CN110863137B - Method for manufacturing hot-dip aluminum-zinc steel plate - Google Patents
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- CN110863137B CN110863137B CN201810994567.3A CN201810994567A CN110863137B CN 110863137 B CN110863137 B CN 110863137B CN 201810994567 A CN201810994567 A CN 201810994567A CN 110863137 B CN110863137 B CN 110863137B
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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
- 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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- 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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- 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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- 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
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—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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- 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
- C21D2211/003—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
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Abstract
The invention discloses a manufacturing method of a hot-dip aluminum-zinc steel plate, which mainly solves the technical problems that in the prior art, a hot-dip aluminum-zinc steel plate with the thickness of 2.0-2.5 mm is easy to generate surface crease defects and a plating layer has large spangles during production. The invention provides a manufacturing method of a hot-dip aluminum-zinc steel plate, which comprises the following steps of continuously casting molten steel to obtain a continuous casting plate blank; heating the continuous casting plate blank to 1180-1240 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, and a hot rolled steel coil is obtained by coiling at 400-600 ℃; and uncoiling the hot-rolled steel coil again, then carrying out acid pickling, cold rolling, annealing by a horizontal continuous annealing furnace, hot-dipping aluminum and zinc, cooling and flattening after plating, and coiling to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 2.0-2.5 mm. Elongation after fracture A of hot-dip aluminum-zinc plated steel plate with thickness of 2.0-2.5 mm80mm32-38% and no transverse crease on the surface. The hot-dip aluminum-zinc plated steel plate is used in the industries of household appliances and the like.
Description
Technical Field
The invention relates to a method for manufacturing a hot-dip aluminum-zinc steel plate, in particular to a method for manufacturing a hot-dip aluminum-zinc steel plate with the thickness of 2.0-2.5 mm, and belongs to the technical field of iron-based alloys.
Background
The hot-dip aluminum-zinc alloy coated steel plate is widely applied to the fields of building industry, household appliance industry, industrial instrument industry, automobile industry and the like due to excellent corrosion resistance, heat resistance, oxidation resistance, coating property, processability and economy.
The patent publication date is 2004, 11/3/h, publication number CN1542158A, entitled "hot-dip aluminum-zinc alloy steel sheet and manufacturing method thereof", which discloses a conventional aluminum-zinc alloy plated steel sheet and manufacturing process, and does not relate to the problems of crease quality control, hot rolling process, cold rolling process, and aluminum-zinc plating process.
Patent publication No. CN101736195A, 6/16/2010, entitled "hot-dip aluminum-zinc alloy steel sheet and method for producing the same", discloses a high-strength aluminum-zinc alloy-plated steel sheet having Nb content of 0.005-0.03% and Ti content of 0.001-0.02%, and requires a hot rolling process and an aluminum-zinc plating process that do not involve control of crease defects.
The patent publication date is 2013, 4 and 17, and the publication number is CN103045981A, and the name is 'a hot-dip aluminum-zinc alloy containing rare earth and magnesium and a preparation method thereof', and the patent publication discloses a hot-dip aluminum-zinc alloy containing rare earth and magnesium and a preparation method thereof, and solves the problems of poor processing formability of the existing alloy hot-dip plate and poor blackening resistance of a coating, the invention firstly provides a hot-dip aluminum-zinc alloy containing rare earth and magnesium, which comprises the following components in percentage by weight: 54-59% of aluminum, 1.2-1.8% of silicon, 0.05-0.15% of rare earth, 0.3-0.7% of magnesium and the balance of zinc and inevitable impurities; the rare earth is cerium or lanthanum or a mixed rare earth of cerium and lanthanum, and the core of the rare earth is a novel plating technology.
