CN113718167A - Hot-dip aluminum-zinc steel plate with yield strength of 330MPa for liquid crystal backboard - Google Patents
Hot-dip aluminum-zinc steel plate with yield strength of 330MPa for liquid crystal backboard Download PDFInfo
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- C22C38/00—Ferrous alloys, e.g. steel alloys
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- C21D1/26—Methods of annealing
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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
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- 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
- C21D8/0221—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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- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/573—Continuous furnaces for strip or wire with cooling
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/003—Cementite
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Abstract
The invention discloses a hot-dip aluminum-zinc steel plate for a liquid crystal backboard with yield strength of 330MPa, which mainly solves the problem of 0.28-0.35mm of liquid in the prior artThe hot-dip aluminum-zinc steel plate for the crystal back plate has low strength and is distorted after processing and forming. The invention provides a hot-dip aluminum-zinc steel plate for a liquid crystal backboard with a yield strength of 330MPa, which comprises the following chemical components in percentage by weight: c: 0.09-0.11%, Si: 0-0.03%, Mn: 0.41-0.55%, P: 0-0.015%, S: 0-0.015%, Al: 0.01-0.03%, Mn/S is more than or equal to 40, and the balance is Fe and inevitable impurity elements. Yield strength R of hot-dip aluminum-zinc plated steel plateP0.2330 to 380MPa, elongation after break A80mm26-30%, and the yield strength range of the steel plate in the width direction is less than 8 MPa.
Description
Technical Field
The invention relates to a cold-rolled hot-dipped aluminum-zinc steel plate, in particular to a hot-dipped aluminum-zinc steel plate for a liquid crystal back plate with a yield strength of 330MPa, and specifically relates to a hot-dipped aluminum-zinc steel plate for manufacturing a back plate of a liquid crystal display with a thickness of 0.28-0.35mm and a manufacturing method thereof, belonging to the technical field of iron-based alloy.
Background
The hot-dip aluminum-zinc steel plate has better atmospheric corrosion resistance and heat resistance, has beautiful spangles on the surface, and is widely applied to the fields of buildings, household appliances and the like.
More and more electronic display screens in modern life and industry adopt a liquid crystal mode for display, and a component of the liquid crystal display for supporting the liquid crystal screen is a liquid crystal module which is divided into a module frame and a module backboard. The aluminum-zinc plated product is applied to a module backboard in a large amount due to the excellent performance, and the normal use specification is 0.5-0.6 mm. With the continuous upgrade of products, the development of low cost requires higher strength and thin gauge aluminum-zinc plated products to meet the backplane processing requirements. The module backplate course of working is more complicated, and the steel sheet realizes through slitting, cutting board and stamping forming, and the liquid crystal backplate product after the punching press has higher requirement to unevenness after the punching press, if take place the distortion after the punching press, the module backplate can contact with liquid crystal light source fluorescent tube when the assembly, damages the fluorescent tube.
Therefore, as the thickness of the backboard is reduced to 0.28-0.35mm, users need the aluminum-zinc plated product with yield strength of 330MPa and uniform performance to meet the rigidity requirement of the backboard, and meanwhile, the problem that the backboard is not distorted in the machining process is also met.
The application publication number CN101948981A discloses a hot-dip galvanized steel sheet, a manufacturing method and application thereof, and an LED liquid crystal television rear shell, mainly solving the problems that the product with a complex structure and large stretching is easy to crack, and the like, wherein the thickness of the hot-dip galvanized steel sheet is 0.6mm, and the requirement of material thinning cannot be met.
Chinese patent application publication No. CN105506469A discloses an anti-impact-distortion aluminum-zinc-plated steel and a manufacturing method thereof, mainly solving the technical problem that the existing aluminum-zinc-plated steel plate product is distorted in the stamping process. The technical scheme is as follows: an anti-impact-distortion aluminum-zinc-plated steel comprises the following chemical components in percentage by weight: c: 0.02 to 0.08%, Si: 0.01-0.03%, Mn: 0.10-0.4%, Al: 0.01-0.06%, P less than or equal to 0.015%, S less than or equal to 0.010%, and the balance of Fe and inevitable impurity elements. The die is suitable for a 0.5-0.6mm aluminum-zinc-plated steel plate for stamping 15-21-inch liquid crystal backboard modules, and can not meet the requirement of material thinning.
