CN115386782B - Low-cost high-strength galvanized sheet and manufacturing process of sandwich panel thereof - Google Patents

Low-cost high-strength galvanized sheet and manufacturing process of sandwich panel thereof Download PDF

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CN115386782B
CN115386782B CN202210985541.9A CN202210985541A CN115386782B CN 115386782 B CN115386782 B CN 115386782B CN 202210985541 A CN202210985541 A CN 202210985541A CN 115386782 B CN115386782 B CN 115386782B
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coil
rolled
temperature
rolling
equal
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CN115386782A (en
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陈一鸣
黄俊杰
孟庆格
胡宽辉
祝洪川
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Wuhan Iron and Steel Co Ltd
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Wuhan Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips
    • 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

Abstract

The invention discloses a manufacturing process of a low-cost high-strength galvanized sheet, which comprises the steps of desulfurizing molten iron and controlling S to be less than or equal to 0.002%; smelting in an electric furnace or a converter, and refining molten steel; controlling the superheat degree of the ladle molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm and the blank pulling speed at 3.0-6.0 m/min; after the descaling treatment, the steel enters a soaking pit, and phosphorus is removed again before entering a rolling mill; the thickness of the finish rolling outlet is 1.8-2.3 mm; the final rolling finishing temperature is 840-900 ℃, laminar cooling is carried out, and the rolled strip steel is cooled to the coiling temperature of 460-540 ℃ to obtain a hot rolled coil; pickling the hot rolled coil by a pickling line to obtain a pickled coil; rolling the pickling coil into a rolled hard coil by a reversible single stand, wherein the thickness of the rolled hard coil is 0.25-0.35 mm; cleaning the surface of the rolled hard coil, and then feeding the rolled hard coil into an annealing furnace, wherein the process comprises preheating strip steel, soaking, feeding the rolled hard coil into a zinc pot, final cooling, the heating speed of a preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the feeding temperature of the zinc pot is 480-500 ℃, the final cooling temperature is 140-160 ℃, the running speed of the strip steel is 80-120 m/min, the dew point in the annealing furnace is-20 to-50 ℃, the hydrogen content in the furnace is 1-10%, and the residual oxygen is 1-20 ppm.

Description

Low-cost high-strength galvanized sheet and manufacturing process of sandwich panel thereof
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a high-strength galvanized sheet.
Background
The sandwich board is a product commonly used in the current building, and has good fireproof, heat-insulating and sound-insulating effects. The metal surface sandwich board is a sandwich board formed by filling a layer of core material between two layers of metal plates, and combining different core materials with different plate-type metal surfaces, and can be respectively suitable for different building requirements, including a plurality of building fields of industrial plants, public buildings, combined houses, purification engineering and the like. The metal surface material of the metal surface sandwich panel can be made of various materials such as color-coated plates, galvanized plates, aluminum materials and the like, wherein the galvanized plates are widely applied due to low price, but the galvanized plates are not as light as the aluminum materials and the like in the aspect of sandwich panel weight, so that the galvanized plates are limited in the aspect of light building application.
For the sandwich panel material with metal surface, the weight of the sandwich panel material is about 50 percent of the total weight, the thickness of the galvanized sheet which is currently mainly used is 0.5-0.8 mm, the strength is concentrated at 270-300 MPa, and a high-strength thinning space exists. The metal surface sandwich panel surface material is thinned in a high strength way, so that the weight reduction of the sandwich panel is realized under the condition that the performance of the sandwich panel is not reduced. Meanwhile, the sandwich panel industry is sensitive to price, so that a low-cost scheme is required to be adopted for high reinforcement of the metal surface sandwich panel surface material.
The invention adopts the low-cost high-strength galvanized sheet as the sandwich panel surface material and matches with the improved sandwich panel manufacturing process, thereby realizing the light weight of the sandwich panel and being an innovative invention which can bring economic benefit and can be popularized in large-scale market.
CN101956126a discloses a cold-base high-strength galvanized sheet and a production method, the chemical composition ratio of which is C:0.17 to 0.23 percent; mn:0.65 to 0.85 percent; si: less than or equal to 0.15 percent; p: less than or equal to 0.015 percent; s: less than or equal to 0.012%; als:0.015 to 0.030 percent. The Mn content (0.65-0.85%) in the component design of the invention is higher, the production cost of ton steel is increased, and the welding performance of the steel belt is influenced by the high C, mn content.
