WO2021057899A1 - 一种高扩孔复相钢及其制造方法 - Google Patents

一种高扩孔复相钢及其制造方法 Download PDF

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WO2021057899A1
WO2021057899A1 PCT/CN2020/117724 CN2020117724W WO2021057899A1 WO 2021057899 A1 WO2021057899 A1 WO 2021057899A1 CN 2020117724 W CN2020117724 W CN 2020117724W WO 2021057899 A1 WO2021057899 A1 WO 2021057899A1
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phase steel
expansion
manufacturing
steel
rolling
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PCT/CN2020/117724
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English (en)
French (fr)
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刘春粟
张玉龙
张思良
杨峰
倪亚平
王金涛
张瀚龙
王明
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宝山钢铁股份有限公司
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Priority to US17/762,627 priority Critical patent/US20220341010A1/en
Priority to KR1020227012051A priority patent/KR20220073762A/ko
Priority to JP2022519055A priority patent/JP7375179B2/ja
Priority to EP20869076.8A priority patent/EP4036267A4/en
Publication of WO2021057899A1 publication Critical patent/WO2021057899A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C47/00—Winding-up, coiling or winding-off metal wire, metal band or other flexible metal material characterised by features relevant to metal processing only
    • B21C47/02—Winding-up or coiling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • C—CHEMISTRY; METALLURGY
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    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
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    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
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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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/02—Hardening by precipitation
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0242—Flattening; Dressing; Flexing
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G3/00—Apparatus for cleaning or pickling metallic material
    • C23G3/02—Apparatus for cleaning or pickling metallic material for cleaning wires, strips, filaments continuously
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • 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
    • C21D2211/004—Dispersions; Precipitations
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G3/00—Apparatus for cleaning or pickling metallic material
    • C23G3/02—Apparatus for cleaning or pickling metallic material for cleaning wires, strips, filaments continuously
    • C23G3/027—Associated apparatus, e.g. for pretreating or after-treating

Definitions

  • the invention relates to a steel grade and a manufacturing method thereof, in particular to a complex phase steel and a manufacturing method thereof.
  • automobile chassis parts such as control arms, tie rods, and spring seats.
  • automobile chassis parts such as control arms include stamping, flanging, reaming, etc.; therefore, they not only have certain requirements for strength and elongation, but also have certain requirements for reaming performance.
  • the publication number is CN103602895A
  • the publication date is February 26, 2014
  • the Chinese patent document entitled "A 780MPa-level high-expanded steel plate with tensile strength and its manufacturing method” discloses a high-expansion tensile strength of 780MPa
  • the steel plate and its manufacturing method have a Si content of 0.5-1.5% and a relatively high content, which is easy to form the formation of iron olivine (2FeO-SiO2) scale and is difficult to remove, and it is difficult to obtain a strip steel with a higher grade surface.
  • the red iron sheet on the surface of the steel plate is difficult to control, it is difficult to accurately measure the temperature during the hot rolling process, resulting in unstable product performance.
  • the publication number is CN108570604A, and the publication number is September 25, 2018.
  • the Chinese patent document titled "A 780MPa-grade hot-rolled and pickled high-reamed steel strip and its production method” discloses a 780MPa-grade hot-rolled and pickled
  • the high-expansion steel and its production method have an Al content of 0.2-0.6%, a high content, and easy oxidation during continuous casting. At the same time, it adopts a three-stage cooling method and has low production stability.
  • the publication number is CN105483545A
  • the publication date is April 13, 2016,
  • the Chinese patent document entitled "A 800MPa-grade hot-rolled high-expansion steel sheet and its manufacturing method” discloses an 800MPa-class hot-rolled high-expansion steel sheet and The manufacturing method contains 0.2-1.0% Si.
  • the Si content is relatively high, and red iron skin is easily formed on the surface, which is not conducive to the control of the surface and the coiling temperature.
  • it contains 0.03-0.08Nb, and the Nb content is relatively high, the cost is high, and it needs to be cooled in sections after rolling, and the cooling process is complicated.
  • One of the objectives of the present invention is to provide a high-expansion complex phase steel, which can simultaneously meet the needs of hole expansion and better plasticity, and is compatible with traditional materials such as low-alloy high-strength steel and ferritic horses.
  • the two phases of the high-expansion complex-phase steels are ferrite and bainite, so the hardness difference is smaller, so that it has good hole expansion performance and cold forming performance.
  • the present invention proposes a high-expansion complex phase steel, the microstructure of which is ferrite + bainite, and the chemical element mass percentage of the high-expansion complex phase steel is:
  • C In the high-expansion complex phase steel of the present invention, considering that the level of carbon content largely determines the tensile strength level of the steel plate, carbon is used for solid solution strengthening and the formation of sufficient precipitation strengthening phases to Ensure the strength of the steel, but a high mass percentage of carbon will cause the carbide particles to be coarse, which is not conducive to the hole expansion performance. If the mass percentage of carbon is too low, the strength of the steel plate will decrease. In order to ensure the strength of the steel, the expansion can be high. The hole has good forming and welding performance. In the technical scheme of the present invention, the mass percentage of C is controlled to be 0.06-0.09%.
  • Si plays a solid solution strengthening effect to increase the strength of the steel plate.
  • the addition of silicon can increase the work hardening rate and the uniform elongation and total elongation under a given strength.
  • silicon can also prevent the precipitation of carbides and reduce the appearance of pearlite phases.
  • the silicon content in the steel easily causes the surface defects of iron olivine (2FeO-SiO 2 ) oxide scale to form on the surface of the steel plate, which has a negative effect on the surface quality.
  • the appearance of red iron sheet is not conducive to the temperature control in the hot rolling process, and ultimately leads to the stability of product performance.
  • the high-expansion complex phase steel of the present invention controls the mass percentage of silicon to 0.05-0.5%.
  • Al is a deoxidizing element of steel, reducing oxide inclusions in the steel and pure steel, which is beneficial to improve the formability of the steel plate, but the mass percentage of aluminum is relatively high , Will produce oxidation, further affecting continuous casting production. Based on this, the mass percentage of Al in the high-expansion complex phase steel of the present invention is controlled to be 0.02-0.1%.
