of direct reduced iron may be 20% by weight to 40% by weight. According to one embodiment of the present invention, the content ratio (Y) of direct reduced iron may be about 10% by weight to 40% by weight.
  • the content ratio (Z) of iron scrap exceeds a preset range, the content ratio of tramp elements increases and the required physical properties of the final steel product are not achieved. Conversely, if the content ratio (Z) of iron scrap is less than a preset range, the effect of reducing carbon dioxide emissions may be minimal.
  • the content ratio of iron scrap may be 20 to 60% by weight. According to one embodiment of the present invention, the content ratio of iron scrap may be about 20 to 60% by weight.
  • molten iron, direct reduced iron, and iron scrap are charged into the melting furnace. Charging of each raw material may be performed sequentially or simultaneously.
  • each raw material may be performed multiple times to prevent slag overflow or to achieve an appropriate melting reaction.
  • the step of dissolving the raw materials (S13) may be performed in an electric arc furnace (EAF).
  • EAF electric arc furnace
  • the electric furnace may be an alternating current electric furnace.
  • a direct current electric furnace can also be applied.
  • step S20 of manufacturing semi-finished products semi-finished products such as slabs, blooms, and billets are manufactured using the molten metal manufactured in step S10.
  • step S20 may be performed by a continuous casting process.
  • the continuous casting process is a process of casting and rolling simultaneously while passing molten metal through a plurality of segments arranged in a row to cast a semi-finished product with a predetermined width and thickness.
  • step S20 is not limited to the above.
  • step S20 may include a forging process followed by a continuous casting process. Specifically, it is possible to produce a bloom in a continuous casting process and then manufacture a forged slab with preset dimensions through a forging process.
  • the semi-finished product is reheated, and then the heated semi-finished product is rolled into a hot-rolled steel sheet having a preset thickness and width.
  • the thickness of the hot rolled steel sheet may be 2 to 5 mm.
  • the thickness of the hot rolled steel sheet is not limited to the above.
  • the step of manufacturing a hot rolled steel sheet (S30) includes a reheating step (S31), a hot rolling step (S32), a cooling step (S33), and a winding step (S34).
  • the semi-finished product is reheated in a preset temperature range.
  • the reheating step (S31) can re-dissolve the components segregated in step (S20).
  • the reheating temperature (RT) is lower than the preset temperature range, the re-dissolution efficiency of segregated components decreases, and the bending processability of the final product may deteriorate. Conversely, if the reheating temperature is higher than the preset temperature range, the precipitate may become coarse and the surface quality of the hot rolled steel may deteriorate.
  • the reheating temperature is limited to the range of 1150°C to 1350°C. In one embodiment of the present invention, the reheating temperature is limited to a range of about 1150°C to 1350°C.
  • the reheated semi-finished product is hot rolled. If the finishing delivery temperature (FDT) is lower than the preset range in step S32, problems such as mixed structure due to abnormal rolling may occur. Conversely, if the finish rolling temperature exceeds the preset range, the crystal grains of the hot rolled steel sheet may be formed coarsely, causing a decrease in the physical properties of the final product.
  • FDT finishing delivery temperature
  • the finish rolling temperature is limited to the range of 880°C to 930°C. According to one embodiment of the present invention, the finish rolling temperature is limited to a range of about 880°C to 930°C.
  • the hot rolled steel sheet is cooled. If the cooling rate is less than a preset range in step S33, a ferrite structure may be formed instead of a bainite structure. Conversely, if the cooling rate exceeds the preset range, the transformation of martensite structure instead of bainitic structure is activated, which may reduce machinability.
  • the cooling rate is limited to the range of 60 °C/sec to 110 °C/sec. According to one embodiment of the present invention, the cooling rate is limited to a range of about 60 °C/sec to 110 °C/sec.
  • step (S34) the cooled hot rolled steel sheet is wound into a coil shape. If the winding temperature in step S34 is below the preset range, winding may not be easy. Conversely, if the coiling temperature is above the preset range, surface scale may form even inside the hot rolled steel sheet.
  • the coiling temperature is limited to the range of 380°C to 480°C. According to one embodiment of the present invention, the coiling temperature is limited to a range of about 380°C to 480°C.
  • the amount of carbon dioxide generated during manufacturing steel products can be significantly reduced by significantly reducing the amount of molten iron used compared to the existing blast furnace-converter process.
  • an electric furnace product with excellent physical properties can be produced by controlling the content of tramp elements within an acceptable range compared to existing electric furnace products.
  • the addition content ratio of molten pig iron, direct reduced iron, and iron scrap can be adjusted within a preset range, so that it is possible to flexibly respond even if a problem occurs in the supply and demand of specific raw materials.
  • Examples 1 to 6 are experimental examples that satisfy the raw material content ratio according to the embodiment of the present invention, and Comparative Examples 1 to 4 are experimental examples that deviate from the raw material content ratio.
  • the examples and comparative examples differ only in the content ratio of raw materials (molten iron, direct reduced iron, and iron scrap), and all other conditions (eg, process conditions) are the same.
  • the maximum values of the copper content ratio (K1) of the hot rolled steel sheets according to Examples 1 to 6 were 0.12 or less, but the maximum values of the copper content ratio (K1) of the hot rolled steel sheets according to Comparative Examples 1 to 4 were 0.12 or more. It was.
  • the maximum values of the tin content ratio (K2) of the hot-rolled steel sheets according to Examples 1 to 6 were 0.012 or less, but the maximum values of the tin content ratio (K2) of the hot-rolled steel sheets according to Comparative Examples 1 to 4 were 0.012 or more.
  • Table 2 below shows product characteristics of hot rolled steel sheets according to Examples 1 to 6 and Comparative Examples 1 to 4 shown in Table 1.
  • the pretreatment characteristics were evaluated for appearance, film weight, and crystal grain size after phosphate (zinc phosphate) chemical conversion coating treatment on the surface of the hot rolled steel sheet.
  • the appropriate range for the film weight is 1.8 to 3.0 g/m2
  • the appropriate range for the crystal particles is 2 to 10 ⁇ m.
  • the hot rolled steel sheets according to Examples 1 to 6 and Comparative Examples 3 to 4 showed “good” in the bending test.
  • the hot rolled steel sheets according to Comparative Examples 1 and 2 showed “defects” due to microcracks occurring.
  • the hot rolled steel sheets according to Examples 1 to 6 showed “good” in the pretreatment characteristic evaluation.
  • the hot rolled steel sheets according to Comparative Examples 1 to 4 showed “defect” in pretreatment characteristic evaluation.
  • the hot rolled steel sheets according to Examples 1 to 6 showed an M-1 grade (good) in the adhesion evaluation.
  • the hot rolled steel sheets according to Comparative Examples 1 to 4 showed a grade of M-3 (poor) or M-2 (poor) in the adhesion evaluation.
  • the hot rolled steel sheets according to the embodiments of the present invention showed excellent characteristics in all bending test evaluations, pretreatment characteristic evaluations, paintability evaluations, and weldability evaluations, but the hot rolled steel sheets according to the comparative examples had at least one of the above evaluation items. A defect occurred in the above situation.
  • Vehicle parts according to the present invention are manufactured using hot rolled steel sheets according to the above-described embodiments of the present invention.
  • the vehicle part may be a lower arm.
  • hot rolled steel sheets can be used to manufacture commercial vehicle frames, special purpose vehicle parts, and passenger car parts.
  • Table 3 shows the evaluation of punch machinability and wire machinability of lower arms manufactured by processing hot rolled steel sheets according to Examples 1 to 6 and Comparative Examples 1 to 4 shown in Table 1.
  • Figure 8 is a diagram for explaining the evaluation results in Table 3.
  • the lower arms according to Examples 1 to 6 and Comparative Examples 3 to 4 showed “good” in the punch machinability evaluation and wire machinability evaluation.
  • the lower arms according to Comparative Examples 1 and 2 showed “defect” in the machinability evaluation and wire machinability evaluation.

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Abstract

A method for manufacturing a hot rolled steel sheet according to an embodiment of the present invention comprises the steps of: manufacturing a molten metal; manufacturing a semi-finished product; and manufacturing a hot rolled steel sheet. A raw material of the molten metal comprises X wt% of molten iron, Y wt% of direct reduced iron, and Z wt% of iron scrap, the hot rolled steel sheet comprises K1 wt% or less of copper (Cu), and X, Y, Z, and K1 satisfy formula 1 and formula 2. [Formula 1] (a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) = K1 [Formula 2] K1 ≤ 0.12

Description

열연 강판, 차량용 부품 및 이를 제조하는 방법Hot rolled steel sheets, vehicle parts, and methods for manufacturing the same
본 발명은 열연 강판, 차량용 부품 및 이를 제조하는 방법에 관한 것이다.The present invention relates to hot rolled steel sheets, vehicle parts, and methods for manufacturing the same.
일반적으로 강을 제조하는 방법에는 고로-전로 공정과 전기로 공정이 있다. Generally, methods for manufacturing steel include the blast furnace-converter process and the electric furnace process.
고로-전로 공정은 고로(高爐)에 철광석과 유연탄(예컨대, 코크스)을 장입하고 열풍으로 녹여 용선을 제조하는 공정과 고로에서 출선된 용선을 전로에 장입하여 탄소 등 불순물을 제거하여 용강을 제조하는 공정을 포함한다.The blast furnace-converter process is a process of charging iron ore and bituminous coal (e.g., coke) into a blast furnace and melting them with hot air to produce molten iron, and charging molten iron from the blast furnace into a converter to remove impurities such as carbon to produce molten steel. Includes process.
전기로 공정은 철 스크랩(STEEL SCRAP)을 전기로(ELECTRIC ARC FURNACE; EAF)에 의해 용융시켜 용강을 제조하는 공정을 포함한다.The electric furnace process includes manufacturing molten steel by melting iron scrap (STEEL SCRAP) in an electric arc furnace (ELECTRIC ARC FURNACE; EAF).
전술한 두 가지 방법에 의해 제조된 용강은 연속 주조(CONTINUOUS CASTING) 공정에 의해 반제품으로 만들어지고, 반제품은 후속된 압연(ROLLING) 공정을 통해 수요자 니즈에 적합한 치수를 갖는 최종 제품으로 만들어진다.Molten steel manufactured by the two methods described above is made into a semi-finished product through a continuous casting process, and the semi-finished product is made into a final product with dimensions suitable for the needs of the consumer through a subsequent rolling process.
한편, 최근에는 각 산업 분야에서 배출되는 온실가스로 인해 급격한 기후 변화가 국제적인 문제로 화두되고 있다.Meanwhile, rapid climate change has recently become an international issue due to greenhouse gases emitted from each industrial field.
이산화탄소는 대표적인 온실가스이다. 철강 산업 분야는 여러 산업 분야 중에서도 이산화탄소의 배출 비중이 높은 산업 분야로 알려져 있다.Carbon dioxide is a representative greenhouse gas. The steel industry is known as an industry with a high proportion of carbon dioxide emissions among other industrial fields.
예컨대, 고로-전로 공정은 코크스(COKES)의 연소에 의해 생성되는 일산화탄소(CO)를 환원제로 이용하기 때문에 많은 양의 이산화탄소를 배출하고 있다.For example, the blast furnace-converter process emits a large amount of carbon dioxide because it uses carbon monoxide (CO) generated by combustion of coke as a reducing agent.
이에, 주요 철강사들은 고로-전로 공정에 비해 상대적으로 이산화탄소의 배출이 적은 전기로 공정 개발에 집중하고 있는 실정이다.Accordingly, major steel companies are focusing on developing electric furnace processes that emit relatively less carbon dioxide compared to the blast furnace-converter process.
다만, 철 스크랩을 주 원료로 사용하는 전기로 제품은 트램프(Tramp) 원소의 양이 많다는 문제가 있다. 트램프 원소는 철강 제품에 미량으로 존재하는 불순합금원소를 말한다.However, electric furnace products that use iron scrap as the main raw material have a problem with the large amount of tramp elements. Tramp elements refer to impure alloy elements that exist in trace amounts in steel products.
구체적으로, 트램프 원소는 모재인 철에 쉽게 고용되지 못하고 계면에 집적하는 경향을 가진다. 이에 따라, 트램프 원소가 허용치 이상인 경우, 압연 시 표면 및 내부에 크랙을 발생시킬 수 있다. 또한, 트램프 원소는 고온에서 연성을 현저히 감소시키는 열간취성의 주요한 요인으로 작용할 수 있다.Specifically, tramp elements are not easily dissolved in iron, the base material, and tend to accumulate at the interface. Accordingly, if the tramp element is above the allowable value, cracks may occur on the surface and inside during rolling. Additionally, tramp elements can act as a major factor in hot embrittlement, which significantly reduces ductility at high temperatures.