CN101348880a discloses a method for producing high-strength galvanized sheet for structure, the chemical composition ratio is C:0.16 to 0.20 percent; mn:0.9 to 1.1 percent; si is less than or equal to 0.05%; p is less than or equal to 0.020%; s is less than or equal to 0.020%; als:0.02 to 0.06 percent. The Mn content (0.9-1.1%) in the component design of the invention is higher, the cost of ton steel is increased, and the welding performance of the steel belt is influenced by the high C, mn content.
CN106756521a discloses a production process of a hot dip galvanized sheet for a high-strength structure, and the chemical composition ratio of the hot dip galvanized sheet is C:0.08 to 0.20 percent; mn:0.25 to 0.60 percent; si:0.01 to 0.03 percent; p:0.02 to 0.04 percent; s:0.03 to 0.05 percent; ni:0.05 to 0.10 percent; cr:0.08 to 0.12 percent. The invention contains Ni element and Cr element in the component design, and has higher content (Ni 0.05-0.10 percent and Cr 0.08-0.12 percent), high cost of Ni and Cr alloy and increased ton steel cost.
CN112226681a discloses a low-cost high-strength galvanized sheet SGC570 for structure and its production method, the chemical composition ratio is C:0.03 to 0.05 percent, si: less than or equal to 0.03 percent, mn:0.15 to 0.25 percent, P: less than or equal to 0.020%, S: less than or equal to 0.010%, alt: 0.020-0.050%, ca: 0.0008-0.0020%, and the balance of Fe and unavoidable impurities, wherein the component of the invention has low C content and Ca element content, and the elongation is necessarily lower by adopting low-temperature annealing in the process flow.
The thickness of the galvanized sheet is 0.5-0.8 mm, the strength is concentrated at 270-300 MPa, and the weight of the galvanized sheet is more than half of that of the finished sandwich panel. The thickness of the metal panel of the sandwich panel is reduced, so that the weight of the sandwich panel can be effectively reduced, and the weight is reduced. However, the reduction in thickness of the metal panel increases the difficulty of processing, such as the tendency to crease, and reduces the strength of the sandwich panel, so that the strength must be increased while the thickness of the metal panel is reduced. However, the strength of the metal panel is improved too high, which results in difficult molding in the production process of the sandwich panel.
The metal surface of the sandwich plate realizes light weight and reduces cost, and meanwhile, the strength and the processing performance of the sandwich plate are guaranteed to be the technical problems to be solved urgently.
Disclosure of Invention
The invention aims to provide a manufacturing process of a high-strength galvanized sheet for a metal surface sandwich panel, which realizes light weight and cost reduction, ensures strength and processing performance, and ensures that the yield strength of the obtained high-strength galvanized sheet is equal to or greater than 380MPa, the tensile strength is equal to or greater than 420MPa, and the elongation is equal to or greater than 12 percent, and can further improve the strength of the galvanized sheet in a baking process for processing the sandwich panel, so that the yield strength is equal to or greater than 420MPa, the tensile strength is equal to or greater than 460MPa, and the elongation is equal to or greater than 8 percent.
In order to achieve the above purpose, the following technical scheme is adopted:
a manufacturing process of a low-cost high-strength galvanized sheet comprises the following steps:
(1) Steelmaking: desulfurizing molten iron, and controlling S to be less than or equal to 0.002%;
(2) Refining: smelting in an electric furnace or a converter, and refining molten steel;
(3) Continuous casting: controlling the superheat degree of the ladle molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm and the blank pulling speed at 3.0-6.0 m/min; after the descaling treatment, the steel enters a soaking pit, and phosphorus is removed again before entering a rolling mill;
(4) And (3) hot rolling: the thickness of the finish rolling outlet is 1.8-2.3 mm;
(5) And (3) coiling: the final rolling finishing temperature is 840-900 ℃, laminar cooling is carried out, and the rolled strip steel is cooled to the coiling temperature of 460-540 ℃ to obtain a hot rolled coil;
(6) Acid washing: pickling the hot rolled coil by a pickling line to obtain a pickled coil;
(7) Cold rolling: rolling the pickling coil into a rolled hard coil by a reversible single stand, wherein the thickness of the rolled hard coil is 0.25-0.35 mm;
(8) Hot galvanizing: cleaning the surface of the rolled hard coil, and then feeding the rolled hard coil into an annealing furnace, wherein the process comprises preheating strip steel, soaking, feeding the rolled hard coil into a zinc pot, final cooling, the heating speed of a preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the feeding temperature of the zinc pot is 480-500 ℃, the final cooling temperature is 140-160 ℃, the running speed of the strip steel is 80-120 m/min, the dew point in the annealing furnace is-20 to-50 ℃, the hydrogen content in the furnace is 1-10%, and the residual oxygen is 1-20 ppm.