  • Mn In the high-expansion complex phase steel of the present invention, manganese is a solid solution strengthening element, and a low mass percentage of manganese will lead to insufficient strength, but a high mass percentage of manganese will lead to a decrease in the plasticity of the steel plate. Manganese also delays the pearlite transformation, improves the hardenability of the steel and reduces the bainite transformation temperature, refines the substructure of the steel, and ensures that the substructure of the lath is obtained. Under the premise of ensuring the tensile strength of the product, at the same time Has good formability. Based on this, the mass percentage of Mn in the high-expansion complex phase steel of the present invention is controlled at 1.5-1.8%.
  • chromium increases the incubation period of pearlite and ferrite in the CCT curve, inhibits the formation of pearlite and ferrite, and is beneficial to the formation of bainite structure , which is ultimately beneficial to the improvement of strength and hole expansion rate.
  • mass percentage of chromium is less than 0.15%, the impact on the CCT curve is not significant, but when the mass percentage of Cr is higher, the cost will be higher. Based on this, the mass percentage of Cr in the high-expansion complex phase steel of the present invention is controlled at 0.3-0.6%.
  • Niobium is one of the important precipitation strengthening and fine-grain strengthening elements in the high-expansion complex phase steel of the present invention. It exists in the form of fine precipitation during cooling after rolling or after coiling. Precipitation strengthening to increase strength. At the same time, the presence of niobium is conducive to refining grains, improving strength and toughness, while reducing the strength difference between ferrite and bainite matrix, which is conducive to the improvement of hole expansion rate, but when the mass percentage of Nb is higher than 0.03 %, the strengthening effect of Nb is close to saturation, and the cost is higher. Therefore, in the high-expansion complex phase steel of the present invention, the mass percentage of Nb is controlled to be Nb ⁇ 0.03%.
  • the mass percentage of Nb can be preferably set to 0.015-0.03%.
  • titanium is one of the important precipitation strengthening and fine-grain strengthening elements. Titanium plays two roles in this case. One is related to impurity elements in steel. Nitrogen combines to form TiN. This is because the free nitrogen atoms in the steel are unfavorable to the impact toughness of steel. Adding a small amount of titanium can fix the free nitrogen, which is beneficial to the expansion rate and the improvement of the impact toughness; the second is to cooperate with niobium to improve the impact toughness. To the best effect of refining austenite grains and precipitation strengthening. However, in this case, the mass percentage of Ti should not be too much. TiN with a larger size is easy to form, which is detrimental to the impact toughness of steel. Therefore, in the high-expansion complex phase steel of the present invention, the mass percentage of Ti is controlled to be Ti: 0.05-0.12%.
  • the Nb element content is 0.015-0.03%.
  • the unavoidable impurity elements should be controlled as low as possible, but considering cost control and process limitations, therefore, P ⁇ 0.03%, S ⁇ 0.02%, and N ⁇ 0.005% can be controlled.
  • the mass percentage of N is controlled to N ⁇ 0.005% because nitrogen reacts with titanium to form TiN particles and precipitates under high temperature conditions. Oversized TiN particles will become local deformation micro-cracks of the steel plate, which will ultimately affect the hole expansion rate.
  • the nitrogen content in steel must be controlled.
  • the mass percentage of P is controlled to P ⁇ 0.03% because: the phosphorus in steel is generally solid-dissolved in ferrite, reducing the toughness of steel, but high phosphorus is not good for weldability, and at the same time, phosphorus at grain boundaries Segregation is not conducive to the hole expansion performance of strip steel, so the phosphorus content should be reduced as much as possible.
  • the mass percentage of S is controlled at S ⁇ 0.02% because the sulfur content and the form of sulfide are the main factors affecting the formability.
  • the mass percentage of chemical elements satisfies at least one of the following formulas:
  • the mass percentage of Nb and Ti is limited to satisfy 0.08% ⁇ 3.3Nb+Ti ⁇ 0.20% to control the precipitation strengthening of about 100-200MPa, and it is possible to use high titanium composition design without adding niobium and At the same time, the high hole expansion and plasticity requirements required by this case can be achieved, and the cost can be reduced at the same time.
  • the microstructure has microalloy precipitates, and the microalloy precipitates include (Ti, Nb)C and NbN.
  • the tensile strength and the mass percentage of chemical elements satisfy:
  • the tensile strength Rm 343+789 ⁇ C+170 ⁇ Si+132 ⁇ Mn+195 ⁇ Cr+843 ⁇ (Nb+Ti)-207 ⁇ Al, the dimension of the tensile strength Rm is MPa.
  • the tensile strength Rm is generally 790 to 850 MPa.
  • the transverse tensile strength thereof ⁇ 780MPa, yield strength ⁇ 700MPa, elongation A 50 ⁇ 15%, punched hole expansion rate ⁇ 50%.
  • the hole-expansion rate is greater than or equal to 70%.
  • the yield strength is ⁇ 730 MPa.
  • the transverse tensile strength is greater than or equal to 8000 MPa.
  • the transverse tensile strength is ⁇ 800MPa
  • the yield strength is ⁇ 730MPa
  • the elongation rate A 50 is ⁇ 15%
  • the punching hole expansion rate is ⁇ 70%.
  • another object of the present invention is to provide a method for manufacturing the above-mentioned high-expansion complex-phase steel, by which a high-expansion complex-phase steel with good hole expansion performance and cold forming performance can be obtained.
  • the present invention proposes the above-mentioned manufacturing method of the high-expansion complex phase steel, which includes the following steps:
  • Hot rolling control the total reduction ratio ⁇ 80%, control the rough rolling to roll in the recrystallization area, the rough rolling exit temperature is 1020-1100°C; the finishing rolling process adopts the quasi-constant speed rolling process, and the finishing speed is controlled At 6-12m/s, control the rolling acceleration ⁇ 0.005m/s 2 ; control the final rolling temperature to 840-900°C;
  • control delay time is 0-8s, laminar cooling cooling rate is 40-70°C/s;
  • the total reduction ratio of hot rolling is controlled to be ⁇ 80%; at the same time, it is ensured that the rough rolling is rolled in the recrystallization zone, and the precipitation of microalloys in the austenite zone is avoided;
  • the rough rolling outlet temperature is controlled at 1020-1100°C;
  • the finishing rolling process adopts the quasi-constant speed rolling process, the rolling acceleration is less than or equal to 0.005m/s 2 , the finishing rolling speed is controlled at 6-12m/s;
  • the final rolling temperature is controlled between 840-900°C, Rolling in the unrecrystallized region is used to refine the grains and at the same time facilitate the deformation-induced precipitation; under the premise of ensuring the target temperature, the stability of the air cooling time is guaranteed during constant speed rolling, which is beneficial to the control of the delayed cooling time.
