CN113584375B - 600 MPa-grade low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel with enhanced hole expansion performance and production method thereof - Google Patents

600 MPa-grade low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel with enhanced hole expansion performance and production method thereof Download PDF

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CN113584375B
CN113584375B CN202110646887.1A CN202110646887A CN113584375B CN 113584375 B CN113584375 B CN 113584375B CN 202110646887 A CN202110646887 A CN 202110646887A CN 113584375 B CN113584375 B CN 113584375B
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steel
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陈忠
郑笑芳
何丹丹
崔磊
计遥遥
葛浩
刘永刚
詹华
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Maanshan Iron and Steel Co Ltd
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
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    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips
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    • C21—METALLURGY OF IRON
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    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—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
    • C21D2211/009—Pearlite

Abstract

The invention discloses 600 MPa-grade low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel with enhanced hole expansion performance and a production method thereof, and belongs to the technical field of hot-dip galvanized automobile high-strength steel. The dual-phase steel comprises the following main chemical elements in percentage by mass: c: 0.05-0.09%, Si: 0.05-0.20%, Mn: 0.9-1.5%, Cr: 0.15-0.45%, Mo: 0.10 to 0.50%, Ti: 0.01-0.05%, Als: 0.01-0.08%, B: 0.0005 to 0.0065%, Nb: 0.01-0.05%, Cu: 0.05-0.80%, Ni: 0.05-0.90%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, N is less than or equal to 0.005%, and the balance of Fe and inevitable impurities. The produced 600 MPa-grade alloyed hot-dip galvanized dual-phase steel with the hole expansion rate of 41.5-69.0% is suitable for complex automobile parts with high requirements on flanging hole expansion forming performance.

Description

600 MPa-grade low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel with enhanced hole expansion performance and production method thereof
Technical Field
The invention belongs to the technical field of high-strength steel for hot-dip galvanized automobiles, and particularly relates to 600 MPa-level low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel with enhanced hole expansion performance and a production method thereof.
Background
Since the 21 st century, the China automobile industry has always presented a good situation of high-speed development, and since 2009, China automobile production and sales were continuously cicada and were the first world. However, the automobile industry, as an important energy consumption industry, has become one of the most important sources of atmospheric environmental pollution in China. Therefore, the application of the advanced high-strength steel is the most effective way for improving the safety performance of the automobile and realizing the light weight of the whole automobile so as to achieve the effects of energy conservation and emission reduction.
With the higher and higher requirements of the automobile outer covering piece on the corrosion resistance, the application prospect of the galvanized automobile plate is wider and wider. The surface quality of the electrogalvanized automobile sheet is the best, but the coating thickness is not enough and the corrosion resistance is not good enough. Meanwhile, the electrogalvanizing process has great environmental pollution and can not meet the requirement of environmental protection. The corrosion resistance of the hot galvanizing automobile plate is better, but the welding performance and the coating performance of the pure zinc coating are poorer. The alloying annealing process is to heat the pure zinc coating band steel to a certain temperature in an alloying furnace, and the iron of the substrate and the zinc of the pure zinc layer have phase change reaction to generate a light gray zinc-iron alloy coating. Compared with a pure zinc coating, the coating has better corrosion resistance, welding performance and coating performance.
In the technical field of high-strength steel for hot-dip galvanized automobiles, the 600 MPa-grade alloyed hot-dip galvanized dual-phase steel has excellent strength and plasticity matching, excellent corrosion resistance, welding performance and coating performance, and becomes the preferred steel for structural parts and reinforcing parts in automobile manufacturing host factories. Various large iron and steel enterprises are continuously exploring production process technologies with lower production cost, better corrosion resistance, better mechanical property and more stable surface quality for 600 MPa-level alloying hot galvanizing dual-phase steel.
The hole expansion rate is a key index for evaluating the formability of the alloying hot galvanizing dual-phase steel, in particular to the flanging hole expansion formability. The hard phase martensite of the alloying hot galvanizing dual-phase steel has extremely high strength, the soft phase ferrite has relatively low strength, the strength difference of the two phases is very large, no intermediate strength transition phase exists, the plastic deformation coordination of the two-phase structure is poor, and the hole expansion rate of the alloying hot galvanizing dual-phase steel is generally low. The lower hole expansion rate ensures that the material is easy to crack when the alloying hot galvanizing dual-phase steel is subjected to a flanging and hole expanding forming process. Therefore, on the premise of ensuring the performance indexes of yield strength, tensile strength and elongation of the galvannealed dual-phase steel, the hole expansion rate of the galvannealed dual-phase steel is improved as much as possible, and the flanging hole expansion forming performance of the galvannealed dual-phase steel is further improved, so that the galvannealed dual-phase steel has extremely important practical application value.
Chinese patent publication No. CN 109852900A discloses '600 MPa-grade hot-galvanized dual-phase steel with different yield ratios and a production method thereof', which comprises the following main chemical elements in percentage by mass: c: 0.070-0.120%, Si is less than or equal to 0.05%, Mn: 1.50-1.90%, Alt: 0.030-0.070%, 0.15-0.35% of Cr, 0.13-0.24% of Mo, less than or equal to 0.015% of P, less than or equal to 0.005% of S, less than or equal to 0.005% of N, less than or equal to 0.005% of O, and the balance of Fe and inevitable impurities. The patented technological process comprises heating, hot rolling, cooling and curling, acid rolling, hot galvanizing and finishing of a plate blank, and reasonable chemical elements and content design thereof as well as effective control of key technological parameters of all working procedures, so that 600 MPa-grade hot galvanizing dual-phase steel with good surface quality and different yield ratios is produced by adopting the same chemical element composition system, and the small-batch order requirement of special mechanical property requirements of different automobile manufacturer host factories is met. The temperature of a fast cooling section of the hot galvanizing process technology control related to the invention patent is 465 +/-5 ℃, and the temperature of hot dip galvanizing is 465 +/-5 ℃, which can not meet the process control requirement at all for thin strip steel with the thickness of 0.60-0.80 mm, because the strip steel is discharged from an annealing furnace to be hot dip galvanized, a descending section of dozens of meters exists between the strip steel and the hot dip galvanizing, the temperature of the thin strip steel can be rapidly reduced in the operation process of dozens of seconds, and the temperature of the hot dip galvanizing is obviously lower, thereby obviously influencing the mechanical property of a finished product and the surface quality of a zinc layer. Meanwhile, the average Mn element content in the product of the invention reaches 1.80%, and for 600 MPa-grade hot-dip galvanized dual-phase steel, a banded structure is easily generated due to too high Mn content, the uniformity of the structure is influenced, and the flanging and reaming forming performance of the hot-dip galvanized dual-phase steel can be obviously reduced.
