CN110551939A - Hot-dip galvanized steel plate with yield strength of 320MPa and production method thereof - Google Patents
Hot-dip galvanized steel plate with yield strength of 320MPa and production method thereof Download PDFInfo
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- CN110551939A CN110551939A CN201810562001.3A CN201810562001A CN110551939A CN 110551939 A CN110551939 A CN 110551939A CN 201810562001 A CN201810562001 A CN 201810562001A CN 110551939 A CN110551939 A CN 110551939A
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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
- 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
- C22C38/02—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
- 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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- Heat Treatment Of Sheet Steel (AREA)
Abstract
The invention discloses a hot-dip galvanized steel sheet with a yield strength of 320MPa and a production method thereof, and mainly solves the technical problem that the surface of the hot-dip galvanized steel sheet with the yield strength of 320MPa produced in the prior art has a color difference defect. The invention provides a hot-dip galvanized steel sheet with yield strength of 320MPa, which comprises the following chemical components in percentage by weight: c: 0.071-0.090%, Si: 0-0.05%, Mn: 0.20-0.40%, P: 0.03-0.05%, S: 0-0.02%, Alt: 0.020-0.080% and the balance of Fe and inevitable impurities. The transverse post-fracture elongation A80mm of a hot-dip galvanized steel sheet with the thickness of 0.25-0.35mm is 27-32%, and the color difference value delta E of the surface of the hot-dip galvanized steel sheet is less than 1; the hot dip galvanized steel sheet is mainly used in the household appliance industry.
Description
Technical Field
the invention relates to a hot-dip galvanized steel sheet, in particular to a hot-dip galvanized steel sheet with yield strength of 320MPa and a production method thereof, and specifically relates to a hot-dip galvanized steel sheet with a thickness of 0.25-0.35mm for the household appliance industry, belonging to the technical field of iron-based alloy.
Background
With the requirement of cost reduction in the household appliance industry, hot-dip galvanized products for household appliances develop towards high-strength thin specifications, and the products with the application have higher requirements on the surface quality of hot-dip galvanized steel plates. Steel products are often strengthened with C, Mn elements or the strength of the products is increased by fine grain strengthening and precipitation strengthening by adding small amounts of microalloying elements (Ti or Nb).
Chinese patent publication No. CN101348880A discloses a method for producing a structural high-strength galvanized sheet, which comprises the following components and structures: contains C in weight percent: 0.16-0.20%, Mn: 0.9% -1.1%, Si: less than or equal to 0.05 percent, Als: 0.02% -0.06%, P: less than or equal to 0.020%, S: less than or equal to 0.020%, and the balance being iron.
The Chinese patent document with application publication number CN102787271A discloses a production method of a 460 MPa-grade hot-dip galvanized steel plate for a high-surface quality structure and a product thereof, and the components and the structure of the hot-dip galvanized steel plate are as follows: contains (by weight percent) C0.040% -0.10%; si: less than or equal to 0.060 percent; 0.60 to 0.80 percent of Mn; p is less than or equal to 0.035%; s is less than or equal to 0.035%; 0.020-0.060 percent of Al; nb and Ti are less than or equal to 0.080 percent, and the balance is iron.
The two patents adopt C, Mn strengthening or Ti and Nb microalloy strengthening, and practice shows that the cold-rolled steel sheets produced by the two strengthening modes, particularly rolled thin cold-rolled steel sheets, have obvious emulsion spots on the surfaces, and the defects of poor surface color of hot-galvanized finished products are caused because the cold-rolled steel sheets are difficult to remove by a conventional degreasing process. The analysis shows that due to the two strengthening modes, the cold rolling load is large, the generated rolling deformation heat is large, the temperature of the surface of the steel plate is high, and the emulsion spots and the steel plate matrix are tightly combined.
Disclosure of Invention
The invention aims to provide a hot-dip galvanized steel sheet with a yield strength of 320MPa and a production method thereof, and mainly solves the technical problem that the surface of the hot-dip galvanized steel sheet with the yield strength of 320MPa produced in the prior art has a color difference defect.