  • laminar cooling the use of front-stage cooling and retardation control cooling mode is conducive to the recovery of grains and microalloy precipitation, mainly by controlling the speed of the finishing strip and the position of the starting valve to control the delay time. 0-8s, laminar cooling rate is 40-70°C/s.
  • a continuous casting process can be used, and the degree of superheat, secondary cooling water, and appropriate light reduction can be controlled to control the center segregation of the continuous casting slab.
  • the heating temperature is 1200-1260°C.
  • the heating temperature can be set at 1200-1260°C, and the temperature can be kept for 1 to 3 hours to better obtain advantageous effects.
  • the temperature exceeds 1260°C, there will be a tendency of coarsening of the crystal grains, which is not conducive to the toughness of the steel plate.
  • the iron scale is thick, which is not conducive to the dephosphorization of the scale. Therefore, the heating temperature is preferably set to 1200-1260°C.
  • step (4) the phosphorus removal pressure is controlled to be 15-35 MPa.
  • the coiling temperature is 480-560°C.
  • the coiling temperature is controlled at 480-560°C to control the bainite transformation and microalloy precipitation.
  • the high coiling temperature will lead to more ferrite and pearlite content, which is not conducive to the increase of the hole expansion rate; the lower coiling temperature, the less ferrite content, and the less precipitation amount, and may appear Martensite structure, low elongation. Therefore, controlling the coiling temperature between 480-560°C can solve the problem of matching between elongation and hole expansion.
  • step (7) the leveling rolling force is controlled to be 100-800 tons, and the leveling elongation is less than or equal to 1.5%.
  • step (8) the pickling speed is controlled at 60-100m/min, the temperature of the last pickling tank in the pickling process is controlled at 80-90°C, and the iron ion concentration is controlled at 30- 40g/L.
  • the high-expansion complex phase steel of the present invention can simultaneously meet the needs of hole expansion and better plasticity, and compared with the traditional materials of low-alloy high-strength steel and ferritic martensitic dual-phase steel, the high-expansion hole in this case Since the two phases of the complex phase are ferrite and bainite, the difference in hardness is small, so that it has good hole expansion performance and cold forming performance.
  • the manufacturing method of the present invention also has the above-mentioned advantages and beneficial effects.
  • Fig. 1 is a metallographic microstructure diagram of the high-expansion complex phase steel of Example 1.
  • FIG. 2 is a SEM microstructure diagram of the high-expansion complex phase steel of Example 1.
  • FIG. 2 is a SEM microstructure diagram of the high-expansion complex phase steel of Example 1.
  • Figure 3 illustrates the surface morphology of the oxide scale of the steel strip with good surface.
  • Figure 4 illustrates the surface morphology of the surface oxide scale of the strip steel on the surface of NG1.
  • Figure 5 illustrates the changes in the mechanical properties of the high-expansion complex phase steel of Example 3 under different flattening deformations.
  • Heating The heating temperature is 1200-1260°C.
  • Hot rolling control the total reduction ratio ⁇ 80%, control the rough rolling to roll in the recrystallization area, the rough rolling exit temperature is 1020-1100°C; the finishing rolling process adopts the quasi-constant speed rolling process, and the finishing speed is controlled At 6-12m/s, the control rolling acceleration is less than or equal to 0.005m/s 2 ; the final rolling temperature is controlled at 840-900°C.
  • Phosphorus removal pressure is controlled at 15-35MPa.
  • control delay time is 0-8s
  • laminar cooling cooling rate is 40-70°C/s.
  • Coiling temperature is 480-560°C.
  • the smoothing rolling force is controlled to be 100-800 tons, and the smoothing elongation is less than or equal to 1.5%.
  • the pickling speed is controlled at 60-100m/min
  • the temperature of the last pickling tank in the pickling process is controlled at 80-90°C
  • the iron ion concentration is controlled at 30-40g/L.
  • Table 1 lists the high-expansion complex phase steels of Examples 1-7 and the manufacturing method thereof, and the mass percentage ratios of the chemical elements of Comparative Examples 1-6.
  • Table 2 lists the high-expansion complex phase steels of Examples 1-7 and the manufacturing method thereof, and the specific process parameters of the comparative steel plates of Comparative Examples 1-6.
  • the size of the test piece is 150 ⁇ 150mm
  • the size of the punching hole is ⁇ 10mm
  • the clearance is specified as 12.5%
  • the 60° cone weight is used from the shear surface Reaming is performed to obtain the inner diameter d when the crack penetrates through the thickness of the plate.
  • the tensile standard is taken along the transverse JIS 5# tensile specimen to determine the mechanical properties; the 180° bending performance is implemented in accordance with the GB/T232-2010 standard.
  • Table 3 lists the high-expansion complex phase steels of Examples 1-7 and the manufacturing method thereof, and the mechanical performance test results of the comparative steel plates of Comparative Examples 1-6.
  • the transverse tensile strength of the high-expansion complex phase steels of the examples of this case is ⁇ 780MPa
  • the yield strength is ⁇ 700MPa
  • the punching hole expansion rate ⁇ 50%.
  • Comparative Example 2 does not meet the requirement of 0.2% ⁇ Cr-0.5(Si+Al) ⁇ 0.42%. Compared with Example 1, the two use the same process system. However, Comparative Example 2 is not conducive to the transformation of the bainite structure, and the large amount of polygonal ferrite and pearlite in the structure is not conducive to the improvement of the strength and the improvement of the hole expansion rate.
  • Comparative Example 3 In Table 1, comparing Comparative Example 3 and Example 2, it can be found that the Ti content of Comparative Example 3 is relatively low, which does not satisfy 0.08% ⁇ 3.3Nb+Ti ⁇ 0.20%; the two use the same process system, but In proportion 3, the grain refinement effect is small, and the precipitation strengthening effect is weak, and the tensile strength cannot reach more than 780MPa.
  • Comparative Example 4 the heating temperature is relatively low, which is not conducive to the solid solution of Ti and Nb, and it is not conducive to the precipitation of fine carbides of Nb and Ti during the subsequent cooling and coiling process. Increase in strength.
