CN115386782A - Low-cost high-strength galvanized sheet and manufacturing process of sandwich board thereof - Google Patents
Low-cost high-strength galvanized sheet and manufacturing process of sandwich board thereof Download PDFInfo
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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
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- 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
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Abstract
The invention discloses a manufacturing process of a low-cost high-strength galvanized sheet, which is characterized in that molten iron is desulfurized, and S is controlled to be less than or equal to 0.002 percent; smelting in an electric furnace or a converter, and refining molten steel; controlling the superheat degree of the tundish molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm, and the blank drawing speed at 3.0-6.0 m/min; after descaling, the steel plate enters a soaking pit and dephosphorization is carried out again before entering a rolling mill; the thickness of a finish rolling outlet is 1.8-2.3 mm; finishing the rolling at 840-900 ℃, carrying out laminar cooling, and cooling the rolled strip steel to a 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 acid-washed coil into a hard-rolled coil by a reversible single frame, wherein the thickness of the hard-rolled coil is 0.25-0.35 mm; the surface of the hard rolled coil is cleaned and then enters an annealing furnace, the process comprises preheating, soaking, zinc pot entering and final cooling of strip steel, the heating speed of the preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the zinc pot entering temperature 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 percent, and the residual oxygen is 1-20 ppm.
Description
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 buildings, and has good fireproof, heat insulation and sound insulation effects. The metal surface sandwich board is characterized in that a layer of core material is filled between two layers of metal plates, and different core materials and sandwich boards with different plate-type metal surfaces are combined, so that the sandwich board can be respectively suitable for different building requirements, and comprises multiple building fields such as industrial plants, public buildings, combined houses, purification engineering and the like. The metal surface material of the metal surface sandwich plate can adopt 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 better than the materials such as the aluminum materials in the aspect of light weight of the sandwich plate, so that the light weight building application of the galvanized plates is limited to a certain extent.
For the metal surface sandwich board, the weight of the surface material accounts for about 50 percent of the total weight, the thickness of the galvanized sheet which is mainly applied at present is 0.5-0.8 mm, the strength is concentrated at 270-300 MPa, and a high-strength thinning space exists. By means of high-strength thinning of the surface material of the metal surface sandwich board, the light weight of the sandwich board is realized under the condition that the performance of the sandwich board is not reduced. Meanwhile, the sandwich board industry is sensitive to price, so a low-cost scheme is required to be adopted for high strengthening of the metal surface sandwich board surface material.
The invention adopts the low-cost high-strength galvanized sheet as the surface material of the sandwich panel, and is matched with the improved sandwich panel manufacturing process, thereby realizing the lightweight of the sandwich panel, and being an innovative invention which can bring economic benefits and can be popularized in large-scale market.
CN101956126A discloses a cold-base high-strength galvanized sheet and a production method thereof, wherein the chemical component ratio 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 percent; and Als:0.015 to 0.030 percent. The Mn content (0.65-0.85%) in the component design is higher, the production cost of each ton of steel is increased, and meanwhile, the welding performance of the steel strip is influenced due to the high C and Mn contents.
CN101348880A discloses a production method of a structural high-strength galvanized sheet, which comprises the following chemical components: 0.16 to 0.20 percent; mn:0.9 to 1.1 percent; si is less than or equal to 0.05 percent; p is less than or equal to 0.020%; s is less than or equal to 0.020%; and 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 meanwhile, the welding performance of the steel strip is influenced due to the high contents of C and Mn.
CN106756521A discloses a production process of a hot-dip galvanized plate for a high-strength structure, which comprises the following chemical components: 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, has high content (0.05-0.10% of Ni and 0.08-0.12% of Cr), has high Ni and Cr alloy cost, and increases the cost of steel per ton.
CN112226681A discloses a low-cost high-strength galvanized sheet SGC570 for a structure and a production method thereof, wherein the chemical component ratio of the SGC570 is as follows: 0.03 to 0.05%, si: less than or equal to 0.03 percent, mn:0.15 to 0.25%, P: less than or equal to 0.020%, S: less than or equal to 0.010%, alt:0.020 to 0.050%, ca:0.0008 to 0.0020 percent, and the balance of Fe and inevitable impurities, the invention has low content of C and Ca in the component design, and the elongation is inevitably low by adopting low-temperature annealing in the process flow.