The technical scheme adopted by the invention is that a hot-dip galvanized steel sheet with the yield strength of 320MPa is characterized in that a substrate comprises the following chemical components in percentage by weight: c: 0.071-0.090%, Si: 0-0.05%, Mn: 0.20-0.40%, P: 0.03-0.05%, S: 0-0.02%, Alt: 0.020-0.080% and the balance of Fe and inevitable impurities.
The metallographic structure of the hot-dip galvanized steel sheet is ferrite, a small amount of pearlite and free cementite, the grain size of the structure is I7-9 grade, the yield strength R P0.2 of the hot-dip galvanized steel sheet with the thickness of 0.25-0.35mm is 320-390 Mpa, the tensile strength R m is 420-480 Mpa, the transverse post-fracture elongation A 80mm is 27-32%, and the color difference value delta E of the surface of the hot-dip galvanized steel sheet is less than 1.
The reason why the chemical composition of the hot-dip galvanized steel sheet having a yield strength of 320MPa grade according to the present invention is limited to the above range is as follows:
Carbon: c exists in the form of interstitial atoms and cementite in the steel, has a strong strengthening effect in the steel, and in order to strengthen the material, it is necessary to retain a certain amount of carbon in the material to improve the strength, but this element is too high, the plastic deformation resistance of the material increases, and the cold rolling load is too high. Too low carbon raises the Ar3 temperature of the material, making it more likely to roll in the two-phase region to produce a mixed-grain structure if the material is thin. Meanwhile, the strength of the final product is difficult to guarantee. The content range of C is set to be 0.071-0.09%;
Silicon: si is an element that improves the strength of a steel product, but Si easily generates scales during hot rolling, is difficult to remove by high-pressure water for hot rolling, remains on a hot-rolled steel sheet as red scales, and such deep-seated scales are difficult to wash off by pickling on the hot-rolled steel sheet, and thus surface defects of the steel sheet occur after cold rolling, which affects the appearance. The silicon content is set to be below 0.05 percent;
Manganese: mn and C are the same strengthening elements of steel, proper addition of Mn in steel is beneficial to improving the strength, a small amount of Mn can be combined with S to generate MnS, the surface hot brittleness is reduced, the surface quality problem is avoided, but excessive addition can improve the plastic deformation resistance of the material, increase the cold rolling load, and simultaneously increase the cost. The Mn content range of the invention is set to be 0.20-0.40%;
Phosphorus: p is a strengthening element, and a strengthening mechanism and iron atoms are replaced to form a solid solution, so that the matrix lattice of Fe is distorted, the dislocation density is increased, and the strengthening effect is achieved. P strengthening can be stronger than other substitutional solid solution strengthening elements such as Mn and Si. Meanwhile, compared with steel added with Nb and Ti alloy elements for precipitation strengthening and C-gap solid solution strengthening, the phosphorus solid solution strengthened steel has the advantages that the strength loss caused by the process from hot rolling to cold rolling annealing production of the strip steel is small, and the effect is obvious in phosphorus strengthened steel. In order to produce cold-rolled annealed sheets with certain strength, only lower rolling mill load is required, the generated cold-rolled rolling deformation heat is less, the temperature of the surface of a steel sheet is low, and the residual emulsion spots are easy to clean. The content range of P is set to be 0.03-0.05 percent;
sulfur: sulfur forms sulfide inclusions in the steel, reducing its ductility and toughness. When steel is rolled, the anisotropy of the steel is increased due to the elongation of MnS inclusions along the rolling direction, and steel plates are delaminated when the anisotropy is severe. The technical scheme of the invention sets S to be less than or equal to 0.02 percent;
Aluminum: aluminum is added as a deoxidizer during steelmaking, the deoxidizing effect of the material is poor when the aluminum content in the steel is less than 0.02%, and a large amount of Al2O3 impurities are generated in the steel; addition of an excessive amount of aluminum to steel promotes precipitation of nitrogen, which is disadvantageous in material strengthening. The Al content range of the invention is set to be 0.02-0.080%.