  • the comparative example 5 uses a lower coiling temperature, there will be a certain amount of martensite in the supercooled structure, which is not conducive to the improvement of elongation and hole expansion.
  • Comparative Example 6 uses a larger amount of flattening, and compared with Example 1, the elongation loss is 3.4%.
  • Example 4 To compare the effects of different surface states of hot rolling on the uniformity of mechanical properties, the composition and process of Example 4 are used, and different descaling pressures are set to obtain strip steel with different surface states.
  • the poorer the surface treatment effect The greater the surface roughness, the higher the corresponding strength and the lower the elongation.
  • Table 4 lists the effects of different surface states on the mechanical properties.
  • Figures 3 and 4 respectively show the topography of different surface states.
  • Figure 3 illustrates the surface morphology of the surface oxide scale of the strip steel with a good surface
  • Figure 4 illustrates the surface morphology of the surface oxide scale of the strip steel with the surface "NG1".
  • Fig. 1 is a metallographic microstructure diagram of the high-expansion complex phase steel of Example 1.
  • FIG. 2 is a SEM microstructure diagram of the high-expansion complex phase steel of Example 1.
  • FIG. 2 is a SEM microstructure diagram of the high-expansion complex phase steel of Example 1.
  • the microstructure of the high-expansion complex phase steel in this case is ferrite + bainite, and the microstructure has microalloy precipitates, and the microalloy precipitates include (Ti, Nb ) C and NbN.
  • Figure 5 illustrates the changes in the mechanical properties of the high-expansion complex phase steel of Example 3 under different flattening deformations.
  • the high-expansion complex phase steel of the present invention can simultaneously meet the needs of hole expansion and better plasticity, and compared with traditional materials, low-alloy high-strength steel and ferritic martensitic dual-phase steel, Because the two phases of the high-expansion complex phase are ferrite and bainite, the hardness difference is small, and at the same time, it has good hole expansion performance and cold forming performance.
  • the manufacturing method of the present invention also has the above-mentioned advantages and beneficial effects.

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Abstract

本发明公开了一种高扩孔复相钢，其微观组织为铁素体+贝氏体，高扩孔复相钢的化学元素质量百分比为：C：0.06-0.09％，Si：0.05-0.5％，Al：0.02-0.1％，Mn：1.5-1.8％，Cr：0.3-0.6％，Nb≤0.03％，Ti：0.05-0.12％，余量为Fe和其他不可避免的杂质。此外，本发明还公开了一种上述的高扩孔复相钢的制造方法，其包括步骤：(1)冶炼和铸造；(2)加热；(3)热轧；(4)除磷；(5)层流冷却：控制豫迟时间为0-8s，层流冷却冷速为40-70℃/s；(6)卷取；(7)平整；(8)酸洗。该高扩孔复相钢可以同时满足扩孔和塑性较好的需要。

Description

一种高扩孔复相钢及其制造方法 技术领域
本发明涉及一种钢种及其制造方法，尤其涉及一种复相钢及其制造方法。
背景技术
随着汽车强量化发展，越来越多的车型采用80kg级别的热轧酸洗钢板生产汽车底盘件，如控制臂、横拉杆、弹簧座等。例如汽车底盘件如控制臂其在成型过程包括冲压，翻边，扩孔等；因此其不但对强度和延伸率有一定的要求，更对扩孔性能有一定的要求。