Patent publication date is 7/9/2014, publication number CN103911551A, entitled "a hot-dip aluminum-zinc alloy steel sheet and a method for manufacturing the same", which discloses a hot-dip aluminum-zinc alloy steel sheet comprising a steel sheet base material and an aluminum-zinc alloy plating layer on a surface of the steel sheet base material, wherein the steel sheet base material contains 0.01 to 0.039% of C, 0.15 to 0.19% of Mn, 0.015% or less of P, 0.02 to 0.07% of Al, 0.005 to 0.025% of Ti, 0.05% or less of Si, 0.015% or less of S, 99.59 to 99.8% of Fe, and the balance being unavoidable impurities, based on the total weight of the steel sheet base material, and a method for manufacturing the above hot-dip aluminum-zinc alloy steel sheet, which does not involve a method for controlling a crease defect.
The patent publication date is 2014, 8 and 20, and the publication number is CN103993149A, namely a patent document of 'cold rolled steel plate and a preparation method thereof, and a hot-dip aluminum-zinc alloy steel plate and a preparation method thereof', and discloses a hot-dip aluminum-zinc alloy steel plate with lower cost, high strength and better surface quality, a preparation method thereof, a cold rolled steel plate for preparing the hot-dip aluminum-zinc alloy steel plate and a preparation method thereof. The preparation method of the cold-rolled steel sheet comprises the following steps: sequentially carrying out hot rolling, coiling, cold rolling and annealing on a plate blank, wherein the coiling temperature is 570-630 ℃; the cold rolling reduction is 75-85%; the annealing conditions include: the temperature is 630-; the slab comprises the following components: c: 0.01-0.08%, Si: less than or equal to 0.05 percent, Mn: 0.1-0.4%, P: less than or equal to 0.025 percent, S: less than or equal to 0.02 percent, Nb: 0.01-0.05%, Al: 0.02-0.08%, the balance of Fe and inevitable impurities, and a control method of crease defects is not involved.
The patent publication date is 24/9/2014, publication number CN104060165A, entitled "hot-dip aluminum-zinc alloy steel sheet and method for producing same", which discloses a hot-dip aluminum-zinc alloy steel sheet comprising a steel sheet base material and an aluminum-zinc alloy plating layer on the surface of the steel sheet base material, wherein the steel sheet base material contains 0.04-0.12% of C, 0.2-0.6% of Mn, 0.02-0.1% of P, 0.01-0.05% of Ti, 0.02-0.07% of Al, 0.05% or less of Si, 0.015% or less of S, 98.99-99.71% of Fe, and the balance unavoidable impurities, based on the total weight of the steel sheet base material, and a method for producing the above hot-dip aluminum-zinc alloy steel sheet.
The patent publication date is 2018, 4 and 13, and publication number CN107904490A, entitled "structural thin hot-dip aluminum-zinc alloy steel plate and preparation method thereof" discloses a thin structural hot-dip aluminum-zinc alloy steel plate and preparation method thereof. Aiming at the problems of poor strength, poor coating quality, high cost and the like of hot-dip aluminum-zinc alloy steel plates produced in the prior art, the invention provides a hot-dip aluminum-zinc alloy steel plate, which comprises the following base materials: according to weight percentage, the content of C is less than or equal to 0.05-0.12%, the content of Si is less than or equal to 0.05%, the content of Mn is less than or equal to 0.2-0.5%, the content of P is less than or equal to 0.04-0.08%, the content of S is less than or equal to 0.015%, the content of Ti is less than or equal to 0.02-0.04%, the content of Al is 0.010-0.080%, and the balance is Fe and unavoidable. The method only relates to a preparation method of a hot-dip aluminum-zinc plated steel plate with the thickness of 0.4-2.0 mm and the yield strength of more than 350 MPa.
The hot-dip aluminum-zinc plated steel plate manufactured by the cold-rolled substrate adopted by the prior art has the technical problems that the hot-dip aluminum-zinc plated steel plate with the thickness of more than 2.0mm is easy to generate the defect of transverse crease on the surface and has larger zinc coating spangles during production, and the prior industry lacks effective solutions.