A production method of a hot-dip galvanized steel sheet with 320 MPa-level yield strength 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: 0.071-0.090%, Si: 0-0.05%, Mn: 0.20-0.40%, P: 0.03-0.05%, S: 0-0.02%, Alt: 0.020-0.080% of Fe and inevitable impurities as the rest;
Heating the continuous casting plate blank to 1150-1200 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section type rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 850-890 ℃; the thickness of the steel plate after finish rolling is 2.0-2.8 mm, the laminar cooling adopts front-section cooling, and the coiling temperature is 580-640 ℃ to obtain a hot-rolled steel coil;
And uncoiling the hot-rolled steel coil again, then carrying out acid pickling, cold rolling, degreasing, annealing in a horizontal continuous annealing furnace, hot galvanizing and leveling, and coiling to obtain a finished hot-galvanized steel plate with the thickness of 0.25-0.35mm, wherein the cold rolling reduction is 83-91%, the temperature of the strip steel in a hard rolling state after cold rolling in the annealing section of the horizontal continuous annealing furnace is 710-750 ℃, the annealing time of the strip steel in the annealing section is 35-50 s, the temperature of the strip steel in a zinc pot is 480-plus-one-530 ℃, the temperature of the zinc liquid in the hot-dip galvanizing pot is 450-plus-one 470 ℃, the hot-dip galvanizing time is 2-4s, and the leveling elongation is 0.5-0..
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 continuous casting slab enables the slab to be completely austenitized, and is beneficial to rolling and structure control. The heating temperature is too low to be completely austenitized, and compounds such as AlN are not fully dissolved, so that the strength of a finished product is negatively influenced to a certain extent; energy consumption is wasted due to overhigh temperature. The heating temperature of the invention is set to 1150-1200 ℃.
2. Setting of finish Rolling finishing temperature
when hot rolling is carried out, the material is completely austenite recrystallization rolling, so that the cold rolling process cannot be eliminated in order to avoid mixed crystals caused by the fact that the material enters a two-phase region for rolling, and the final rolling temperature is higher than the Ar3 phase transformation point. The finish rolling finishing temperature of the invention is set to 850-890 ℃.
3. setting of laminar cooling system and hot rolling coiling temperature
The temperature is less than 580 ℃, the temperature difference between final rolling and coiling is large, so that the cooling rate is high, the crystal grains of the hot rolled plate are refined, the yield strength of the hot rolled plate is high, and the cold rolling load is large. On the contrary, the temperature is higher than 640 ℃, the crystal grains are coarse, and the strength of the final product cannot be ensured. The coiling temperature of the invention is set to be 580-640 ℃.
4. Setting of Cold Rolling reduction
The cold rolling reduction rate is determined by the thickness of a hot rolled steel plate of a raw material plate and the thickness of a finished product of a cold rolled steel plate, and the thickness value of the finished hot galvanized steel plate is 0.25-0.35 mm; on one hand, the hot rolled steel plate cannot be too thin, otherwise the temperature of the hot rolled steel plate is reduced too fast, and the hot rolling finishing temperature cannot be guaranteed; on the other hand, if the hot-rolled steel sheet is too thick, the cold rolling reduction is too large, and the rolling force of the cold rolling mill train is too high, which is not favorable for cleaning the residual emulsion. The cold rolling reduction is set to be 83-91%.
5. Setting of annealing temperature and annealing time
the properties of finished products are influenced by three processes of recovery, recrystallization and grain growth of the cold-rolled hard steel in the annealing process. The annealing temperature greatly affects the punching properties of the material, and if the annealing temperature is too low, although the hardness can be significantly increased, a fibrous structure is produced because of incomplete recrystallization, and the workability is deteriorated. Too high annealing temperature will cause grain growth and lower strength. The annealing temperature of the steel strip in the horizontal continuous annealing furnace is set to 710-750 ℃, and the annealing time is set to 35-50 s.