이에, 일반적으로 전기로 제품은 표면품질 특성을 높게 요구하는 자동차 강판과 같은 고급 강재에 적용하기에는 한계가 있는 실정이다.Accordingly, electric furnace products generally have limitations in being applied to high-quality steel materials such as automobile steel plates that require high surface quality characteristics.
상술한 문제를 해결하기 위하여, 본 발명은 고로-전로 공정에서 발생하는 이산화탄소의 배출량을 저감할 수 있는 열연 강판, 차량용 부품 및 이를 제조하는 방법을 제공하는데 그 목적이 있다.In order to solve the above-described problems, the purpose of the present invention is to provide a hot rolled steel sheet, vehicle parts, and a method of manufacturing the same that can reduce carbon dioxide emissions generated in the blast furnace-converter process.
본 발명은 전기로를 이용해 기존 전기로 제품보다 월등한 물성을 갖는 열연 강판, 차량용 부품 및 이를 제조하는 방법을 제공하는데 그 목적이 있다.The purpose of the present invention is to provide a hot rolled steel sheet, vehicle parts, and a method for manufacturing the same using an electric furnace having superior physical properties than existing electric furnace products.
본 발명은 특정 원료 수급에 영향을 최소화하여 원료 선택의 유연성을 갖는 열연 강판, 차량용 부품 및 이를 제조하는 방법을 제공하는데 그 목적이 있다.The purpose of the present invention is to provide a hot rolled steel sheet, vehicle parts, and a method of manufacturing the same with flexibility in raw material selection by minimizing the impact on the supply and demand of specific raw materials.
본 발명의 과제들은 이상에서 언급한 과제들로 제한되지 않으며, 언급되지 않은 또 다른 과제들은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다.The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.
본 발명의 일 실시 예에 따른 열연 강판을 제조하는 방법은, 용탕을 제조하는 단계, 반제품을 제조하는 단계, 및 열연 강판을 제조하는 단계를 포함한다.A method of manufacturing a hot-rolled steel sheet according to an embodiment of the present invention includes manufacturing a molten metal, manufacturing a semi-finished product, and manufacturing a hot-rolled steel sheet.
상기 용탕의 원료는 용선 X 중량%, 직접환원철 Y 중량% 및 철 스크랩 Z 중량%를 포함하고, 상기 열연 강판은 K1 중량% 이하의 구리(Cu)를 포함하고, 상기 X, Y, Z 및 K1은 식 1 및 식 2를 만족한다.The raw materials of the molten metal include molten pig iron satisfies Equation 1 and Equation 2.
[식 1][Equation 1]
(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) = K1(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) = K1
[식 2][Equation 2]
K1 ≤ 0.12K1 ≤ 0.12
상기 식 1에서 a1, a2 및 a3 각각은 용선의 구리 함량비(중량%), 직접환원철의 구리 함량비(중량%) 및 철 스크랩의 구리 함량비(중량%)를 의미한다.In Equation 1, a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap.
본 발명의 일 실시 예에 따르면, 상기 X + Y + Z = 100 일 수 있다.According to an embodiment of the present invention, X + Y + Z = 100.
본 발명의 일 실시 예에 따르면, 상기 식 1에서 a1 ≤ 0.03, a2 ≤ 0.02, a3 ≤ 0.18 일 수 있다.According to an embodiment of the present invention, in Equation 1 above, a1 ≤ 0.03, a2 ≤ 0.02, and a3 ≤ 0.18.
본 발명의 일 실시 예에 따르면, 상기 열연 강판은 K2 중량% 이하의 주석(Sn)을 포함하고, 상기 X, Y, Z 및 K2는 식 3 및 식 4를 만족한다.According to one embodiment of the present invention, the hot rolled steel sheet contains tin (Sn) of K2 wt% or less, and X, Y, Z, and K2 satisfy Equations 3 and 4.
[식 3][Equation 3]
(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) = K2(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) = K2
[식 4][Equation 4]
K2 ≤ 0.012K2 ≤ 0.012
상기 식 3에서 b1, b2 및 b3 각각은 용선의 주석 함량비(중량%), 직접환원철의 주석 함량비(중량%) 및 철 스크랩의 주석 함량비(중량%)를 의미한다.In Equation 3, b1, b2, and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap.
본 발명의 일 실시 예에 따르면, b1 ≤ 0.003, b2 ≤ 0.002, b3 ≤ 0.018 일 수 있다.According to an embodiment of the present invention, b1 ≤ 0.003, b2 ≤ 0.002, and b3 ≤ 0.018.
본 발명의 일 실시 예에 따르면, 20 ≤ X ≤ 60 일 수 있다.According to an embodiment of the present invention, 20 ≤ X ≤ 60.
본 발명의 일 실시 예에 따르면, 10 ≤ Y ≤ 40 일 수 있다.According to an embodiment of the present invention, 10 ≤ Y ≤ 40.
본 발명의 일 실시 예에 따르면, 20 ≤ Z ≤ 60 일 수 있다.According to one embodiment of the present invention, 20 ≤ Z ≤ 60.
본 발명의 일 실시 예에 따르면, 상기 용탕을 생산하는 단계는 전기로를 이용해 상기 원료를 용해할 수 있다.According to one embodiment of the present invention, in the step of producing the molten metal, the raw material may be melted using an electric furnace.
본 발명의 일 실시 예에 따르면 열연 강판은, 중량% 기준으로, 탄소: 0.07 ~ 0.12 %, 규소: 0.3 ~ 0.8 %, 망간: 1.5 ~ 2.0 %, 인: 0.02 % 이하, 황: 0.005 % 이하, 구리: 0.12 % 이하(0 제외), 주석: 0.012 % 이하(0 제외), 잔부 철(Fe) 및 불가피적 불순물을 포함한다.According to an embodiment of the present invention, the hot rolled steel sheet contains, on a weight percent basis, carbon: 0.07 to 0.12%, silicon: 0.3 to 0.8%, manganese: 1.5 to 2.0%, phosphorus: 0.02% or less, sulfur: 0.005% or less, Copper: 0.12% or less (excluding 0), Tin: 0.012% or less (excluding 0), including the balance iron (Fe) and inevitable impurities.
상기 열연 강판은 용선 X 중량%, 직접환원철 Y 중량% 및 철 스크랩 Z 중량%를 용해시켜 제조되고, 상기 X, Y 및 Z는 식 1을 만족한다.The hot-rolled steel sheet is manufactured by melting molten iron X weight%, direct reduced iron Y weight%, and iron scrap Z weight%, and X, Y, and Z satisfy Equation 1.
[식 1][Equation 1]
(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) ≤ 0.12(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) ≤ 0.12
상기 식 1에서 a1, a2 및 a3 각각은 용선의 구리 함량비(중량%), 직접환원철의 구리 함량비(중량%) 및 철 스크랩의 구리 함량비(중량%)를 의미한다.In Equation 1, a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap.
본 발명의 일 실시 예에 따르면, 상기 X + Y + Z = 100 일 수 있다.According to an embodiment of the present invention, X + Y + Z = 100.
본 발명의 일 실시 예에 따르면, 상기 a1 ≤ 0.03, a2 ≤ 0.02, a3 ≤ 0.18 일 수 있다.According to an embodiment of the present invention, a1 ≤ 0.03, a2 ≤ 0.02, and a3 ≤ 0.18.
본 발명의 일 실시 예에 따르면, X, Y 및 Z는 식 2를 만족한다.According to one embodiment of the present invention, X, Y and Z satisfy Equation 2.
[식 2][Equation 2]
(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) ≤ 0.012(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) ≤ 0.012
상기 식 2에서 b1, b2 및 b3 각각은 용선의 주석 함량비(중량%), 직접환원철의 주석 함량비(중량%) 및 철 스크랩의 주석 함량비(중량%)를 의미한다.In Equation 2, b1, b2, and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap.
본 발명의 일 실시 예에 따르면, b1 ≤ 0.003, b2 ≤ 0.002, b3 ≤ 0.018 일 수 있다.According to an embodiment of the present invention, b1 ≤ 0.003, b2 ≤ 0.002, and b3 ≤ 0.018.
본 발명의 일 실시 예에 따르면, 20 ≤ X ≤ 60, 10 ≤ Y ≤ 40, 20 ≤ Z ≤ 60 일 수 있다.According to an embodiment of the present invention, 20 ≤ X ≤ 60, 10 ≤ Y ≤ 40, and 20 ≤ Z ≤ 60.
본 발명의 일 실시 예에 따르면, 상기 열연 강판은 크롬(Cr), 니오븀(Nb), 티타늄(Ti) 및 보론(B) 중 하나 이상의 원소를 더 포함할 수 있다.According to one embodiment of the present invention, the hot rolled steel sheet may further include one or more elements selected from chromium (Cr), niobium (Nb), titanium (Ti), and boron (B).
본 발명의 일 실시 예에 따른 차량용 부품은 중량% 기준으로, 탄소: 0.07 ~ 0.12 %, 규소: 0.3 ~ 0.8 %, 망간: 1.5 ~ 2.0 %, 인: 0.02 % 이하, 황: 0.005 % 이하, 구리: 0.12 % 이하(0 제외), 주석: 0.012 % 이하(0 제외), 잔부 철(Fe) 및 불가피적 불순물을 포함한다.Vehicle parts according to an embodiment of the present invention contain, on a weight percent basis, carbon: 0.07 to 0.12%, silicon: 0.3 to 0.8%, manganese: 1.5 to 2.0%, phosphorus: 0.02% or less, sulfur: 0.005% or less, copper : 0.12% or less (excluding 0), Tin: 0.012% or less (excluding 0), including remaining iron (Fe) and inevitable impurities.
상기 차량용 부품의 모재는 용선 X 중량%, 직접환원철 Y 중량% 및 철 스크랩 Z 중량%를 용해시켜 제조되고, 상기 X, Y 및 Z는 식 1을 만족한다.The base material of the vehicle parts is manufactured by dissolving molten iron X weight %, direct reduced iron Y weight %, and iron scrap Z weight %, and the
[식 1][Equation 1]
(a1 × X + a2 × Y +a3 × Z)/(X +Y + Z) ≤ 0.12(a1 × X + a2 × Y +a3 × Z)/(X +Y + Z) ≤ 0.12
상기 식 1에서 a1, a2 및 a3 각각은 용선의 구리 함량비(중량%), 직접환원철의 구리 함량비(중량%) 및 철 스크랩의 구리 함량비(중량%)를 의미하고, a1 ≤ 0.03, a2 ≤ 0.02, a3 ≤ 0.18 이다.In Equation 1, a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap, a1 ≤ 0.03, a2 ≤ 0.02, a3 ≤ 0.18.
본 발명의 일 실시 예에 따르면, 상기 X + Y + Z = 100 일 수 있다.According to an embodiment of the present invention, X + Y + Z = 100.
본 발명의 일 실시 예에 따르면, 상기 X, Y 및 Z는 식 2를 만족한다.According to an embodiment of the present invention, X, Y, and Z satisfy Equation 2.
[식 2][Equation 2]
(b1 × X +b2 × Y +b3 × Z)/(X +Y + Z) ≤ 0.012(b1 ×
상기 식 2에서 b1, b2 및 b3 각각은 용선의 주석 함량비(중량%), 직접환원철의 주석 함량비(중량%) 및 철 스크랩의 주석 함량비(중량%)를 의미하고, b1 ≤ 0.003, b2 ≤ 0.002, b3 ≤ 0.018 이다.In Equation 2, b1, b2 and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap, b1 ≤ 0.003, b2 ≤ 0.002, b3 ≤ 0.018.
본 발명의 일 실시 예에 따르면, 20 ≤ X ≤ 60, 10 ≤ Y ≤ 40, 20 ≤ Z ≤ 60 일 수 있다.According to an embodiment of the present invention, 20 ≤ X ≤ 60, 10 ≤ Y ≤ 40, and 20 ≤ Z ≤ 60.
본 발명의 일 실시 예에 따르면, 기존 고로-전로 공정 대비 용선 사용량을 대폭 감소시켜 철강 제품 제조 시 발생하는 이산화탄소의 양을 현저히 감소시킬 수 있다.According to one embodiment of the present invention, the amount of carbon dioxide generated during manufacturing steel products can be significantly reduced by significantly reducing the amount of molten iron used compared to the existing blast furnace-converter process.
본 발명의 일 실시 예에 따르면, 기존 전기로 제품 대비 트램프 원소의 함량을 허용치 범위 내로 제어하여 우수한 물성을 갖는 전기로 제품을 생산할 수 있다.According to an embodiment of the present invention, an electric furnace product with excellent physical properties can be produced by controlling the content of tramp elements within an acceptable range compared to existing electric furnace products.