Disclosure of Invention
The invention aims to provide a manufacturing method of a hot-dip aluminum-zinc steel plate, which mainly solves the technical problems that in the prior art, a hot-dip aluminum-zinc steel plate with the thickness of 2.0-2.5 mm is easy to generate transverse crease defects on the surface and has large zinc flowers on a coating when being produced, improves the product quality of the hot-dip aluminum-zinc steel plate with the thickness of 2.0-2.5 mm, and reduces the production cost of the hot-dip aluminum-zinc steel plate with the thickness of 2.0-2.5 mm.
In the prior art, hot-dip aluminum-zinc steel plates with the thickness of more than or equal to 2.0-2.5 mm are all produced by common hot-rolled steel plates, and are easy to generate surface transverse crease defects and large in plating zinc flowers during production. Through years of research, the applicant finds that the hot-dip aluminum-zinc steel plate has a yield platform, and the hot-dip aluminum-zinc steel plate generates plastic deformation when passing through the steering process of a steering roller or a tension roller, and macroscopically shows as a surface crease defect. The production process measures for eliminating the yield platform of the steel plate comprise the following steps: 1. the hot rolling process is improved, and aims to refine grains of a hot rolled plate, reduce C, N precipitation and improve yield strength; 2. the cold rolling and annealing process is improved, and the improvement aims to prevent the abnormal growth of crystal grains from generating so as to reduce the yield strength; 3. the improvement of the aluminum-zinc plating and cooling process after plating aims at realizing rapid cooling, thinning spangles and improving the mechanical properties of a plating layer and a substrate.
The technical idea of the method is that the technical problem of surface crease defect caused by a yield platform is eliminated by scientifically designing the reasonable matching of the components of the hot-dip aluminum-zinc plated steel plate, the hot rolling process, the cold rolling, the annealing, the hot dipping process, the cooling after plating and the leveling process, so that the purpose of solving the surface crease defect of the hot-dip aluminum-zinc plated steel plate is achieved, and the hot-dip aluminum-zinc plated steel plate with the thickness of 2.0-2.5 mm, which has fine spangles, beautiful plating layer and stable base material performance is obtained; the coating of the hot-dip aluminum-zinc steel plate has fine spangles and attractive appearance.
The invention adopts the technical scheme that the method for manufacturing the hot-dip aluminum-zinc steel plate 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: 0.02-0.10%, Si is less than or equal to 0.045%, Mn: 0.10-0.40%, P is less than or equal to 0.025%, S is less than or equal to 0.025%, Alt: 0.010-0.060% of iron and inevitable impurities;
heating the continuous casting plate blank to 1180-1240 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 6-pass rolling, the rolling is carried out above the austenite recrystallization temperature, the finishing temperature of the rough rolling is 1030-1080 ℃, the thickness of an intermediate blank after the rough rolling is controlled to be 38-42mm, the finish rolling is 7-pass continuous rolling, the rolling is carried out in an austenite single-phase region, the finishing temperature of the finish rolling is 880-920 ℃, the thickness of a steel plate after the finish rolling is 4.0-6.0 mm, the laminar cooling adopts front-section cooling, and the hot rolled steel coil is coiled when the coiling temperature is 400-600 ℃;
the hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing by a horizontal continuous annealing furnace, hot dipping of aluminum and zinc, cooling after plating and leveling, and is coiled to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 2.0-2.5 mm, wherein the cold rolling reduction rate is 45-66%, the temperature of the cold-rolled hard strip steel in the annealing soaking section of the horizontal continuous annealing furnace after cold rolling is 750-800 ℃, the annealing time of the strip steel in the soaking section is 45-85s, the temperature of the strip steel when entering a zinc pot is 550-630 ℃, the temperature of aluminum and zinc liquid in the zinc pot is 580-610 ℃, and the speed of the strip steel passing through the zinc pot is 50-100 m/min; the cooling after plating comprises forced air cooling and air mist cooling, wherein the forced air cooling is to cool the strip steel by using low-temperature air at the temperature of 7-10 ℃ at the position with the vertical distance of 600-800 mm from an air knife right above the air knife, the cooling speed is more than or equal to 15 ℃/s, and the forced air cooling time is 1-3 s, so that the method can quickly promote the nucleation and crystallization of a plating layer, obtain fine, uniform spangles and attractive plating layer appearance, and improve the comprehensive performance of the plating layer; when the temperature of the strip steel is less than or equal to 460 ℃, carrying out aerial fog cooling on the strip steel, wherein the cooling speed is more than or equal to 30 ℃/s, and the cooling time is more than or equal to 2s, and the cooling speed can improve the mechanical property of the steel plate; stopping gas spray cooling of the strip steel when the temperature of the strip steel is less than or equal to 350 ℃; the flat elongation is 0.6-1.2%.