Chinese patent publication No. CN 110983196A discloses '600 MPa-grade hot-rolled galvanized high-hole-expansion steel and a production method thereof', and the main chemical elements of the steel comprise the following components in percentage by mass: c: 0.05-0.1%, Si: 0.1-0.2% of Mn, 0.9-1.6% of Ti, 0.03-0.08% of Al, 0.01-0.4% of P, 0.01-0.1% of Nb, less than or equal to 0.015% of S, and the balance of Fe and inevitable impurities. The invention has the technical processes of molten iron pretreatment, converter smelting, refining, continuous casting, hot rolling, leveling, acid washing and hot galvanizing, and the product has high Al content, the inclusion of alumina is increased, the plasticity of steel is damaged, and the castability of smelting is reduced. Meanwhile, the content of P in the invention is too high, the P is taken as a harmful impurity element dissolved in steel in a solid solution manner, the toughness of the steel can be obviously reduced, and the P has obvious segregation tendency and is not easy to eliminate by a heat treatment process. The high-strength steel for 600MPa hot-dip galvanized automobiles has very high requirement on the purity of steel billets in the steelmaking process. The purity of the steel billet is obviously influenced due to the excessively high content of Al and P elements. The microstructure of the 600 MPa-grade hot-rolled galvanized high-expansion-ratio steel consists of 80-90% of ferrite and 10-20% of bainite, and a martensite-phase structure is not generated. Meanwhile, the patent product of the invention adds expensive alloy elements with too high content, increases the production cost and influences the market competitiveness of the product.
Chinese patent publication No. CN 105603325B discloses "600 MPa grade vanadium-containing hot-dip galvanized dual-phase steel and a preparation method thereof", which comprises the following main chemical elements in percentage by mass: c: 0.04-0.10%, Si: 0.10-0.60% of Mn, 1.30-1.90% of Mn, 0.10-0.50% of Cr, 0.05-0.25% of Mo, 0.01-0.06% of Al, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.006% of N, and the balance of Fe and inevitable impurities. The patented process flow of the invention comprises smelting, hot rolling, acid rolling and hot galvanizing annealing, and the content of alloy elements Cr and Mo is reduced by adding trace V, Si. The mean value of the tensile strength of the product is 620MPa, the strength of steel is not high enough, and the product can not meet the dent resistance requirements of automobile reinforcing parts and anti-collision parts.
Chinese patent publication No. CN 105506467B discloses 'a galvanized dual-phase steel for 600MPa class sedan and a production method thereof', which comprises the following main chemical elements in percentage by mass: 0.04-0.09% of C, less than or equal to 0.01% of Si, 1.0-2.5% of Mn, 0.01-0.08% of Als, 0.01-0.30% of Mo or 0.02-0.09% of Cr, 0.001-0.03% of Nb, less than or equal to 0.015% of P, less than or equal to 0.010% of S, less than or equal to 0.005% of N, and the balance of Fe and inevitable impurities. The process flow of the invention comprises smelting, refining, continuous casting, heating of casting blank, finish rolling, curling, acid washing, cold rolling, hot galvanizing and finishing, the mean value of Mn element content in the product is up to 1.65%, and for 600MPa grade hot galvanizing dual-phase steel, the high Mn content is easy to generate banded structure, the uniformity of the structure is reduced, and the flanging and reaming forming performance of the hot galvanizing dual-phase steel is reduced. The mean value of the curling temperature of the hot rolling process is close to 580 ℃, and the effect of refining grains is not obvious. Meanwhile, the average value of the continuous annealing temperature of the hot galvanizing process is more than 810 ℃, excessive bainite structures can be generated, the strength of steel is reduced, the maximum value of the tensile strength of a product is only 650MPa, and the requirement of the dent resistance of an automobile reinforcement and an anti-collision part can not be met.
Chinese patent publication No. CN 110093491A discloses a cold-rolled hot-galvanized dual-phase steel and a manufacturing method thereof, and the main chemical element compositions and the mass percentage contents of the steel are as follows: 0.14-0.18% of C, 0.20-0.40% of Si, 1.50-1.90% of Mn, 0.30-0.60% of Cr, 0.010-0.030% of Ti, 0.02-0.06% of Als, less than or equal to 0.020% of P, less than or equal to 0.012% of S, less than or equal to 0.007% of N, and the balance of Fe and inevitable impurities. The technological process of the invention comprises smelting, casting, hot rolling, acid washing, cold rolling, strip steel heating and cooling, and hot galvanizing, wherein the average value of Cr element content of the product is up to 0.525%, which can obviously affect the surface quality of casting blanks in the continuous casting process, further affect the surface wettability during hot dip galvanizing in the hot galvanizing process, and reduce the surface quality of hot galvanizing finished products. The average Mn element content is up to 1.65%, banded structures are easily generated in steel, the uniformity of the structures is reduced, and the flanging, reaming and forming performances of hot galvanizing finished products are reduced.
In the technical field of high-strength steel for hot-dip galvanized automobiles, the flanging hole-expanding formability of 600 MPa-grade alloying hot-dip galvanized dual-phase steel is obviously lower than that of 600 MPa-grade cold-rolled dual-phase steel bare plates (without a coating) and even lower than that of 600 MPa-grade hot-rolled dual-phase steel bare plates (without a coating), the industrial mass production is realized, and the hole-expanding rate of the 600 MPa-grade alloying hot-dip galvanized dual-phase steel which is applied in large quantities in a host factory of an automobile manufacturer is generally lower than 35.0% (tested according to the requirements specified by the national standard GB/T15825.4-2008) and even lower.
The prior art does not disclose how to adopt the titanium-boron-niobium-copper-nickel microalloyed low-carbon-low-silicon-low-manganese chemical composition design, the low-temperature curling process and the high-temperature slow cooling process, and the reasonable process flow is matched: molten iron pretreatment → converter smelting → alloy fine tuning station → LF furnace refining → RH furnace refining → continuous casting steel making → hot rolling → acid pickling and cold rolling → continuous annealing → hot dip galvanizing → overaging → finishing, so as to comprehensively improve the flanging, reaming and forming performance of the 600 MPa-level alloying hot galvanizing dual-phase steel.
Disclosure of Invention
1. Problems to be solved
Aiming at the problem of poor flanging and reaming formability of a 600 MPa-grade alloying hot-dip galvanized dual-phase steel product in the prior art, the invention provides the 600 MPa-grade low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel with enhanced reaming performance, on the basis of the traditional 600 MPa-grade alloying hot-dip galvanized dual-phase steel, the processes of titanium-boron-niobium-copper-nickel microalloying low-carbon-low-silicon-low-manganese chemical component design, a low-temperature curling process, a high-temperature slow cooling process and a hot-dip galvanizing process are accurately controlled according to the thickness grade, and a reasonable process flow is matched: molten iron pretreatment → converter smelting → alloy fine tuning station → LF furnace refining → continuous casting steelmaking → hot rolling → acid pickling and cold rolling → continuous annealing → hot dip galvanizing → alloying → overaging → finishing, eliminating band-shaped tissues and improving the uniformity of steel plate tissues and performances; the hard phase crystal grains are refined, and the strength and toughness of the steel are comprehensively improved; the ferrite is refined and strengthened, and the strength difference between the soft phase ferrite and the hard phase martensite is reduced; a proper amount of granular bainite structures with intermediate strength and a buffering transition effect are introduced between the soft phase ferrite and the hard phase martensite, so that 600 MPa-grade alloyed hot-dip galvanized dual-phase steel with the product porosity of 41.5-69% is produced, and meanwhile, the surface coating quality of the steel is good, and the steel is suitable for being used as a complex forming automobile part with high requirements on flanging, reaming and forming performances.