公开号为CN103602895A，公开日为2014年2月26日，名称为“一种抗拉强度780MPa级高扩孔钢板及其制造方法”的中国专利文献公开了一种抗拉强度780MPa级高扩孔钢板及其制造方法，其Si含量为0.5-1.5％，含量较高，容易形成铁橄榄石(2FeO-SiO2)氧化铁皮的形成而难以去除，难以获得较高等级表面的带钢。同时由于钢板表面的红铁皮较难控制，导致在热轧测温过程中，难以准确测量，导致产品性能不稳定性。
公开号为CN108570604A，公开号为2018年9月25日，名称为“一种780MPa级热轧酸洗高扩孔钢带及其生产方法”的中国专利文献公开了一种780MPa级热轧酸洗高扩孔钢及其生产方法，其成分Al含量为0.2-0.6％，含量较高，连铸过程容易氧化，同时其采用的是三段冷却方式，生产稳定性较低。
公开号为CN105483545A，公开日为2016年4月13日，名称为“一种800MPa级热轧高扩孔钢板及其制造方法”的中国专利文献公开了一种800MPa级热轧高扩孔钢板及其制造方法，其成分含有0.2-1.0％Si，Si含量相对较高，表面容易形成红铁皮，不利于表面和卷取温度的控制。同时含有0.03-0.08Nb，Nb含量也相对较高，成本较高，且轧后需进行分段冷却，冷却工艺复杂。
在现有技术中，材料的强度越高，材料的长度和宽度稳定性就会越难控制。基于此，期望获得一种高扩孔复相钢，其兼具良好的扩孔性能和冷成形性能，且可以实现稳定化制造生产。
发明内容
本发明的目的之一在于提供一种高扩孔复相钢，该高扩孔复相钢可以同时满足扩孔和塑性较好的需要，并且与传统材料低合金高强度钢、铁素体马氏体双相钢相比，该高扩孔复相钢的两相为铁素体、贝氏体，因此硬度差较小，使得其具有良好的扩孔性能和冷成形性能。
为了实现上述目的，本发明提出了一种高扩孔复相钢，其微观组织为铁素体+贝氏体，高扩孔复相钢的化学元素质量百分比为：
C：0.06-0.09％，Si：0.05-0.5％，Al：0.02-0.1％，Mn：1.5-1.8％，Cr：0.3-0.6％，Nb≤0.03％，Ti：0.05-0.12％，余量为Fe和其他不可避免的杂质。
在本发明所述的高扩孔复相钢中，各化学元素的设计原理如下所述：
C：在本发明所述的高扩孔复相钢中，考虑到碳含量的高低很大程度上决定了钢板的抗拉强度级别，碳用于固溶强化和形成足够的析出强化相，以保证钢的强度，但碳的质量百分比较高会使碳化物颗粒粗大，不利于扩孔性能，而碳的质量百分比太低则会使钢板的强度降低，为了保证钢种强度下即能高扩孔，又具备良好的成形和焊接性能，在本发明所述的技术方案中控制C的质量百分比为0.06-0.09％。
Si：在本发明所述的高扩孔复相钢中，硅起到固溶强化作用，提高钢板的强度，同时添加硅可加大加工硬化速率和给定强度下的均匀延伸率和总延伸率，有助于改善钢板的延伸率。此外，硅还可以阻止碳化物的析出，减少珠光体相的出现。但是钢中含硅容易使钢板表面形成铁橄榄石(2FeO-SiO 2)氧化铁皮的表面缺陷，对表面质量有不良影响。同时红铁皮的出现不利于热轧过程中温度的控制，最终导致不利于产品性能的稳定性。基于此，本发明所述的高扩孔复相钢将硅的质量百分比控制为0.05-0.5％。
Al：在本发明所述的高扩孔复相钢中，Al是钢的脱氧元素，减少钢中的氧化物夹杂、纯净钢质，有利于提高钢板的成形性能，但是铝的质量百分比较高，会产生氧化，进一步影响连铸生产。基于此，在本发明所述的高扩孔复相钢中将Al的质量百分比控制为0.02-0.1％。
Mn：在本发明所述的高扩孔复相钢中，锰是固溶强化元素，锰的质量百分比较低，会导致强度不足，但是锰的质量百分比较高会导致钢板的塑性降低。锰同时推迟珠光体转变，提高钢的淬透性且降低贝氏体转变温度，使钢的组织亚结构细化， 并保证获得板条亚结构组织，在保证产品抗拉强度的前提下，同时具有良好的成形性。基于此，在本发明所述的高扩孔复相钢中将Mn的质量百分比控制在1.5-1.8％。
Cr：在本发明所述的高扩孔复相钢中，铬使CCT曲线中珠光体和铁素体的孕育期增长，抑制珠光体和铁素体的形成，有利于贝氏体组织的形成，最终有利于强度和扩孔率的提升，铬的质量百分比小于0.15％时，对CCT曲线影响不显著，但Cr的质量百分比较高时，则会导致成本较高。基于此，在本发明所述的高扩孔复相钢中将Cr的质量百分比控制在0.3-0.6％。
Nb：在本发明所述的高扩孔复相钢中，铌是重要的析出强化和细晶强化元素之一，在轧制结束后的冷却中或卷取后以细小析出的形式存在，利用析出强化来提高强度。同时铌的存在有利于细化晶粒，提高强度和韧性，同时缩小铁素体和贝氏体基体之间的强度差，从而有利于扩孔率的提升，但当Nb的质量百分比高于0.03％时，Nb的强化效果接近饱和，并且成本较高。因此，在本发明所述的高扩孔复相钢中，将Nb的质量百分比控制在Nb≤0.03％。考虑到当Nb的质量百分比低于0.015％时，NbC析出不足，难以发挥析出强化的目的，因此，在一些优选的实施方式中，可以优选地将Nb的质量百分比设置为0.015-0.03％。
Ti：在本发明所述的高扩孔复相钢中，钛是重要的析出强化和细晶强化元素之一，钛在本案中起到的作用有两个，一是与钢中的杂质元素氮结合形成TiN，这是因为钢中游离的氮原子对钢的冲击韧性不利，加入微量钛可将游离的氮固定，有利于扩孔率的发挥和提升冲击韧性；二是与铌配合，起到最佳的细化奥氏体晶粒的作用和析出强化作用。但在本案中Ti的质量百分比不宜太多，容易形成尺寸较大的TiN，对钢的冲击韧性不利。因此，在本发明所述的高扩孔复相钢中，控制Ti的质量百分比为Ti：0.05-0.12％。
进一步地，在本发明所述的高扩孔复相钢中，其中Nb元素含量为0.015-0.03％。
进一步地，在本发明所述的高扩孔复相钢中，在其他不可避免的杂质中，P≤0.03％，S≤0.02％，N≤0.005％。
上述方案中，不可避免的杂质元素应当控制的越低越好，但是考虑到成本控制以及工艺限制，因而，可以控制P≤0.03％，S≤0.02％，N≤0.005％。其中，将N的质量百分比控制在N≤0.005％是因为：氮在高温条件下就与钛反应形成TiN颗粒析出，过大的TiN颗粒会成为钢板局部变形微裂纹，最终影响扩孔率，因此必须对钢中氮含量进行控制。
而对于P而言，将P的质量百分比控制在P≤0.03％是因为：钢中磷一般固溶在铁素体中，降低钢的韧性，但高磷对焊接性不利，同时晶界处磷偏聚，不利于带钢的扩孔性能，故应尽量减少磷含量。
在上述方案中，将S的质量百分比控制在S≤0.02％是因为：硫含量和硫化物的形态是影响成形性的主要因素，硫化物的数量越多，尺寸越大，对扩孔性能越不利。
进一步地，在本发明所述的高扩孔复相钢中，其化学元素质量百分含量满足下列各式的至少其中之一：
0.2％≤Cr-0.5(Si+Al)≤0.42％；
0.08％≤3.3Nb+Ti≤0.20％。
在上述方案中，控制0.2％≤Cr-0.5(Si+Al)≤0.42％，以使得珠光体和铁素体转变区往右移，推迟珠光体和铁素体的转变，有利于贝氏体相的形成，从而达到高强度和高扩孔的目的。