According to the scheme, the molten steel refining chemical composition in the step 2 comprises the following components in percentage by weight: c:0.08 to 0.12 percent, mn:0.45% -0.7%, si: less than or equal to 0.05 percent, als: 0.030-0.060%, P: less than or equal to 0.020%, S: less than or equal to 0.002 percent, and the balance of Fe and unavoidable impurities.
According to the scheme, the casting blank in the step 3 is subjected to descaling treatment before being put into a soaking pit, and the pressure of the descaling water is controlled to be more than or equal to 200bar; the soaking tapping temperature is 1150-1200 ℃; and (3) high-pressure water is used for descaling before entering the rolling mill, and the pressure of the descaling water is controlled to be more than or equal to 250bar.
According to the scheme, the first-pass reduction rate and the second-pass reduction rate are controlled to be more than or equal to 50% in the step 4.
According to the scheme, in the step 7, a reversible rolling mill is adopted to perform cold rolling for 4-7 passes, and the cold rolling reduction is 80-90%.
The manufacturing process of the sandwich panel adopts the low-cost high-strength galvanized sheet as a metal surface layer; comprises roll forming, core material filling, assembling and baking; wherein the baking time is 1-3 min, and the baking temperature is 150-300 ℃.
The molten steel refining chemical composition of the invention comprises the following components in percentage by weight: c:0.08 to 0.12 percent, mn:0.45% -0.7%, si: less than or equal to 0.05 percent, als: 0.030-0.060%, P: less than or equal to 0.020%, S: less than or equal to 0.002 percent, and the balance of Fe and unavoidable impurities.
C: carbon plays a role in improving the strength of steel by solid solution strengthening, but the content is too high, a large amount of hard phases such as bainite, martensite and the like are easy to form in the cooling process after finish rolling, the content is higher, the strength is higher, the plasticity and the formability of the steel plate are reduced, and therefore, the C content in the steel is selected to be 0.08-0.12%.
Mn: manganese has the solid solution strengthening effect, can reduce the phase change driving force, enable the curve of 'C' to move right, improve the hardenability of steel, enlarge the gamma-phase region, and can reduce the Ms point of steel, and is an important element obtained by matching high strength with high plasticity, so the content of the manganese is limited to be in the range of 0.45-0.7%.
Si: si is a solid solution strengthening element, which can obviously improve the strength of steel, but 2 FeO.SiO is easy to form on the surface of the steel plate in the hot rolling process with excessively high Si content 2 (fayalite) oxide scale, hot rolling descaling is not easy to remove,the Si content should not be too high, so that the Si content in the present invention is 0.05% or less.
Als: al is a deoxidizer, reduces the oxygen content in steel and reduces inclusions in steel, thereby improving the toughness of the steel, but the Al content is too high, coarse AlN particles are easy to form, and the toughness of the steel is reduced, so that the Al content is 0.030-0.060 percent.
P: p is an impurity element in steel, tends to gather in grain boundaries and affects toughness of products, so that the lower the content is, the better the content is, and the content should be controlled to be less than 0.020% according to actual control level.
S: s is an impurity element in steel, is easy to generate segregation at a grain boundary, forms sulfide with Fe and Mn in the steel and has low melting point, reduces cold bending, reaming and extensibility of the steel, and is required to be sufficiently removed in steelmaking and controlled to be less than 0.002%.