The invention also aims to provide a production method of 600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced hole expansion performance.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced hole expansion performance comprises the following main chemical elements in percentage by mass: c: 0.05-0.09%, Si: 0.05-0.20%, Mn: 0.9-1.5%, Cr: 0.15-0.45%, Mo: 0.10 to 0.50%, Ti: 0.01-0.05%, Als: 0.01-0.08%, B: 0.0005 to 0.0065%, Nb: 0.01-0.05%, Cu: 0.05-0.80%, Ni: 0.05-0.90%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, N is less than or equal to 0.005%, and the balance of Fe and inevitable impurities.
Further, the main chemical elements comprise the following components in percentage by mass: c: 0.06-0.08%, Si: 0.10 to 0.15%, Mn: 1.0-1.25%, Cr: 0.20-0.45%, Mo: 0.15-0.25%, Ti: 0.01 to 0.025%, Als: 0.02-0.06%, B: 0.0005 to 0.0035%, Nb: 0.01-0.035%, Cu: 0.08-0.60%, Ni: 0.09-0.50 percent of the total weight of the alloy, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
Furthermore, the hot-rolled coil of the hot-dip galvanized dual-phase steel has a microstructure of ferrite, pearlite and bainite.
Further, the hot dip galvanized dual phase steel contains 55.5-69.5% by volume of polygonal ferrite, 18-28% by volume of lath martensite and 12.5-16.5% by volume of granular bainite, and the average grain size is 10.5-12. In order to ensure that the tensile strength of the product reaches the strength grade of 600MPa, the volume percentage of lath martensite cannot be less than 18%, and in order to ensure that the elongation of the product is not less than 25.0%, the volume percentage of lath martensite cannot exceed 28%. A proper amount of granular bainite structure with intermediate strength and buffer transition effect is introduced between the soft phase ferrite and the hard phase martensite, so that higher flanging hole expansion forming performance is ensured. The hot galvanizing procedure adopts a pre-oxidation-reduction process to ensure that the surface coating quality of the steel is good.
Further, the hot-dip galvanized dual-phase steel has a thickness of 0.60-2.50 mm, a yield strength of 380-410 MPa, a tensile strength of 660-695 MPa, an elongation of 25.0-31.5%, an n value of 0.18-0.20, and a hole expansion rate of 41.5-69.0%.
The invention also provides a production method of the 600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced hole expansion performance, which comprises the following steps:
(1) pretreating molten iron;
(2) smelting in a converter;
(3) an alloy fine tuning station;
(4) refining in an LF furnace;
(5) continuous casting steel making;
(6) hot rolling;
(7) acid pickling and cold rolling;
(8) continuous annealing;
(9) hot-dip galvanizing;
(10) alloying;
(11) overaging the alloyed hot-dip galvanized coil;
(12) and (6) finishing.
Further, in the step (1), the front slag skimming bright surface is more than or equal to 70.0%, the rear slag skimming bright surface is more than or equal to 80.0%, and the molten iron desulphurization target [ S ] is less than or equal to 0.010%.
Further, in the step (2), the end point temperature of the converter is 1625-1660 ℃, argon is blown in the whole process during tapping, deoxidation alloying is carried out, and slag blocking operation is carried out in time after tapping is finished.
Further, in the step (3), the temperature of the incoming molten steel is 1560-1600 ℃, and the content of Als is adjusted to 0.02-0.06% according to the oxygen determination result.
Further, in the step (4), the temperature of the discharged molten steel is singly opened to 1565-1580 ℃, the continuous casting time is 1560-1576 ℃, the continuous casting treatment time is less than or equal to 90.0min, the bottom blowing system of the steel ladle adopts whole argon blowing, the strong stirring time after each batch of alloy is added is more than or equal to 3.0min, the weak stirring time is more than or equal to 5.0min, the white slag making operation is strengthened, the top slag of the steel ladle is fully reduced, and the content of chemical elements is adjusted to a target value.
Further, in the step (5), the temperature of the tundish molten steel is controlled to be 15-30 ℃ above the liquidus target temperature, the variation range of the crystallizer liquid level is controlled to be +/-5 mm, the continuous casting machine is used for dynamic soft reduction, and the casting blank is preferably hot-charged and rolled.
Further, in the step (6), continuous rolling is carried out on six racks, high-pressure descaling is carried out on a primary inlet and a secondary outlet, the heating temperature of a plate blank is 1200-1260 ℃, the heat preservation time of the plate blank in a furnace is 2.5-5.0 h, the final rolling temperature is 860-900 ℃, the curling temperature is 465-515 ℃, and a front-section cooling process is adopted to obtain a hot-rolled coil with a microstructure of ferrite, pearlite and bainite; the heating temperature of the plate blank is more than 1200 ℃, so that the defects of the casting blank can be eliminated, the deformation resistance of steel can be reduced, and if the heating temperature of the plate blank is too high, a large number of iron scales can be generated on the surface of a hot-rolled coil to influence the surface quality of a finished product in a hot galvanizing process; if the finishing temperature is less than 860 ℃, the two-phase region of ferrite and austenite is rolled, so that the rolling load is too large, and the structure and the performance of the hot-rolled steel plate are easy to be uneven; the low-temperature curling process is adopted, and aims to obtain a hot-rolled coil with a microstructure of ferrite, pearlite and bainite through controlled cooling, refine grains, obtain a fine and uniform microstructure and comprehensively improve the strength and the plastic toughness of the steel.
Further, in the step (7), the hot-rolled strip steel is subjected to hydrochloric acid tank pickling to remove iron scales on the surface of the strip steel, cold rolling is performed after conventional pickling, the reduction ratio is 50.0-69.0%, and if the reduction ratio is larger than 69.0%, the capacity of equipment is insufficient; if the reduction rate is less than 50.0%, the deformation energy storage is increased insufficiently, and the grain refining effect is not obvious.
