CN113444972A - Low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate and preparation method thereof - Google Patents
Low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate and preparation method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 79
- 239000010959 steel Substances 0.000 title claims abstract description 79
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 27
- 238000005096 rolling process Methods 0.000 claims abstract description 20
- 238000005246 galvanizing Methods 0.000 claims abstract description 16
- 239000000126 substance Substances 0.000 claims abstract description 16
- 238000003723 Smelting Methods 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 9
- 238000005098 hot rolling Methods 0.000 claims abstract description 7
- 239000002253 acid Substances 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims description 23
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 22
- 229910052725 zinc Inorganic materials 0.000 claims description 22
- 239000011701 zinc Substances 0.000 claims description 22
- 229910000859 α-Fe Inorganic materials 0.000 claims description 16
- 229910001563 bainite Inorganic materials 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 15
- 229910000734 martensite Inorganic materials 0.000 claims description 15
- 238000005097 cold rolling Methods 0.000 claims description 11
- 230000009467 reduction Effects 0.000 claims description 11
- 238000007747 plating Methods 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 238000004321 preservation Methods 0.000 claims description 5
- 229910052717 sulfur Inorganic materials 0.000 claims description 5
- 230000033116 oxidation-reduction process Effects 0.000 claims description 4
- 238000002791 soaking Methods 0.000 claims description 4
- 238000005266 casting Methods 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 claims description 3
- 238000005554 pickling Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 13
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 238000004886 process control Methods 0.000 abstract description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 239000011572 manganese Substances 0.000 description 10
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 6
- 238000000137 annealing Methods 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 6
- 238000005452 bending Methods 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000003712 anti-aging effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 150000002697 manganese compounds Chemical class 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
- B21B37/76—Cooling control on the run-out table
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
-
- 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
- C21D2211/002—Bainite
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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
-
- 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
- C21D2211/008—Martensite
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
The invention discloses a low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate and a preparation method thereof, belonging to the technical field of cold-rolled strip production. The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate comprises the following chemical components in percentage by weight: 0.06-0.12% of C, 0.10-0.50% of Si, 1.50-1.80% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 0.015-0.070% of Als0, less than or equal to 0.0060% of N, 0.20-0.50% of Cr0.20, and the balance of Fe and inevitable impurities; the preparation method comprises the working procedures of smelting, hot rolling, acid rolling, hot galvanizing and the like. According to the invention, through reasonable matching of components and processes, the prepared steel plate has the yield strength of 320-380MPa, the tensile strength of 610-660MPa and the elongation A8020.0-29.0 percent and 60.0-75.0 percent of hole expansion rate, the invention has simple process control and low production cost, and can effectively solve the problem of poor mechanical property of the prior 600 MPa-grade hot-dip galvanized complex-phase steel plate.
Description
Technical Field
The invention belongs to the technical field of cold-rolled strip production, relates to hot-galvanized complex phase steel produced by adopting continuous hot-galvanizing, and particularly relates to a low-cost 600 MPa-grade hot-galvanized complex phase steel plate and a preparation method thereof.
Background
In recent years, with the development of the automobile industry and the requirements of energy conservation and emission reduction, automobile steel gradually develops to high-strength steel, and meanwhile, the number of formed parts such as bending flanges and the like applied to the high-strength steel is increased day by day. The traditional high-strength steel is mainly dual-phase steel, the structure of the high-strength steel mainly comprises a softer ferrite matrix and martensite with higher strength, and the structure has the performance characteristics of lower yield ratio, higher strength and the like and is suitable for producing stamping parts; however, the hardness difference between the ferrite phase and the martensite phase is large, so that the bending performance and the hole expanding performance are low, and the production of hole expanding flanging and bending forming parts cannot be met. Therefore, bainite needs to be introduced outside the ferrite + martensite two phases, and the martensite is dispersed and distributed on the ferrite matrix, so that the bending performance and the hole expanding performance are improved while the strength of the material is ensured, the requirements of flanging and bending forming parts are met, and the material can be used for manufacturing workpieces with complex shapes.