Chinese patent application publication No. CN106319354A discloses a medium-sized backboard stamping distortion resistant galvanized steel and a manufacturing method thereof, mainly solving the technical problem of distortion in the stamping process of a 22-29 inch liquid crystal backboard module, the substrate of the invention comprises the following chemical components (by weight percent): c: 0.010-0.019%, Si: 0.01-0.03%, Mn: 0.05 to 0.09%, Al: 0.01-0.06%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, B: 0.0010-0.0020%, and the balance of Fe and inevitable impurity elements. The method is suitable for 0.5-0.6mm galvanized steel sheets for stamping liquid crystal backboard modules, and can not meet the requirement of material thinning.
Chinese patent application publication No. CN106319354A discloses a medium-sized backboard stamping distortion resistant galvanized steel and a manufacturing method thereof, mainly solving the technical problem of distortion in the stamping process of a 22-29 inch liquid crystal backboard module, the substrate of the invention comprises the following chemical components (by weight percent): c: 0.010-0.019%, Si: 0.01-0.03%, Mn: 0.05 to 0.09%, Al: 0.01-0.06%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, B: 0.0010-0.0020%, and the balance of Fe and inevitable impurity elements. The method is suitable for 0.5-0.6mm galvanized steel sheets for stamping liquid crystal backboard modules, and can not meet the requirement of material thinning.
The application publication number CN108004464A discloses a hot-dip galvanized steel sheet for a large-size liquid crystal display back plate and a manufacturing method thereof, and mainly solves the technical problem that the existing hot-dip galvanized steel sheet is bulged and twisted in the process of stamping the 32-55 inch liquid crystal display back plate. The invention provides a hot-dip galvanized steel sheet for a large-size liquid crystal display back plate, which comprises the following chemical components in percentage by weight: c: 0.0005-0.0009%, Si: 0-0.03%, Mn: 0.05 to 0.12%, Ti: 0.02 to 0.04%, Nb: 0.0005-0.0009%, N is less than or equal to 0.0030%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, B: 0.0002 to 0.0004 percent of Fe and the balance of inevitable impurity elements. The hot-dip galvanized steel sheet meets the stamping processing requirement of a 32-55-inch liquid crystal display back plate, is suitable for a galvanized steel sheet with the thickness of 0.50-0.80 mm, and can not meet the thinning requirement of the material.
The prior cold-rolled hot-dipped aluminum-zinc steel plate of the liquid crystal backboard can not meet the requirement of a high-strength backboard with the thickness of 0.28-0.35 mm.
Disclosure of Invention
The invention aims to provide a hot-dip aluminum-zinc steel plate for a liquid crystal backboard with a yield strength of 330MPa and a manufacturing method thereof, mainly solves the technical problems that the hot-dip aluminum-zinc steel plate for the liquid crystal backboard with a yield strength of 0.28-0.35mm in the prior art is low in strength and is twisted after being processed and formed, and meets the forming and processing requirements of the liquid crystal module industry on the hot-dip aluminum-zinc steel plate for the liquid crystal backboard with a yield strength of 0.28-0.35 mm.
The invention adopts the technical idea that the low-carbon aluminum killed steel is adopted, the steel plate structure is regulated and controlled through a hot rolling process, a large compression ratio, cold rolling rapid annealing and cooling, so that the ferrite, free cementite and pearlite structures are obtained, the requirements of high yield and performance uniformity of materials are met, and the problem of stamping distortion of the hot-dip aluminum-zinc steel plate with the thin specification of 0.28-0.35mm is solved.
The invention adopts the technical scheme that a hot-dip aluminum-zinc steel plate for a liquid crystal backboard with a yield strength of 330MPa is characterized in that the base plate comprises the following chemical components in percentage by weight: c: 0.09-0.11%, Si: 0-0.03%, Mn: 0.41-0.55%, P: 0-0.015%, S: 0-0.015%, Al: 0.01-0.03%, Mn/S is more than or equal to 40, and the balance is Fe and inevitable impurity elements.