본 발명의 일 실시 예에 따르면, 용선, 직접환원철 및 철 스크랩의 첨가 함량비를 사전 설정된 범위 내에서 조절할 수 있어 특정 원료의 수급에 문제가 발생하더라도 유연하게 대응할 수 있다. According to one embodiment of the present invention, the addition content ratio of molten pig iron, direct reduced iron, and iron scrap can be adjusted within a preset range, so that it is possible to flexibly respond even if a problem occurs in the supply and demand of specific raw materials.
도 1은 본 발명의 일 실시 예에 따른 열연 강판을 제조하는 방법을 나타내는 순서도이다.1 is a flowchart showing a method of manufacturing a hot rolled steel sheet according to an embodiment of the present invention.
도 2는 도 1의 순서도에서 용탕을 제조하는 단계를 상세히 나타내는 순서도이다.Figure 2 is a flowchart showing in detail the steps for manufacturing molten metal in the flowchart of Figure 1.
도 3은 표 2에 기재된 비교예 3 및 실시예 6의 굽힘 시험 평가결과를 나타내는 사진 대용 도면이다.Figure 3 is a photographic representation showing the bending test evaluation results of Comparative Example 3 and Example 6 shown in Table 2.
도 4는 표 2에 기재된 비교예 3 및 실시예 6의 전처리 특성 평가결과를 나타내는 사진 대용 도면이다.Figure 4 is a photographic diagram showing the pretreatment characteristic evaluation results of Comparative Example 3 and Example 6 shown in Table 2.
도 5는 표 2에 기재된 도장성 평가 중 부착성을 평가하는 방법을 설명하기 위한 도면이다.Figure 5 is a diagram for explaining a method of evaluating adhesion among the paintability evaluations shown in Table 2.
도 6은 표 2에 기재된 실시예 6의 내충격성 평가 후의 모습을 나타내는 사진 대용 도면이다.Figure 6 is a diagram instead of a photograph showing the state after impact resistance evaluation of Example 6 shown in Table 2.
도 7은 표 2에 기재된 비교예1, 비교예3, 및 실시예 6의 용접성 평가 후의 모습을 나타내는 사진 대용 도면이다.Figure 7 is a photographic diagram showing the state after weldability evaluation of Comparative Example 1, Comparative Example 3, and Example 6 shown in Table 2.
도 8은 표 3에 기재된 실시예 6의 와이어 가공성 평가 후의 모습을 나타내는 사진 대용 도면이다.Figure 8 is a diagram instead of a photograph showing the wire processability of Example 6 shown in Table 3 after evaluation.
본 명세서에서 사용된 모든 용어 (기술 용어 및 과학 용어 포함)는 본 발명이 속하는 기술 분야의 당업자에 의해 일반적으로 이해되는 것과 동일한 의미를 갖는다.All terms (including technical terms and scientific terms) used in this specification have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains.
일반적으로 사용되는 사전에서 정의된 용어와 같은 용어는 관련 기술의 맥락에서 의미와 일치하는 의미를 갖는 것으로 해석되어야 하고, 이상적인 또는 지나치게 형식적인 의미로 해석되지 않는 한, 명시적으로 여기에서 정의된다.Terms as defined in commonly used dictionaries are explicitly defined herein, and should be construed as having meanings consistent with their meanings in the context of the relevant technology, unless interpreted in an idealized or overly formal sense.
제1, 제2, 및 제3 등의 용어들은 다양한 성분, 영역, 부분 또는 층을 설명하기 위해 사용되나, 이에 한정되는 것은 아니다. 이러한 용어들은 어느 성분, 영역, 부분 또는 층들을 다른 성분, 다른 부분 또는 다른 층을 구별하기 위해서 사용된다.Terms such as first, second, and third are used to describe various components, regions, parts, or layers, but are not limited thereto. These terms are used to distinguish one component, region, portion or layer from another component, portion or layer.
본 명세서에서 일 부분이 다른 부분의 "위에" 또는 "상에" 있다는 것은 일 부분의 바로 위에 다른 부분이 있는 경우에만 한정되는 것이 아니라 일 부분과 다른 부분 사이에 또 다른 부분이 있는 경우도 포함하는 것이다.In this specification, the fact that one part is “on” or “on” another part is not limited to the case where there is another part directly above the one part, but also includes the case where there is another part between one part and the other part. will be.
본 명세서에서 추가 원소를 더 포함하는 것의 의미는 잔부인 철(Fe)을 대체하여 포함하는 것을 의미하며, 특별히 언급하지 않는 한 %는 중량%를 의미한다.In this specification, further inclusion of additional elements means inclusion in place of the remaining iron (Fe), and unless specifically stated, % means weight percent.
이하, 도면을 참조하여 본 발명의 실시예를 상세히 설명한다.Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
본 발명의 일 실시예에 따른 열연 강판의 성분Components of a hot rolled steel sheet according to an embodiment of the present invention
본 발명의 일 실시 예에 따른 열연 강판은 철(Fe), 탄소(C), 규소(Si), 망간(Mn), 인(P), 황(S), 구리(Cu), 및 주석(Sn)을 포함한다.The hot rolled steel sheet according to an embodiment of the present invention includes iron (Fe), carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), copper (Cu), and tin (Sn). ) includes.
본 발명의 일 실시 예에 따른 열연 강판은 알루미늄(Al), 크롬(Cr), 니오븀(Nb), 티타늄(Ti), 보론(B) 및 질소(N) 중 하나 이상을 더 포함할 수 있다.The hot rolled steel sheet according to an embodiment of the present invention may further include one or more of aluminum (Al), chromium (Cr), niobium (Nb), titanium (Ti), boron (B), and nitrogen (N).
예컨대, 본 실시 예에 따른 열연 강판은, 중량% 기준으로, 탄소(C): 0.07 ~ 0.12, 규소(Si): 0.3 ~ 0.8 , 망간(Mn): 1.5 ~ 2.0 , 인(P): 0.02 이하, 황(S): 0.005 이하, 알루미늄(Al): 0.2 ~ 0.5 , 구리(Cu): 0.1 미만(0 제외), 주석(Sn): 0.01 미만(0 제외), 크롬(Cr): 0.5 ~ 1.1, 니오븀(Nb): 0.05 ~ 0.1, 티타늄(Ti): 0.06 ~ 1.1, 보론(B): 0.001 ~ 0.0035, 질소(N): 0.006 이하, 잔부 철(Fe) 및 기타 불가피하게 첨가되는 불순물을 포함할 수 있다.For example, the hot rolled steel sheet according to this embodiment has, on a weight percent basis, carbon (C): 0.07 to 0.12, silicon (Si): 0.3 to 0.8, manganese (Mn): 1.5 to 2.0, and phosphorus (P): 0.02 or less. , Sulfur (S): 0.005 or less, Aluminum (Al): 0.2 to 0.5, Copper (Cu): less than 0.1 (excluding 0), Tin (Sn): less than 0.01 (excluding 0), Chromium (Cr): 0.5 to 1.1 , Niobium (Nb): 0.05 ~ 0.1, Titanium (Ti): 0.06 ~ 1.1, Boron (B): 0.001 ~ 0.0035, Nitrogen (N): 0.006 or less, including the balance iron (Fe) and other unavoidably added impurities. can do.
이하, 열연 강판의 성분 및 각 성분 범위에 대하여 설명한다.Hereinafter, the components of hot rolled steel sheets and the ranges of each component will be described.
[탄소(C): 0.07 중량% 이상 0.12 중량% 이하][Carbon (C): 0.07% by weight or more and 0.12% by weight or less]
탄소(C)는 필요한 강도의 확보를 위한 불가결한 원소이다. 예컨대, 탄소(C)는 베이나이트 조직의 강도 확보하기 위해 첨가할 수 있다. 또한, 탄소(C)는 석출물의 균형을 확보하기 위해 첨가할 수 있다.Carbon (C) is an essential element for securing the necessary strength. For example, carbon (C) can be added to secure the strength of the bainite structure. Additionally, carbon (C) can be added to ensure the balance of precipitates.
다만, 탄소(C)의 첨가량이 과할 경우, 강판의 가공성 및 용접성이 저하될 수 있다. 반대로, 탄소(C)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.However, if the amount of carbon (C) added is excessive, the processability and weldability of the steel plate may decrease. Conversely, if the amount of carbon (C) added is insufficient, the above-described addition effect may be insufficient.
이에, 본 발명의 일 실시 예에서 탄소(C)의 함량은 0.07 중량% ~ 0.12 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the carbon (C) content may be 0.07% by weight to 0.12% by weight.
본 발명의 일 실시 예에 따르면, 탄소(C)의 함량은 약 0.07 중량% ~ 0.12 중량%, 바람직하게는 약 0.09 중량% ~ 0.10 중량% 일 수 있다.According to one embodiment of the present invention, the carbon (C) content may be about 0.07% by weight to 0.12% by weight, preferably about 0.09% by weight to 0.10% by weight.
[규소(Si): 0.3 중량% 이상 0.8 중량% 이하][Silicon (Si): 0.3% by weight or more and 0.8% by weight or less]
규소(Si)는 고용강화원소이다. 예컨대, 규소(Si)는 페라이트에 고용되는 페라이트 안정화 원소로 연성의 열화없이 강도를 상승시킬 수 있다. 규소(Si)는 탄화물(carbide)의 형성을 억제하여 강판의 연신율을 향상시킬 수 있다.Silicon (Si) is a solid solution strengthening element. For example, silicon (Si) is a ferrite stabilizing element dissolved in ferrite and can increase strength without deteriorating ductility. Silicon (Si) can improve the elongation of steel sheets by suppressing the formation of carbides.
다만, 규소(Si)의 첨가량이 과할 경우, 열연강판의 표면에 산화스케일에 의한 표면결함을 발생시키고, 용접성을 저하시킬 수 있다. 반대로, 규소(Si)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.However, if the amount of silicon (Si) added is excessive, surface defects due to oxidation scale may occur on the surface of the hot rolled steel sheet and deteriorate weldability. Conversely, if the amount of silicon (Si) added is insufficient, the above-described addition effect may be insufficient.
이에, 본 발명의 일 실시 예에서 규소의 함량은 0.3 중량% ~ 0.8 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 규소의 함량은 약 0.3 중량% ~ 0.8 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the silicon content may be 0.3% by weight to 0.8% by weight. According to one embodiment of the present invention, the silicon content may be about 0.3% by weight to 0.8% by weight.
[망간(Mn): 1.5 중량% 이상 2.0 중량% 이하][Manganese (Mn): 1.5% by weight or more and 2.0% by weight or less]
망간은 고용강화와 소입성을 개선하는 효과를 통해 강의 강도를 향상시킨다. 망간은 펄라이트 변태를 억제하고 베이나이트 조직을 얻기 위해 불가결한 성분이다.Manganese improves the strength of steel through strengthening solid solution and improving hardenability. Manganese is an essential ingredient to suppress pearlite transformation and obtain bainite structure.
다만, 망간(Mn)의 첨가량이 과할 경우, 가공성을 열화시키고 용접성을 저해할 수 있다. 반대로, 망간(Mn)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.However, if the amount of manganese (Mn) added is excessive, processability may deteriorate and weldability may be impaired. Conversely, if the amount of manganese (Mn) added is insufficient, the above-described addition effect may be insufficient.
이에, 본 발명의 일 실시 예에서 망간(Mn)의 함량은 1.5 중량% ~ 2.0 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 망간(Mn)의 함량은 약 1.5 중량% ~ 2.0 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content of manganese (Mn) may be 1.5% by weight to 2.0% by weight. According to one embodiment of the present invention, the content of manganese (Mn) may be about 1.5% by weight to 2.0% by weight.
[황(S): 0.005 중량% 이하][Sulfur (S): 0.005% by weight or less]
황(S)은 인성 및 용접성을 저해하고, 열간압연 시 비금속 개재물(황화합물)을 증가시켜 강의 가공성을 저해할 수 있다. 이에, 본 발명의 일 실시 예에서 황(S)의 함량은 0.005 중량% 이하 일 수 있다. 본 발명의 일 실시 예에 따르면, 황(S)의 함량은 약 0.005 중량% 이하 일 수 있다.Sulfur (S) can impair toughness and weldability and increase non-metallic inclusions (sulfur compounds) during hot rolling, thereby impairing the workability of steel. Therefore, in one embodiment of the present invention, the content of sulfur (S) may be 0.005% by weight or less. According to one embodiment of the present invention, the sulfur (S) content may be about 0.005% by weight or less.
[인(P): 0.02 중량% 이하][Phosphorus (P): 0.02% by weight or less]
인(P)은 입계 편석 및 고온 균열을 조장하는 불순원소이다. 이에, 본 발명의 일 실시 예에서 인(P)의 함량은 0.02 중량% 이하 일 수 있다. 본 발명의 일 실시 예에 따르면, 인(P)의 함량은 약 0.02 중량% 이하 일 수 있다.Phosphorus (P) is an impurity element that promotes grain boundary segregation and high-temperature cracking. Accordingly, in one embodiment of the present invention, the content of phosphorus (P) may be 0.02% by weight or less. According to one embodiment of the present invention, the phosphorus (P) content may be about 0.02% by weight or less.