Patent CN103627953A disclosed on 3/12/2014 is an aluminum-containing complex phase steel insensitive to equal temperature and time and a production method thereof (600MPa strength level), and comprises the following chemical components in percentage by weight: 0.15 to 0.17 percent of C, 0.10 to 0.20 percent of Si, 1.45 to 1.55 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 1.20 to 1.40 percent of Al, less than or equal to 0.0060 percent of N, and the balance of Fe and inevitable impurities. The rolling process adopts 860-900 ℃ finish rolling, 640-680 ℃ coiling and cold rolling reduction rate of 60-70%; the zinc plating adopts uniform heating at 790-810 ℃, slow cooling temperature at 710-730 ℃ and zinc pot temperature at 460-480 ℃. The invention adopts higher C content, which is not beneficial to the forming and welding performance, and higher Al content can cause the problems of difficult continuous casting, reduced steel purity, difficult cleaning of hot-rolled iron scale and poor hot-dip galvanizing surface quality in the smelting process.
A hot-rolled multiphase steel with 650MPa tensile strength disclosed in patent CN105950984A of 2016, 9, 21 and a production method thereof comprises the following chemical components in percentage by weight: 0.06 to 0.10 percent of C, less than or equal to 0.3 percent of Si, 0.90 to 1.30 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.008 percent of S, 0.020 to 0.070 percent of Als, 0.01 to 0.03 percent of Nb, and the balance of Fe and inevitable impurities. The heating temperature is controlled to 1250-; the finishing temperature of rough rolling is 1080-. The cooling process is controlled by adopting a five-section mode: the first section cooling speed is 80-180 ℃/s, the cooling is carried out to 720 ℃ of 680-; wherein, the first section, the third section and the fifth section adopt water cooling, and the second section and the fourth section adopt air cooling. The five-section type cooling process adopted by the patent is complex and difficult to produce, particularly the first section cooling rate requires very high cooling strength of 80-180 ℃/s, and the third and fifth sections cooling rates also require very high strength, so that the five-section type cooling process is not beneficial to popularization in conventional units. In addition, it is a hot rolled product, and is inferior in product thickness precision, surface quality, and the like.
Disclosure of Invention
The invention aims to solve the technical problem that the mechanical property of the existing 600 MPa-grade hot-dip galvanized complex-phase steel plate is poor.
The technical scheme adopted by the invention for solving the technical problems is as follows: the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate comprises the following chemical components in percentage by weight: 0.06-0.12% of C, 0.10-0.50% of Si, 1.50-1.80% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 0.015-0.070% of Als, less than or equal to 0.0060% of N, 0.20-0.50% of Cr, and the balance of Fe and inevitable impurities.
Further, the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate comprises the following chemical components in percentage by weight: 0.08 to 0.10 percent of C, 0.20 to 0.35 percent of Si, 1.60 to 1.75 percent of Mn, 0.03 to 0.06 percent of Als, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.003 percent of N, 0.35 to 0.40 percent of Cr, and the balance of Fe and inevitable impurities.
The microstructure of the low-cost 600 MPa-grade hot-dip galvanized complex phase steel plate consists of 55-65% of ferrite, 15-20% of island-shaped distributed martensite and 15-30% of bainite.
Further, the average grain size of ferrite was 10.0. mu.m, the average grain size of martensite was 3.5. mu.m, and the average grain size of bainite was 7.0. mu.m.
The yield strength of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate is 320-380MPa, the tensile strength is 610-660MPa, and the elongation rate A is8020.0-29.0% and 60.0-75.0% of hole expansion rate.
The preparation method of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate comprises the following steps:
a. smelting: smelting according to the chemical components of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate, and casting into a plate blank;
b. a hot rolling procedure: heating, dephosphorizing, rough rolling, finish rolling and laminar cooling the plate blank to obtain a hot rolled coil, controlling the finish rolling temperature to be 900-;
c. acid rolling process: pickling the hot rolled coil, and then cold rolling to obtain thin strip steel, wherein the thickness of the strip steel is controlled to be 0.7-2.5mm, and the reduction rate is 55-79%;
d. hot galvanizing procedure: the thin strip steel is heated to 300 ℃, 700 ℃ and 760 ℃ 780 ℃ in stages at the speed of 15-20 ℃/s, 4-10 ℃/s and 0.5-3 ℃/s, then cooled to 600 ℃ and 470 ℃ at the speed of 1-5 ℃/s, then rapidly cooled to 450 ℃ and 470 ℃ at the speed of 10-25 ℃/s, and finally enters a zinc bath for zinc plating.