6. Setting of the temperature of the strip in the zinc pot
In the hot dip coating process, the temperature of the strip steel entering a pot influences the uniformity of the thickness of the zinc layer, and for thin materials, the temperature of zinc liquid on the surface of the strip steel after the strip steel is discharged from a new pot is fast, so the temperature of the strip steel entering the pot is higher than the temperature of the zinc liquid, otherwise, the edge of the zinc layer is easy to thicken, and the hot dip coating time influences the thickness of the alloy layer. The temperature of the strip steel in the pot is set to be 480-530 ℃, the dip plating time is set to be 2-4s, and the temperature of the zinc liquid is controlled to be 450-470 ℃.
7. Setting of the Flat elongation
The main purpose of leveling is to eliminate the yield platform of the material and simultaneously to micro-adjust the mechanical properties. The flat elongation of the invention is 0.5-0.9%.
The metallographic structure of the hot-dip galvanized steel sheet is ferrite, a small amount of pearlite and free cementite, the grain size of the structure is I7-9 grade, the yield strength R P0.2 of the hot-dip galvanized steel sheet with the thickness of 0.25-0.35mm is 320-390 Mpa, the tensile strength R m is 420-480 Mpa, the transverse post-fracture elongation A 80mm is 27-32%, the surface quality of a finished hot-dip galvanized steel sheet is good, and the color difference delta E is less than 1.
compared with the prior art, the invention has the following positive effects: 1. according to the invention, through the optimized combination of the design of material components, the control of hot rolling finishing temperature and coiling temperature, the annealing temperature and annealing time of the horizontal continuous annealing furnace, the hot dip coating process and the leveling process, the produced 320 MPa-level 0.25 mm-0.35 mm hot dip galvanized steel plate has good surface quality, and can meet the use requirements of household appliance appearance parts. 2. The production method has low requirement on the degreasing process capacity, does not need to add alloy elements, has low production cost and can bring considerable economic benefit.
Drawings
FIG. 1 is a photograph of a metallographic structure of a hot-dip galvanized steel sheet according to example 1 of the present invention.
Detailed Description
The invention is further illustrated by the following examples 1-4, as shown in tables 1-4:
Table 1 shows the chemical composition (in weight%) of the substrate of the hot-dip galvanized steel sheet according to the example of the present invention, with the balance being Fe and unavoidable impurities.
Table 1 chemical composition of substrate of hot dip galvanized steel sheet according to example of the present invention, unit: weight percent of
| Element(s) | C | Si | Mn | P | S | Alt |
| The invention | 0.071-0.090 | ≤0.050 | 0.20-0.40 | 0.03-0.05 | ≤0.020 | 0.020-0.080 |
| Example 1 | 0.072 | 0.010 | 0.36 | 0.048 | 0.010 | 0.045 |
| Example 2 | 0.078 | 0.020 | 0.32 | 0.044 | 0.009 | 0.030 |
| example 3 | 0.081 | 0.025 | 0.31 | 0.039 | 0.015 | 0.029 |
| Example 4 | 0.089 | 0.016 | 0.23 | 0.031 | 0.011 | 0.056 |
The molten steel is refined through a converter smelting molten steel and an LF refining furnace in sequence to obtain molten steel meeting the requirement on chemical composition, and the molten steel is continuously cast to obtain a continuous casting slab, wherein the thickness of the continuous casting slab is 210-230 mm, the width of the continuous casting slab is 800-1300 mm, and the length of the continuous casting slab is 5000-10000 mm.
And (3) sending the fixed-length plate blank produced in the steel-making process to a heating furnace for reheating, discharging from the furnace for dephosphorization, and sending to a continuous hot continuous rolling mill for rolling. And after controlled rolling by a rough rolling mill and a finish rolling continuous rolling unit, cooling to a set temperature for coiling to produce a hot rolled steel coil. The hot rolling process control is shown in Table 2.