[알루미늄(Al): 0.02 중량% 이상 0.5 중량% 이하][Aluminum (Al): 0.02% by weight or more and 0.5% by weight or less]
알루미늄(Al)은 대표적인 탈산제이다. 알루미늄(Al)은 출강 전 또는 출강 중 전로에 첨가되어 핀홀이나 비금속 개재물 발생을 억제시킨다. 알루미늄(Al)은 강 중의 질소와 결합하여 질화물(AlN)을 형성한다. Aluminum (Al) is a representative deoxidizing agent. Aluminum (Al) is added to the converter before or during steel tapping to suppress the generation of pinholes or non-metallic inclusions. Aluminum (Al) combines with nitrogen in steel to form nitride (AlN).
질화물인 AlN은 입계에 석출되어 강의 결정립 미세화에 효과적이며, 이를 통해 강의 인성을 향상 시킬 수 있다.AlN, a nitride, precipitates at grain boundaries and is effective in refining the grains of steel, thereby improving the toughness of steel.
또한, AIN은 고온산화방지에 효과적으로 작용하여 슬라브 제조 시 균열을 방지할 수 있다.In addition, AIN effectively prevents high-temperature oxidation and can prevent cracks when manufacturing slabs.
다만, 알루미늄(Al)의 첨가량이 과할 경우, 개재물 형성에 의한 결함을 발생시킬 수 있다. 반대로, 알루미늄(Al)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.However, if the amount of aluminum (Al) added is excessive, defects may occur due to the formation of inclusions. Conversely, if the amount of aluminum (Al) added is insufficient, the above-described addition effect may be insufficient.
이에, 본 발명의 일 실시 예에서 알루미늄(Al)의 함량은 0.02 중량% ~ 0.5 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 알루미늄(Al)의 함량은 약 0.02 중량% ~ 0.5 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content of aluminum (Al) may be 0.02% by weight to 0.5% by weight. According to one embodiment of the present invention, the content of aluminum (Al) may be about 0.02% by weight to 0.5% by weight.
[구리(Cu): 0.12 중량% 이하(0제외) / 주석(Sn): 0.012 중량% 이하(0제외)][Copper (Cu): 0.12% by weight or less (excluding 0) / Tin (Sn): 0.012% by weight or less (excluding 0)]
구리(Cu)와 주석(Sn)은 철 스크랩으로부터 혼입될 수 있다. 구리(Cu)와 주석(Sn)은 제강 과정에서는 거의 제거되지 못하는 원소로서, 트램프(Tramp) 원소에 해당한다. 트램프 원소는 압연 시 표면 및 내부에 크랙을 발생시킬 수 있다. 또한, 트램프 원소는 고온에서 연성을 현저히 감소시키는 열간취성의 주요한 요인으로 작용할 수 있다.Copper (Cu) and tin (Sn) can be mixed from iron scrap. Copper (Cu) and tin (Sn) are elements that can hardly be removed during the steelmaking process and correspond to tramp elements. Tramp elements can cause cracks on the surface and inside during rolling. Additionally, tramp elements can act as a major factor in hot embrittlement, which significantly reduces ductility at high temperatures.
특히, 주석(Sn)은 강재에 인산염 피막 형성 시, 인산염의 크기의 불균일 및 인산염 부착량의 안정성을 저해한다.In particular, tin (Sn) inhibits the unevenness of the size of phosphate and the stability of the amount of phosphate adhesion when forming a phosphate film on steel.
이에, 본 발명의 일 실시 예에서 구리(Cu)와 주석(Sn)의 함량은 각각 0.12 중량% 이하(0제외) 및 0.012 중량% 이하(0제외) 일 수 있다. 본 발명의 일 실시 예에 따르면, 구리(Cu)와 주석(Sn)의 함량은 각각 약 0.12 중량% 이하(0제외) 및 약 0.012 중량% 이하(0제외) 일 수 있다.Accordingly, in one embodiment of the present invention, the content of copper (Cu) and tin (Sn) may be 0.12% by weight or less (excluding 0) and 0.012% by weight or less (excluding 0), respectively. According to one embodiment of the present invention, the content of copper (Cu) and tin (Sn) may be about 0.12% by weight or less (excluding 0) and about 0.012% by weight or less (excluding 0), respectively.
[크롬(Cr): 0.5 중량% 이상 1.1 중량% 이하][Chrome (Cr): 0.5% by weight or more and 1.1% by weight or less]
크롬(Cr)은 고용강화원소이다. 크롬(Cr)은 페라이트 변태를 지연시켜 마르텐사이트와 베이나이트의 형성을 도울 수 있다.Chromium (Cr) is a solid solution strengthening element. Chromium (Cr) can help the formation of martensite and bainite by delaying ferrite transformation.
다만, 크롬(Cr)의 첨가량이 과할 경우, 미세조직을 불균일하게 하여 가공성을 저해할 수 있다. 반대로, 크롬(Cr)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.However, if the amount of chromium (Cr) added is excessive, the microstructure may become uneven and machinability may be impaired. Conversely, if the amount of chromium (Cr) added is insufficient, the above-described addition effect may be insufficient.
이에, 본 발명의 일 실시 예에서 크롬(Cr)의 함량은 0.5 중량% ~ 1.1 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 크롬(Cr)의 함량은 약 0.5 중량% ~ 1.1 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content of chromium (Cr) may be 0.5% by weight to 1.1% by weight. According to one embodiment of the present invention, the content of chromium (Cr) may be about 0.5% by weight to 1.1% by weight.
[니오븀(Nb): 0.05 중량% 이상 0.1 중량% 이하][Niobium (Nb): 0.05% by weight or more and 0.1% by weight or less]
니오븀(Nb)은 결정립을 미세화시켜 강도와 충격인성 향상에 효과적이다.Niobium (Nb) is effective in improving strength and impact toughness by refining crystal grains.
다만, 니오븀(Nb)의 첨가량이 과할 경우, 재결정을 과도하게 지연시키고, 이에 따라 석출물이 조대해져 가공성을 저하시킬 수 있다. 반대로, 니오븀(Nb)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.However, if the amount of niobium (Nb) added is excessive, recrystallization may be excessively delayed, and precipitates may become coarse, thereby reducing processability. Conversely, if the amount of niobium (Nb) added is insufficient, the above-described addition effect may be insufficient.
이에, 본 발명의 일 실시 예에서 니오븀(Nb)의 함량은 0.05 중량% ~ 0.1 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 니오븀(Nb)의 함량은 약 0.05 중량% ~ 0.1 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content of niobium (Nb) may be 0.05% by weight to 0.1% by weight. According to one embodiment of the present invention, the content of niobium (Nb) may be about 0.05% by weight to 0.1% by weight.
[티타늄(Ti): 0.06 중량% 이상 1.1 중량% 이하][Titanium (Ti): 0.06% by weight or more and 1.1% by weight or less]
티타늄(Ti)은 강 중의 질소와 결합하여 질화물(TiN)을 형성하여 결정립의 성장을 억제하고, 자유 질소의 생성을 억제할 수 있다. 다만, 티타늄(Ti)의 첨가량이 과할 경우, 과도한 석출물이 형성되어 충격인성을 저하시킬 수 있다. 반대로, 티타늄(Ti)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.Titanium (Ti) combines with nitrogen in steel to form nitride (TiN), which can suppress the growth of crystal grains and the production of free nitrogen. However, if the amount of titanium (Ti) added is excessive, excessive precipitates may be formed, which may reduce impact toughness. Conversely, if the amount of titanium (Ti) added is insufficient, the above-described addition effect may be insignificant.
이에, 본 발명의 일 실시 예에서 티타늄(Ti)의 함량은 0.06 중량% ~ 1.1 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 티타늄(Ti)의 함량은 약 0.06 중량% ~ 1.1 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content of titanium (Ti) may be 0.06% by weight to 1.1% by weight. According to one embodiment of the present invention, the content of titanium (Ti) may be about 0.06% by weight to 1.1% by weight.
[보론(B): 0.001 중량% 이상 0.0035 중량% 이하][Boron (B): 0.001% by weight or more and 0.0035% by weight or less]
보론(B)은 페라이트 변태를 억제시켜 강도를 향상시킨다. 다만, 보론(B)의 첨가량이 과할 경우, 용접성과 가공성을 저하킬 수 있다. 반대로, 보론(B)의 첨가량이 부족할 경우, 전술한 첨가 효과가 미비할 수 있다.Boron (B) improves strength by suppressing ferrite transformation. However, if the amount of boron (B) added is excessive, weldability and processability may be reduced. Conversely, if the amount of boron (B) added is insufficient, the above-described addition effect may be insufficient.
이에, 본 발명의 일 실시 예에서 보론(B)의 함량은 0.001 중량% ~ 0.0035 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 보론(B)의 함량은 약 0.001 중량% ~ 0.0035 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content of boron (B) may be 0.001% by weight to 0.0035% by weight. According to one embodiment of the present invention, the content of boron (B) may be about 0.001% by weight to 0.0035% by weight.
[질소(N): 0.006 중량% 이하][Nitrogen (N): 0.006% by weight or less]
질소(N)는 극히 미량 존재로도 강의 기계적 성질에 큰 영향을 미칠 수 있다. 예컨대, 질소(N)는 인장 강도와 항복 강도를 증가시키는 반면 연신율을 저하시킬 수 있다. 또한, 자유 질소는 변형시효를 야기할 수 있다. Nitrogen (N), even in extremely small amounts, can have a significant impact on the mechanical properties of steel. For example, nitrogen (N) can increase tensile strength and yield strength while decreasing elongation. Additionally, free nitrogen can cause strain aging.
이에, 본 발명의 일 실시 예에서 질소(N)의 함량은 0.006 중량% 이하일 수 있다. 본 발명의 일 실시 예에 따르면, 질소(N)의 함량은 0.006 중량% 이하일 수 있다.Accordingly, in one embodiment of the present invention, the nitrogen (N) content may be 0.006% by weight or less. According to one embodiment of the present invention, the nitrogen (N) content may be 0.006% by weight or less.
잔부는 Fe 및 불가피한 불순물을 포함한다. 불가피한 불순물에 대해서는 열연 강판의 제조 공정 과정에서 혼입되는 불순물이며, 이는 해당 분야에서 널리 알려져 있으므로, 구체적인 설명은 생략한다.The balance includes Fe and inevitable impurities. Regarding unavoidable impurities, they are impurities mixed in during the manufacturing process of hot rolled steel sheets, and since these are widely known in the field, detailed descriptions will be omitted.
본 발명의 일 실시예에서 전술한 합금 성분 외에 원소의 추가를 배제하는 것은 아니며, 본 발명의 기술 사상을 해치지 않는 범위 내에서 다양하게 포함될 수 있다. 추가 원소를 더 포함하는 경우 잔부인 Fe를 대체하여 포함한다.In one embodiment of the present invention, the addition of elements other than the above-described alloy components is not excluded, and various elements may be included within a range that does not impair the technical spirit of the present invention. If additional elements are included, they are included by replacing the remaining Fe.
이상과 같이 일 실시예에 따른 강판의 강 성분 및 성분 범위를 살펴보았으며, 앞서 설명된 실시예 이외에도 본 발명이 그 취지나 범주에서 벗어남이 없이 다른 특정 형태로 구체화될 수 있다는 사실은 해당 기술에 통상의 지식을 가진 이들에게는 자명한 것이다.As described above, the steel composition and composition range of the steel plate according to one embodiment have been examined, and the fact that, in addition to the embodiment described above, the present invention can be embodied in other specific forms without departing from the spirit or scope of the present invention is known in the relevant technology. This is self-evident to those with ordinary knowledge.
열연 강판을 제조하는 방법How to manufacture hot rolled steel sheet
도 1은 본 발명의 일 실시 예에 따른 강재를 제조하는 방법을 나타내는 순서도이다.1 is a flowchart showing a method of manufacturing steel according to an embodiment of the present invention.
도 1을 참조하면, 강재를 제조하는 방법은 용탕을 제조하는 단계(S10), 반제품을 제조하는 단계(S20) 및 열연 강판을 제조하는 단계(S30)를 포함한다.Referring to FIG. 1, the method of manufacturing steel includes manufacturing a molten metal (S10), manufacturing a semi-finished product (S20), and manufacturing a hot rolled steel sheet (S30).
용탕을 제조하는 단계(S10)는 원료를 용해시켜 쇳물(예컨대, 용강)을 만드는 단계를 말한다. 원료는 광석 기반의 재료와 철 스크랩을 포함할 수 있다.The step of manufacturing molten metal (S10) refers to the step of making molten metal (eg, molten steel) by dissolving raw materials. Raw materials may include ore-based materials and iron scrap.