In the step c, the cold rolling reduction is reduced by 3-5% when the thickness specification of the cold-rolled thin strip steel is increased by 0.3 mm.
In the step d, a pre-oxidation-reduction technology is adopted during heating, and soaking and heat preservation are needed for 25-90s after heating is finished.
In the step d, after the rapid cooling is finished, the zinc is uniformly insulated and enters a zinc pool for galvanizing for 10-40s, and the zinc is cooled to the room temperature at the speed of more than or equal to 5 ℃/s after being discharged from the zinc pool.
In the step d, the speed of the machine set is 70-160m/min, and the speed of the machine set is reduced by 13-17m/min when the thickness specification of the cold-rolled thin strip steel is increased by 0.3 mm.
The invention has the beneficial effects that: c and Si in the components of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate designed by the invention can be dissolved in ferrite and austenite in a solid manner to improve the strength of the steel, and Mn can improve the hardenability within the cooling rate capability range of a conventional continuous annealing/galvanizing production line; al is a strong deoxidizing element, so that the oxygen content in steel can be ensured to be as low as possible, and crystal grains can be refined; cr plays a role in solid solution strengthening in complex phase steel, and the strength and plasticity of the steel can be improved by changing the phase transition temperature of the steel and changing the form and distribution of martensite.
The final rolling temperature adopted by the invention enables the final deformation to be within the austenitizing temperature, thereby effectively avoiding the mixed crystal from reducing the product performance; the adoption of the lower curling temperature can avoid the separation of a V-containing second phase in the hot rolling process, the separation of the V-containing second phase in the annealing process is realized to the greatest extent, the precipitation strengthening effect is achieved, and meanwhile, the curling temperature is in a bainite transformation region, so that grains can be refined and the banded structure can be reduced; the cold rolling reduction rate is controlled to ensure that the microstructure of the strip steel is crushed, scraped and deformed to store energy, and austenitizing and recrystallizing are facilitated in the heat treatment process.
In the hot galvanizing procedure of the invention, the pre-oxidation-reduction function is adopted in heating, so that the precipitated elements can be well controlled, the internal and external oxidation conditions of the alloy elements are changed, the Si content can be properly added without causing the deterioration of the surface quality of a coating, the deformed structure is recrystallized and partially austenitized, and the galvanizing annealing (two-phase region) is used for controlling the ratio of ferrite to austenite; by adopting the cooling rate of the invention to slowly cool to 600-660 ℃, part of austenite can be converted into oriented periphytic ferrite, and the enrichment of residual austenite C and alloy elements can be realized; the steel strip structure can rapidly enter a bainite transformation temperature region by rapidly cooling to 450-470 ℃, so that the generation of pearlite is prevented; the zinc plating is carried out for 10-40s after balanced heat preservation, so that bainite can be conveniently generated, and a zinc layer is coated on the strip steel; after galvanization, the residual austenite can be transformed into martensite by cooling at the speed of more than or equal to 5 ℃/s.
The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate disclosed by the invention has the advantages that the design of chemical components is matched with the process, the combined action influences the microstructure of steel so as to generate corresponding mechanical properties, the yield strength of the steel plate disclosed by the invention is 320-grade and 380MPa, the tensile strength is 610-grade and 660MPa, and the elongation rate A is A8020.0-29.0% and 60.0-75.0% of hole expansion rate; the microstructure of the steel plate consists of 55-65% of ferrite, 15-20% of island-shaped distributed martensite and 15-30% of bainite, the components of the steel plate prepared by the invention do not use precious metal elements such as Mo, Nb, Ni and the like, the process control is simple, and the production cost is low.
Drawings
FIG. 1 is a metallographic structure diagram of example 1.
FIG. 2 is an electron scan diagram of example 1.
Detailed Description
The technical solution of the present invention can be specifically implemented as follows.
The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate comprises the following chemical components in percentage by weight: 0.06-0.12% of C, 0.10-0.50% of Si, 1.50-1.80% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 0.015-0.070% of Als, less than or equal to 0.0060% of N, 0.20-0.50% of Cr, and the balance of Fe and inevitable impurities.