Furthermore, the hot rolling coiling temperature is 500-550 ℃, and the effect is good.
Furthermore, the temperature of the strip steel entering the zinc pot is 580-590 ℃, and the effect is good.
Furthermore, the temperature of the aluminum zinc liquid in the zinc pot is 600-610 ℃, and the effect is good.
The metallographic structure of the hot-dip aluminum-zinc steel plate produced by the method is ferrite, free cementite and trace granular pearlite, the grain size grade of the structure is I7-9 grade, and the yield strength R of the hot-dip aluminum-zinc steel plate with the thickness of 2.0-2.5 mmP0.2230 to 300MPa, tensile strength Rm320-360 Mpa, elongation after break A80mm30-38%, the steel plate has no surface crease defect, and the zinc flower of the plating layer is fine, uniform and beautiful.
The hot-dip aluminum-zinc plated steel plate produced by the method is mainly used in the industries of household appliances, electric power, buildings and the like.
The production process adopted by the invention has the following reasons:
1. setting of heating temperature of continuous casting slab
In order to ensure the finish rolling temperature, the hot rolling process is carried out in an austenite region, and the temperature of the continuous casting plate blank taken out of a heating furnace cannot be too low; the low temperature of the furnace can prevent the second phase particles such as titanium compounds and the like from being dissolved and dispersed fine precipitates from being generated in the subsequent process, thereby not playing the role of precipitation strengthening; if the heating temperature of the plate blank is too high, thicker iron scale can be generated on the surface of the plate blank, and the plate blank is easy to press into the surface of the strip steel in the subsequent hot rolling rough rolling and finish rolling processes, so that the surface quality of a finished product is influenced. The heating temperature of the plate blank is set to 1180-1240 ℃.
2. Finish rolling finish temperature setting
The finish rolling process of the invention needs to roll in an austenite single-phase region, and if the finish rolling temperature is too low, the finish rolling process can deteriorate the organization performance of the product when rolling in a ferrite and austenite two-phase region; if the finish rolling finishing temperature is set to be too high, not only is the production line difficult to reach, but also the iron scale on the surface of the steel plate is serious and is difficult to remove during acid cleaning, so that the surface quality is influenced; the finish rolling temperature of the invention is set to 880-920 ℃.
3. Setting of coiling temperature in Hot Rolling
If the hot rolling coiling temperature is too high, the recrystallized grains are easy to grow up and the yield strength is reduced during the subsequent cold rolling annealing; if the hot rolling coiling temperature is too low, the performance stability of the whole coil of the steel coil is influenced, and the second phase particles with smaller sizes are unfavorable for subsequent cold rolling annealing; the coiling temperature set by the invention is 400-600 ℃, and the preferable coiling temperature is 500-550 ℃.
4. Setting of laminar cooling mode after finish rolling
When finish rolling is completed, if the steel sheet is cooled at a low speed, i.e., by post-cooling, ferrite grains are coarse, and the yield strength is lowered. Therefore, the invention sets the laminar cooling mode after finish rolling to adopt front-stage cooling.