TABLE 2 control parameters of the Hot Rolling Process of the invention
And uncoiling the hot-rolled steel coil again, then carrying out acid pickling, cold rolling, degreasing, annealing by a horizontal continuous annealing furnace, hot galvanizing and leveling, and coiling to obtain the hot-galvanized steel coil with the thickness of 0.25-0.35 mm. The degreasing adopts the conventional process, and the annealing process comprises the following steps: the temperature of the rolled hard strip steel subjected to cold rolling in the annealing section of the horizontal continuous annealing furnace is 710-750 ℃, the annealing time of the strip steel in the soaking section is 35-50 s, the temperature of the strip steel in a zinc pot is 480-fold and 530 ℃, the temperature of zinc liquid in a hot-dip galvanizing pot is 450-fold and 470 ℃, the hot-dip galvanizing time is 2-4s, and the flat elongation is 0.5-0.9%. The control parameters of the cold rolling, degreasing, annealing, hot dipping and flattening processes are shown in the table 3.
TABLE 3 control parameters of the cold rolling, annealing, hot dipping, and leveling processes of the examples of the present invention
Referring to fig. 1, the metallographic structure of the hot-dip galvanized steel sheet obtained by the method is ferrite, a small amount of pearlite and free cementite, the grain size of the structure is I7-9 grade, the yield strength R P0.2 of the hot-dip galvanized steel sheet with the thickness of 0.25-0.35mm is 320-390 MPa, the tensile strength R m is 420-480 MPa, the transverse post-fracture elongation A 80mm is 27-32%, and the finished hot-dip galvanized steel sheet has good surface quality and no color difference on the surface.
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 for tensile test, the color difference of the steel plate surface is tested by a color difference meter. The mechanical properties of the steel sheet are shown in Table 4.
TABLE 4 mechanical properties of hot-dip galvanized steel sheets according to examples 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 (3)
1. A hot-dip galvanized steel sheet with a yield strength of 320MPa comprises, by weight, 0.071-0.090% of C, 0-0.05% of Si, 0.20-0.40% of Mn, 0.03-0.05% of P, 0-0.02% of S, 0.020-0.080% of Alt, and the balance Fe and inevitable impurities, wherein the hot-dip galvanized steel sheet has a metallographic structure of ferrite, a small amount of pearlite and free cementite, a structure grain size of I7-9 grade, a yield strength R P0.2 of the hot-dip galvanized steel sheet with a thickness of 0.25-0.35mm of 320-390 MPa, a tensile strength R m of 420-480 MPa, a transverse post-fracture elongation A 80mm of 27-32%, and a color difference value delta E of the surface of the hot-dip galvanized steel sheet is less than 1.
2. A production method of a hot-dip galvanized steel sheet with 320 MPa-level yield strength 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: 0.071-0.090%, Si: 0-0.05%, Mn: 0.20-0.40%, P: 0.03-0.05%, S: 0-0.02%, Alt: 0.020-0.080% of Fe and inevitable impurities as the rest;
Heating the continuous casting plate blank to 1150-1200 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section type rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 850-890 ℃; the laminar cooling adopts front-section cooling, and the coiling temperature is 580-640 ℃ to obtain a hot-rolled steel coil;
And uncoiling the hot-rolled steel coil again, then carrying out acid pickling, cold rolling, degreasing, annealing in a horizontal continuous annealing furnace, hot galvanizing and leveling, and coiling to obtain a finished hot-galvanized steel plate with the thickness of 0.25-0.35mm, wherein the cold rolling reduction is 83-91%, the temperature of the strip steel in a hard rolling state after cold rolling in the annealing section of the horizontal continuous annealing furnace is 710-750 ℃, the annealing time of the strip steel in the annealing section is 35-50 s, the temperature of the strip steel in a zinc pot is 480-plus-one-530 ℃, the temperature of the zinc liquid in the hot-dip galvanizing pot is 450-plus-one 470 ℃, the hot-dip galvanizing time is 2-4s, and the leveling elongation is 0.5-0..