At present, the thickness of the galvanized plate of the sandwich plate taking the galvanized plate as the panel is 0.5-0.8 mm, the strength is concentrated at 270-300 MPa, and the weight accounts for more than half of the weight of the finished sandwich plate. By reducing the thickness of the metal panel of the sandwich board, the weight of the sandwich board can be effectively reduced, and the light weight is realized. However, the thickness of the metal panel is reduced, which increases the processing difficulty, for example, the problem of easy crease is easy to occur, and the strength of the sandwich panel is reduced, so the strength must be improved while the thickness of the metal panel is reduced. However, the strength of the metal panel is increased too high, which causes difficulty in forming the sandwich panel in the production process.
The technical problem to be solved urgently is to ensure the strength and the processing performance of the metal surface of the sandwich plate while realizing light weight and reducing cost.
Disclosure of Invention
The invention aims to provide a manufacturing process of a high-strength galvanized plate for a metal surface sandwich plate, which ensures the strength and the processing performance while realizing light weight and reducing cost, the yield strength of the obtained high-strength galvanized plate is not less than 380MPa, the tensile strength is not less than 420MPa, and the elongation is not less than 12%, and the strength of the galvanized plate can be further improved in a baking process of sandwich plate processing, so that the yield strength is not less than 420MPa, the tensile strength is not less than 460MPa, and the elongation is not less than 8%.
In order to achieve the purpose, the technical scheme is as follows:
a manufacturing process of a low-cost high-strength galvanized plate comprises the following steps:
(1) Steel making: desulfurizing the 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 tundish molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm, and the blank drawing speed at 3.0-6.0 m/min; after descaling, the steel plate enters a soaking pit and dephosphorization is carried out again before entering a rolling mill;
(4) Hot rolling: the thickness of a finish rolling outlet is 1.8-2.3 mm;
(5) Coiling: the finishing temperature of the final rolling is 840-900 ℃, laminar cooling is carried out, the rolled strip steel is cooled to the coiling temperature of 460-540 ℃, and a hot rolled coil is obtained;
(6) Acid washing: pickling the hot rolled coil by a pickling line to obtain a pickled coil;
(7) Cold rolling: rolling the acid-washed coil into a hard-rolled coil by a reversible single frame, wherein the thickness of the hard-rolled coil is 0.25-0.35 mm;
(8) Hot galvanizing: the surface of the hard rolled coil is cleaned and then enters an annealing furnace, the process comprises preheating, soaking, zinc pot entering and final cooling of strip steel, the heating speed of the preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the zinc pot entering temperature 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 percent, 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%, mn:0.45% -0.7%, si: less than or equal to 0.05 percent, als:0.030 to 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 inevitable impurities.
According to the scheme, in the step 3, the casting blank is subjected to descaling treatment before entering a soaking furnace, and the pressure of descaling water is controlled to be more than or equal to 200bar; the temperature of soaking and discharging is 1150-1200 ℃; and (3) descaling by high-pressure water before entering the rolling mill, and controlling the pressure of the descaling water to be more than or equal to 250bar.
According to the scheme, the first and second pass reduction rates are controlled to be more than or equal to 50% in the step 4.
According to the scheme, a reversible rolling mill is adopted in the step 7 for carrying out cold rolling for 4-7 passes, and the cold rolling reduction rate is 80-90%.
A manufacturing process of a sandwich board adopts the low-cost high-strength galvanized sheet as a metal surface layer; the method comprises the steps of 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 by weight percent: c:0.08 to 0.12%, mn:0.45% -0.7%, si: less than or equal to 0.05 percent, als:0.030 to 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 inevitable impurities.
C: carbon plays a role in improving the strength of steel through solid solution strengthening in steel, but the content is too high, a large amount of hard phases such as bainite and martensite are easily formed in the cooling process after finish rolling, the higher the content and the higher the strength are, and the plasticity and the formability of the steel plate are reduced, so the content of C in the steel is selected to be 0.08-0.12%.