Further, it is characterized byIn the step (8), in order to effectively clean impurities such as rolling oil, iron powder and the like on the surface of the strip steel before plating, the strip steel is subjected to alkali washing degreasing in an alkali washing tank of a pre-cleaning section and alkali washing degreasing in an alkali washing tank of an electrolytic cleaning section, is preheated to 190-250 ℃, is operated to an annealing furnace for reversion recrystallization continuous annealing, and when the thickness of the strip steel is not less than 0.60mm and not more than 0.60mm<When the thickness is 1.00mm, the annealing temperature of the heating section is 780 +/-10 ℃, the annealing temperature of the soaking section is 775 +/-5 ℃, and the production line speed is 105 +/-10 m/min; when the thickness of the strip steel is less than or equal to 1.00mm<When the thickness is 1.50mm, the annealing temperature of the heating section is 785 +/-10 ℃, the annealing temperature of the soaking section is 780 +/-5 ℃, and the production line speed is 100 +/-5 m/min; when the thickness of the strip steel is less than or equal to 1.50mm<When the thickness is 2.00mm, the annealing temperature of the heating section is 790 +/-10 ℃, the annealing temperature of the soaking section is 785 +/-5 ℃, and the production line speed is 95 +/-5 m/min; when the thickness of the strip steel is less than or equal to 2.00mm<When the thickness is 2.25mm, the annealing temperature of the heating section is 795 +/-10 ℃, the annealing temperature of the soaking section is 790 +/-5 ℃, and the production line speed is 90 +/-5 m/min; when the thickness of the strip steel is less than or equal to 2.25mm<When the thickness is 2.50mm, the annealing temperature of the heating section is 800 +/-5 ℃, the annealing temperature of the soaking section is 790 +/-5 ℃, and the production line speed is 85 +/-5 m/min; adjusting the content of water vapor introduced into a preheating section to a heating section in the annealing furnace, controlling the dew point temperature of the heating section to be in the range of 0-25 ℃, inhibiting surface enrichment of Si and Mn elements on the surface of the strip steel, and improving the wettability of the surface of the strip steel; after fully completing recovery recrystallization of the strip steel, slowly cooling the strip steel, wherein the slowly cooling temperature is controlled to be 690-710 ℃, and quickly cooling the strip steel after slow cooling, and the quick cooling temperature is controlled to be 490-505 ℃; reducing gas H in annealing furnace 2 5.0-10.0% by volume (the balance being N) 2 )。
Further, in the step (9), the aluminum content of the molten zinc is 0.10-0.15%, the iron content is 0.025-0.035% (the balance being Zn and inevitable impurities), the hot galvanizing temperature is 465-480 ℃, and the cooling temperature after the hot galvanizing is controlled at 395-415 ℃.
Further, in the step (10), when the thickness of the strip steel is not less than 0.60mm and less than 1.00mm, the power of the main induction heater is 1350 +/-50 kW, and the power of the edge induction heater is 180 +/-10 kW; when the thickness of the strip steel is less than or equal to 1.00mm and less than 1.50mm, the power of the main induction heater is 1400 +/-50 kW, and the power of the edge induction heater is 190 +/-10 kW; when the thickness of the strip steel is less than or equal to 1.50mm and less than 2.00mm, the power of the main induction heater is 1450 +/-50 kW, and the power of the edge induction heater is 200 +/-10 kW; when the thickness of the strip steel is less than or equal to 2.00mm and less than 2.25mm, the power of the main induction heater is 1550 +/-50 kW, and the power of the edge induction heater is 210 +/-10 kW; when the thickness of the strip steel is less than or equal to 2.25mm and less than 2.50mm, the power of the main induction heater is 1600 +/-50 kW, and the power of the edge induction heater is 215 +/-10 kW.
Further, in the step (11), the overaging temperature of the galvannealing coil is controlled to be 255-325 ℃, the heat preservation time is 15-25 min, and in order to perform low-temperature tempering treatment, on the premise of ensuring that no transformation of martensite structure occurs, the mechanical properties are comprehensively improved, especially the ductility and toughness of the galvannealing coil are improved, the porosity of the surface of the coating is reduced, the corrosion resistance of the coating is improved, and the interface bonding force between the coating and the substrate is enhanced.
Further, in the step (12), when the thickness is more than or equal to 0.60mm and less than 1.00mm, the finishing elongation is 0.2 +/-0.05%; when the thickness is more than or equal to 1.00mm and less than 1.50mm, the finishing elongation is 0.3 +/-0.05 percent; when the thickness is more than or equal to 1.50mm and less than 2.00mm, the finishing elongation is 0.4 +/-0.05 percent; when the thickness is more than or equal to 2.00mm and less than 2.25mm, the finishing elongation is 0.5 +/-0.05 percent; when the thickness is more than or equal to 2.25mm and less than 2.50mm, the finishing elongation is 0.6 +/-0.05 percent; the yield platform is eliminated, the number and density of dislocation are adjusted, the yield strength of steel is improved, the shape of the plate is controlled, the surface roughness of the coating is endowed, and the subsequent coating quality is facilitated.
The invention discloses 600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced hole expansion performance, which has the following chemical element effects and content control reasons:
c: c is the most basic and effective solid solution strengthening element in the steel material and is necessary for obtaining enough strength, but the carbon content is too high, the ductility and toughness of the steel material can be reduced, and meanwhile, the flanging hole expanding forming performance and the welding performance can be damaged, so that the C content is controlled to be 0.06-0.08%.
Si: the solubility of Si in carbide is extremely low, the formation of carbide can be effectively inhibited, the formation of carbon-rich austenite is facilitated, the carbon-rich austenite is kept to room temperature along with the retained austenite, and the purity of ferrite is obviously improved. The content of Si element is increased, the tensile strength is obviously improved, but the Si content is too high, and the platability of the surface of the strip steel is deteriorated. The invention controls the Si content to be 0.10-0.15%.
Mn: mn is an important solid solution strengthening element for remarkably improving the tensile strength and the yield strength of steel, can improve the hardenability of the steel, expand a gamma phase region, stabilize austenite, reduce the martensite start transformation temperature Ms and increase the content of residual austenite. However, due to the fact that the content of Mn is too high, a steel material is very easy to form a strip-shaped structure in a continuous casting process, the strip-shaped structure is not easy to eliminate, the uniformity of the structure is reduced, the plasticity and toughness of a galvanized finished product are affected, and particularly the flanging, reaming and forming performance of the galvanized finished product is remarkably reduced. Therefore, the Mn content is controlled to be 1.0-1.25%.
Cr: cr can remarkably improve the hardenability of steel, the strength of a galvanized finished product is insufficient due to too low Cr content, the corrosion resistance of the steel is influenced, however, the surface quality of a casting blank is remarkably influenced due to the Cr content exceeding 0.45%, meanwhile, the generation of a bainite structure is remarkably influenced due to too high Cr content, and a certain amount of bainite structure needs to be introduced in the process design disclosed by the invention. Therefore, the Cr content is controlled to be 0.20-0.45%.