The main production process point of the low-cost high-strength galvanized sheet is hot rolling coiling temperature and a galvanization annealing process. When the hot rolling coiling temperature is too high, the crystal grains of the cold-rolled raw material coil are coarse, the strength is low, and the strength of the final cold-rolled product is reduced. The coiling temperature is too low, so that the requirement on the laminar cooling capacity of the production line is high, and the plate head is easy to tilt before coiling, which is unfavorable for coiling, so that the coiling temperature is controlled to be 460-540 ℃. The heating speed and the soaking section temperature of the heating section are mainly controlled in the galvanization annealing process, and the shape and the size of ferrite grains and the precipitation quantity and the size of carbide are controlled by the rapid heating of the heating section and the proper soaking section temperature, so that the mechanical property of the galvanized sheet is controlled. The heating speed of the heating section is 40-60 ℃/s, and the soaking temperature is 580-640 ℃.
The sandwich board processing technology mainly comprises roll forming, core material filling, assembling baking and the like, and a baking technology is generally adopted after the assembly of the sandwich board is completed, so that the internal gluing is solidified. According to the invention, the baking temperature and time are controlled by utilizing the baking process, so that the carbide precipitation quantity and size of the sandwich panel metal panel are further controlled, and the strength of the sandwich panel metal panel is improved, thereby improving the strength of the whole sandwich panel. The baking time is 1-3 min, and the baking temperature is 150-300 ℃.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a high-strength galvanized sheet with low cost, no microalloy elements are added, the yield strength is not less than 380MPa, the tensile strength is not less than 420MPa, the elongation is not less than 8%, and the thickness is 0.25-0.35 mm, and the galvanized sheet is used for manufacturing a metal surface sandwich panel.
The hot rolling adopts 460-540 ℃ low-temperature coiling, and the hot rolling is performed by heating the galvanized sheet rapidly through a heating section and controlling the proper ferrite grain size, carbide precipitation quantity and size through proper soaking section temperature in the galvanization annealing process, so that the finished product performance of the galvanized sheet is controlled.
And the processing of the sandwich panel is finished, the baking temperature and time are controlled, the carbide precipitation quantity and size of the sandwich panel metal panel are further controlled, and the strength of the sandwich panel metal panel is improved again, so that the strength of the whole sandwich panel is improved, and the sandwich panel is light through high-strength thinning of the sandwich panel metal panel.
Drawings
Fig. 1: example 1 hot rolled structure at different hot rolling coiling temperatures.
Fig. 2: comparative example 6 hot rolled structures at different hot rolling coiling temperatures.
Fig. 3: example 1 structure under different hot dip galvannealing processes.
Fig. 4: comparative example 7 structure under different hot dip galvannealing processes.
Fig. 5: comparative example 8 structure under different hot dip galvannealing processes.
FIG. 6, example 1, tissue under different baking processes.
Fig. 7: comparative example 9 tissue under different baking processes.
Detailed Description
The following examples further illustrate the technical aspects of the present invention, but are not intended to limit the scope of the present invention.
The specific embodiment provides a manufacturing process of a low-cost high-strength galvanized sheet, which comprises the following steps:
(1) Steelmaking: desulfurizing molten iron, and controlling S to be less than or equal to 0.002%;
(2) Refining: smelting in an electric furnace or a converter, and refining molten steel;
(3) Continuous casting: controlling the superheat degree of the ladle molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm and the blank pulling speed at 3.0-6.0 m/min; after the descaling treatment, the steel enters a soaking pit, and phosphorus is removed again before entering a rolling mill;
(4) And (3) hot rolling: the thickness of the finish rolling outlet is 1.8-2.3 mm;
(5) And (3) coiling: the final rolling finishing temperature is 840-900 ℃, laminar cooling is carried out, and the rolled strip steel is cooled to the coiling temperature of 460-540 ℃ to obtain a hot rolled coil;
(6) Acid washing: pickling the hot rolled coil by a pickling line to obtain a pickled coil;
(7) Cold rolling: rolling the pickling coil into a rolled hard coil by a reversible single stand, wherein the thickness of the rolled hard coil is 0.25-0.35 mm;
(8) Hot galvanizing: cleaning the surface of the rolled hard coil, and then feeding the rolled hard coil into an annealing furnace, wherein the process comprises preheating strip steel, soaking, feeding the rolled hard coil into a zinc pot, final cooling, the heating speed of a preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the feeding temperature of the zinc pot is 480-500 ℃, the final cooling temperature is 140-160 ℃, the running speed of the strip steel is 80-120 m/min, the dew point in the annealing furnace is-20 to-50 ℃, the hydrogen content in the furnace is 1-10%, and the residual oxygen is 1-20 ppm.