Further, the hot-dip aluminum-zinc plated steel plate of the invention has the following chemical components in percentage by weight: c: 0.105 to 0.11%, Si: 0-0.03%, Mn: 0.45-0.55%, P: 0-0.015%, S: 0-0.0050%, Al: 0.01-0.03%, Mn/S is more than or equal to 40, and the balance is Fe and inevitable impurity elements.
The invention relates to a hot-dip aluminum-zinc steel plateThe metallographic structure of the steel plate is ferrite, free cementite and pearlite, the grain size grade of the ferrite is I9.5-I10 grade, and the yield strength R of the hot-dip aluminum-zinc steel plate with the thickness of 0.28-0.35mmP0.2Is 330 to 380MPa, Rm385 to 425MPa, elongation after break A80 mm26-30%, and the yield strength range of the steel plate in the width direction is less than 8 MPa.
The reason why the chemical composition of the substrate of the hot-dip aluminum-zinc plated steel sheet for the liquid crystal back panel with the yield strength of 330MPa is limited to the above range is as follows:
carbon: the steel is treated with solid solution of strengthening elements to control the yield strength of the material, and the uniformity of the material is ensured while the material is strengthened, so that the carbon content is set to 0.09-0.11%, preferably 0.105-0.11%.
Silicon: the ferrite solid solution strengthening element and the addition of Si are not beneficial to the combination of a coating of hot-dip aluminum and zinc, so that silicon alloy is not added in the production and manufacturing process, the silicon alloy is a residual element, and the content of Si is designed to be 0-0.03%.
Manganese: in the invention, in order to obtain a steel plate with proper performance, a small amount of manganese is added to reduce the phase transformation point Ar3 of the material and ensure the uniformity of the material structure, and in order to obtain the product with high yield, the manganese content is set to be 0.41-0.55%, and preferably 0.45-0.55%.
Aluminum: the main purpose of adding Al into the steel is deoxidation, and from the perspective of reducing cost, Al: 0.01 to 0.03 percent.
Sulfur: s in the steel is an impurity element, and the cost of steel-making and desulphurization can be increased by excessively low S content. The technical scheme of the invention sets the S content to be 0-0.015%, and preferably the sulfur content to be 0-0.0050%.
Phosphorus: p in the steel is an impurity element, and the cost is increased due to the excessively low P content. The technical scheme of the invention sets the P content to be 0-0.015%.
Manganese to sulfur ratio: in order to obtain a more uniform yield strength in the sheet width direction, the manganese-sulfur ratio contributes to the uniformity of the structure. The ratio of the weight content of manganese to the weight content of sulfur in the steel is set to be more than or equal to 40, namely, Mn/S is more than or equal to 40.
The manufacturing method of the hot-dip aluminum-zinc steel plate for the liquid crystal backboard with the yield strength of 330MPa comprises the following steps:
continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following chemical components in percentage by weight: c: 0.09-0.11%, Si: 0-0.03%, Mn: 0.41-0.55%, P: 0-0.015%, S: 0-0.015%, Al: 0.01-0.03%, Mn/S is more than or equal to 40, and the balance is Fe and inevitable impurity elements;
heating the continuous casting plate blank to 1100-1150 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 830-840 ℃; the thickness of the finish-rolled steel plate is 2.8-3.0 mm, the laminar cooling adopts front-section cooling, and the coiling temperature is 610-630 ℃ to obtain a hot-rolled steel coil;
the hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing in a horizontal continuous annealing furnace, hot aluminum and zinc plating and leveling, and is coiled to obtain a finished hot aluminum and zinc plated steel plate with the thickness of 0.28-0.35mm, wherein the cold rolling reduction rate is 88-90%, the heating temperature of the cold rolled hard strip steel in the annealing in the horizontal continuous annealing furnace is 610-620 ℃, the temperature of the soaking section is 781-790 ℃, the annealing time of the strip steel in the soaking section is 32-42 s, the annealed strip steel is cooled to 590-600 ℃, the cooling speed is 12-15 ℃/s, and the strip steel is directly put into a zinc pot to be subjected to hot dip aluminum and zinc plating; the flat elongation is 0.8-1.0%.
