CN110343971B - Ultrahigh-strength hot-galvanized complex-phase steel and production method thereof - Google Patents
Ultrahigh-strength hot-galvanized complex-phase steel and production method thereof Download PDFInfo
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- 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
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- 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
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- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
Abstract
The invention relates to ultrahigh-strength hot-galvanized complex phase steel and a production method thereof, belonging to the technical field of complex phase steel metallurgy. The chemical components of the hot galvanizing complex phase steel provided by the invention comprise: 0.09-0.16%, Si: 0.20 to 0.50%, Mn: 1.70-2.50%, P is less than or equal to 0.025%, S is less than or equal to 0.005%, Mo: 0.20-0.60%, Al: 0.02-0.08%, Nb: 0.010-0.070%, Ti: 0.030-0.070%, and N is less than or equal to 0.006%, the preparation method comprises the working procedures of smelting, hot rolling, acid rolling and hot galvanizing annealing, and the hot galvanizing annealing adopts a pre-oxidation reduction process. The hot-dip galvanized complex phase steel prepared by the invention has excellent forming performance, welding performance and galvanizing performance and meets the requirements of high strength and high elongation.
Description
Technical Field
The invention belongs to the technical field of multiphase steel metallurgy, and particularly relates to ultrahigh-strength hot-galvanized multiphase steel and a production method thereof.
Background
With the development of automobile lightweight technology, the development of automobile steel towards high-strength steel has become a necessary trend. The complex phase steel has the characteristics of high tensile strength, excellent plasticity and the like, and becomes the preferred high-strength steel for automobiles.
The patent (CN109023106A) discloses a cold-rolled hot-galvanized complex phase steel and a preparation method thereof, wherein the cold-rolled hot-galvanized complex phase steel comprises the following chemical components in percentage by weight: c: 0.08-0.12%, Si: 0.3-0.6%, Mn: 2.0-2.5%, P: less than or equal to 0.02 percent, S: less than or equal to 0.015 percent, Al: 0.1-0.4%, Cr: 0.2-0.5%, Mo: 0.1 to 0.4%, Nb: 0.03-0.06%, Ti: 0.03-0.06%, B: 0.002-0.003%, and the balance of Fe and inevitable impurities. Although the hot-dip galvanized complex-phase steel is obtained through the chemical components and the preparation method, the Mn content is higher, and Cr and B are added, so that the cost and the rolling load are obviously increased.
The patent (CN108486500A) discloses a cold-rolled hot-galvanized complex phase steel and a production method thereof, and the chemical components of the steel are as follows: c: 0.05-0.13%, Si: 0.1 to 0.5%, Mn: 1.5-2.5%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Al: 0.1-0.6%, Cr: 0.2-0.6%, Mo: 0.1 to 0.5%, Nb: 0.01-0.06%, Ti: 0.01 to 0.06%, and the balance of Fe and inevitable impurities. Although the hot-dip galvanized complex-phase steel is obtained through the chemical components and the preparation method thereof, the Cr is added, and the cost and the rolling load are obviously increased.
Patent (CN105247089A) discloses a method for producing high-strength hot-dip galvanized complex phase steel strip, which comprises the following chemical components in percentage by weight: c: 0.13 to 0.19%, Mn: 1.70-2.50%, Si: less than or equal to 0.15 percent, Al: 0.40-1.00%, Cr: 0.05 to 0.25%, Nb: 0.01-0.05%, P: less than or equal to 0.10 percent, Ca: less than or equal to 0.004%, S: less than or equal to 0.05 percent, N: not more than 0.007%, wherein Al + Si is more than 0.40% and less than 1.05%, and Mn + Cr is more than 1.90%, and the steel strip has a complex phase microstructure comprising, in volume percent, 8-12% of retained austenite, 20-50% of bainite, less than 10% of martensite, and the balance ferrite. Although the hot-dip galvanized complex-phase steel is obtained through the chemical components and the preparation method, the contents of C and Mn are higher, and the weldability is reduced. With the addition of Cr, the cost and rolling load are significantly increased.