3. The method for producing a hot-dip galvanized steel sheet with a yield strength of 320MPa according to claim 2, wherein the thickness of the hot-rolled steel sheet is controlled to be 2.0 to 2.8mm after finish rolling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810562001.3A CN110551939A (en) | 2018-06-04 | 2018-06-04 | Hot-dip galvanized steel plate with yield strength of 320MPa and production method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810562001.3A CN110551939A (en) | 2018-06-04 | 2018-06-04 | Hot-dip galvanized steel plate with yield strength of 320MPa and production method thereof |
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| CN110551939A true CN110551939A (en) | 2019-12-10 |
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| CN (1) | CN110551939A (en) |
Cited By (8)
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| CN112899562A (en) * | 2021-01-15 | 2021-06-04 | 山东钢铁集团日照有限公司 | Micro-carbon hot-dip galvanized steel strip with stable yield strength control and production method thereof |
| CN113718166A (en) * | 2020-05-25 | 2021-11-30 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum-zinc steel plate with yield strength of 320MPa and manufacturing method thereof |
| CN113718167A (en) * | 2020-05-25 | 2021-11-30 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum-zinc steel plate with yield strength of 330MPa for liquid crystal backboard |
| CN114643279A (en) * | 2022-01-29 | 2022-06-21 | 安阳钢铁股份有限公司 | Method for controlling shape of ultrathin ultra-wide steel strip for continuous galvanizing |
| CN115094343A (en) * | 2022-05-26 | 2022-09-23 | 安阳钢铁集团有限责任公司 | Ultrathin wide-width high-strength continuous hot-dip galvanized steel for household appliances and production method thereof |
| CN115505832A (en) * | 2021-06-07 | 2022-12-23 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum-zinc steel plate for liquid crystal backboard with yield strength of 340MPa |
| CN116837287A (en) * | 2023-06-26 | 2023-10-03 | 包头钢铁（集团）有限责任公司 | Hot galvanizing low-alloy high-strength steel for automobile structure and production method thereof |
| CN117026077A (en) * | 2023-07-31 | 2023-11-10 | 包头钢铁（集团）有限责任公司 | Hot galvanizing substrate for economical building profiled steel sheet and production method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113718166A (en) * | 2020-05-25 | 2021-11-30 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum-zinc steel plate with yield strength of 320MPa and manufacturing method thereof |
| CN113718167A (en) * | 2020-05-25 | 2021-11-30 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum-zinc steel plate with yield strength of 330MPa for liquid crystal backboard |
| CN113718166B (en) * | 2020-05-25 | 2022-12-06 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum-zinc steel plate with yield strength of 320MPa and manufacturing method thereof |
| CN112899562A (en) * | 2021-01-15 | 2021-06-04 | 山东钢铁集团日照有限公司 | Micro-carbon hot-dip galvanized steel strip with stable yield strength control and production method thereof |
| CN115505832A (en) * | 2021-06-07 | 2022-12-23 | 上海梅山钢铁股份有限公司 | Hot-dip aluminum-zinc steel plate for liquid crystal backboard with yield strength of 340MPa |
| 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 |
| CN114643279A (en) * | 2022-01-29 | 2022-06-21 | 安阳钢铁股份有限公司 | Method for controlling shape of ultrathin ultra-wide steel strip for continuous galvanizing |
| CN115094343A (en) * | 2022-05-26 | 2022-09-23 | 安阳钢铁集团有限责任公司 | Ultrathin wide-width high-strength continuous hot-dip galvanized steel for household appliances and production method thereof |
| CN116837287A (en) * | 2023-06-26 | 2023-10-03 | 包头钢铁（集团）有限责任公司 | Hot galvanizing low-alloy high-strength steel for automobile structure and production method thereof |
| CN117026077A (en) * | 2023-07-31 | 2023-11-10 | 包头钢铁（集团）有限责任公司 | Hot galvanizing substrate for economical building profiled steel sheet and production method thereof |
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