The production process adopted by the invention has the following reasons:
1. setting of heating temperature of continuous casting slab
The heating process of the economical continuous casting slab needs lower heating temperature, and in order to prevent austenite grain size from growing after the slab is heated and reduce the yield strength of a finished steel plate, the heating temperature of the low-carbon aluminum killed steel adopted by the invention is set to be 1100-1150 ℃.
2. Setting of finish Rolling finishing temperature
As the carbon element in the steel is designed to be medium and low carbon, the weight content of the added carbon in the steel is 0.09-0.11 percent and the weight content of the manganese in the steel is 0.41-0.55 percent, the range of the phase change point A3 is 820-plus 830 ℃ through material tests and calculation, and after a large number of tests, the finish rolling is finished at the temperature close to the phase change point in order to achieve the purposes of high strength and uniformity of the material, so the finish rolling temperature is set to be 830-840 ℃. The steel comprises the following components in percentage by weight: c: 0.105 to 0.11%, Mn: 0.45-0.55%, S: 0-0.0050%, Mn/S is not less than 40, and when the matched finish rolling finishing temperature is 830-840 ℃, more uniform yield strength in the width direction of the steel plate can be obtained, so that a smaller extreme difference value of the yield strength in the width direction of the steel plate can be obtained.
3. Cooling method and setting of hot-rolling coiling temperature
After finish rolling, a rapid cooling mode is adopted to obtain fine grain structures, and the strength is improved. The design of the patent mainly considers grain refinement, and simultaneously ensures that the material obtains a certain pearlite structure and a certain carbon dissolved in ferrite in the coiling process, and prepares for obtaining a final structure for subsequent cooling annealing. Pearlite is fully precipitated when the temperature is too high, and the requirement for controlling the pearlite cannot be met when the temperature is too low, and the hot rolled steel coil is obtained by coiling at the coiling temperature of 610-630 ℃ by comprehensively considering that the laminar cooling adopts front-stage cooling.
4. Setting of Cold Rolling reduction
The invention provides a cold rolling process of the aluminum-zinc-plated steel plate for the liquid crystal backboard with the yield strength of 330 MPa. The high-strength steel hot rolled coil which is hot rolled and contains the components is uncoiled again, surface iron scales are removed through acid washing, and then the high-strength steel hot rolled coil is subjected to multiple cold rolling on a cold continuous rolling mill or a reciprocating single-stand rolling mill, so that the further strengthening effect is considered, the high-compression-ratio mode is adopted to obtain the thinning and homogenizing effect of rolled grains, and the cold rolling reduction rate is 88-90%.
5. Setting of annealing temperature and post-annealing cooling process
In order to obtain a steel plate with recrystallized ferrite, free cementite and pearlite structures and obtain a steel strip, solid-dissolved carbon in the hot rolling process is precipitated in a ferrite mode in annealing, through continuous tests, the patent finds that rapid annealing at a higher temperature and slow cooling after annealing are favorable for controlling uniform precipitation of the free cementite in the ferrite structures. Therefore, the heating temperature of the strip steel in the horizontal continuous annealing furnace is set to be 610-620 ℃, the temperature of the soaking section is set to be 781-790 ℃, the annealing time of the strip steel in the soaking section is set to be 32-42 s, the annealed strip steel is cooled to be 590-600 ℃, the cooling speed is 12-15 ℃/s, and the strip steel is directly put into a zinc pot to be subjected to hot-dip aluminum-zinc plating;
6. setting of the Flat elongation
In order to eliminate the influence of the upper yield point of the material on the uniformity of the material performance in the forming process, the stable processing performance can be obtained by determining the set flat elongation to be 0.8-1.0% through repeated tests.
The metallographic structure of the hot-dip aluminum-zinc steel plate produced by the method is ferrite, free cementite and pearlite, the ferrite grain size grade is I9.5-I10 grade, and the yield strength R of the hot-dip aluminum-zinc steel plateP0.2Is 330 to 380MPa, Rm385 to 425MPa, elongation after break A80mm26-30%, and the yield strength range of the steel plate in the width direction is less than 8 MPa.