In summary, the mechanical properties of complex phase steel are considered in one way, and the factors such as forming property, galvanization property and welding property are not considered comprehensively in the prior art.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides ultrahigh-strength hot-dip galvanized complex phase steel, which comprises the following chemical components in percentage by weight: 0.09-0.16%, Si: 0.20 to 0.50%, Mn: 1.70-2.50%, P is less than or equal to 0.025%, S is less than or equal to 0.005%, Mo: 0.20-0.60%, Al: 0.02-0.08%, Nb: 0.010-0.070%, Ti: 0.030-0.070%, N is less than or equal to 0.006%, the balance being Fe and unavoidable impurities, and the balance being Fe and unavoidable impurities.
Preferably, the ultrahigh-strength hot-dip galvanized complex-phase steel comprises the following chemical components in percentage by weight: 0.10 to 0.15%, Si: 0.30 to 0.50%, Mn: 1.80-2.40%, Mo: 0.20 to 0.50%, Al: 0.02 to 0.07%, Nb: 0.020 to 0.060%, Ti: 0.030-0.060%, P is less than or equal to 0.020%, S is less than or equal to 0.005%, N is less than or equal to 0.006%, and the balance of Fe and inevitable impurities.
The invention also discloses a production method of the high-strength hot-dip galvanized complex phase steel, which comprises the following steps:
(1) smelting: smelting according to the set chemical components;
(2) a hot rolling procedure: heating, dephosphorizing, hot rolling and laminar cooling a casting blank to obtain a hot rolled coil;
(3) acid rolling process: washing the hot rolled coil with acid and then cold rolling;
(4) hot galvanizing annealing: and (4) after hot galvanizing annealing, preparing the hot galvanizing complex phase steel.
Wherein, the smelting process in the step (1) is carried out according to the chemical components of the high-strength hot-dip galvanized complex phase steel.
Wherein the start rolling temperature of the finish rolling in the hot rolling procedure in the step (2) is 1050-1150 ℃, the finish rolling temperature is 860-930 ℃, and the coiling temperature is 580-640 ℃.
Wherein the cold rolling reduction rate of the acid rolling procedure in the step (3) is 35-50%.
And (3) in the hot galvanizing annealing process in the step (4), heating in an oxidation furnace, then carrying out recrystallization annealing in a reduction furnace with protective atmosphere, and finally entering a zinc pot for hot galvanizing under the sealed condition. Furthermore, the heating temperature in the oxidation furnace is controlled to be 760-810 ℃.
Wherein the dew point temperature of the protective atmosphere in the furnace in the hot galvanizing annealing procedure in the step (4) is-25 to-60 ℃.
Wherein the annealing temperature is 830-870 ℃, the zinc bath is rapidly cooled from the annealing temperature to the temperature of 440-460 ℃ of the zinc bath nose, the rapid cooling rate CR1 is 50-80 ℃/s, and the zinc bath is cooled to the room temperature at the final cooling rate CR2 of 4-10 ℃/s after galvanization.
The invention has the beneficial effects that:
the hot-dip galvanized dual-phase steel adopts C, Mn below to ensure the excellent welding performance of the hot-dip galvanized dual-phase steel, the Nb and Ti are added to improve the strength and toughness of the hot-dip galvanized dual-phase steel through grain refinement and precipitation strengthening, and the low-cost Si is adopted to inhibit the precipitation of carbides so that austenite is fully enriched with carbon to improve the strength of the hot-dip galvanized dual-phase steel; the hot galvanizing annealing of the invention adopts a pre-oxidation reduction process to improve the galvanizing quality of the surface of the dual-phase steel; the hot-dip galvanized dual-phase steel prepared by the method disclosed by the invention is excellent in forming performance, welding performance and galvanizing performance, has the yield strength of 866-887 MPa, the tensile strength of 1120-1130 MPa and the elongation (A80) of 10.6-11.8%, meets the requirements of high strength and high elongation, and has remarkable economic and social benefits.
Drawings
FIG. 1 is a microstructure topography of the hot-dip galvanized complex phase steel obtained in example 1.