5. Cold rolling reduction setting
Due to the increase of the cold rolling deformation, the recrystallization of the subsequent annealing can be promoted, and a fine grain structure is obtained, so that the strength of the steel plate is improved; if the deformation is too high, the load of the rolling mill is too large, and the shape and the production stability of the strip steel are influenced; the invention sets the cold rolling reduction rate to be 45-66%.
6. Setting of annealing temperature and annealing time
In order to ensure that the steel coil after cold rolling can be effectively recrystallized and annealed, the precipitation of solid solution carbon is obtained, the content of free cementite is increased, and the setting of the annealing soaking temperature is required to be high enough according to the characteristic that the soaking section of the horizontal annealing furnace is short, the temperature (annealing temperature) of the strip steel in the soaking section of the horizontal continuous annealing furnace is set to be 750-800 ℃, and the annealing time of the strip steel in the soaking section of the horizontal continuous annealing furnace is set to be 45-85 s.
7. Setting of hot-dip aluminum-zinc plating process parameters
The temperature of the strip steel when entering the zinc pot has great influence on the temperature of the hot galvanizing pot when the thick steel plate absorbs heat and releases heat much higher than the thin steel plate is continuously produced in large scale, which is a technical difficulty for producing the products; in order to ensure the quality of the coating layer during aluminum and zinc plating, the temperature of the strip steel entering the zinc pot is controlled to be 550-630 ℃, the sufficient temperature for effective chemical reaction between the strip steel and the coating liquid is ensured, and the preferable temperature is controlled to be 580-590 ℃ when the strip steel enters the zinc pot.
The temperature of the aluminum-zinc liquid is ensured to be stable by dynamically controlling the heating power of the zinc pot, thereby preventing the quality of a coating from being abnormal and reducing the occurrence amount of surface defects of strip steel, and the temperature of the aluminum-zinc liquid is set to be 580-610 ℃, and the preferred temperature of the aluminum-zinc liquid is 600-610 ℃.
In order to reduce the retention time of a steel plate in a zinc pot and prevent the quality of a coating from being abnormal and improve the speed of strip steel passing through the zinc pot as much as possible under the condition that the conditions allow, the speed of the strip steel passing through the zinc pot is set to be 50-100 m/min.
8. Post-plating cooling
The post-plating cooling of the hot-dip aluminum zinc comprises forced air cooling and air mist cooling, wherein the forced air cooling is that the strip steel is cooled by low-temperature air with the temperature of 7-10 ℃ at the position with the vertical distance of 600-800 mm from an air knife right above the air knife, the cooling speed is more than or equal to 15 ℃/s, and the forced air cooling time is 1-3 s, so that the method can quickly promote the nucleation and crystallization of a plating layer, obtain fine, uniform spangles and attractive plating layer appearance, and improve the comprehensive performance of the plating layer; when the temperature of the strip steel is less than or equal to 460 ℃, carrying out aerial fog cooling on the strip steel, wherein the cooling speed is more than or equal to 30 ℃/s, and the cooling time is more than or equal to 2s, and the cooling speed can improve the mechanical property of the steel plate; stopping the aerial fog cooling when the temperature of the strip steel is less than or equal to 350 ℃; the method realizes the defect of no crease on the surface of the strip steel through the scientific design of the cooling process after plating.
9. Setting of the Flat elongation
The flattening can not only ensure the good plate shape of the strip steel, but also correspondingly improve the yield strength of the material through proper flattening rate, and the flattening elongation rate of the invention is 0.6-1.2%.
The metallographic structure of the hot-dip aluminum-zinc steel plate produced by the method is ferrite, free cementite and trace granular pearlite, the grain size grade of the structure is I7-9 grade, and the yield strength R of the hot-dip aluminum-zinc steel plate with the thickness of 2.0-2.5 mmP0.2230 to 300MPa, tensile strength Rm320-360 Mpa, elongation after break A80mm30-38%, and the steel plate has no surface crease defect.