Compared with the prior art, the invention has the following positive effects: 1. the metallographic structure of the hot-dip aluminum-zinc steel plate is recrystallized and recrystallized ferrite, free cementite and pearlite, so that the purposes of high strength and uniform performance of the material are achieved, and the control of the distortion problem of the thin hot-dip aluminum-zinc steel plate with the thickness of 0.28-0.35mm in the forming and processing process is met. 2. The design of the invention has better economy, and only the economic elements of carbon and manganese are added, thereby achieving the purpose of high strength and having the characteristic of low composition, and the invention is particularly easy to implement in the actual smelting production process. 3. The finish rolling of the critical phase transition point temperature in the hot rolling structure regulation and control method is very beneficial to improving the uniformity of the yield strength of the material plate in the width direction, can refine crystal grains and improve the strength, and simultaneously achieves the aims of high strength and performance uniformity of the material. 4. The method of the invention adopts a large compression ratio method, has very good effects of further refining the crystal grains and improving the uniformity of the material structure, can achieve the aims of high strength and performance uniformity of the material, is easy to implement cold rolling and does not increase more cost. 5. The cold rolling structure regulating method in the method is very beneficial to setting the temperature of rapid annealing and controlling the uniform precipitation of cementite by slow cooling after annealing, provides method guarantee for obtaining high strength and uniform performance of thin-specification products, and is stable in implementation process.
Drawings
FIG. 1 is a photograph of a metallographic structure of a hot-dip aluminum-zinc plated steel sheet according to example 4 of the present invention.
Detailed Description
The present invention is further described below with reference to examples 1 to 6, which are shown in tables 1 to 4.
Table 1 shows the chemical composition (in weight%) of the substrate of the hot-dip aluminum-zinc coated steel sheet according to the example of the present invention, and the balance Fe and inevitable impurities.
Table 1 chemical composition of substrate of hot-dip aluminum-zinc coated steel sheet of example of the present invention, unit: and (4) weight percentage.
Smelting in a converter to obtain a continuous casting billet meeting the requirement on chemical components, wherein the thickness of the continuous casting billet is 210-240 mm, the width of the continuous casting billet is 800-1300 mm, and the length of the continuous casting billet is 5000-10000 mm.
Heating the continuous casting plate blank to 1100-1150 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 830-840 ℃; adopting front-section cooling for laminar cooling, and coiling at the coiling temperature of 610-630 ℃ to obtain a hot-rolled steel coil; the hot rolling process control is shown in Table 2.
TABLE 2 Hot Rolling Process control parameters of the inventive examples
The hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing in a horizontal continuous annealing furnace, hot aluminum and zinc plating and leveling, and is coiled to obtain a finished hot aluminum and zinc plated steel plate with the thickness of 0.28-0.35mm, wherein the cold rolling reduction rate is 88-90%, the temperature of the strip steel in a hard rolling state after cold rolling is 610-620 ℃ at the annealing temperature of the horizontal continuous annealing furnace, the temperature of a soaking section is 781-790 ℃, the annealing time of the strip steel in the soaking section is 32-42 s, the annealed strip steel is cooled to 590-600 ℃, the cooling speed is 12-15 ℃/s, and the strip steel is directly put into a zinc pot to be subjected to hot dip aluminum and zinc plating; the flat elongation is 0.8-1.0%. The control parameters of the cold rolling, annealing and flattening processes are shown in Table 3.
TABLE 3 control parameters for the cold rolling, annealing and temper rolling process of the examples of the invention
Referring to fig. 1, the metallographic structure of the hot-dip aluminum-zinc steel plate produced by the method is ferrite, free cementite and pearlite, the ferrite grain size is I9.5-I10 grade, and the yield strength R of the hot-dip aluminum-zinc steel plateP0.2Is 330 to 380MPa, Rm385 to 425MPa, elongation after break A80mm26-30%, and the yield strength range of the steel plate in the width direction is less than 8 MPa.