광석 기반의 재료는 용선과 직접환원철을 포함할 수 있다. 용선은 철광석(Iron Ore)과 코크스(Coke)를 고로(高爐)에 장입하고, 열풍을 불어넣어 철광석을 환원 및 용융시킴으로써 제조될 수 있다.Ore-based materials may include molten iron and direct reduced iron. Molten iron can be manufactured by charging iron ore and coke into a blast furnace and blowing hot air to reduce and melt the iron ore.
직접환원철은 고체 상태의 철광석을 환원가스(일산화탄소, 수소 등)를 이용해 환원시켜 제조될 수 있다. 예컨대, 직접환원철은 DRI(Direct Reduction Iron) 또는 HBI(Hot Briquetted Iron)일 수 있다. 직접환원철은 펠렛(Pellet) 형태로 가공될 수 있다.Directly reduced iron can be manufactured by reducing solid iron ore using a reducing gas (carbon monoxide, hydrogen, etc.). For example, direct reduced iron may be Direct Reduction Iron (DRI) or Hot Briquetted Iron (HBI). Directly reduced iron can be processed into pellet form.
다만, 직접환원철의 종류와 가공 형태가 전술한 바에 한정되는 것은 아니다.However, the type and processing form of direct reduced iron are not limited to the above.
철 스크랩(Steel Scrap)은 제철 과정 또는 사용 불능 상태의 철강 제품에서 얻을 수 있다.Steel scrap can be obtained from steelmaking or from unusable steel products.
한편, 용선은 불순물의 함량이 적어 고품질의 강 제품을 생산하는데 적합하나, 용선 제조 과정에서 다량의 이산화탄소를 배출한다는 문제가 있다. 예컨대, 용선 1톤 생산시 배출되는 이산화탄소의 양은 약 2톤이다.Meanwhile, molten iron has a low content of impurities and is suitable for producing high-quality steel products, but there is a problem in that a large amount of carbon dioxide is emitted during the molten iron manufacturing process. For example, the amount of carbon dioxide emitted when producing 1 ton of molten iron is about 2 tons.
전기로 용강은 철 스크랩을 전기로에 용해시켜 제조된다. 전기로 용강은 제조 과정에서 고로 공정 대비 이산화탄소의 배출량이 적다. 예컨대, 용강의 이산화탄소 배출량은 용선의 1/4 수준이다.Electric furnace molten steel is manufactured by melting iron scrap in an electric furnace. Electric furnace molten steel emits less carbon dioxide during the manufacturing process than the blast furnace process. For example, the carbon dioxide emissions of molten steel are about 1/4 of that of molten iron.
다만, 전기로 용강으로 생산된 철강 제품은 트램프원소와 같은 불순물의 함량이 높아 차량용 부품과 같은 고품질 강 제품에서 요구하는 물성을 만족하기 어렵다.However, steel products produced from electric furnace molten steel have a high content of impurities such as tramp elements, making it difficult to satisfy the physical properties required for high-quality steel products such as automobile parts.
전술한 문제를 해결하기 위하여, 본 발명의 일 실시 예에 따른 용탕을 제조하는 단계(S10)는 광석 기반의 재료인 용선과 직접환원철, 그리고 철 스크랩을 전기로에 장입하고, 이를 용해시켜 용탕을 제조한다.In order to solve the above-described problem, the step (S10) of manufacturing molten metal according to an embodiment of the present invention is to charge molten iron, direct reduced iron, and iron scrap, which are ore-based materials, into an electric furnace and melt them to manufacture molten metal. do.
도 2는 도 1의 순서도에서 용탕을 제조하는 단계를 상세히 나타내는 순서도이다. Figure 2 is a flowchart showing in detail the steps for manufacturing molten metal in the flowchart of Figure 1.
도 2를 참조하면, 용탕을 제조하는 단계(S10)는 원료를 준비하는 단계(S11), 원료를 장입하는 단계(S12) 및 원료를 용해하는 단계(S13)를 포함할 수 있다.Referring to FIG. 2, the step of manufacturing molten metal (S10) may include preparing raw materials (S11), charging the raw materials (S12), and dissolving the raw materials (S13).
원료를 준비하는 단계(S11)에서는 용선, 직접환원철 및 철 스크랩 각각을 사전 설정된 함량비에 따라 준비한다.In the step of preparing raw materials (S11), molten iron, direct reduced iron, and iron scrap are each prepared according to a preset content ratio.
구체적으로 용선의 함량비를 X, 직접환원철의 함량비를 Y, 그리고 철 스크랩의 함량비를 Z라 각각 정의한다. 또한, 후술하는 열간압연하는 단계에서 생산되는 열연 강판의 구리(Cu) 함량의 최댓값을 K1, 주석(Sn) 함량의 최댓값을 K2라 각각 정의한다. 각 함량비는 중량% 기준이다. X + Y + Z의 합은 100일 수 있다.Specifically, the content ratio of molten pig iron is defined as X, the content ratio of direct reduced iron as Y, and the content ratio of iron scrap as Z. In addition, the maximum value of the copper (Cu) content of the hot rolled steel sheet produced in the hot rolling step described later is defined as K1, and the maximum value of the tin (Sn) content is defined as K2. Each content ratio is based on weight percent. The sum of X + Y + Z may be 100.
본 발명의 일 실시 예에 따르면, X, Y, Z, K1 및 K2는 하기 식 1 내지식 4를 만족한다.According to one embodiment of the present invention, X, Y, Z, K1, and K2 satisfy Equations 1 to 4 below.
[식 1][Equation 1]
(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) = K1(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) = K1
[식 2][Equation 2]
K1 ≤ 0.12K1 ≤ 0.12
[식 3][Equation 3]
(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) = K2(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) = K2
[식 4][Equation 4]
K2 ≤ 0.012K2 ≤ 0.012
상기 식 1에서 a1, a2 및 a3 각각은 용선의 구리 함량비, 직접환원철의 구리 함량비 및 철 스크랩의 구리 함량비를 의미한다.In Equation 1, a1, a2, and a3 each mean the copper content ratio of molten iron, the copper content ratio of direct reduced iron, and the copper content ratio of iron scrap.
상기 식 3에서 b1, b2 및 b3 각각은 용선의 주석 함량비, 직접환원철의 주석 함량비 및 철 스크랩의 주석 함량비를 의미한다.In Equation 3, b1, b2, and b3 each refer to the tin content ratio of molten iron, the tin content ratio of direct reduced iron, and the tin content ratio of iron scrap.
용선의 구리 함량비(a1)는 0.03 중량%(0 제외) 이하일 수 있다. 직접환원철의 구리 함량비(a2)는 0.02 중량%(0 제외) 이하일 수 있다. 철 스크랩의 구리 함량비(a3)는 0.18 중량%(0 제외) 이하일 수 있다.The copper content ratio (a1) of molten iron may be 0.03% by weight (excluding 0) or less. The copper content ratio (a2) of direct reduced iron may be 0.02% by weight (excluding 0) or less. The copper content ratio (a3) of iron scrap may be 0.18% by weight (excluding 0) or less.
본 발명의 일 실시 예에 따르면, 용선의 구리 함량비(a1)는 약 0.03 중량%(0 제외) 이하일 수 있다. 직접환원철의 구리 함량비(a2)는 약 0.02 중량%(0 제외) 이하일 수 있다. 철 스크랩의 구리 함량비(a3)는 약 0.18 중량%(0 제외) 이하일 수 있다.According to one embodiment of the present invention, the copper content ratio (a1) of molten iron may be about 0.03% by weight (excluding 0) or less. The copper content ratio (a2) of direct reduced iron may be about 0.02% by weight (excluding 0) or less. The copper content ratio (a3) of the iron scrap may be about 0.18% by weight (excluding 0) or less.
직접환원철의 주석 함량비(b2)는 0.002 중량%(0 제외) 이하일 수 있다. 철 스크랩의 주석 함량비(b3)는 0.018 중량%(0 제외) 이하일 수 있다. 용선의 주석 함량비(b1)는 0.003 중량%(0 제외) 이하일 수 있다.The tin content ratio (b2) of direct reduced iron may be 0.002% by weight (excluding 0) or less. The tin content ratio (b3) of iron scrap may be 0.018% by weight (excluding 0) or less. The tin content ratio (b1) of molten iron may be 0.003% by weight (excluding 0) or less.
본 발명의 일 실시 예에 따르면, 직접환원철의 주석 함량비(b2)는 약 0.002 중량%(0 제외) 이하일 수 있다. 철 스크랩의 주석 함량비(b3)는 약 0.018 중량%(0 제외) 이하일 수 있다. 용선의 주석 함량비(b1)는 약 0.003 중량%(0 제외) 이하일 수 있다.다만, 구리 함량비(a1, a2, a3)와 주석 함량비(b1, b2, b3)는 각 원료의 품질, 가공도 등에 따라 소정의 범위에서 증가하거나 감소할 수도 있다.According to one embodiment of the present invention, the tin content ratio (b2) of direct reduced iron may be about 0.002% by weight (excluding 0) or less. The tin content ratio (b3) of iron scrap may be about 0.018% by weight (excluding 0) or less. The tin content ratio (b1) of molten iron may be less than about 0.003% by weight (excluding 0). However, the copper content ratio (a1, a2, a3) and tin content ratio (b1, b2, b3) depend on the quality of each raw material, It may increase or decrease within a certain range depending on the degree of processing, etc.
본 발명의 일 실시 예에 따르면, 용선의 함량비(X)가 사전 설정된 범위 초과인 경우, 이산화탄소 배출량의 저감 효과가 미비할 수 있다. 반대로, 용선의 함량비(X)가 사전 설정된 범위 미만인 경우, 열원 부족으로 인하여 다른 원료(즉, 철 스크랩과 직접환원철)의 용해가 적절히 수행되지 않을 수 있다.According to an embodiment of the present invention, when the content ratio (X) of molten iron exceeds a preset range, the effect of reducing carbon dioxide emissions may be insufficient. Conversely, if the molten iron content ratio (
이에, 본 발명의 일 실시 예에서 용선의 함량비(X)는 20 중량% ~ 60 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 용선의 함량비(X)는 약 20 중량% ~ 60 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content ratio (X) of molten iron may be 20% by weight to 60% by weight. According to one embodiment of the present invention, the content ratio (X) of molten iron may be about 20% by weight to 60% by weight.
본 발명의 일 실시 예에 따르면, 직접환원철의 함량비(Y)가 사전 설정된 범위 초과인 경우, 용탕 내 맥석량을 증가함에 따라 전기로 공정온도를 높게 유지해야 하여 에너지 효율을 저하시킨다. 또한, 정련능이 감소하는 결과를 초래하여 탈인 공정시 슬래그 매이킹(SLAG MAKING)을 보정하기 위한 별도의 설계가 요구된다.According to one embodiment of the present invention, when the content ratio (Y) of direct reduced iron exceeds a preset range, the electric furnace process temperature must be maintained high as the amount of gangue in the molten metal increases, thereby reducing energy efficiency. In addition, it results in a decrease in refining ability, so a separate design is required to correct slag making during the dephosphorization process.
반대로, 직접환원철의 함량비(Y)가 사전 설정된 범위 미만인 경우, 이를 대체하기 위해 용선이나 철 스크랩의 함량비가 불가피하게 높아진다. 예컨대, 직접환원철을 대신해 용선 함량비가 높아지게 되면 이산화탄소 배출저감 효과가 미비해질 수 있다. 직접환원철을 대신해 철 스크랩의 함량비가 높아지면 트램프 원소(즉, 구리 내지 주석)의 함량비가 높아지는 문제를 야기할 수 있다.Conversely, if the content ratio (Y) of direct reduced iron is below the preset range, the content ratio of molten iron or iron scrap inevitably increases to replace it. For example, if the molten iron content ratio is increased in place of direct reduced iron, the effect of reducing carbon dioxide emissions may be insignificant. If the content ratio of iron scrap increases instead of direct reduced iron, it may cause the problem of an increase in the content ratio of tramp elements (i.e., copper or tin).
이에, 본 발명의 일 실시 예에서 직접환원철의 함량비(Z)는 20 중량% ~ 40 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 직접환원철의 함량비(Y)는 약 10 중량% ~ 40 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content ratio (Z) of direct reduced iron may be 20% by weight to 40% by weight. According to one embodiment of the present invention, the content ratio (Y) of direct reduced iron may be about 10% by weight to 40% by weight.
본 발명의 일 실시 예에 따르면, 철 스크랩의 함량비(Z)가 사전 설정된 범위 초과인 경우, 트램프 원소의 함량비가 높아져 최종 강 제품의 요구 물성을 달성하지 못한다. 반대로, 철 스크랩의 함량비(Z)가 사전 설정된 범위 미만인 경우, 이산화탄소 배출저감 효과가 미비할 수 있다.According to one embodiment of the present invention, when the content ratio (Z) of iron scrap exceeds a preset range, the content ratio of tramp elements increases and the required physical properties of the final steel product are not achieved. Conversely, if the content ratio (Z) of iron scrap is less than a preset range, the effect of reducing carbon dioxide emissions may be minimal.