Compared with the prior art, the invention has the following positive effects: 1. the hot-rolled low-carbon aluminum killed steel with the traditional SPHC brand is used as a base material, and the hot-rolled aluminum-zinc plated steel plate with the thickness of 2.0-2.5 mm is obtained through the combined control of key hot rolling, horizontal furnace continuous annealing and hot plating processes, so that the finished product has no surface crease defect, small spangles and attractive plating layer. 2. The invention provides a hot-dip aluminum-zinc plated steel plate with the thickness of 2.0-2.5 mm, which is continuously annealed by a horizontal annealing furnace and is produced under the condition of 50m/min of the lowest speed when passing through a zinc pot, wherein the microstructure of the steel plate is ferrite, free cementite and trace granular pearlite, and the grain size grade of the ferrite is I7-9 grade.
Detailed Description
The present invention is further illustrated below with reference to examples 1 to 4, which are shown in tables 1 to 4. Table 1 shows the chemical composition (in weight percent) of the substrate of the hot-dip aluminum-zinc coated steel sheet according to the embodiment of the present invention, and the balance Fe and inevitable impurities.
Table 1 chemical composition of substrate of hot dip galvanized steel sheet according to example of the present invention, unit: and (4) weight percentage.
According to the design requirements of the material components, molten steel meeting the requirements on chemical components is obtained by smelting in a converter, the molten steel is subjected to vacuum decarburization and degassing treatment in an RH furnace, the pure degassing time of the molten steel in the RH furnace is longer than 8 minutes, the molten steel is subjected to continuous casting under the protection of Ar blowing in the whole process to obtain a continuous casting slab, the thickness of the continuous casting slab is 210-230 mm, the width of the continuous casting slab is 900-1600 mm, and the length of the continuous casting slab is 8500-11000 mm.
And (3) sending the fixed-length plate blank produced in the steel-making process to a heating furnace for reheating, taking out the plate blank from the furnace for descaling, and sending the plate blank to a hot continuous rolling mill for rolling. The rolling is controlled by a rough rolling and finish rolling continuous rolling unit, the coiled steel is cooled by laminar flow, the laminar flow adopts front section cooling, qualified hot rolled steel coils are produced, and the thickness of the hot rolled steel plates is 4.0-6.0 mm. The hot rolling process control parameters are shown in Table 2.
TABLE 2 Hot Rolling Process control parameters of the inventive examples
And uncoiling the hot rolled steel coil again, then carrying out acid pickling, cold rolling, annealing in a horizontal continuous annealing furnace, hot-dipping aluminum and zinc plating, cooling and leveling after plating, and coiling to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 2.0-2.5 mm. The annealing process comprises the following steps: the temperature of the rolled hard strip steel after cold rolling in the annealing soaking section of the horizontal continuous annealing furnace is 750-800 ℃, the annealing time of the strip steel in the soaking section is 45-85s, and the flat elongation is 0.6-1.2%. The control parameters of the cold rolling, annealing and flattening processes are shown in Table 3.
TABLE 3 control parameters of the cold rolling, annealing and leveling processes of the examples of the present invention
The hot-dip aluminum-zinc plated steel plate obtained by the method has the metallographic structure of ferrite, free cementite and trace granular pearlite, the structural grain size grade is I7-9 grade, and the yield strength R of the hot-dip aluminum-zinc plated steel plate with the thickness of 2.0-2.5 mmP0.2230 to 300MPa, tensile strength Rm320-360 Mpa, elongation after break A80mm30-38%, the steel plate has no surface crease defect, and the zinc flower of the plating layer is fine, uniform and beautiful.
The hot dip galvanized steel sheet obtained by the invention is subjected to a tensile test on a GB/T228.1-2010 metal material part 1: room temperature test method the mechanical properties of the hot-dip aluminized steel sheet are shown in Table 4.