When the hot rolling coiling temperature is too high, the crystal grains of the cold-rolled raw material coil are coarse, the strength is low, and the strength of the final cold-rolled product is reduced. The coiling temperature is too low, so that the requirement on the laminar cooling capacity of the production line is high, and the plate head is easy to tilt before coiling, which is unfavorable for coiling, so that the coiling temperature is controlled to be 460-540 ℃. The heating speed and the soaking section temperature of the heating section are mainly controlled in the galvanization annealing process, and the shape and the size of ferrite grains and the precipitation quantity and the size of carbide are controlled by the rapid heating of the heating section and the proper soaking section temperature, so that the mechanical property of the galvanized sheet is controlled. The heating speed of the heating section is 40-60 ℃/s, and the soaking temperature is 580-640 ℃.
Specifically, in the step 2, the chemical composition of molten steel refining is as follows by weight percent: c:0.08 to 0.12 percent, mn:0.45% -0.7%, si: less than or equal to 0.05 percent, als: 0.030-0.060%, P: less than or equal to 0.020%, S: less than or equal to 0.002 percent, and the balance of Fe and unavoidable impurities.
Specifically, in the step 3, the casting blank is subjected to descaling treatment before being put into a soaking pit, and the pressure of descaling water is controlled to be more than or equal to 200bar; the soaking tapping temperature is 1150-1200 ℃; and (3) high-pressure water is used for descaling before entering the rolling mill, and the pressure of the descaling water is controlled to be more than or equal to 250bar.
Specifically, in the step 4, the first-pass reduction rate and the second-pass reduction rate are controlled to be more than or equal to 50 percent.
Specifically, in the step 7, a reversible rolling mill is adopted to perform cold rolling for 4-7 passes, and the cold rolling reduction is 80-90%.
The specific embodiment also provides a manufacturing process of the sandwich panel by using the low-cost high-strength galvanized sheet as the metal surface layer; comprises roll forming, core material filling, assembling and baking; wherein the baking time is 1-3 min, and the baking temperature is 150-300 ℃. The baking process is utilized to further control the carbide precipitation quantity and size of the sandwich panel metal panel by controlling the baking temperature and time, and the strength of the sandwich panel metal panel is improved, so that the strength of the whole sandwich panel is improved. The baking time is 1-3 min, and the baking temperature is 150-300 ℃.
Table 1 shows the chemical component values of the examples and comparative examples of the present invention.
Table 2 shows a list of values of the main process parameters of each example and comparative example of the present invention.
Table 3 shows a list of performance test cases for each example of the present invention and comparative example.
TABLE 1
Numbering device C Si Mn P S Als
1 0.10609 0.01308 0.38218 0.015 0.00907 0.04771
2 0.1007 0.00952 0.37901 0.01296 0.00609 0.04973
3 0.10503 0.01152 0.37605 0.0149 0.00704 0.04621
TABLE 2
TABLE 3 Table 3
Numbering device RP0.2(MPa) Rm(MPa) A％
Example 1 434 488 12.2
Example 2 441 509 10.0
Example 3 427 478 14.9
Example 4 436 496 11.9
Example 5 443 513 9.06
Comparative example 6 401 445 19.9
Comparative example 7 417 458 21.4
Comparative example 8 359 413 25.5
Comparative example 9 412 467 14.8
As can be seen from examples 1-5 of Table 3, the present invention improves the strength of the metal panel of the sandwich panel by reasonably matching the components of the metal panel of the sandwich panel with the design of the production process, thereby providing a scheme for realizing the light weight of the sandwich panel by high-strength thinning of the metal panel. The above examples are only the best illustration and are not limiting of the embodiments of the invention.
FIGS. 1 and 2 show hot rolling structures of example 1 and comparative example 6 at different hot rolling coiling temperatures; the lower coiling temperature can obtain a fine hot-rolled grain structure, is favorable for recrystallization in a galvanization annealing process to obtain a grain-refined cold-rolled structure according to the genetic characteristics of the structure, and improves the strength and the elongation of the product.