이에, 본 발명의 일 실시 예에서 철 스크랩의 함량비는 20 ~ 60 중량% 일 수 있다. 본 발명의 일 실시 예에 따르면, 철 스크랩의 함량비는 약 20 ~ 60 중량% 일 수 있다.Accordingly, in one embodiment of the present invention, the content ratio of iron scrap may be 20 to 60% by weight. According to one embodiment of the present invention, the content ratio of iron scrap may be about 20 to 60% by weight.
원료를 장입하는 단계(S12)에서는 용선, 직접환원철 및 철 스크랩을용융로에 장입한다. 각 원료의 장입은 순차적으로 수행되거나 동시에 수행될 수 있다.In the step of charging raw materials (S12), molten iron, direct reduced iron, and iron scrap are charged into the melting furnace. Charging of each raw material may be performed sequentially or simultaneously.
또한, 각 원료의 장입은 슬래그의 넘침 현상을 방지하거나 적절한 용융 반응을 위해 복수 회에 거쳐 수행될 수 있다.Additionally, the charging of each raw material may be performed multiple times to prevent slag overflow or to achieve an appropriate melting reaction.
원료를 용해하는 단계(S13)는 전기로(EAF; Electric Arc Furnace)에서 수행될 수 있다. 본 실시 예에서 전기로는 교류전기로일 수 있다. 다만, 이에 한정되는 것은 아니며, 직류전기로를 적용할 수도 있다.The step of dissolving the raw materials (S13) may be performed in an electric arc furnace (EAF). In this embodiment, the electric furnace may be an alternating current electric furnace. However, it is not limited to this, and a direct current electric furnace can also be applied.
반제품을 제조하는 단계(S20)에서는 단계(S10)에서 제조된 용탕을 이용해 슬라브(Slab), 블룸(Bloom) 및 빌렛(Billet) 등과 같은 반제품을 제조한다.In the step S20 of manufacturing semi-finished products, semi-finished products such as slabs, blooms, and billets are manufactured using the molten metal manufactured in step S10.
예컨대, 단계(S20)는 연속주조공정(Continuous Casting)에 의해 수행될 수 있다. 연속주조공정은 용탕을 일렬로 배열된 복수 개의 세그먼트를 통과시키면서 주조와 압연을 동시에 수행하여 소정의 폭과 두께를 갖는 반제품을 주조하는 공정이다.For example, step S20 may be performed by a continuous casting process. The continuous casting process is a process of casting and rolling simultaneously while passing molten metal through a plurality of segments arranged in a row to cast a semi-finished product with a predetermined width and thickness.
다만, 단계(S20)가 전술한 바에 한정되는 것은 아니다. 예컨대, 단계(S20)는 연속주조공정에 후속된 단조공정을 포함할 수 있다. 구체적으로, 연속주조공정에서 블룸을 생산한 후, 이를 단조공정을 통해 사전 설정된 치수를 갖는 단조 슬라브를 제조하는 것도 가능하다.However, step S20 is not limited to the above. For example, step S20 may include a forging process followed by a continuous casting process. Specifically, it is possible to produce a bloom in a continuous casting process and then manufacture a forged slab with preset dimensions through a forging process.
열연 강판를 제조하는 단계(S30)에서는 반제품을 재가열한 후, 가열된 반제품을 사전 설정된 두께와 폭을 갖는 열연 강판으로 압연(rolling)한다. 예컨대, 열연 강판의 두께는 2 ~ 5 mm일 수 있다. 다만, 열연 강판의 두께가 전술한 바에 한정되는 것은 아니다.In the step (S30) of manufacturing a hot-rolled steel sheet, the semi-finished product is reheated, and then the heated semi-finished product is rolled into a hot-rolled steel sheet having a preset thickness and width. For example, the thickness of the hot rolled steel sheet may be 2 to 5 mm. However, the thickness of the hot rolled steel sheet is not limited to the above.
구체적으로, 열연 강판을 제조하는 단계(S30)는 재가열하는 단계(S31), 열간압연하는 단계(S32), 냉각하는 단계(S33) 및 권취하는 단계(S34)를 포함한다.Specifically, the step of manufacturing a hot rolled steel sheet (S30) includes a reheating step (S31), a hot rolling step (S32), a cooling step (S33), and a winding step (S34).
재가열하는 단계(S31)에서는 사전 설정된 온도 범위에서 반제품을 재가열한다. 재가열하는 단계(S31)는 단계(S20)에서 편석된 성분을 재고용시킬 수 있다.In the reheating step (S31), the semi-finished product is reheated in a preset temperature range. The reheating step (S31) can re-dissolve the components segregated in step (S20).
재가열 온도(Reheating Temperature; RT)가 사전 설정된 온도 범위보다 낮을 경우, 편석된 성분의 재고용 효율이 감소하며, 최종 제품의 굽힘 가공성이 저하될 수 있다. 반대로, 재가열 온도가 사전 설정된 온도 범위보다 높을 경우, 석물출이 조대화되고 열연 강재의 표면 품질이 저하될 수 있다.If the reheating temperature (RT) is lower than the preset temperature range, the re-dissolution efficiency of segregated components decreases, and the bending processability of the final product may deteriorate. Conversely, if the reheating temperature is higher than the preset temperature range, the precipitate may become coarse and the surface quality of the hot rolled steel may deteriorate.
이에, 본 발명에서는 재가열 온도를 1150 ℃ ~ 1350 ℃ 범위로 제한한다. 본 발명의 일 실시 예에서 재가열 온도를 약 1150 ℃ ~ 1350 ℃ 범위로 제한한다.Accordingly, in the present invention, the reheating temperature is limited to the range of 1150°C to 1350°C. In one embodiment of the present invention, the reheating temperature is limited to a range of about 1150°C to 1350°C.
열간압연하는 단계(S32)에서는 재가열된 반제품을 열간압연한다. 단계(S32)에서 마무리 압연온도(Finishing Delivery Temperaturel; FDT)가 사전 설정된 범위보다 낮은 경우, 이상역 압연에 의한 혼립 조직이 발생하는 등의 문제가 발생할 수 있다. 반대로, 마무리 압연온도가 사전 설정된 범위를 초과할 경우, 열연 강판의 결정립이 조대하게 형성되어 최종 제품의 물성저하를 야기할 수 있다.In the hot rolling step (S32), the reheated semi-finished product is hot rolled. If the finishing delivery temperature (FDT) is lower than the preset range in step S32, problems such as mixed structure due to abnormal rolling may occur. Conversely, if the finish rolling temperature exceeds the preset range, the crystal grains of the hot rolled steel sheet may be formed coarsely, causing a decrease in the physical properties of the final product.
이에, 본 실시 예에서 마무리 압연온도는 880 ℃ ~ 930 ℃ 범위로 제한한다. 본 발명의 일 실시 예에 따르면, 마무리 압연온도는 약 880 ℃ ~ 930 ℃ 범위로 제한한다.Accordingly, in this embodiment, the finish rolling temperature is limited to the range of 880°C to 930°C. According to one embodiment of the present invention, the finish rolling temperature is limited to a range of about 880°C to 930°C.
냉각하는 단계(S33)에서는 열연 강판을 냉각한다. 단계(S33)에서 냉각 속도가 사전 설정된 범위 미만인 경우, 베이나이트 조직 대신 페라이트 조직이 형성될 수 있다. 반대로, 냉각 속도가 사전 설정된 범위 초과인 경우, 베이나이트 조직 대신 마르텐사이트 조직의 변태가 활성화되어 가공성을 저하시킬 수 있다.In the cooling step (S33), the hot rolled steel sheet is cooled. If the cooling rate is less than a preset range in step S33, a ferrite structure may be formed instead of a bainite structure. Conversely, if the cooling rate exceeds the preset range, the transformation of martensite structure instead of bainitic structure is activated, which may reduce machinability.
이에, 본 실시 예에서 냉각 속도는 60 ℃/sec ~ 110 ℃/sec 범위로 제한한다. 본 발명의 일 실시 예에 따르면, 냉각 속도는 약 60 ℃/sec ~ 110 ℃/sec 범위로 제한한다.Therefore, in this embodiment, the cooling rate is limited to the range of 60 °C/sec to 110 °C/sec. According to one embodiment of the present invention, the cooling rate is limited to a range of about 60 °C/sec to 110 °C/sec.
권취하는 단계(S34)에서는 냉각된 열연 강판을 코일 형태로 권취한다. 단계(S34)에서 권취 온도가 사전 설정된 범위 미만인 경우, 권취가 용이하지 않을 수 있다. 반대로, 권취 온도가 사전 설정된 범위 초과인 경우, 표면 스케일(scale)이 열연 강판의 내부까지 형성될 수 있다.In the winding step (S34), the cooled hot rolled steel sheet is wound into a coil shape. If the winding temperature in step S34 is below the preset range, winding may not be easy. Conversely, if the coiling temperature is above the preset range, surface scale may form even inside the hot rolled steel sheet.
이에, 본 실시 예에서 권취 온도는 380 ℃ ~ 480 ℃ 범위로 제한한다. 본 발명의 일 실시 예에 따르면, 권취 온도는 약 380 ℃ ~ 480 ℃ 범위로 제한한다.Accordingly, in this embodiment, the coiling temperature is limited to the range of 380°C to 480°C. According to one embodiment of the present invention, the coiling temperature is limited to a range of about 380°C to 480°C.
결과적으로, 본 발명의 일 실시 예에 따르면, 기존 고로-전로 공정 대비 용선 사용량을 대폭 감소시켜 철강 제품 제조 시 발생하는 이산화탄소의 양을 현저히 감소시킬 수 있다.As a result, according to an embodiment of the present invention, the amount of carbon dioxide generated during manufacturing steel products can be significantly reduced by significantly reducing the amount of molten iron used compared to the existing blast furnace-converter process.
본 발명의 일 실시 예에 따르면, 기존 전기로 제품 대비 트램프 원소의 함량을 허용치 범위 내로 제어하여 우수한 물성을 갖는 전기로 제품을 생산할 수 있다.According to an embodiment of the present invention, an electric furnace product with excellent physical properties can be produced by controlling the content of tramp elements within an acceptable range compared to existing electric furnace products.
본 발명의 일 실시 예에 따르면, 용선, 직접환원철 및 철 스크랩의 첨가 함량비를 사전 설정된 범위 내에서 조절할 수 있어 특정 원료의 수급에 문제가 발생하더라도 유연하게 대응할 수 있다.According to one embodiment of the present invention, the addition content ratio of molten pig iron, direct reduced iron, and iron scrap can be adjusted within a preset range, so that it is possible to flexibly respond even if a problem occurs in the supply and demand of specific raw materials.
본 발명에 따른 열연 강판의 특성Characteristics of hot rolled steel sheet according to the present invention
이하에서는 표 1 및 표 2를 통해 본 발명의 실시예들와 비교예들을 비교한다. 도 3 내지 도 8은 표 2의 평가결과를 설명하기 위한 도면이다.Below, examples of the present invention and comparative examples are compared through Tables 1 and 2. Figures 3 to 8 are diagrams for explaining the evaluation results in Table 2.
하기 표 1은 실시예 1 내지 6은 본 발명의 실시예에 따른 원료 함량비를 만족하는 실험예들이고, 비교예 1 내지 4는 상기 원료 함량비를 벗어난 실험예들이다.In Table 1 below, Examples 1 to 6 are experimental examples that satisfy the raw material content ratio according to the embodiment of the present invention, and Comparative Examples 1 to 4 are experimental examples that deviate from the raw material content ratio.
실시예들과 비교예들은 원료(용선, 직접환원철 및 철스크랩)의 함량비에만 차이를 보이며, 나머지 조건(예컨대, 공정 조건)은 모두 동일하다.The examples and comparative examples differ only in the content ratio of raw materials (molten iron, direct reduced iron, and iron scrap), and all other conditions (eg, process conditions) are the same.
Figure PCTKR2023010559-appb-img-000001
Figure PCTKR2023010559-appb-img-000001
표 1을 참조하면, 실시예 1 내지 6에 따른 열연 강판의 구리 함량비(K1)의 최댓값들은 0.12 이하였으나, 비교예 1 내지 4에 따른 열연 강판의 구리 함량비(K1)의 최댓값들은 0.12 이상이었다.Referring to Table 1, the maximum values of the copper content ratio (K1) of the hot rolled steel sheets according to Examples 1 to 6 were 0.12 or less, but the maximum values of the copper content ratio (K1) of the hot rolled steel sheets according to Comparative Examples 1 to 4 were 0.12 or more. It was.