TABLE 4 mechanical properties of hot-dip aluminum-zinc plated steel sheets according to embodiments of the present invention
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 method for manufacturing a hot-dip aluminum-zinc steel plate is characterized by comprising 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: 0.02-0.10%, Si is less than or equal to 0.045%, Mn: 0.10-0.40%, P is less than or equal to 0.025%, S is less than or equal to 0.025%, Alt: 0.010-0.060% of iron and inevitable impurities;
heating the continuous casting plate blank to 1180-1240 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 6-pass rolling, the rolling is carried out above the austenite recrystallization temperature, the finishing temperature of the rough rolling is 1030-1080 ℃, the thickness of an intermediate blank after the rough rolling is controlled to be 38-42mm, the finish rolling is 7-pass continuous rolling, the rolling is carried out in an austenite single-phase region, the finishing temperature of the finish rolling is 880-920 ℃, the laminar cooling after the finish rolling adopts front-section cooling, and a hot rolled steel coil is coiled when the coiling temperature is 400-600 ℃;
the hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing by a horizontal continuous annealing furnace, hot dipping of aluminum and zinc, cooling after plating and leveling, and is coiled to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 2.0-2.5 mm, wherein the cold rolling reduction rate is 45-66%, the temperature of the cold-rolled hard strip steel in the annealing soaking section of the horizontal continuous annealing furnace after cold rolling is 750-800 ℃, the annealing time of the strip steel in the soaking section is 45-85s, the temperature of the strip steel when entering a zinc pot is 550-630 ℃, the temperature of aluminum and zinc liquid in the zinc pot is 580-610 ℃, and the speed of the strip steel passing through the zinc pot is 50-100 m/min; the cooling after plating comprises forced air cooling and air fog cooling, wherein the forced air cooling is to cool the strip steel by using low-temperature air at the temperature of 7-10 ℃ at the position with the vertical distance of 600-800 mm from the air knife right above the air knife, the cooling speed is more than or equal to 15 ℃/s, and the forced air cooling time is 1-3 s; when the temperature of the strip steel is less than or equal to 460 ℃, carrying out aerial fog cooling on the strip steel, wherein the cooling speed is more than or equal to 30 ℃/s, and the cooling time is more than or equal to 2 s; stopping gas spray cooling of the strip steel when the temperature of the strip steel is less than or equal to 350 ℃; the flat elongation is 0.6-1.2%.
2. The method of manufacturing a hot-dip aluminum-zinc plated steel sheet according to claim 1, wherein the thickness of the hot-rolled steel sheet after the finish hot rolling is controlled to be 4.0 to 6.0 mm.
3. The method for producing a hot-dip Al-Zn alloy steel sheet as set forth in claim 1, wherein the hot rolling coiling temperature after the finish hot rolling is 500-550 ℃.
4. The method for manufacturing a hot-dip aluminum-zinc steel plate as set forth in claim 1, wherein the strip temperature in the zinc pot is 580-590 ℃.
5. The method for manufacturing a hot-dip aluminized and galvanized steel sheet according to claim 1, wherein the temperature of the aluminum-zinc liquid in the zinc pot is 600-610 ℃.
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| CN115181885B (en) * | 2021-04-02 | 2023-08-11 | 宝山钢铁股份有限公司 | 590 MPa-level high-formability hot-dip aluminum zinc or hot-dip zinc aluminum magnesium dual-phase steel and rapid heat treatment manufacturing method |
| CN115505832B (en) * | 2021-06-07 | 2023-09-05 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum zinc-plated steel plate with yield strength of 340MPa for liquid crystal backboard |
| CN113502438B (en) * | 2021-07-08 | 2022-10-11 | 攀钢集团攀枝花钢钒有限公司 | Zinc-aluminum-magnesium alloy coating steel plate/belt for stamping and preparation method thereof |
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