According to the part 1 of a GB/T228.1-2010 metal material tensile test, the hot-dip aluminum-zinc plated steel plate obtained by the invention: room temperature test method the mechanical properties of the steel sheets are shown in Table 4.
TABLE 4 mechanical properties and grain size of hot-dip aluminum-zinc coated steel sheets according to the examples of the present invention
Example 4 yield Strength R of Steel sheetP0.2363MPa, tensile strength 409MPa, and elongation after fracture A80mm27 percent, the yield strength difference of the steel plate in the width direction is 7MPa, and hot rolling structure regulation and high pressure are utilized through the component design of low-carbon steelThe technology of the shrinkage ratio and the rapid annealing process realizes the manufacture of the hot-dip aluminum-zinc steel plate for the thin-specification liquid crystal module.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (5)
1. A hot-dip aluminum-zinc steel plate for a liquid crystal backboard with a yield strength of 330MPa comprises the following chemical components in percentage by weight: c: 0.09-0.11%, Si: 0-0.03%, Mn: 0.41-0.55%, P: 0-0.015%, S: 0-0.015%, Al: 0.01-0.03%, Mn/S is more than or equal to 40, and the balance is Fe and inevitable impurity elements; the metallographic structure of the hot-dip aluminum-zinc steel plate is ferrite, free cementite and pearlite, and the grain size grade of the ferrite is I9.5-I10 grade.
2. The hot-dip Al-Zn-coated steel sheet for liquid crystal back sheets having a yield strength of 330MPa as set forth in claim 1, wherein the yield strength R of the hot-dip Al-Zn-coated steel sheet having a thickness of 0.28 to 0.35mmP0.2Is 330 to 380MPa, Rm385 to 425MPa, elongation after break A80mm26-30%, and the yield strength range of the steel plate in the width direction is less than 8 MPa.
3. The hot-dip aluminum-zinc steel plate for the liquid crystal backboard with the yield strength of 330MPa as claimed in claim 1, wherein the substrate of the hot-dip aluminum-zinc steel plate comprises the following chemical components in percentage by weight: c: 0.105 to 0.11%, Si: 0-0.03%, Mn: 0.45-0.55%, P: 0-0.015%, S: 0-0.0050%, Al: 0.01-0.03%, Mn/S is more than or equal to 40, and the balance is Fe and inevitable impurity elements.
4. A manufacturing method of a hot-dip aluminum-zinc steel plate for a liquid crystal backboard with a yield strength of 330MPa is characterized by comprising the following steps:
the method comprises the following steps of continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following chemical components in percentage by weight: c: 0.09-0.11%, Si: 0-0.03%, Mn: 0.41-0.55%, P: 0-0.015%, S: 0-0.015%, Al: 0.01-0.03%, Mn/S is more than or equal to 40, and the balance is Fe and inevitable impurity elements;
heating the continuous casting plate blank to 1100-1150 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 830-840 ℃; adopting front-section cooling for laminar cooling, and coiling at the coiling temperature of 610-630 ℃ to obtain a hot-rolled steel coil;
the hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing in a horizontal continuous annealing furnace, hot aluminum and zinc plating and leveling, and is coiled to obtain a finished hot aluminum and zinc plated steel plate with the thickness of 0.28-0.35mm, wherein the cold rolling reduction rate is 88-90%, the heating temperature of the cold rolled hard strip steel in the annealing in the horizontal continuous annealing furnace is 610-620 ℃, the temperature of the soaking section is 781-790 ℃, the annealing time of the strip steel in the soaking section is 32-42 s, the annealed strip steel is cooled to 590-600 ℃, the cooling speed is 12-15 ℃/s, and the strip steel is directly put into a zinc pot to be subjected to hot dip aluminum and zinc plating; the flat elongation is 0.8-1.0%.
5. The method for manufacturing a hot-dip Al-Zn-plated steel sheet for a liquid crystal back sheet having a yield strength of 330MPa according to claim 4, wherein the thickness of the hot-rolled steel sheet is controlled to be 2.8 to 3.0mm after the finish rolling.
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