또한, 실시예 1 내지 6에 따른 열연 강판의 주석 함량비(K2)의 최댓값들 0.012 이하였으나, 비교예 1 내지 4에 따른 열연 강판의 주석 함량비(K2)의 최댓값들은 0.012 이상이었다.In addition, the maximum values of the tin content ratio (K2) of the hot-rolled steel sheets according to Examples 1 to 6 were 0.012 or less, but the maximum values of the tin content ratio (K2) of the hot-rolled steel sheets according to Comparative Examples 1 to 4 were 0.012 or more.
하기 표 2는 표 1에 기재된 실시예 1 내지 6과 비교예 1 내지 4에 따른 열연 강판들의 제품 특성을 나타낸다.Table 2 below shows product characteristics of hot rolled steel sheets according to Examples 1 to 6 and Comparative Examples 1 to 4 shown in Table 1.
표 2에서 굽힘 시험 평가의 조건은 R/T=0.94, 1.5이다. R은 굽힘 시험의 지그 직경(단위: mm)이며, T는 시험 강판의 두께(단위: mm)이다.In Table 2, the conditions for bending test evaluation are R/T=0.94, 1.5. R is the jig diameter of the bending test (unit: mm), and T is the thickness of the test steel plate (unit: mm).
표 2에서 전처리 특성은 열연 강판 표면에 인산염(인산아연계) 화성피막처리 후, 외관, 피막 중량, 결정입자의 크기를 평가하였다. 전처리 특성 평가에서 피막 중량은 1.8 ~ 3.0 g/m2이 적정 범위이고, 결정입자는 2 ~ 10 ㎛이 적정 범위이다.In Table 2, the pretreatment characteristics were evaluated for appearance, film weight, and crystal grain size after phosphate (zinc phosphate) chemical conversion coating treatment on the surface of the hot rolled steel sheet. In evaluating pretreatment characteristics, the appropriate range for the film weight is 1.8 to 3.0 g/m2, and the appropriate range for the crystal particles is 2 to 10 ㎛.
표 2에서 도장성 평가 중 부착성 평가는 열연 강판의 도장면에 테이핑 시험 후 테이핑으로 인해 탈착되는 도장 영역의 비율로 판단하였다.In Table 2, the adhesion evaluation during the paintability evaluation was judged by the ratio of the painted area detached due to taping after the taping test on the painted surface of the hot rolled steel sheet.
표 2에서 도장성 평가 중 내충격성 평가는 열연 강판의 도장면에 500g 추를 50 cm 낙하거리에서 충격을 가했을 때, 도장면의 결함 여부를 평가하였다.In Table 2, among the paintability evaluations, the impact resistance evaluation evaluated whether there were defects in the painted surface of a hot-rolled steel sheet when a 500g weight was applied to the painted surface from a dropping distance of 50 cm.
표 2에서 용접성 평가는 송급속도 6 ~ 11 m/min에서 용접 라인을 따라 형성되는 용착금속(즉, 비드)를 평가하였다.In Table 2, the weldability evaluation evaluated the deposited metal (i.e., bead) formed along the welding line at a feed speed of 6 to 11 m/min.
Figure PCTKR2023010559-appb-img-000002
Figure PCTKR2023010559-appb-img-000002
[굽힘 시험 평가결과][Bending test evaluation results]
표 2 및 도 3을 참조하면, 실시예 1 ~ 6과 비교예 3 ~ 4 따른 열연 강판은 굽힘 시험에서 "양호"를 보였다. 이와 비교하여, 비교예 1과 2에 따른 열연 강판에서는 미세 크랙이 발생하여 "불량"을 보였다.Referring to Table 2 and Figure 3, the hot rolled steel sheets according to Examples 1 to 6 and Comparative Examples 3 to 4 showed “good” in the bending test. In comparison, the hot rolled steel sheets according to Comparative Examples 1 and 2 showed “defects” due to microcracks occurring.
굽힘 시험 평가결과를 참조할 때, K1(구리 함량비)와 K2(주석 함량비)의 최댓값이 각각 0.16 및 0.016 이상일 때, 굽힘 특성이 급격하게 저하되었다.Referring to the bending test evaluation results, when the maximum values of K1 (copper content ratio) and K2 (tin content ratio) were more than 0.16 and 0.016, respectively, the bending properties rapidly deteriorated.
[전처리 특성 평가결과][Pre-treatment characteristics evaluation results]
표 2 및 도 4를 참조하면, 실시예 1 ~ 6에 따른 열연 강판은 전처리 특성평가에서 "양호"를 보였다. 이와 비교하여, 비교예 1 ~ 4에 따른 열연 강판은 전처리 특성 평가에서 "불량"을 보였다.Referring to Table 2 and Figure 4, the hot rolled steel sheets according to Examples 1 to 6 showed "good" in the pretreatment characteristic evaluation. In comparison, the hot rolled steel sheets according to Comparative Examples 1 to 4 showed “defect” in pretreatment characteristic evaluation.
전처리 특성 평가결과를 참조할 때, 구리 함량비의 최댓값과 주석 함량비의 최댓값이 각각 0.13과 0.013 이상일 때, 열연 강판의 표면에 형성된 피막의 결정 입자의 크기가 불균해지는 것을 확인하였다.When referring to the pretreatment characteristic evaluation results, it was confirmed that when the maximum value of the copper content ratio and the maximum value of the tin content ratio were 0.13 and 0.013 or more, respectively, the size of the crystal grains of the film formed on the surface of the hot rolled steel sheet became uneven.
[도장성 평가 중 부착성 평가][Adhesion evaluation during paintability evaluation]
표 2 및 도 5를 참조할 때, 참조하면, 실시예 1 ~ 6에 따른 열연 강판은 부착성 평가에서 M-1 등급(양호)을 보였다. 이와 비교하여, 비교예 1 ~ 4에 따른 열연 강판은 부착성 평가에서 M-3 등급(불량)이나 M-2 등급(불량)을 보였다.Referring to Table 2 and Figure 5, the hot rolled steel sheets according to Examples 1 to 6 showed an M-1 grade (good) in the adhesion evaluation. In comparison, the hot rolled steel sheets according to Comparative Examples 1 to 4 showed a grade of M-3 (poor) or M-2 (poor) in the adhesion evaluation.
부착성 평가 결과를 볼 때, K1(구리 함량비)와 K2(주석 함량비)의 최댓값이 각각 0.13, 0.013 이상일 때, 열연 강판과 도장면 사이의 결합 강도가 급격히 저하되는 것을 확인하였다. Looking at the adhesion evaluation results, it was confirmed that when the maximum values of K1 (copper content ratio) and K2 (tin content ratio) were 0.13 and 0.013 or more, respectively, the bond strength between the hot rolled steel sheet and the painted surface rapidly decreased.
[도장성 평가 중 내충격성 평가][Impact resistance evaluation during paintability evaluation]
표 2 및 도 6를 참조할 때, 실시예 1 ~ 6에 따른 열연 강판은 내충격성 평가에서 "양호"를 보였으나, 비교예 1 ~ 4에 따른 열연 강판은 내충격성 평가에서 "불량"을 보였다.Referring to Table 2 and Figure 6, the hot rolled steel sheets according to Examples 1 to 6 showed "good" in the impact resistance evaluation, but the hot rolled steel sheets according to Comparative Examples 1 to 4 showed "poor" in the impact resistance evaluation. .
부착성 평가 결과를 볼 때, K1(구리 함량비)와 K2(주석 함량비)의 최댓값이 각각 0.13, 0.013 이상일 때, 열연 강판의 도장면의 내충격성이 급격히 저하되는 것을 확인하였다.Looking at the adhesion evaluation results, it was confirmed that when the maximum values of K1 (copper content ratio) and K2 (tin content ratio) were 0.13 and 0.013 or more, respectively, the impact resistance of the painted surface of the hot rolled steel sheet rapidly decreased.
[용접성 평가][Weldability evaluation]
표 2 및 도 7을 참조할 때, 실시예 1 ~ 6에 따른 열연 강판은 "양호"를 보였으나, 비교예 1 ~ 4에 따른 열연 강판은 용착량이 부족하거나 용락이 발생하였다.Referring to Table 2 and Figure 7, the hot rolled steel sheets according to Examples 1 to 6 showed “good” results, but the hot rolled steel sheets according to Comparative Examples 1 to 4 had insufficient welding or melting occurred.
용접성 평가 결과를 볼 때, K1(구리 함량비)와 K2(주석 함량비)의 최댓값이 각각 0.16, 0.016 이상할 때, 열연 강판의 용접성이 급격하게 저하되는 것을 확인하였다.Looking at the weldability evaluation results, it was confirmed that when the maximum values of K1 (copper content ratio) and K2 (tin content ratio) were more than 0.16 and 0.016, respectively, the weldability of the hot rolled steel sheet deteriorated rapidly.
결론적으로 본 발명의 실시예들에 따른 열연 강판은 굽힘 시험 평가, 전처리 특성평가, 도장성 평가 및 용접성 평가에서 모두 우수한 특성을 보였으나, 비교예들에 따른 열연 강판은 상기 평가 항목들 중 적어도 하나 이상에서 불량이 발생하였다.In conclusion, the hot rolled steel sheets according to the embodiments of the present invention showed excellent characteristics in all bending test evaluations, pretreatment characteristic evaluations, paintability evaluations, and weldability evaluations, but the hot rolled steel sheets according to the comparative examples had at least one of the above evaluation items. A defect occurred in the above situation.
본 발명에 따른 차량용 부품Vehicle parts according to the present invention
본 발명에 따른 차량용 부품은 전술한 본 발명의 실시 예에 따른 열연 강판을 이용해 제조된다. 예컨대, 차량용 부품은 로워암(lower arm)일 수 있다. 다만, 차량용 부품의 종류가 이에 한정되는 것은 아니며, 열연 강판을 이용해 상용차 프레임, 특장차 부품, 승용차 부품 등을 제조할 수도 있다.Vehicle parts according to the present invention are manufactured using hot rolled steel sheets according to the above-described embodiments of the present invention. For example, the vehicle part may be a lower arm. However, the types of vehicle parts are not limited to this, and hot rolled steel sheets can be used to manufacture commercial vehicle frames, special purpose vehicle parts, and passenger car parts.
표 3은 표 1에 기재된 실시예 1 ~ 6 및 비교예 1 ~ 4에 따른 열연 강판을 가공하여 제조된 로워암들의 펀치 가공성과 와이어 가공성 평가를 나타낸다. 도 8은 표 3의 평가결과를 설명하기 위한 도면이다.Table 3 shows the evaluation of punch machinability and wire machinability of lower arms manufactured by processing hot rolled steel sheets according to Examples 1 to 6 and Comparative Examples 1 to 4 shown in Table 1. Figure 8 is a diagram for explaining the evaluation results in Table 3.
Figure PCTKR2023010559-appb-img-000003
Figure PCTKR2023010559-appb-img-000003
표 3 및 도 8에 따르면, 실시예 1 ~ 6 및 비교예 3 ~ 4에 따른 로워암은 펀치 가공성 평가와 와이어 가공성 평가에서 "양호"를 보였다. 다만, 비교예 1 및 2에 따른 로워암은 가공성 평가와 와이어 가공성 평가에서 "불량"을 보였다.According to Table 3 and Figure 8, the lower arms according to Examples 1 to 6 and Comparative Examples 3 to 4 showed "good" in the punch machinability evaluation and wire machinability evaluation. However, the lower arms according to Comparative Examples 1 and 2 showed “defect” in the machinability evaluation and wire machinability evaluation.
이러한 이유는 열연 강판에 함유된 구리 및 주석의 함량비 각각이 0.13 및 0.013을 초과하여 부품 가공성이 저하된 것으로 생각된다.The reason for this is thought to be that the content ratio of copper and tin contained in the hot rolled steel sheet exceeds 0.13 and 0.013, respectively, resulting in a decrease in part processability.
이상과 같이 본 발명에 따른 바람직한 실시예를 살펴보았으며, 앞서 설명된 실시예 이외에도 본 발명이 그 취지나 범주에서 벗어남이 없이 다른 특정 형태로 구체화될 수 있다는 사실은 해당 기술에 통상의 지식을 가진 이들에게는 자명한 것이다.As described above, preferred embodiments according to the present invention have been examined, and the fact that the present invention can be embodied in other specific forms in addition to the embodiments described above without departing from the spirit or scope thereof is recognized by those skilled in the art. It is self-evident to them.
즉, 상술된 실시예는 제한적인 것이 아니라 예시적인 것으로 여겨져야 하고, 이에 따라 본 발명은 상술한 설명에 한정되지 않고 첨부된 청구항의 범주 및 그 동등 범위 내에서 변경될 수도 있다.That is, the above-described embodiments should be considered illustrative rather than restrictive, and accordingly, the present invention is not limited to the above description and may be modified within the scope of the appended claims and their equivalents.