Mn: manganese plays a role in solid solution strengthening, can reduce phase change driving force, enables a C curve to move to the right, improves the hardenability of steel, enlarges a gamma phase region, can reduce Ms points of the steel, is an important element obtained by matching high strength and high plasticity, and therefore, the content of the manganese is limited to be 0.45-0.7 percent.
Si: si is a solid solution strengthening element, which can significantly improve the strength of steel, but 2 FeO. SiO is easily formed on the surface of the steel plate during the hot rolling process with excessively high Si content 2 The (fayalite) oxide skin is not easy to remove by hot rolling descaling, and the content of Si is not too high, so that the content of Si is less than or equal to 0.05 percent in the invention.
And Als: al is a deoxidizer, and has an effect of reducing the oxygen content in steel and reducing inclusions in steel to improve the toughness of steel, but Al content is too high to easily form coarse AlN particles and reduce the toughness of steel, so that the Al content in the present invention is 0.030 to 0.060%.
P: p is an impurity element in steel, is easy to segregate in grain boundaries and affects the toughness of products, so the lower the content of P is, the better the content is, and the content of P is controlled to be below 0.020% according to an actual control level.
S: s is an impurity element in steel, is easy to generate segregation in a crystal boundary, forms low-melting-point sulfide with Fe and Mn in the steel, reduces cold bending, hole expansion and extensibility of the steel, and is fully removed during steel making and controlled to be below 0.002%.
The main production process points of the low-cost high-strength galvanized sheet are hot rolling coiling temperature and galvanizing annealing process. When the hot rolling coiling temperature is too high, the crystal grains of the cold rolling raw material coil are coarse, the strength is lower, and the strength of the final cold rolling product is reduced. The coiling temperature is too low, which not only has high requirement on the laminar cooling capability of a production line, but also is easy to tilt the head of the plate before coiling and is not beneficial to coiling, so the coiling temperature is controlled to be 460-540 ℃. In the galvanizing annealing process, the heating speed and the temperature of the heating section are mainly controlled, and the shape and the size of ferrite grains and the precipitation quantity and the size of carbide are controlled through the rapid heating of the heating section and the proper temperature of the soaking section, so that the mechanical property of the galvanized plate is controlled. In the invention, the heating speed of the heating section is 40-60 ℃/s, and the soaking temperature is 580-640 ℃.
The sandwich panel processing technology mainly comprises roll forming, core material filling, assembling and baking and the like, and a baking process is generally carried out after the sandwich panel is assembled, so that the inner part is coated with glue and cured. The invention further controls the carbide precipitation quantity and size of the metal panel of the sandwich board by controlling the baking temperature and time by utilizing the baking process, and improves the strength of the metal panel of the sandwich board, thereby improving the strength of the whole sandwich board. 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 plate with low cost, no microalloy element, yield strength of not less than 380MPa, tensile strength of not less than 420MPa, elongation of not less than 8%, thickness of 0.25-0.35 mm, and application in manufacturing metal surface sandwich plates.
The hot rolling adopts low-temperature coiling at 460-540 ℃, and the galvanizing annealing process controls the proper ferrite grain size and the carbide precipitation quantity and size through the rapid heating of the heating section and the proper soaking section temperature, thereby controlling the finished product performance of the galvanized sheet.
The sandwich board is processed, the baking process is utilized, the carbide precipitation quantity and size of the metal panel of the sandwich board are further controlled by controlling the baking temperature and time, the strength of the metal panel of the sandwich board is improved again, and therefore the strength of the whole sandwich board is improved.
Drawings
FIG. 1: example 1 hot rolled structures at different hot rolled coiling temperatures.
FIG. 2: comparative example 6 hot rolled structure at different hot rolled coiling temperatures.
FIG. 3: example 1 structure under different hot galvanizing annealing processes.
FIG. 4: comparative example 7 structure under different hot galvanizing annealing processes.
FIG. 5: and the structure of the comparative example 8 under different hot galvanizing annealing processes.