另外，在本技术方案中，限定Nb、Ti的质量百分比满足0.08％≤3.3Nb+Ti≤0.20％，以控制析出强化约100-200MPa，并且可以在采用高钛成分设计时，不添加铌并同时达到本案所需要的高扩孔以及塑性要求的目的，同时还可以达到降低成本的目的。
进一步地，在本发明所述的高扩孔复相钢中，其微观组织具有微合金析出物，微合金析出物包括(Ti，Nb)C以及NbN。
进一步地，在本发明所述的高扩孔复相钢中，其抗拉强度与化学元素质量百分含量满足：
抗拉强度Rm＝343+789×C+170×Si+132×Mn+195×Cr+843×(Nb+Ti)-207×Al，抗拉强度Rm量纲为MPa。
在本技术方案中，基于上述公式和本案的化学元素成分配比，抗拉强度Rm一般在790～850MPa。
进一步地，在本发明所述的高扩孔复相钢中，其横向抗拉强度≥780MPa，屈服强度≥700MPa，延伸率A 50≥15％，冲孔扩孔率≥50％。
优选地，在本发明所述的高扩孔复相钢中，冲孔扩孔率≥70％。
优选地，在本发明所述的高扩孔复相钢中，屈服强度≥730MPa。
优选地，在本发明所述的高扩孔复相钢中，横向抗拉强度≥8000MPa。
优选地，在本发明所述的高扩孔复相钢中，横向抗拉强度≥800MPa，屈服强度 ≥730MPa，延伸率A 50≥15％，冲孔扩孔率≥70％。
相应地，本发明的另一目的还在于提供一种上述的高扩孔复相钢的制造方法，通过该制造方法可以获得具有良好的扩孔性能和冷成形性能的高扩孔复相钢。
为了达到上述发明目的，本发明提出了上述的高扩孔复相钢的制造方法，其包括步骤：
(1)冶炼和铸造；
(2)加热；
(3)热轧：控制总压下率≥80％，控制粗轧在再结晶区域轧制，粗轧出口温度为1020-1100℃；精轧过程采用准恒速轧制工艺，精轧速度控制在6-12m/s，控制轧钢加速度≤0.005m/s 2；控制终轧温度为840-900℃；
(4)除磷；
(5)层流冷却：控制豫迟时间为0-8s，层流冷却冷速为40-70℃/s；
(6)卷取；
(7)平整；
(8)酸洗。
在本发明所述的制造方法中，控制热轧的总压下率≥80％；同时保证粗轧在再结晶区域轧制，以及避免奥氏体区的微合金析出；粗轧出口温度控制在1020-1100℃；精轧过程采用准恒速轧制工艺，轧钢加速度≤0.005m/s 2，精轧的速度控制在6-12m/s；终轧温度控制为840-900℃之间，在未再结晶区域轧制，用于细化晶粒，同时有利于形变诱导析出；在保证目标温度的前提下，恒速轧制时时保证空冷时间的稳定，有利于豫迟冷却时间的控制。
此外，在层流冷却中，采用前段冷却和豫迟控制冷却模式有利于晶粒的回复和微合金析出，主要通过控制精轧带钢的速度和起始阀门的位置，以控制豫迟时间在0-8s，层流冷却冷速为40-70℃/s。
此外，可以在一些优选的实施方式中，采用连铸工艺，并且控制过热度、二冷水、以及适当的轻压下，以控制连铸坯的中心偏析。
进一步地，在本发明所述的制造方法中，在步骤(2)中，加热温度为1200-1260℃。
上述方案中，考虑到为了使得Ti和Nb充分固溶，可以将加热温度设置在1200-1260℃，并且保温1～3h以更好地获得有利效果。而当温度超过1260℃时，会有晶粒粗化的趋势，不利于钢板的韧性；同时氧化铁皮较厚，不利于氧化铁皮的除 磷，因此优选地将加热温度设置为1200-1260℃
进一步地，在本发明所述的制造方法中，在步骤(4)中，除磷压力控制为15-35MPa。
上述方案中，考虑到铁橄榄石(2FeO-SiO 2)会导致钢的氧化层致密，当热轧表面氧化铁皮除磷效果不好时，破碎的氧化皮表面由于粗糙度较大，在层流冷却过程中会减少水的流动，局部水的囤积会进一步的影响带钢的局部性能，影响了带钢局部冷却不均匀，因此除磷效果不好不仅会导致材料表面的差异，还会导致性能的差异，基于此，可以优选地高压除磷水系统，并且将除磷压力控制为15-35MPa。
进一步地，在本发明所述的制造方法中，在步骤(6)中，卷取温度为480-560℃。
上述方案中，控制卷取温度为480～560℃，以控制贝氏体转变和微合金析出。其中，卷取温度高，会导致铁素体和珠光体含量较多，不利于扩孔率的提升；卷取温度较低，铁素体含量较少，同时析出量较少，并有可能出现马氏体组织，延伸率较低。因而，控制卷取温度在480-560℃之间可以解决延伸率和扩孔率之间的匹配问题。
进一步地，在本发明所述的制造方法中，在步骤(7)中，平整轧制力控制为100-800吨，并且满足平整延伸率≤1.5％。
在一些优选的实施方式中，在步骤(8)中，酸洗速度控制在60-100m/min，酸洗过程最后的一个酸洗酸槽温度控制80-90℃、铁离子浓度控制为30-40g/L。
本发明所述的高孔扩复相钢具有如下所述的优点以及有益效果：
本发明所述的高扩孔复相钢可以同时满足扩孔和塑性较好的需要，并且与传统材料低合金高强度钢、铁素体马氏体双相钢相比，本案的高扩孔复相由于两相为铁素体、贝氏体，硬度差较小，使得其具有良好的扩孔性能和冷成形性能。
此外，本发明所述的制造方法也同样具有上述的优点以及有益效果。
附图说明
图1为实施例1的高扩孔复相钢的金相显微组织图。
图2为实施例1的高扩孔复相钢的SEM显微组织图。
图3示意了表面良好的带钢的表面氧化皮表面形貌。
图4示意了表面NG1的带钢的表面氧化皮表面形貌。
图5示意了实施例3的高扩孔复相钢在不同平整变形量下力学性能的变化。
具体实施方式
下面将结合说明书附图和具体的实施例对本发明所述的高扩孔复相钢及其制造方法做进一步的解释和说明，然而该解释和说明并不对本发明的技术方案构成不当限定。
实施例1-7以及对比例1-6
上述实施例1-7的高扩孔复相钢及其制造方法以及对比例1-6的对比钢板采用以下步骤制得：
(1)按照表1所示的化学成分进行冶炼和铸造，采用转炉炼钢，钢水经过RH真空脱气处理、LF炉脱硫处理，其中控制P≤0.015％，S≤0.005％。连铸时，控制过热度、二冷水、以及适当的轻压下，以控制连铸坯的中心偏析。
(2)加热：加热温度为1200-1260℃。
(3)热轧：控制总压下率≥80％，控制粗轧在再结晶区域轧制，粗轧出口温度为1020-1100℃；精轧过程采用准恒速轧制工艺，精轧速度控制在6-12m/s，控制轧钢加速度≤0.005m/s 2；控制终轧温度为840-900℃。
(4)除磷：除磷压力控制为15-35MPa。
(5)层流冷却：控制豫迟时间为0-8s，层流冷却冷速为40-70℃/s。
(6)卷取：卷取温度为480-560℃。
(7)平整：平整轧制力控制为100-800吨，并且满足平整延伸率≤1.5％。
(8)酸洗：酸洗速度控制在60-100m/min，酸洗过程最后的一个酸洗酸槽温度控制80-90℃、铁离子浓度控制为30-40g/L。
表1列出了实施例1-7的高扩孔复相钢及其制造方法以及对比例1-6的各化学元素的质量百分配比。
表1.(wt％，余量为Fe和除了P、S以及N以外的其他不可避免的杂质)
Figure PCTCN2020117724-appb-000001
Figure PCTCN2020117724-appb-000002
表2列出了实施例1-7的高扩孔复相钢及其制造方法以及对比例1-6的对比钢板的具体工艺参数。
表2.