Detailed Description
The invention provides ultrahigh-strength hot-dip galvanized complex phase steel, which comprises the following chemical components in percentage by weight: 0.09-0.16%, Si: 0.20 to 0.50%, Mn: 1.70-2.50%, P is less than or equal to 0.025%, S is less than or equal to 0.005%, Mo: 0.20-0.60%, Al: 0.02-0.08%, Nb: 0.010-0.070%, Ti: 0.030-0.070%, N is less than or equal to 0.006%, and the balance of Fe and inevitable impurities.
Preferably, the chemical components of the complex phase steel comprise, by weight percent, C: 0.10 to 0.15%, Si: 0.30 to 0.50%, Mn: 1.80-2.40%, Mo: 0.20 to 0.50%, Al: 0.02 to 0.07%, Nb: 0.020 to 0.060%, Ti: 0.030-0.060%, P is less than or equal to 0.020%, S is less than or equal to 0.005%, N is less than or equal to 0.006%, and the balance of Fe and inevitable impurities.
The design idea of the chemical components of the dual-phase steel is as follows:
carbon: c is one of the most important components of the complex phase steel and determines the strength, plasticity and forming performance of the steel plate. C is the most obvious element for the solid solution strengthening effect in the steel material, the solid solution C content in the steel is increased by 0.1 percent, and the strength can be improved by about 450 MPa. When the content of C is too low, the stability of austenite and the martensite hardenability are reduced, so that the strength is low, and the content of C in the dual-phase steel is generally not lower than 0.02%; when the content of C is too high, the plasticity and the welding performance of the dual-phase steel are reduced, and the content of C in the dual-phase steel is generally not higher than 0.15 percent. Therefore, the content of C in the invention is 0.09-0.16%.
Silicon: si can be dissolved in ferrite and austenite in a solid solution mode to improve the strength of the steel, the effect of the Si is second to C, P, and the Si is stronger than Mn, Cr, Ti, Ni and other elements; si can also inhibit the precipitation of carbides in ferrite, so that solid-solution C atoms are fully enriched in austenite, thereby improving the stability of the ferrite. However, when the content of Si is too high, the surface iron scale formed by Si in the heating furnace is difficult to remove, so that the dephosphorization difficulty is increased; meanwhile, SiO2 is easily enriched and formed on the surface in the annealing process, thereby causing surface defects such as plating leakage and the like. Therefore, the Si content of the invention is 0.20-0.50%.
Manganese: mn is a good deoxidizer and desulfurizer, and is also a common solid solution strengthening element in steel, and the content of Mn in dual-phase steel is generally not less than 1.20%. Mn can be combined with C to form various carbides to play a role in precipitation strengthening, and can also be dissolved in a matrix to enhance the solid solution strengthening effect. Mn is easily combined with S to form a high melting point compound MnS, thereby eliminating or weakening hot embrittlement caused by FeS and improving hot workability of the steel. Mn can improve the stability of austenite and shift the C curve to the right, thereby obviously reducing the critical cooling rate of martensite. However, when the Mn content is too high, the surface is easily enriched in the annealing process to form a large amount of manganese compounds, thereby causing the reduction of the surface galvanizing quality. Therefore, the Mn content is 1.70 to 2.50% in the present invention.
Molybdenum: mo acts similarly to Cr, significantly retarding pearlite and bainite transformation, thereby obtaining a high volume fraction of martensite to ensure strength. In addition, since the Gibbs free energy of Mo oxide is equivalent to that of Fe oxide, Mo does not affect the surface galvanizing quality of the dual-phase steel, but the cost is high. Therefore, in the present invention, the Mo content is 0.20 to 0.60%.
Niobium: nb mainly exists in the form of NbC in the complex phase steel, and has the functions of remarkable grain refinement and dispersion precipitation strengthening. In the hot galvanizing annealing heating process, the undissolved NbC particles can pin the ferrite grain boundary, thereby playing the role of refining grains; when the annealing temperature is increased to a two-phase region, the NbC dissolution temperature is lower, so that the NbC is fully dissolved in a matrix, and solid-solution C atoms are enriched into austenite to improve the stability of the NbC; during cooling, NbC in the ferrite will re-precipitate, producing significant precipitation strengthening. Therefore, the Nb content is 0.010-0.070%.