FIG. 6, example 1 tissue under different baking processes.
FIG. 7 is a schematic view of: comparative example 9 texture under different baking processes.
Detailed Description
The following examples further illustrate the technical solutions of the present invention, but should not be construed as limiting the scope of the present invention.
The specific embodiment provides a manufacturing process of a low-cost high-strength galvanized plate, which comprises the following steps:
(1) Steel making: desulfurizing the 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 tundish molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm, and the blank drawing speed at 3.0-6.0 m/min; after descaling, the steel plate enters a soaking pit and dephosphorization is carried out again before entering a rolling mill;
(4) Hot rolling: the thickness of a finish rolling outlet is 1.8-2.3 mm;
(5) Coiling: the finishing temperature of the final rolling is 840-900 ℃, laminar cooling is carried out, the rolled strip steel is cooled to the coiling temperature of 460-540 ℃, and a hot rolled coil is obtained;
(6) Acid washing: pickling the hot rolled coil by a pickling line to obtain a pickled coil;
(7) Cold rolling: rolling the acid-washed coil into a hard-rolled coil by a reversible single frame, wherein the thickness of the hard-rolled coil is 0.25-0.35 mm;
(8) Hot galvanizing: the surface of a hard roll is cleaned and then enters an annealing furnace, the process comprises preheating strip steel, soaking, zinc pot entering and final cooling, the heating speed of a preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the zinc pot entering temperature 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 rolling raw material coil are coarse, the strength is lower, and the strength of the final cold rolling product is reduced. The coiling temperature is too low, which not only has high requirement on the laminar cooling capability of a production line, but also is easy to tilt the head of the plate before coiling and is not beneficial to coiling, so the coiling temperature is controlled to be 460-540 ℃. In the galvanizing annealing process, the heating speed and the temperature of the heating section are mainly controlled, and the shape and the size of ferrite grains and the precipitation quantity and the size of carbide are controlled through the rapid heating of the heating section and the proper temperature of the soaking section, so that the mechanical property of the galvanized plate is controlled. In the invention, the heating speed of the heating section is 40-60 ℃/s, and the soaking temperature is 580-640 ℃.
Specifically, the molten steel refining chemical composition in the step 2 comprises the following components in percentage by weight: c:0.08 to 0.12%, mn: 0.45-0.7%, si: less than or equal to 0.05 percent, als:0.030 to 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 inevitable impurities.
Specifically, in the step 3, the casting blank is subjected to descaling treatment before entering the soaking furnace, and the pressure of descaling water is controlled to be more than or equal to 200bar; the temperature of soaking and discharging is 1150-1200 ℃; and (3) descaling by high-pressure water before entering the rolling mill, and controlling the pressure of the descaling water to be more than or equal to 250bar.
Specifically, the first and second pass reduction rates are controlled to be more than or equal to 50% in the step 4.
Specifically, in the step 7, a reversible mill is adopted to perform cold rolling for 4-7 passes, and the cold rolling reduction rate is 80-90%.
The specific embodiment also provides a manufacturing process of the sandwich board which uses the low-cost high-strength galvanized sheet as the metal surface layer; the method comprises the steps of 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 metal panel of the sandwich board by controlling the baking temperature and time, and the strength of the metal panel of the sandwich board is improved, so that the strength of the whole sandwich board is improved. The baking time is 1-3 min, and the baking temperature is 150-300 ℃.
Table 1 is a table of values of chemical components for each example and comparative example of the present invention.
Table 2 is a list of values of the main process parameters of the examples and comparative examples of the present invention.
Table 3 is a table of the performance tests of each example of the present invention and comparative example.
TABLE 1
| Numbering | 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
| Numbering | 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 the examples 1-5 in Table 3, the invention improves the strength of the metal panel of the sandwich board by the sandwich board production process with reasonable design matching of the components of the metal panel of the sandwich board and the production process, thereby providing a scheme for realizing the lightweight of the sandwich board by the high-strength thinning of the metal panel. The above examples are merely preferred examples and are not intended to limit the embodiments of the present invention.