Mo: mo is a strengthening element which can remarkably improve the hardenability of the steel and can remarkably delay the formation of pearlite during cooling. Too high Mo content may reduce the toughness of the steel and is expensive. Comprehensively, the Mo content is controlled to be 0.15-0.25%.
Ti: ti is a strong carbonitride forming element, and forms TiC and TiN with C, N elements, thereby not only playing a role of precipitation strengthening, but also refining hard phase grains and comprehensively improving the strength and toughness of the steel plate. The ferrite is refined and strengthened, the strength difference between the soft phase ferrite and the hard phase martensite is reduced, and the flanging and hole expanding forming performance of the steel plate is improved. Meanwhile, the presence of Ti prevents chemically active B from reacting with N, so that B exists in solid solution. In order to control the production cost, the Ti content is controlled to be 0.01-0.025%.
And Als: al can promote the generation of ferrite, improve the stability of the ferrite, inhibit the transfer of C element in the retained austenite and stabilize the retained austenite. If the Al content is too high, the weldability and hot workability of the steel material may deteriorate. Therefore, the Al content is controlled to be 0.02-0.06%.
B: b is a trace element which can obviously improve the hardenability of austenite, inhibits the segregation of P element at a crystal boundary, strengthens the crystal boundary, improves the toughness of steel, obviously improves the formability of a steel plate, and especially can improve the flanging and hole-expanding formability of the steel plate. However, the transformation of pearlite and bainite can be inhibited when the content is too high, and a certain amount of bainite structure needs to be introduced into the process design of the invention, and the content of B is controlled to be 0.0005-0.0035% by comprehensively considering.
Nb: nb is used as an important microalloying element for grain refinement and precipitation strengthening, and easily forms stable carbonitride Nb (C, N) with C, N element, and the carbonitride precipitation plays a role in pinning relative to dislocation and preventing grain boundary migration, thereby further playing a role in grain refinement and comprehensively improving the strength and toughness of the steel plate. The ferrite is refined and strengthened, the strength difference between the soft phase ferrite and the hard phase martensite is reduced, and the flanging and hole expanding forming performance of the steel plate is improved. However, if the amount of Nb is too low or too high, the contribution to the improvement of strength and toughness is not significant. Meanwhile, the price is high, and the content of Nb is controlled to be 0.01-0.035% by comprehensively considering.
Cu: the Cu is used as a precipitation strengthening element, can improve the yield strength of steel, improve the uniformity of steel plate structure and performance, reduce the ductile-brittle transition temperature, and is beneficial to improving the flanging, reaming and forming performance of the steel plate. The Cu and the Cr act synergistically, so that the corrosion resistance of the steel can be obviously improved. However, the Cu content is too high, Cu element segregation is easy to occur in the heating process of the continuous casting plate blank, the hot working performance of steel is reduced, the copper brittleness phenomenon occurs, and meanwhile, very sticky iron oxide scales are generated on the surface of the steel, so that the surface quality of a galvanized finished product is influenced. Meanwhile, Cu is a noble metal. Comprehensively considering, the Cu content is controlled to be 0.08-0.60%.
Ni: ni is an important alloy element for forming and stabilizing austenite, is insoluble in carbide and completely enters the austenite, expands a gamma phase region, reduces the critical cooling speed of steel, improves the hardenability of the steel, is particularly added with Cr, has strong effect on improving the hardenability of the steel, and comprehensively improves the strength and toughness of the steel plate. The ferrite is refined and strengthened, the strength difference between the soft phase ferrite and the hard phase martensite is reduced, and the flanging and hole expanding forming performance of the steel plate is improved. The high-temperature oxidation resistance and corrosion resistance of the steel are improved, but Ni belongs to precious metals, so that the addition of Ni is not too high in order to reduce the production cost, and the Ni content is controlled to be 0.09-0.50% in the invention in comprehensive consideration.
P: p is a harmful impurity element dissolved in steel in a solid state, and significantly reduces the toughness of steel. Meanwhile, P has obvious segregation tendency and is not easy to eliminate by a heat treatment process. The invention controls the content of P below 0.020%.
S: s is a harmful impurity element in steel, can cause the steel to have hot brittleness, and obviously reduces the toughness and the ductility of the steel, so the content of S is controlled to be less than 0.010 percent.
N: n can improve the strength and the welding performance of steel, but is not beneficial to controlling inclusions, so the content of N is controlled below 0.005 percent.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the titanium-boron-niobium-copper-nickel microalloyed low-carbon-low-silicon-low-manganese chemical composition design and the low-temperature curling process are adopted, hard phase grains are refined, and the strength and toughness of the steel are improved comprehensively; ferrite is refined and strengthened, the strength difference between soft phase ferrite and hard phase martensite is reduced, and 600 MPa-grade alloying hot galvanizing dual-phase steel with high surface quality and enhanced flanging hole expansion forming performance is obtained;
(2) eliminating a banded structure, improving the uniformity of the structure and performance of the steel plate, obtaining a fine uniform structure with the average grain size of 10.5-12, and remarkably improving the flanging, reaming and forming performance of the 600 MPa-level alloying hot galvanizing dual-phase steel;
(3) by adopting a high-temperature slow cooling process, a proper amount of granular bainite structure with intermediate strength and a buffer transition effect is introduced between the soft phase ferrite and the hard phase martensite, so that the plastic deformation coordination between the soft phase ferrite and the hard phase martensite is obviously improved, and the flanging and reaming forming performance of the 600 MPa-level alloying hot-dip galvanized dual-phase steel is obviously improved;
(4) the reasonable process flow is matched: molten iron pretreatment → converter smelting → alloy fine tuning station → LF furnace refining → continuous casting steelmaking → hot rolling → acid pickling and cold rolling → continuous annealing → hot dip galvanizing → alloying → overaging → finishing, which enhances the precipitation strengthening effect of copper, improves the strength and toughness of steel comprehensively, improves the uniformity of steel plate structure and performance, and obviously improves the flanging, reaming and forming performance of 600 MPa-level galvannealed dual-phase steel;
(5) the process of the hot galvanizing procedure is accurately controlled according to the thickness grade, and the stable performance of the product which cannot be thick is realized; on the premise that the strength meets the requirements of national standard GB/T2518 and 2019, the flanging and reaming formability of 600 MPa-level alloying hot galvanizing dual-phase steel is remarkably improved, the product reaming rate is 41.5-69.0%, and the steel is more suitable for being used as a complex forming automobile part with high requirements on flanging and reaming formability.
Drawings
FIG. 1 is SEM microstructure picture of 600MPa grade low manganese nickel containing alloyed hot dip galvanized dual phase steel (F: ferrite, M: martensite, B: bainite).
Detailed Description
The present invention will be further illustrated with reference to the following examples.
The main chemical element composition and the mass percentage content of the 600 MPa-level low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced hole expansion performance are shown in the table 1.