When the content of Si is too high, surface iron scale which is difficult to remove can be formed in the heating furnace, the dephosphorization difficulty is increased, and SiO is easily formed by enriching to the surface in annealing2Surface defects such as plating leakage and the like are caused; when the content of Mn is too high, the Mn is easy to enrich to the surface in the annealing process, and a large amount of manganese compounds are formed, so that the surface galvanizing quality is reduced; the AlN has the main functions of refining grains and obtaining anti-aging performance, and when the content of Als is less than 0.010 percent, the effect cannot be exerted; however, the addition of a large amount of aluminum easily forms alumina agglomerates; cr is the most effective element for delaying bainite transformation, and has a much greater effect of delaying bainite transformation than pearlite transformation. Therefore, preferably, the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate comprises the following chemical components in percentage by weight: 0.08 to 0.10 percent of C, 0.20 to 0.35 percent of Si, 1.60 to 1.75 percent of Mn, 0.03 to 0.06 percent of Als, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.003 percent of N, 0.35 to 0.40 percent of Cr, and the balance of Fe and inevitable impurities.
The yield strength of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate is 320-380MPa, the tensile strength is 610-660MPa, and the elongation rate A is8020.0 to 29.0%, and a porosity of 60.0 to 75.0%, and a microstructure composed of 55 to 65% of ferrite (average grain size of 10.0 μm), 15 to 20% of martensite distributed in an island shape (average grain size of 3.5 μm), and 15 to 30% of bainite (average grain size of 7.0 μm).
The preparation method of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate comprises the following steps:
a. smelting: smelting according to the chemical components of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate, and casting into a plate blank;
b. a hot rolling procedure: heating, dephosphorizing, rough rolling, finish rolling and laminar cooling the plate blank to obtain a hot rolled coil, controlling the finish rolling temperature to be 900-;
c. acid rolling process: pickling the hot rolled coil, and then cold rolling to obtain thin strip steel, wherein the thickness of the strip steel is controlled to be 0.7-2.5mm, and the reduction rate is 55-79%;
d. hot galvanizing procedure: the thin strip steel is heated to 300 ℃, 700 ℃ and 760 ℃ 780 ℃ in stages at the speed of 15-20 ℃/s, 4-10 ℃/s and 0.5-3 ℃/s, then cooled to 600 ℃ and 470 ℃ at the speed of 1-5 ℃/s, then rapidly cooled to 450 ℃ and 470 ℃ at the speed of 10-25 ℃/s, and finally enters a zinc bath for zinc plating.
In order to increase the adaptability and meet the requirements of different production specifications, therefore, in the step c, the cold rolling reduction rate is preferably reduced by 3-5% for each 0.3mm increase of the thickness specification of the cold-rolled thin strip steel; in the step d, the speed of the machine set is 70-160m/min, and the speed of the machine set is reduced by 13-17m/min when the thickness specification of the cold-rolled thin strip steel is increased by 0.3 mm.
In order to control the precipitated elements and change the internal and external oxidation conditions of the alloy elements, the pre-oxidation-reduction technology is preferably adopted during heating in the step d, and soaking and heat preservation are preferably carried out for 25 to 90 seconds after the heating is finished. .
In order to facilitate the generation of bainite, the residual austenite is converted into martensite, therefore, in the step d, after the rapid cooling is finished, the steel is uniformly insulated, galvanized for 10-40s in a zinc bath, and cooled to room temperature at the speed of more than or equal to 5 ℃/s after being discharged from the zinc bath.
The technical solution and effects of the present invention will be further described below by way of practical examples.
Examples
The embodiment provides two groups of low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plates prepared by adopting the method, and the chemical components of the two groups of low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plates are shown in Table 1.
TABLE 1 Cold rolled dual phase steel chemical composition (wt.%)
| C | Si | Mn | Cr | P | S | N | Als | |
| Example 1 | 0.085 | 0.25 | 1.73 | 0.36 | 0.010 | 0.003 | 0.0024 | 0.035 |
| Example 2 | 0.090 | 0.30 | 1.68 | 0.38 | 0.012 | 0.001 | 0.0032 | 0.043 |
The preparation method of the low-cost high-elongation hot-dip galvanized high-strength steel plate comprises the following specific processes:
A. smelting: through a smelting process, a dual-phase steel slab with chemical compositions shown in Table 1 is prepared.