FIGS. 1 and 2 are hot rolled structures of example 1 and comparative example 6 at different hot rolling coiling temperatures; the fine hot-rolled grain structure can be obtained at a lower coiling temperature, and the recrystallization in a galvanizing annealing process is facilitated to obtain a cold-rolled structure with refined grains according to the genetic characteristics of the structure, so that the strength and the elongation of the product are improved.
FIGS. 3, 4 and 5 show the structures of example 1 and comparative examples 7 and 8 under different hot galvanizing annealing processes; fig. 3 shows a recrystallized incomplete structure and the grains are not completely equiaxial, and fig. 4 and 5 show a completely recrystallized structure and the grains are completely equiaxial. After the crystal grains are completely equiaxed, the elongation percentage A% is improved, but the strength is obviously reduced. The part of the incompletely recrystallized structure is reserved, which is beneficial to improving the strength.
FIGS. 6 and 7 show that the structure of the example 1 and the comparative example 9 under different baking processes shows that the precipitated phases in the structure of FIG. 6 are in a strip distribution characteristic, the number is large, the size is mainly 40 nm-200 nm, the part is 200 nm-500 nm, and the type is carbide. FIG. 7 shows that the precipitated phases are in a band-shaped distribution, and are more in number, the size is mainly 200 nm-500 nm, the part is 40 nm-200 nm, and the type is carbide. Comparing fig. 6 and 7, a higher baking temperature and a longer baking time can obtain a smaller carbide distribution in the texture, thereby improving the strength of the product.
Claims (6)
1. The manufacturing process of the low-cost high-strength galvanized plate is characterized by comprising the following steps of:
(1) Steel making: desulfurizing the 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 tundish molten steel at 15-35 ℃, the thickness of a casting blank at 50-70 mm, and the blank drawing speed at 3.0-6.0 m/min; after descaling, the steel plate enters a soaking pit and dephosphorization is carried out again before entering a rolling mill;
(4) Hot rolling: the thickness of a finish rolling outlet is 1.8-2.3 mm;
(5) Coiling: finishing the rolling at 840-900 ℃, carrying out laminar cooling, and cooling the rolled strip steel to a 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 acid-washed coil into a hard-rolled coil by a reversible single frame, wherein the thickness of the hard-rolled coil is 0.25-0.35 mm;
(8) Hot galvanizing: the surface of the hard rolled coil is cleaned and then enters an annealing furnace, the process comprises preheating, soaking, zinc pot entering and final cooling of strip steel, the heating speed of the preheating section is 40-60 ℃/s, the soaking temperature is 580-640 ℃, the zinc pot entering temperature 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 percent, and the residual oxygen is 1-20 ppm.
2. The manufacturing process of the low-cost high-strength galvanized plate as claimed in claim 1, wherein the chemical composition of molten steel refining in the step 2 is as follows by weight percent: c:0.08 to 0.12%, mn:0.45% -0.7%, si: less than or equal to 0.05 percent, als:0.030 to 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 inevitable impurities.
3. The manufacturing process of the low-cost high-strength galvanized sheet according to claim 1, characterized in that the casting blank in the step 3 is subjected to descaling treatment before being put into a soaking furnace, and the pressure of descaling water is controlled to be more than or equal to 200bar; the temperature of soaking and discharging is 1150-1200 ℃; and (3) carrying out high-pressure water descaling before entering the rolling mill, and controlling the pressure of the descaling water to be more than or equal to 250bar.
4. The process for manufacturing the low-cost high-strength galvanized sheet according to claim 1, wherein the first and second pass reduction ratios in the step 4 are controlled to be not less than 50%.
5. The process for manufacturing low-cost high-strength galvanized sheet according to claim 1, wherein the reversible mill is used for cold rolling in step 7 for 4-7 passes, and the cold rolling reduction is 80-90%.
6. A sandwich panel manufacturing process is characterized in that the low-cost high-strength galvanized sheet as claimed in claim 1 is used as a metal surface layer; the method comprises the steps of roll forming, core material filling, assembling and baking; wherein the baking time is 1-3 min, and the baking temperature is 150-300 ℃.
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