TABLE 1 chemical element composition and mass percent (wt%) of examples and comparative examples
Figure BDA0003109436580000091
Figure BDA0003109436580000101
Note: in Table 1, reference numerals 1 to 12 denote preferred embodiments 1 to 12 of the present invention.
The invention relates to a production method of 600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced hole expansion performance, which comprises the following steps:
(1) the molten iron is pretreated, the front slag skimming bright surface is more than or equal to 70.0 percent, the rear slag skimming bright surface is more than or equal to 80.0 percent, and the molten iron desulphurization target [ S ] is less than or equal to 0.010 percent;
(2) smelting in a converter, wherein the end point temperature of the converter is 1625-1660 ℃, argon is blown in the whole process during tapping, deoxidation alloying is carried out, and slag blocking operation is carried out in time after tapping is finished;
(3) alloy fine adjustment station, wherein the temperature of molten steel entering the station is 1560-1600 ℃, and the Als content is adjusted to 0.02-0.06% according to the oxygen determination result;
(4) refining in an LF furnace, wherein the temperature of the discharged molten steel is singly opened to 1565-1580 ℃, the continuous casting is 1560-1576 ℃, the continuous casting treatment time is less than or equal to 90.0min, the bottom blowing system of the ladle adopts whole-process argon blowing, the strong stirring time after each batch of alloy is added is more than or equal to 3.0min, the weak stirring time is more than or equal to 5.0min, the white slag making operation is enhanced, the top slag of the ladle is fully reduced, and the content of chemical elements is adjusted to a target value;
(5) continuous casting steelmaking, controlling the temperature of molten steel in a tundish to be 15-30 ℃ above a liquidus target temperature, controlling the liquid level variation range of a crystallizer to be +/-5 mm, using dynamic soft reduction by a continuous casting machine, and preferentially adopting hot charging rolling for a casting blank;
(6) hot rolling, continuous rolling by six racks, high-pressure descaling at a primary inlet and a secondary outlet, keeping the temperature of a plate blank at 1200-1260 ℃, keeping the temperature of the plate blank in a furnace for 2.5-5.0 h, keeping the temperature of the final rolling at 860-900 ℃, keeping the curling temperature at 465-515 ℃, and obtaining a hot-rolled coil with a microstructure of ferrite, pearlite and bainite by adopting a front-section cooling process;
(7) pickling and cold rolling, wherein the hot rolled coil is subjected to cold rolling after conventional pickling, and the reduction rate is 50.0-69.0%;
(8) continuous annealing, wherein in order to effectively clean impurities such as rolling oil and iron powder on the surface of the strip steel before plating, the strip steel is subjected to alkali washing degreasing in an alkali washing tank of a pre-cleaning section and alkali washing degreasing in an alkali washing tank of an electrolytic cleaning section, then is preheated to 190-250 ℃, is operated to an annealing furnace for recovery recrystallization continuous annealing, the temperature of a heating section of the steel coil in the annealing furnace is 770-805 ℃, the temperature of a soaking section is 770-795 ℃, slow cooling is carried out after heating and heat preservation, the slow cooling temperature is controlled to 690-710 ℃, fast cooling is carried out after slow cooling, the fast cooling temperature is controlled to 490-505 ℃, and the speed of a production line is 80-115 m/min; are worthy of explanation hereDifferent annealing temperatures and production line speeds are selected according to different thicknesses of the strip steel so as to eliminate fiber tissues of the chilled coils with different thicknesses, so that the chilled coils with different thicknesses can fully complete recovery recrystallization, and the stable performance of products with different thicknesses is realized; when the thickness of the strip steel is less than or equal to 0.60mm<When the thickness is 1.00mm, the annealing temperature of the heating section is 780 +/-10 ℃, the annealing temperature of the soaking section is 775 +/-5 ℃, and the production line speed is 105 +/-10 m/min; when the thickness is not less than 1.00mm<When the thickness is 1.50mm, the annealing temperature of the heating section is 785 +/-10 ℃, the annealing temperature of the soaking section is 780 +/-5 ℃, and the production line speed is 100 +/-5 m/min; when the thickness is less than or equal to 1.50mm<When the thickness is 2.00mm, the annealing temperature of the heating section is 790 +/-10 ℃, the annealing temperature of the soaking section is 785 +/-5 ℃, and the production line speed is 95 +/-5 m/min; when the thickness is less than or equal to 2.00mm<When the thickness is 2.25mm, the annealing temperature of the heating section is 795 +/-10 ℃, the annealing temperature of the soaking section is 790 +/-5 ℃, and the production line speed is 90 +/-5 m/min; when the thickness is less than or equal to 2.25mm<When the thickness is 2.50mm, the annealing temperature of the heating section is 800 +/-5 ℃, the annealing temperature of the soaking section is 790 +/-5 ℃, and the production line speed is 85 +/-5 m/min; adjusting the content of water vapor introduced into a preheating section to a heating section in the annealing furnace, controlling the dew point temperature of the heating section to be in the range of 0-25 ℃, inhibiting surface enrichment of Si and Mn elements on the surface of the strip steel, and improving the wettability of the surface of the strip steel; after fully completing recovery recrystallization of the strip steel, slowly cooling the strip steel, wherein the slowly cooling temperature is controlled to be 690-710 ℃, and quickly cooling the strip steel after slow cooling, and the quick cooling temperature is controlled to be 490-505 ℃; reducing gas H in annealing furnace 2 5.0-10.0% by volume (the balance being N) 2 )。
(9) Hot dip galvanizing, wherein the aluminum content of a zinc liquid is 0.10-0.15%, the iron content is 0.025-0.035% (the balance is Zn and inevitable impurities), the hot galvanizing temperature is 465-480 ℃, the cooling temperature after galvanizing is controlled at 395-415 ℃, and the production line speed is 80-100 m/min;
(10) alloying, namely, enabling the strip steel to ascend to an alloying furnace after galvanizing, wherein the power of a main induction heater of the alloying furnace is 1290-1650 kW, the power of an edge induction heater of the alloying furnace is 165-225 kW, the outlet temperature of a heating section is 535-545 ℃, and the outlet temperature of a soaking section is 465-480 ℃; in order to improve the uniformity of the alloying degree of the strip steel with different thicknesses, the heating power of the alloying furnace is accurately controlled according to the thickness grade, when the thickness is more than or equal to 0.60mm and less than 1.00mm, the power of a main induction heater is 1350 +/-50 kW, and the power of an edge induction heater is 180 +/-10 kW; when the thickness is more than or equal to 1.00mm and less than 1.50mm, the power of the main induction heater is 1400 +/-50 kW, and the power of the edge induction heater is 190 +/-10 kW; when the thickness is less than or equal to 1.50mm and less than 2.00mm, the power of the main induction heater is 1450 +/-50 kW, and the power of the edge induction heater is 200 +/-10 kW; when the thickness is less than or equal to 2.25mm and less than 2.00mm, the power of the main induction heater is 1550 +/-50 kW, and the power of the edge induction heater is 210 +/-10 kW; when the thickness is more than or equal to 2.25mm and less than 2.50mm, the power of the main induction heater is 1600 +/-50 kW, and the power of the edge induction heater is 215 +/-10 kW;
(11) overaging, wherein the overaging temperature of the alloying hot-dip galvanized coil is controlled to be 255-325 ℃, and the heat preservation time is 15-25 min;
(12) finishing, wherein the finishing elongation is less than or equal to 0.65 percent, in order to reduce the difference of the yield strengths of finished products with different thicknesses and realize the stable performance of the finished products with different thicknesses, the finishing elongation is accurately controlled according to the thickness grade of the strip steel, and when the thickness is less than or equal to 0.60mm and less than 1.00mm, the finishing elongation is 0.2 +/-0.05 percent; when the thickness is more than or equal to 1.00mm and less than 1.50mm, the finishing elongation is 0.3 +/-0.05 percent; when the thickness is more than or equal to 1.50mm and less than 2.00mm, the finishing elongation is 0.4 +/-0.05 percent; when the thickness is more than or equal to 2.00mm and less than 2.25mm, the finishing elongation is 0.5 +/-0.05 percent; when the thickness is more than or equal to 2.25mm and less than 2.50mm, the finishing elongation is 0.6 +/-0.05 percent.