FIGS. 3, 4 and 5 show the structure of example 1 and comparative examples 7 and 8 under different hot dip galvanising annealing processes; fig. 3 shows an incompletely recrystallized structure, grains are incompletely equiaxed, and fig. 4 and 5 show completely recrystallized structures, grains are completely equiaxed. After the crystal grains are completely equiaxed, the elongation A% is improved, but the strength is significantly reduced. The partially incompletely recrystallized structure is retained, which is beneficial to improving the strength.
Fig. 6 and 7 show the structures of example 1 and comparative example 9 under different baking processes, the precipitated phases of fig. 6 are in a band-shaped distribution characteristic, the number is large, the size is mainly 40 nm-200 nm, the part is 200 nm-500 nm, and the types are carbide. The precipitated phase in FIG. 7 is characterized by a band-like distribution, a large number of precipitated phases, the size of the precipitated phase is mainly 200 nm-500 nm, the size of the precipitated phase is partly 40 nm-200 nm, and the precipitated phase is carbide. Comparing fig. 6 and 7, a higher firing temperature and longer firing time can achieve a smaller carbide distribution in the tissue, thereby increasing product strength.

Claims (4)

1. The manufacturing process of the sandwich panel is characterized by comprising the following steps of:
(1) Steelmaking: desulfurizing molten iron, and controlling S to be less than or equal to 0.002%;
(2) Refining: smelting in an electric furnace or a converter, and refining molten steel; the chemical composition of the molten steel refining is as follows by weight percent: c: 0.08-0.12%, mn:0.45% -0.7%, si: less than or equal to 0.05 percent, als: 0.030-0.060%, P: less than or equal to 0.020%, S: less than or equal to 0.002 percent, and the balance of Fe and unavoidable impurities;
(3) Continuous casting: controlling the superheat degree of the ladle molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm, and the blank pulling speed at 3.0-6.0 m/min; after the descaling treatment, the steel is fed into a soaking pit, and is descaled again before being fed into a rolling mill;
(4) And (3) hot rolling: the thickness of the finish rolling outlet is 1.8-2.3 mm;
(5) And (3) coiling: the final rolling finishing temperature is 840-900 ℃, laminar cooling is carried out, and the rolled strip steel is cooled to the coiling temperature of 460-510 ℃ to obtain a hot rolled coil;
(6) Acid washing: pickling the hot rolled coil by a pickling line to obtain a pickled coil;
(7) Cold rolling: rolling the pickling coil into a rolled hard coil by a reversible single stand, wherein the thickness of the rolled hard coil is 0.25-0.35 mm;
(8) Hot galvanizing: cleaning the surface of a rolled hard coil, and then, feeding the rolled hard coil into an annealing furnace, wherein the process comprises preheating strip steel, soaking, feeding the rolled hard coil into a zinc pot, and finally cooling, the heating speed of a preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the feeding temperature of the zinc pot is 480-500 ℃, the final cooling temperature is 140-160 ℃, the running speed of the strip steel is 80-120 m/min, the dew point in the annealing furnace is-20 to-50 ℃, the hydrogen content in the furnace is 1-10%, and the residual oxygen is 1-20 ppm;
(9) The high-strength galvanized plate obtained in the step (8) is used as a metal surface layer, and is formed by rolling, filled with core materials, assembled and baked; wherein the baking time is 1-3 min, and the baking temperature is 150-300 ℃.
2. The manufacturing process of the sandwich panel according to claim 1, wherein in the step 3, the casting blank is subjected to descaling treatment before being put into a soaking pit, and the pressure of the descaling water is controlled to be more than or equal to 200bar; the soaking tapping temperature is 1150-1200 ℃; and (3) high-pressure water is used for descaling before entering the rolling mill, and the pressure of the descaling water is controlled to be more than or equal to 250bar.
3. The process for manufacturing the sandwich panel according to claim 1, wherein the first-pass reduction rate and the second-pass reduction rate are controlled to be more than or equal to 50% in the step 4.
4. The process for manufacturing the sandwich panel according to claim 1, wherein in the step 7, a reversible rolling mill is adopted to perform 4-7 passes of cold rolling, and the cold rolling reduction is 80-90%.
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