Figure PCTCN2020117724-appb-000003
Figure PCTCN2020117724-appb-000004
按照按ISO/DIS16630标准中规定的扩孔率测试方法执行，实验样片的尺寸为150×150mm，冲孔的尺寸为Φ10mm，将余隙规定为12.5％，用60°的圆锥重头从剪切面测进行扩孔，求出裂纹贯通板厚时刻的内径d。如果将扩孔前的内径设定为d 0，则由下式求出极限扩孔值λ％。极限扩孔值λ％＝(d-d 0)/d 0×100％。拉伸标准取沿横向JIS 5#拉伸试样测定力学性能；180°折弯性能按照GB/T232-2010标准执行。
表3列出了实施例1-7的高扩孔复相钢及其制造方法以及对比例1-6的对比钢板的力学性能测试结果。
表3.
  厚度/mm 预测Rm/Mpa Rp0.2/MPa Rm/MPa A50/％ λ/％ 180°冷弯
实施例1 3.5 820 742 824 17.5 88 1.5a
实施例2 2.2 832 743 833 16.2 87 1.5a
实施例3 6.0 797 718 793 18.5 82 1.5a
实施例4 5.5 845 706 789 20.1 58 1.5a
实施例5 1.8 823 771 859 15.6 78 1.5a
实施例6 4.0 795 732 812 15.1 76 1.5a
实施例7 3.2 846 752 845 16.8 85 1.5a
对比例1 3.5 914 812 895 11.2 54 2.5a
对比例2 3.5 775 678 765 17.5 53 1.5a
对比例3 3.5 781 661 759 16.8 76 1.5a
对比例4 3.5 820 653 768 17.6 82 1.5a
对比例5 3.5 820 798 923 11.4 34 2.5a
对比例6 3.5 820 785 863 14.2 68 2.0a
由表3可以看出，本案各实施例的高扩孔复相钢的横向抗拉强度≥780MPa，屈服强度≥700MPa，延伸率A 50≥15％，冲孔扩孔率≥50％。
结合表1可以看出，对比例1中Cr-0.5(Si+Al)不满足0.2％≤Cr-0.5(Si+Al) ≤0.42％要求，和实施例1进行对比，两者采用相同的工艺制度，但对比例1中Si含量较高，容易形成铁橄榄石(2FeO-SiO 2)氧化铁皮的形成而难以去除，难于获得较高等级表面的带钢，同时由于表面的红铁皮较难控制，导致在热轧测温过程中，难以准确测量，导致产品性能不稳定性，有铁橄榄石(2FeO-SiO 2)的部位强度过高，延伸率较低。在表1中，对比例2中Cr-0.5(Si+Al)不满足0.2％≤Cr-0.5(Si+Al)≤0.42％要求，和实施例1进行对比，两者采用相同的工艺制度，但对比例2不利于贝氏体组织的转变，组织中大量的多边形铁素体和珠光体，不利于强度的提升和扩孔率的提升。而在表1中，对比例3和实施例2进行对比，可以发现对比例3的Ti含量较低，不满足0.08％≤3.3Nb+Ti≤0.20％；两者采用相同的工艺制度，但对比例3晶粒细化作用较小，并且析出强化作用较弱，抗拉强度不能达到780MPa以上。
另外，结合表2可以看出，对比例4中，加热温度相对较低，不利于Ti和Nb的固溶，在后续冷却和卷取过程中不利于Nb和Ti的细小碳化物析出，不利于强度的提升。而对比例5采用较低的卷取温度，过冷组织中会有一定量的马氏体，不利于延伸率和扩孔率的提升。对比例6采用较大的平整量，相对于实施例1，延伸率损失3.4％。
对比热轧的不同表面状态对力学性能均匀性的影响，采用实施例4的成分及工艺，通过设置不同的除鳞压力，以获得具有不同表面状态的带钢，其中表面处理效果越不好，其表面粗糙度越大，对应的强度越高，延伸率越低。
表4列出了不同表面状态对力学性能的影响。此外，图3和图4分别显示了不同的表面状态的形貌。其中，图3示意了表面良好的带钢的表面氧化皮表面形貌，图4示意了表面为“NG1”的带钢的表面氧化皮表面形貌。
表4.