The specific implementation process comprises the following steps:
the chemical element compositions and the contents thereof in preferred embodiments 1 to 12 are accurately controlled as shown in table 1, and are smelted and cast into a blank according to the process route of molten iron pretreatment → converter smelting → alloy fine tuning station → LF furnace refining → continuous casting steelmaking, hot rolling, acid pickling and cold rolling are performed according to the process technical parameters in table 2, and then continuous annealing, hot dip galvanizing, alloying, overaging and finishing are performed according to the process technical parameters in table 3, so that a 600 MPa-level low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel product with the performance of flanging, reaming and forming performance enhanced as shown in table 4 is obtained.
TABLE 2 technical parameters of the hot-rolling, pickling and cold-rolling processes of the examples and comparative examples
Figure BDA0003109436580000121
TABLE 3 Process parameters for the hot galvanizing procedure of examples and comparative examples
Figure BDA0003109436580000131
TABLE 4 mechanical properties of hot-dip galvanized finished products of examples and comparative examples
Figure BDA0003109436580000141
Note: the method for measuring the mechanical properties (yield strength, tensile strength and elongation) adopts national standard GB/T228.1-2010, the test type number is P6, and the direction of a test sample is transverse. A method for measuring the hole expansion rate of a key technical index for representing the flanging hole expansion forming performance strictly adopts the national standard GB/T15825.4-2008.
FIG. 1 is SEM microstructure picture of 600MPa grade low manganese nickel containing alloyed hot dip galvanized dual phase steel of the invention, wherein, F is polygonal ferrite, M is lath martensite, and B is granular bainite.
The results show that the technical scheme of the invention has good adaptability, the average grain size of the produced 600 MPa-grade low-manganese nickel-containing hot-dip galvanized dual-phase steel is 10.5-12%, the steel contains 55.5-69.5% by volume of polygonal ferrite, 18-28% by volume of lath-shaped martensite and 12.5-16.5% by volume of granular bainite, the yield strength is 380-410 MPa, the tensile strength is 660-695 MPa, the elongation is 25.0-31.5%, the n value is 0.18-0.20, and the hole expansion rate reaches 41.5-69.0% in 12 preferred embodiments on the premise that the strength meets the requirements of national standard GB/T2518 and 2019. The hole expansion rate of the traditional 600 MPa-grade alloying hot galvanizing dual-phase steel in the prior art of the comparative example 1 and the comparative example 2 can not meet the molding requirement of automobile parts of a complex flanging hole expansion molding process.
The above further description of the 600MPa grade low manganese nickel containing galvannealed dual phase steel with enhanced hole expansibility and the method for producing the same are illustrative and not restrictive, and several examples are listed according to the limited scope, therefore, any technical improvement and modification falling within the concept of the general technical method of the present invention shall fall within the protection scope of the present invention.

Claims (8)

1. The production method of 600 MPa-grade low-manganese nickel-containing alloying hot-dip galvanized dual-phase steel with enhanced hole expansion performance is characterized in that the hot-dip galvanized dual-phase steel comprises the following main chemical elements in percentage by mass: c: 0.05-0.09%, Si: 0.05-0.20%, Mn: 0.9-1.5%, Cr: 0.15 to 0.2816%, Mo: 0.10 to 0.50%, Ti: 0.01-0.05%, Als: 0.01-0.08%, B: 0.0005 to 0.0065%, Nb: 0.01-0.05%, Cu: 0.05-0.80%, Ni: 0.05-0.90 percent of Fe, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities; the hot-dip galvanized dual-phase steel contains 55.5-69.5% by volume of polygonal ferrite, 18-28% by volume of lath martensite and 12.5-16.5% by volume of granular bainite, and the average grain size is 10.5-12; the method comprises the following steps: (1) pretreating molten iron; (2) smelting in a converter; (3) an alloy fine tuning station; (4) refining in an LF furnace; (5) continuous casting; (6) hot rolling; (7) acid pickling and cold rolling; (8) continuous annealing; (9) hot-dip galvanizing; (10) alloying; (11) overaging the alloyed hot-dip galvanized coil; in the step (11), the overaging temperature of the galvannealed coil is controlled to be 255-325 ℃, and the heat preservation time is 15-25 min; (12) and (6) finishing.
2. The production method of 600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced hole expansion performance according to claim 1, characterized in that the main chemical elements comprise the following components by mass percent: c: 0.06-0.08%, Si: 0.10 to 0.15%, Mn: 1.0-1.25%, Cr: 0.20 to 0.2816%, Mo: 0.15-0.25%, Ti: 0.01-0.025%, Als: 0.02-0.06%, B: 0.0005 to 0.0035%, Nb: 0.01-0.035%, Cu: 0.08-0.60%, Ni: 0.09-0.50 percent of the total weight of the alloy, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
3. The production method of 600MPa grade low-manganese nickel-containing alloyed hot-dip galvanized dual-phase steel with enhanced hole expansibility according to claim 1 or 2, wherein the hot-dip galvanized dual-phase steel has a hole expansibility of 41.5-69.0%, and the hot-dip galvanized dual-phase steel has a thickness of 0.60-2.50 mm.
4. The production method of 600 MPa-grade low-manganese nickel-containing alloyed hot-dip galvanized dual-phase steel with enhanced hole expansibility according to claim 1 or 2, wherein the yield strength of the hot-dip galvanized dual-phase steel is 380-410 MPa, the tensile strength is 660-695 MPa, the elongation is 25.0-31.5%, and the work hardening index n value is 0.18-0.20.