Titanium: ti is added, so that crystal grains can be refined, and the timeliness and the cold brittleness are reduced. The Ti content is too low, the strength is not enough, and the service performance can not be met. Too high Ti content can obviously improve the strength, influence the service performance and seriously cause the cracking of the stamped parts. Therefore, the Ti content is preferably 0.030% to 0.070%.
Aluminum: al is a common deoxidizer in steel, and can form an AlN pinning grain boundary so as to play a role in refining grains; in addition, Al acts similarly to Si, and suppresses carbide precipitation, thereby making austenite sufficiently rich in carbon. Therefore, the Al content in the invention is 0.02-0.08%.
The invention also provides a production method of the ultrahigh-strength hot-dip galvanized complex phase steel, which comprises the following steps when the steel plate is produced by casting a plate blank:
(1) smelting: smelting according to the designed chemical components, and then casting into a plate blank;
(2) a hot rolling procedure: heating, dephosphorizing, hot rolling and laminar cooling the casting blank to obtain a hot rolled coil, wherein the finish rolling start temperature is 1050-1150 ℃, the finish rolling temperature is 860-930 ℃, and the coiling temperature is 580-640 ℃;
(3) acid rolling process: cold-rolling the hot-rolled coil after acid washing to form cold-rolled thin strip steel, wherein the cold-rolling reduction rate is 35-50%;
(4) hot galvanizing annealing: and (3) carrying out hot galvanizing annealing on the cold-rolled thin strip steel to prepare the hot-galvanized complex phase steel plate. Specifically, annealing treatment is carried out in a furnace, the furnace is taken out of the furnace and cooled to a certain temperature, the zinc is subjected to hot galvanizing in a zinc pool, wherein the dew point temperature of the protective atmosphere in the furnace is-25 to-60 ℃, the annealing temperature is 830 to 870 ℃, the furnace is rapidly cooled from the annealing temperature to the furnace nose temperature of the zinc pool, the rapid cooling rate CR1 is 50 to 80 ℃/s, and the zinc is cooled to the room temperature at the final cooling rate CR2 of 4 to 10 ℃/s after galvanizing. Wherein, the actual gas partial pressure in the furnace is determined by detecting the dew point temperature of the protective atmosphere in the furnace, thereby controlling the content of the appropriate protective atmosphere (such as hydrogen).
In order to improve the surface galvanizing quality of the dual-phase steel, the invention also adopts a pre-oxidation reduction process, specifically, on a continuous hot galvanizing production line, an oxidation furnace and a reduction furnace are included in the line, the strip steel is firstly heated in the oxidation furnace, rolling oil and the like remained on the surface of the strip steel are burnt off, the surface is purified, then recrystallization annealing is carried out through the reduction furnace with protective atmosphere, and finally the strip steel enters a zinc pot for hot galvanizing under the sealed condition. Preferably, the heating temperature in the oxidation furnace is controlled to be 760-810 ℃.
The invention is further illustrated and described by the following examples and comparative examples.