B. A hot rolling procedure: the slab is heated, dephosphorized, hot-rolled and laminar-flow cooled to obtain a hot-rolled coil, and the specific hot-rolling process parameters are shown in table 2.
TABLE 2 Hot Rolling Main Process parameters of Cold-rolled Dual-phase Steel
| The initial rolling temperature/. degree.C | Final Rolling temperature/. degree.C | Coiling temperature/. degree.C | |
| Example 1 | 1063 | 912 | 587 |
| Example 2 | 1082 | 931 | 566 |
C. Acid rolling process: after being acid washed, the hot rolled coil is cold rolled into thin strip steel, wherein the thickness of the thin strip steel of the embodiment 1 is 1.3mm, and the cold rolling reduction rate is 71.0 percent; example 2 had a thickness of 1.6mm and a cold rolling reduction of 67.0%.
D. Hot galvanizing procedure: the cold rolling thin strip steel is heated to 300 ℃, 700 ℃ and 780 ℃ in stages at the heating rates of 15-20 ℃/s, 4-10 ℃/s and 0.5-3 ℃/s respectively; after soaking and heat preservation for 25-90s, slowly cooling to 600-.
TABLE 3 control requirements for cooling rate and holding time of each process stage of hot galvanizing
TABLE 4 temperature requirement for Hot galvanizing procedure
| Annealing temperature of galvanizing | Slow cooling end point temperature | End point temperature of rapid cooling | Temperature of zinc in the zinc pool | |
| Example 1 | 772℃ | 623℃ | 458℃ | 453℃ |
| Example 2 | 765℃ | 651℃ | 462℃ | 457℃ |
FIG. 1 is a metallographic photograph showing a microstructure of a steel material according to the invention obtained from example 1, the microstructure consisting essentially of ferrite (white, about 63% by volume) having an equiaxed average grain size of 10.0 μm + martensite (black, about 18% by volume) distributed at the ferrite grain boundaries + bainite (gray, about 19% by volume).
FIG. 2 is an electron microscope photograph showing the case of example 1, in which ferrite is depressed, martensite is raised without dots (clear) on the upper surface, and bainite is raised with white dots on the upper surface.
The properties of the cold-rolled dual-phase steel and the steels prepared in the examples of the present invention were measured according to GB/T228-2010 "Metal Material Room temperature tensile test method" using products of CN103627953A and CN105950984A as comparative examples, and the test results are shown in Table 5.
TABLE 5 mechanical Properties of Cold-rolled Dual-phase Steel
| Yield strength | Tensile strength | Elongation A80 | Hole enlargement rate (drill) | |
| Example 1 | 338MPa | 613MPa | 27.5％ | 71.5％ |
| Example 2 | 362MPa | 658MPa | 23.0％ | 64.0％ |
| CN103627953A | 412MPa | 624MPa | 31.0％ | - |
| CN105950984A | 598MPa | 699MPa | 20.0％ | - |
Claims (10)
1. The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate is characterized by comprising the following chemical components in percentage by weight: 0.06-0.12% of C, 0.10-0.50% of Si, 1.50-1.80% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 0.015-0.070% of Als0, less than or equal to 0.0060% of N, 0.20-0.50% of Cr0.20, and the balance of Fe and inevitable impurities.
2. The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 1, characterized by comprising the following chemical components in percentage by weight: 0.08 to 0.10 percent of C, 0.20 to 0.35 percent of Si, 1.60 to 1.75 percent of Mn1, 0.03 to 0.06 percent of Als0.03 to 0.06 percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.005 percent of N, 0.003 to 0.40 percent of Cr0.35 to 0.40 percent of N, and the balance of Fe and inevitable impurities.
3. The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 1, characterized in that: the microstructure of the steel plate consists of 55-65% of ferrite, 15-20% of island-shaped martensite and 15-30% of bainite.
4. The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 3, characterized in that: the average grain size of ferrite is 10.0 μm, the average grain size of martensite is 3.5 μm, and the average grain size of bainite is 7.0 μm.