Claims (20)

  1. 용탕을 제조하는 단계;Preparing molten metal;
    반제품을 제조하는 단계; 및manufacturing semi-finished products; and
    열연 강판을 제조하는 단계를 포함하고,Including manufacturing a hot rolled steel sheet,
    상기 용탕의 원료는 용선 X 중량%, 직접환원철 Y 중량% 및 철 스크랩 Z 중량%를 포함하고,The raw materials of the molten metal include X weight% of molten iron, Y weight% of direct reduced iron, and Z weight% of iron scrap,
    상기 열연 강판은 K1 중량% 이하의 구리(Cu)를 포함하고,The hot rolled steel sheet contains copper (Cu) of less than K1% by weight,
    상기 X, Y, Z 및 K1은 식 1 및 식 2를 만족하는 열연 강판을 제조하는 방법:A method of manufacturing a hot rolled steel sheet where X, Y, Z and K1 satisfy Equations 1 and 2:
    [식 1][Equation 1]
    (a1 × X + a2 × Y +a3 × Z)/(X +Y + Z) = K1(a1 × X + a2 × Y +a3 × Z)/(X +Y + Z) = K1
    [식 2][Equation 2]
    K1 ≤ 0.12K1 ≤ 0.12
    상기 식 1에서 a1, a2 및 a3 각각은 용선의 구리 함량비(중량%), 직접환원철의 구리 함량비(중량%) 및 철 스크랩의 구리 함량비(중량%)를 의미한다.In Equation 1, a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap.
  2. 제1 항에 있어서,According to claim 1,
    상기 X + Y + Z = 100 인 열연 강판을 제조하는 방법.A method of manufacturing a hot rolled steel sheet where X + Y + Z = 100.
  3. 제1 항에 있어서,According to claim 1,
    a1 ≤ 0.03;a1 ≤ 0.03;
    a2 ≤ 0.02;a2 ≤ 0.02;
    a3 ≤ 0.18;a3 ≤ 0.18;
    인 열연 강판을 제조하는 방법.Method for manufacturing hot rolled steel sheet.
  4. 제1 항에 있어서,According to claim 1,
    상기 열연 강판은 K2 중량% 이하의 주석(Sn)을 포함하고,The hot rolled steel sheet contains tin (Sn) of less than or equal to K2% by weight,
    X, Y, Z 및 K2는 식 3 및 식 4를 만족하는 열연 강판을 제조하는 방법:X, Y, Z and K2 are a method of manufacturing a hot rolled steel sheet that satisfies Equations 3 and 4:
    [식 3][Equation 3]
    (b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) = K2(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) = K2
    [식 4][Equation 4]
    K2 ≤ 0.012K2 ≤ 0.012
    상기 식 3에서 b1, b2 및 b3 각각은 용선의 주석 함량비(중량%), 직접환원철의 주석 함량비(중량%) 및 철 스크랩의 주석 함량비(중량%)를 의미한다.In Equation 3, b1, b2, and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap.
  5. 제4 항에 있어서,According to clause 4,
    b1 ≤ 0.003;b1 ≤ 0.003;
    b2 ≤ 0.002;b2 ≤ 0.002;
    b3 ≤ 0.018;b3 ≤ 0.018;
    인 열연 강판을 제조하는 방법.Method for manufacturing hot rolled steel sheet.
  6. 제1 항에 있어서,According to claim 1,
    20 ≤ X ≤ 60인 열연 강판을 제조하는 방법.Method for manufacturing hot rolled steel sheet with 20 ≤ X ≤ 60.
  7. 제1 항에 있어서,According to claim 1,
    10 ≤ Y ≤ 40인 열연 강판을 제조하는 방법.Method for manufacturing hot rolled steel sheet with 10 ≤ Y ≤ 40.
  8. 제1 항에 있어서,According to claim 1,
    20 ≤ Z ≤ 60인 열연 강판을 제조하는 방법.Method for manufacturing hot rolled steel sheet with 20 ≤ Z ≤ 60.
  9. 제1 항에 있어서,According to claim 1,
    상기 용탕을 생산하는 단계는 전기로를 이용해 상기 원료를 용해하는 열연 강판을 제조하는 방법.The step of producing the molten metal is a method of manufacturing a hot rolled steel sheet by melting the raw material using an electric furnace.
  10. 중량% 기준으로, 탄소: 0.07 ~ 0.12 %, 규소: 0.3 ~ 0.8 %, 망간: 1.5 ~ 2.0 %, 인: 0.02 % 이하, 황: 0.005 % 이하, 구리: 0.12 % 이하(0 제외), 주석: 0.012 % 이하(0 제외), 잔부 철(Fe) 및 불가피적 불순물을 포함하는 열연 강판이되,By weight percent, Carbon: 0.07 to 0.12 %, Silicon: 0.3 to 0.8 %, Manganese: 1.5 to 2.0 %, Phosphorus: 0.02 % or less, Sulfur: 0.005 % or less, Copper: 0.12 % or less (excluding 0), Tin: It is a hot rolled steel sheet containing 0.012% or less (excluding 0), remaining iron (Fe) and inevitable impurities,
    상기 열연 강판은 용선 X 중량%, 직접환원철 Y 중량% 및 철 스크랩 Z 중량%를 용해시켜 제조되고,The hot-rolled steel sheet is manufactured by dissolving X weight% of molten iron, Y weight% of direct reduced iron, and Z weight% of iron scrap,
    상기 X, Y 및 Z는 식 1을 만족하는 열연 강판:X, Y and Z are hot rolled steel sheets that satisfy Equation 1:
    [식 1][Equation 1]
    (a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) ≤ 0.12(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) ≤ 0.12
    상기 식 1에서 a1, a2 및 a3 각각은 용선의 구리 함량비(중량%), 직접환원철의 구리 함량비(중량%) 및 철 스크랩의 구리 함량비(중량%)를 의미한다.In Equation 1, a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap.
  11. 제10 항에 있어서,According to claim 10,
    상기 X + Y + Z = 100 인 열연 강판.A hot rolled steel sheet where X + Y + Z = 100.
  12. 제10 항에 있어서,According to claim 10,
    a1 ≤ 0.03;a1 ≤ 0.03;
    a2 ≤ 0.02;a2 ≤ 0.02;
    a3 ≤ 0.18;a3 ≤ 0.18;
    인 열연 강판.phosphorus hot rolled steel plate.
  13. 제10 항에 있어서,According to claim 10,
    X, Y 및 Z는 식 2를 만족하는 열연 강판:X, Y and Z are hot rolled steel sheets that satisfy Equation 2:
    [식 2][Equation 2]
    (b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) ≤ 0.012(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) ≤ 0.012
    상기 식 2에서 b1, b2 및 b3 각각은 용선의 주석 함량비(중량%), 직접환원철의 주석 함량비(중량%) 및 철 스크랩의 주석 함량비(중량%)를 의미한다.In Equation 2, b1, b2, and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap.
  14. 제13 항에 있어서,According to claim 13,
    b1 ≤ 0.003;b1 ≤ 0.003;
    b2 ≤ 0.002;b2 ≤ 0.002;
    b3 ≤ 0.018;b3 ≤ 0.018;
    인 열연 강판.phosphorus hot rolled steel plate.
  15. 제13 항에 있어서,According to claim 13,
    20 ≤ X ≤ 60;20 ≤ X ≤ 60;
    10 ≤ Y ≤ 40;10 ≤ Y ≤ 40;
    20 ≤ Z ≤ 60;20 ≤ Z ≤ 60;
    인 열연 강판.phosphorus hot rolled steel plate.
  16. 제10 항에 있어서,According to claim 10,
    상기 열연 강판은 크롬(Cr), 니오븀(Nb), 티타늄(Ti) 및 보론(B) 중 하나 이상의 원소를 더 포함하는 열연 강판.The hot rolled steel sheet further contains one or more elements selected from chromium (Cr), niobium (Nb), titanium (Ti), and boron (B).
  17. 중량% 기준으로, 탄소: 0.07 ~ 0.12 %, 규소: 0.3 ~ 0.8 %, 망간: 1.5 ~ 2.0 %, 인: 0.02 % 이하, 황: 0.005 % 이하, 구리: 0.12 % 이하(0 제외), 주석: 0.012 % 이하(0 제외), 잔부 철(Fe) 및 불가피적 불순물을 포함하는 차량용 부품이되,By weight percent, Carbon: 0.07 to 0.12 %, Silicon: 0.3 to 0.8 %, Manganese: 1.5 to 2.0 %, Phosphorus: 0.02 % or less, Sulfur: 0.005 % or less, Copper: 0.12 % or less (excluding 0), Tin: Vehicle parts containing 0.012% or less (excluding 0), remaining iron (Fe) and inevitable impurities,
    상기 차량용 부품의 모재는 용선 X 중량%, 직접환원철 Y 중량% 및 철 스크랩 Z 중량%를 용해시켜 제조되고,The base material of the vehicle parts is manufactured by dissolving X% by weight of molten iron, Y% by weight of direct reduced iron, and Z% by weight of iron scrap,
    상기 X, Y 및 Z는 식 1을 만족하는 차량용 부품:The X, Y and Z are vehicle parts that satisfy Equation 1:
    [식 1][Equation 1]
    (a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) ≤ 0.12(a1 × X + a2 × Y + a3 × Z)/(X +Y + Z) ≤ 0.12
    상기 식 1에서 a1, a2 및 a3 각각은 용선의 구리 함량비(중량%), 직접환원철의 구리 함량비(중량%) 및 철 스크랩의 구리 함량비(중량%)를 의미하고, a1 ≤ 0.03, a2 ≤ 0.02, a3 ≤ 0.18 이다.In Equation 1, a1, a2, and a3 each mean the copper content ratio (% by weight) of molten iron, the copper content ratio (% by weight) of direct reduced iron, and the copper content ratio (% by weight) of iron scrap, a1 ≤ 0.03, a2 ≤ 0.02, a3 ≤ 0.18.
  18. 제17 항에 있어서,According to claim 17,
    상기 X + Y + Z = 100 인 차량용 부품.Vehicle parts where X + Y + Z = 100.
  19. 제17 항에 있어서,According to claim 17,
    X, Y 및 Z는 식 2를 만족하는 차량용 부품:X, Y and Z are vehicle parts that satisfy Equation 2:
    [식 2][Equation 2]
    (b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) ≤ 0.012(b1 × X + b2 × Y + b3 × Z)/(X +Y + Z) ≤ 0.012
    상기 식 2에서 b1, b2 및 b3 각각은 용선의 주석 함량비(중량%), 직접환원철의 주석 함량비(중량%) 및 철 스크랩의 주석 함량비(중량%)를 의미하고, b1 ≤ 0.003, b2 ≤ 0.002, b3 ≤ 0.018 이다.In Equation 2, b1, b2 and b3 each mean the tin content ratio (% by weight) of molten iron, the tin content ratio (% by weight) of direct reduced iron, and the tin content ratio (% by weight) of iron scrap, b1 ≤ 0.003, b2 ≤ 0.002, b3 ≤ 0.018.
  20. 제17 항에 있어서,According to claim 17,
    20 ≤ X ≤ 60;20 ≤ X ≤ 60;
    10 ≤ Y ≤ 40;10 ≤ Y ≤ 40;
    20 ≤ Z ≤ 60;20 ≤ Z ≤ 60;
    인 차량용 부품.In-vehicle parts.
PCT/KR2023/010559 2022-10-28 2023-07-21 Hot rolled steel sheet, part for vehicle, and method for manufacturing same WO2024090727A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08239704A (en) * 1995-01-06 1996-09-17 Nippon Steel Corp Method for charging raw material in blast furnace
JP2000038612A (en) * 1998-07-17 2000-02-08 Mitsubishi Heavy Ind Ltd Production of molten steel
JP2002249824A (en) * 2001-02-23 2002-09-06 Sumitomo Metal Ind Ltd Method for producing hot rolled steel
JP2010209383A (en) * 2009-03-09 2010-09-24 Jfe Steel Corp Method for producing steel by converter
WO2020080553A1 (en) * 2018-10-19 2020-04-23 日本製鉄株式会社 Hot-rolled steel sheet and method for manufacturing same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08239704A (en) * 1995-01-06 1996-09-17 Nippon Steel Corp Method for charging raw material in blast furnace
JP2000038612A (en) * 1998-07-17 2000-02-08 Mitsubishi Heavy Ind Ltd Production of molten steel
JP2002249824A (en) * 2001-02-23 2002-09-06 Sumitomo Metal Ind Ltd Method for producing hot rolled steel
JP2010209383A (en) * 2009-03-09 2010-09-24 Jfe Steel Corp Method for producing steel by converter
WO2020080553A1 (en) * 2018-10-19 2020-04-23 日本製鉄株式会社 Hot-rolled steel sheet and method for manufacturing same

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