Example 1
The high-formability high-strength hot-dip galvanized dual-phase steel is produced by the following process:
(1) smelting: c: 0.13%, Si: 0.32%, Mn: 1.95%, Mo: 0.28%, Als: 0.047%, Nb: 0.043%, P: 0.020%, S: 0.005%, N: 0.004%, Ti: 0.053 percent, and then casting into a plate blank with the thickness of 200 mm;
(2) a hot rolling procedure: heating, dephosphorizing, hot rolling and laminar cooling the casting blank to obtain a hot rolled coil, wherein the heating temperature is 1250 ℃, the finish rolling temperature is 1070 ℃, the finish rolling temperature is 860-900 ℃, the coiling temperature is 580-620 ℃, and the thickness of the hot rolled plate is 3.75 mm;
(3) acid rolling process: cold-rolling the hot-rolled coil into cold-rolled thin strip steel with the thickness of 2.3mm after acid washing, wherein the cold-rolling reduction rate is 40 percent;
(4) hot galvanizing annealing: and (3) carrying out hot galvanizing annealing on the cold-rolled thin strip steel to prepare the hot-galvanized complex phase steel plate. Wherein the oxidizing furnace is heated to 780 ℃, the dew point temperature of the protective atmosphere in the reducing furnace is-25 to-60 ℃, the annealing temperature is 851 ℃, the annealing temperature is rapidly cooled from the annealing temperature to the temperature of the zinc pool nose of 440 to 460 ℃, the rapid cooling rate CR1 is 63 ℃/s, and the zinc is cooled to the room temperature at the final cooling rate CR2 of 5.0 ℃/s after galvanization.
The hot-dip galvanized complex phase steel microstructure of the embodiment is shown in figure 1 through detection, and has the yield strength of 887MPa, the tensile strength of 1130MPa and the elongation A8010.6 percent, the hot-dip galvanized complex-phase steel of the embodiment has low C, Mn content, a microstructure consisting of ferrite, martensite and bainite, good surface galvanizing quality, good welding performance and high elongation, and meets the requirements of high strength and high elongation.
Example 2
The high-formability high-strength hot-dip galvanized dual-phase steel is produced by the following process:
(1) smelting: c: 0.13%, Si: 0.32%, Mn: 1.95%, Mo: 0.28%, Als: 0.047%, Nb: 0.043%, P: 0.020%, S: 0.005%, N: 0.004%, Ti: 0.053 percent, controlling the content of V in the converter by controlling the content of V in the original molten iron, not additionally adding ferrovanadium, and then casting the molten iron into a plate blank with the thickness of 200 mm;
(2) a hot rolling procedure: heating, dephosphorizing, hot rolling and laminar cooling the casting blank to obtain a hot rolled coil, wherein the heating temperature is 1250 ℃, the finish rolling temperature is 1080 ℃, the finish rolling temperature is 890-930 ℃, the coiling temperature is 610-640 ℃, and the hot rolling thickness is 3.75 mm;
(3) acid rolling process: cold-rolling the hot-rolled coil into cold-rolled thin strip steel with the thickness of 2.3mm after acid washing, wherein the cold-rolling reduction rate is 40.0 percent;
(4) hot galvanizing annealing: and (3) carrying out hot galvanizing annealing on the cold-rolled thin strip steel to prepare the hot-galvanized complex phase steel plate. Wherein the temperature in the oxidation furnace is heated to 775 ℃, the dew point temperature of the protective atmosphere in the reduction furnace is-25 to-60 ℃, the annealing temperature is 848 ℃, the temperature is rapidly cooled from the annealing temperature to the temperature of a zinc pool furnace nose of 440 to 460 ℃, the rapid cooling rate CR1 is 62 ℃/s, and the zinc is cooled to the room temperature at the final cooling rate CR2 of 6.0 ℃/s after galvanization.