5. The method for producing 600MPa grade low-manganese nickel-containing alloyed hot-dip galvanized dual-phase steel with enhanced hole expansibility as claimed in claim 1, wherein in the step (1), the front slag skimming bright surface is more than or equal to 70.0%, the rear slag skimming bright surface is more than or equal to 80.0%, and the molten iron desulphurization target [ S ] is less than or equal to 0.010%; in the step (4), the strong stirring time is more than or equal to 3.0min, and the weak stirring time is more than or equal to 5.0min after each batch of alloy is added; in the step (5), the continuous casting machine is put into use under dynamic soft reduction, and the casting blank is preferably rolled by hot charging; in the step (6), the slab heating temperature is 1200-1260 ℃, the furnace heat preservation time is 2.5-5.0 h, the finish rolling temperature is 860-900 ℃, the coiling temperature is 465-515 ℃, and a front-section cooling process is adopted to obtain a hot-rolled coil with a microstructure of ferrite, bainite and pearlite; in the step (7), the hot-rolled coil is subjected to cold rolling after being subjected to conventional acid pickling, and the reduction ratio is 50.0-69.0%.
6. The method for producing 600MPa grade low-manganese nickel-containing galvannealed dual phase steel with enhanced hole expansibility according to claim 5, wherein in the step (8), when the thickness of the strip steel is more than or equal to 0.60mm and less than 1.00mm, the annealing temperature of the heating section is 780 +/-10 ℃, the annealing temperature of the soaking section is 775 +/-5 ℃, and the production line speed is 105 +/-10 m/min; when the thickness of the strip steel is less than 1.50mm and less than 1.00mm, the annealing temperature of the heating section is 785 +/-10 ℃, the annealing temperature of the soaking section is 780 +/-5 ℃, and the speed of the production line is 100 +/-5 m/min; when the thickness of the strip steel is less than or equal to 1.50mm and less than 2.00mm, the annealing temperature of the heating section is 790 +/-10 ℃, the annealing temperature of the soaking section is 785 +/-5 ℃, and the production line speed is 95 +/-5 m/min; when the thickness of the strip steel is less than 2.25mm and less than or equal to 2.00mm, the annealing temperature of the heating section is 795 +/-10 ℃, the annealing temperature of the soaking section is 790 +/-5 ℃, and the production line speed is 90 +/-5 m/min; when the thickness of the strip steel is less than 2.50mm and less than 2.25mm, the annealing temperature of the heating section is 800 +/-5 ℃, the annealing temperature of the soaking section is 790 +/-5 ℃, and the production line speed is 85 +/-5 m/min; adjusting the content of water vapor introduced into the annealing furnace from the preheating section to the heating section, and controlling the dew point temperature of the heating section to be 0-25 ℃.
7. The production method of 600MPa grade low-manganese nickel-containing alloyed hot-dip galvanized dual-phase steel with enhanced hole expanding performance according to claim 6, characterized in that in the step (9), the aluminum content of the molten zinc is 0.10-0.15%, the iron content is 0.025-0.035%, and the balance is Zn and inevitable impurities, the hot-dip galvanizing temperature is 465-480 ℃, and the cooling temperature after plating is controlled at 395-415 ℃; in the step (10), when the thickness of the strip steel is less than or equal to 0.60mm and less than 1.00mm, the power of the main induction heater is 1350 +/-50 kW, and the power of the edge induction heater is 180 +/-10 kW; when the thickness of the strip steel is less than or equal to 1.00mm and less than 1.50mm, the power of the main induction heater is 1400 +/-50 kW, and the power of the edge induction heater is 190 +/-10 kW; when the thickness of the strip steel is less than or equal to 1.50mm and less than 2.00mm, the power of the main induction heater is 1450 +/-50 kW, and the power of the edge induction heater is 200 +/-10 kW; when the thickness of the strip steel is less than or equal to 2.00mm and less than 2.25mm, the power of the main induction heater is 1550 +/-50 kW, and the power of the edge induction heater is 210 +/-10 kW; when the thickness of the strip steel is less than or equal to 2.25mm and less than 2.50mm, the power of the main induction heater is 1600 +/-50 kW, and the power of the edge induction heater is 215 +/-10 kW.
8. The method for producing 600MPa grade low-manganese nickel-containing galvannealed dual phase steel with enhanced hole expansibility according to claim 6, wherein in the step (12), when the thickness is 0.60mm or less and less than 1.00mm, the finished elongation is 0.2 ± 0.05%; when the thickness is more than or equal to 1.00mm and less than 1.50mm, the finishing elongation is 0.3 +/-0.05 percent; when the thickness is more than or equal to 1.50mm and less than 2.00mm, the finishing elongation is 0.4 +/-0.05 percent; when the thickness is more than or equal to 2.00mm and less than 2.25mm, the finishing elongation is 0.5 +/-0.05 percent; when the thickness is more than or equal to 2.25mm and less than 2.50mm, the finishing elongation is 0.6 +/-0.05 percent.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103492599A (en) * 2011-04-21 2014-01-01 新日铁住金株式会社 High-strength cold-rolled steel sheet with highly even stretchabilty and excellent hole expansibility, and process for producing same
CN103710635A (en) * 2013-12-20 2014-04-09 鞍钢股份有限公司 600MPa class chromium/niobium-containing hot-rolled dual-phase steel plate and production method thereof
CN109943765A (en) * 2019-04-30 2019-06-28 马鞍山钢铁股份有限公司 A kind of 800MPa grades of high-yield-ratio cold-rolled biphase steel and preparation method thereof
CN109943778A (en) * 2019-04-30 2019-06-28 马鞍山钢铁股份有限公司 A kind of 590MPa that reaming is had excellent performance grade cold-rolled biphase steel and its production method
CN112760463A (en) * 2020-12-25 2021-05-07 马鞍山钢铁股份有限公司 Continuous annealing method of 780 MPa-grade microalloyed dual-phase steel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103492599A (en) * 2011-04-21 2014-01-01 新日铁住金株式会社 High-strength cold-rolled steel sheet with highly even stretchabilty and excellent hole expansibility, and process for producing same
CN103710635A (en) * 2013-12-20 2014-04-09 鞍钢股份有限公司 600MPa class chromium/niobium-containing hot-rolled dual-phase steel plate and production method thereof
CN109943765A (en) * 2019-04-30 2019-06-28 马鞍山钢铁股份有限公司 A kind of 800MPa grades of high-yield-ratio cold-rolled biphase steel and preparation method thereof
CN109943778A (en) * 2019-04-30 2019-06-28 马鞍山钢铁股份有限公司 A kind of 590MPa that reaming is had excellent performance grade cold-rolled biphase steel and its production method
CN112760463A (en) * 2020-12-25 2021-05-07 马鞍山钢铁股份有限公司 Continuous annealing method of 780 MPa-grade microalloyed dual-phase steel

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