5. The low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 1, characterized in that: the yield strength of the steel plate is 320-380MPa, the tensile strength is 610-660MPa, and the elongation A is8020.0-29.0% and 60.0-75.0% of hole expansion rate.
6. The method for preparing the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to any one of claims 1 to 5, characterized by comprising the following steps of:
a. smelting: smelting according to the chemical components of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate, and casting into a plate blank;
b. a hot rolling procedure: heating, dephosphorizing, rough rolling, finish rolling and laminar cooling the plate blank to obtain a hot rolled coil, controlling the finish rolling temperature to be 900-;
c. acid rolling process: pickling the hot rolled coil, and then cold rolling to obtain thin strip steel, wherein the thickness of the strip steel is controlled to be 0.7-2.5mm, and the reduction rate is 55-79%;
d. hot galvanizing procedure: the thin strip steel is heated to 300 ℃, 700 ℃ and 760 ℃ 780 ℃ in stages at the speed of 15-20 ℃/s, 4-10 ℃/s and 0.5-3 ℃/s, then cooled to 600 ℃ and 470 ℃ at the speed of 1-5 ℃/s, then rapidly cooled to 450 ℃ and 470 ℃ at the speed of 10-25 ℃/s, and finally enters a zinc bath for zinc plating.
7. The preparation method of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 5, characterized by comprising the following steps of: in the step c, the cold rolling reduction is reduced by 3-5% when the thickness specification of the cold-rolled thin strip steel is increased by 0.3 mm.
8. The preparation method of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 5, characterized by comprising the following steps of: in the step d, a pre-oxidation-reduction technology is adopted during heating, and soaking and heat preservation are needed for 25-90s after heating is finished.
9. The preparation method of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 5, characterized by comprising the following steps of: in the step d, after the rapid cooling is finished, the zinc is uniformly insulated and enters a zinc pool for galvanizing for 10-40s, and the zinc is cooled to the room temperature at the speed of more than or equal to 5 ℃/s after being discharged from the zinc pool.
10. The preparation method of the low-cost 600 MPa-grade hot-dip galvanized complex-phase steel plate according to claim 5, characterized by comprising the following steps of: in the step d, the speed of the machine set is 70-160m/min, and the speed of the machine set is reduced by 13-17m/min when the thickness specification of the cold-rolled thin strip steel is increased by 0.3 mm.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116179941A (en) * | 2022-12-09 | 2023-05-30 | 攀钢集团攀枝花钢铁研究院有限公司 | Low-cost boron-containing 780 MPa-level hot dip galvanized dual-phase steel and preparation method thereof |
| CN116254462A (en) * | 2022-08-17 | 2023-06-13 | 湖南华菱涟钢特种新材料有限公司 | 600 MPa-level galvanized dual-phase steel, preparation process and application thereof |
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| CN101158009A (en) * | 2001-02-27 | 2008-04-09 | 杰富意钢铁株式会社 | Hot dip zinc plated steel sheet having high strength and method for producing the same |
| CN108441763A (en) * | 2018-03-23 | 2018-08-24 | 马钢(集团)控股有限公司 | A kind of tensile strength 1000MPa grades of cold rollings galvanizing by dipping high-strength steel and preparation method thereof |
| CN112522623A (en) * | 2020-11-30 | 2021-03-19 | 攀钢集团攀枝花钢铁研究院有限公司 | Low-carbon equivalent 1180 MPa-grade hot-galvanized dual-phase steel and production method thereof |
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| CN101158009A (en) * | 2001-02-27 | 2008-04-09 | 杰富意钢铁株式会社 | Hot dip zinc plated steel sheet having high strength and method for producing the same |
| CN108441763A (en) * | 2018-03-23 | 2018-08-24 | 马钢(集团)控股有限公司 | A kind of tensile strength 1000MPa grades of cold rollings galvanizing by dipping high-strength steel and preparation method thereof |
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| CN116254462A (en) * | 2022-08-17 | 2023-06-13 | 湖南华菱涟钢特种新材料有限公司 | 600 MPa-level galvanized dual-phase steel, preparation process and application thereof |
| CN116179941A (en) * | 2022-12-09 | 2023-05-30 | 攀钢集团攀枝花钢铁研究院有限公司 | Low-cost boron-containing 780 MPa-level hot dip galvanized dual-phase steel and preparation method thereof |
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