Through detection, the yield strength 866MPa, the tensile strength 1120MPa and the elongation A of the hot-dip galvanized complex-phase steel of the embodiment8011.8% by weight of the hot dip galvanized coating of this exampleThe content of the phase steel C, Mn is low, the microstructure is composed of ferrite, martensite and bainite, the surface galvanizing quality is good, the welding performance is good, the elongation is high, and the requirements of high strength and high elongation are met.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (9)
1. The ultrahigh-strength hot-dip galvanized complex-phase steel is characterized in that: the complex phase steel comprises the following chemical components in percentage by weight: 0.09-0.16%, Si: 0.20 to 0.50%, Mn: 1.70-2.50%, P is less than or equal to 0.025%, S is less than or equal to 0.005%, Mo: 0.20-0.60%, Al: 0.02-0.08%, Nb: 0.010-0.070%, Ti: 0.030-0.070%, N is less than or equal to 0.006%, and the balance of Fe and inevitable impurities; the yield strength of the ultrahigh-strength hot-dip galvanized complex-phase steel is 866-887 MPa, the tensile strength is 1120-1130 MPa, and the elongation A80 is 10.6-11.8%;
the preparation method of the ultrahigh-strength hot-dip galvanized complex-phase steel comprises the following steps:
(1) smelting: smelting according to the set chemical components to obtain a steel billet;
(2) a hot rolling procedure: heating, dephosphorizing, hot rolling and laminar cooling a billet to obtain a hot rolled coil;
(3) acid rolling process: washing the hot rolled coil with acid and then cold rolling;
(4) hot galvanizing annealing: after hot galvanizing annealing, the needed hot galvanizing dual-phase steel is prepared; the annealing temperature is 830-870 ℃, the steel sheet is rapidly cooled from the annealing temperature to the temperature of a zinc pool furnace nose of 440-460 ℃, the rapid cooling rate CR1 is 62-80 ℃/s, and the steel sheet is cooled to the room temperature at the final cooling rate CR2 of 4-10 ℃/s after galvanization.
2. The ultra-high strength hot dip galvanized complex phase steel according to claim 1, characterized in that: the complex phase steel comprises the following chemical components in percentage by weight: 0.10 to 0.15%, Si: 0.30 to 0.50%, Mn: 1.80-2.40%, Mo: 0.20 to 0.50%, Al: 0.02 to 0.07%, Nb: 0.020 to 0.060%, Ti: 0.030-0.060%, P is less than or equal to 0.020%, S is less than or equal to 0.005%, N is less than or equal to 0.006%, and the balance of Fe and inevitable impurities.
3. A method for producing an ultra-high strength hot dip galvanized complex phase steel according to claim 1 or 2, characterized by comprising the steps of:
(1) smelting: smelting according to the set chemical components to obtain a steel billet;
(2) a hot rolling procedure: heating, dephosphorizing, hot rolling and laminar cooling a billet to obtain a hot rolled coil;
(3) acid rolling process: washing the hot rolled coil with acid and then cold rolling;
(4) hot galvanizing annealing: and (4) performing hot galvanizing annealing to prepare the required hot galvanizing dual-phase steel.
4. The method for producing the ultrahigh-strength hot-dip galvanized complex phase steel according to claim 3, characterized by comprising the following steps of: in the step (2), the start rolling temperature of finish rolling in the hot rolling process is 1050-1150 ℃, the finish rolling temperature is 860-930 ℃, and the coiling temperature is 580-640 ℃.
5. The method for producing the ultrahigh-strength hot-dip galvanized complex phase steel according to claim 3 or 4, characterized by comprising the following steps: and (3) the cold rolling reduction rate of the acid rolling process is 35-50%.
6. The method for producing the ultrahigh-strength hot-dip galvanized complex phase steel as claimed in claim 3, characterized by comprising the following steps: and (4) heating in an oxidation furnace, then carrying out recrystallization annealing in a reduction furnace with protective atmosphere, and finally entering a zinc pot for hot galvanizing under the sealed condition.
7. The method for producing the ultrahigh-strength hot-dip galvanized complex phase steel as claimed in claim 6, characterized by comprising the following steps: and the heating temperature in the oxidation furnace is controlled to be 760-810 ℃.
8. The method for producing the ultrahigh-strength hot-dip galvanized complex phase steel according to claim 3 or 6, characterized by comprising the following steps of: the dew point temperature of the protective atmosphere in the furnace in the hot galvanizing annealing procedure in the step (4) is-25 to-60 ℃.
9. The method for producing the ultrahigh-strength hot-dip galvanized complex phase steel according to claim 3, characterized by comprising the following steps of: the annealing temperature is 830-870 ℃, the steel sheet is rapidly cooled from the annealing temperature to the temperature of a zinc pool furnace nose of 440-460 ℃, the rapid cooling rate CR1 is 62-80 ℃/s, and the steel sheet is cooled to the room temperature at the final cooling rate CR2 of 4-10 ℃/s after galvanization.
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