  厚度/mm 除磷压力/MPa 表面粗糙度/μm Rp0.2/MPa Rm/MPa A50/％
表面良好 3.5 20 1.33 706 789 20.1
表面NG1 3.5 8 4.78 835 897 13.5
表面NG2 3.5 5 5.34 864 937 11.8
表面NG3 3.5 9 3.15 760 856 14.5
图1为实施例1的高扩孔复相钢的金相显微组织图。
图2为实施例1的高扩孔复相钢的SEM显微组织图。
结合图1和图2可以看出，本案中的高扩孔复相钢的微观组织为铁素体+贝氏体，微观组织具有微合金析出物，所述微合金析出物包括(Ti，Nb)C以及NbN。
图5示意了实施例3的高扩孔复相钢在不同平整变形量下力学性能的变化。
如图5所示，随着平整量的增加，强度有上升的趋势。
综上所述，本发明所述的高扩孔复相钢可以同时满足扩孔和塑性较好的需要，并且与传统材料低合金高强度钢、铁素体马氏体双相钢相比，本案的高扩孔复相由于两相为铁素体、贝氏体，因此硬度差较小，同时使得其具有良好的扩孔性能和冷成形性能。此外，本发明所述的制造方法也同样具有上述的优点以及有益效果。
需要说明的是，本发明的保护范围中现有技术部分并不局限于本申请文件所给出的实施例，所有不与本发明的方案相矛盾的现有技术，包括但不局限于在先专利文献、在先公开出版物，在先公开使用等等，都可纳入本发明的保护范围。
此外，本案中各技术特征的组合方式并不限本案权利要求中所记载的组合方式或是具体实施例所记载的组合方式，本案记载的所有技术特征可以以任何方式进行自由组合或结合，除非相互之间产生矛盾。
还需要注意的是，以上所列举的实施例仅为本发明的具体实施例。显然本发明不局限于以上实施例，随之做出的类似变化或变形是本领域技术人员能从本发明公开的内容直接得出或者很容易便联想到的，均应属于本发明的保护范围。

Claims (13)

  1. 一种高扩孔复相钢，其特征在于，其微观组织为铁素体+贝氏体，所述高扩孔复相钢的化学元素质量百分比为：
    C：0.06-0.09％，Si：0.05-0.5％，Al：0.02-0.1％，Mn：1.5-1.8％，Cr：0.3-0.6％，Nb≤0.03％，Ti：0.05-0.12％，余量为Fe和其他不可避免的杂质。
  2. 如权利要求1所述的高扩孔复相钢，其特征在于，其中Nb元素含量为0.015-0.03％。
  3. 如权利要求1所述的高扩孔复相钢，其特征在于，在其他不可避免的杂质中，P≤0.03％，S≤0.02％，N≤0.005％。
  4. 如权利要求1所述的高扩孔复相钢，其特征在于，其化学元素质量百分含量需要满足下列各式之一：
    0.2％≤Cr-0.5(Si+Al)≤0.42％；
    0.08％≤3.3Nb+Ti≤0.20％。
  5. 如权利要求1所述的高扩孔复相钢，其特征在于，其微观组织具有微合金析出物，所述微合金析出物包括(Ti，Nb)C以及NbN。
  6. 如权利要求1-5中任意一项所述的高扩孔复相钢，其特征在于，其抗拉强度与化学元素质量百分含量满足：
    抗拉强度Rm＝343+789×C+170×Si+132×Mn+195×Cr+843×(Nb+Ti)-207×Al，其中抗拉强度Rm量纲为MPa。
  7. 如权利要求6所述的高扩孔复相钢，其特征在于，其横向抗拉强度≥780MPa，屈服强度≥700MPa，延伸率A 50≥15％，冲孔扩孔率≥50％。
  8. 如权利要求1所述的高扩孔复相钢，其特征在于，其横向抗拉强度≥800MPa，屈服强度≥730MPa，延伸率A 50≥15％，冲孔扩孔率≥70％。
  9. 如权利要求1-8中任意一项所述的高扩孔复相钢的制造方法，其特征在于，包括步骤：
    (1)冶炼和铸造；
    (2)加热；
    (3)热轧：控制总压下率≥80％，控制粗轧在再结晶区域轧制，粗轧出口温度为1020-1100℃；精轧过程采用准恒速轧制工艺，精轧速度控制在6-12m/s， 控制轧钢加速度≤0.005m/s 2；控制终轧温度为840-900℃；
    (4)除磷；
    (5)层流冷却：控制豫迟时间为0-8s，层流冷却冷速为40-70℃/s；
    (6)卷取；
    (7)平整；
    (8)酸洗。
  10. 如权利要求9所述的制造方法，其特征在于，在所述步骤(2)中，加热温度为1200-1260℃。
  11. 如权利要求9所述的制造方法，其特征在于，在所述步骤(4)中，除磷压力控制为15-35MPa。
  12. 如权利要求9所述的制造方法，其特征在于，在所述步骤(6)中，卷取温度为480-560℃。
  13. 如权利要求9所述的制造方法，其特征在于，在所述步骤(7)中，平整轧制力控制为100-800吨，并且满足平整延伸率≤1.5％。
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009263685A (ja) * 2008-04-22 2009-11-12 Nippon Steel Corp 切断後の特性劣化の少ない高強度鋼板及びその製造方法
CN103602895A (zh) 2013-11-29 2014-02-26 宝山钢铁股份有限公司 一种抗拉强度780MPa级高扩孔钢板及其制造方法
CN104513930A (zh) * 2014-12-19 2015-04-15 宝山钢铁股份有限公司 弯曲和扩孔性能良好的超高强热轧复相钢板和钢带及其制造方法
JP2015199987A (ja) * 2014-04-08 2015-11-12 新日鐵住金株式会社 低温靭性と均一伸びと穴拡げ性に優れた引張強度７８０ＭＰａ以上の高強度熱延鋼板及びその製造方法
CN105483545A (zh) 2014-09-19 2016-04-13 鞍钢股份有限公司 一种800MPa级热轧高扩孔钢板及其制造方法
JP2017025397A (ja) * 2015-07-28 2017-02-02 新日鐵住金株式会社 熱延鋼板およびその製造方法
JP6287623B2 (ja) * 2013-06-25 2018-03-07 新日鐵住金株式会社 高強度熱延鋼板とその製造方法
CN108570604A (zh) 2018-04-28 2018-09-25 唐山钢铁集团有限责任公司 一种780MPa级热轧酸洗高扩孔钢带及其生产方法
CN109594020A (zh) * 2018-12-28 2019-04-09 首钢集团有限公司 一种抗拉强度1000MPa级冷轧复相钢及其制备方法

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101285156B (zh) * 2008-06-05 2010-06-23 广州珠江钢铁有限责任公司 一种700MPa级复合强化贝氏体钢及其制备方法
EP2489748B1 (de) * 2011-02-18 2017-12-13 ThyssenKrupp Steel Europe AG Aus einem Komplexphasenstahl hergestelltes warmgewalztes Stahlflachprodukt und Verfahren zu dessen Herstellung
WO2012127125A1 (fr) * 2011-03-24 2012-09-27 Arcelormittal Investigatión Y Desarrollo Sl Tôle d'acier laminée à chaud et procédé de fabrication associé
KR20130110638A (ko) * 2012-03-29 2013-10-10 현대제철 주식회사 강판 및 그 제조 방법
WO2015099222A1 (ko) * 2013-12-26 2015-07-02 주식회사 포스코 용접성 및 버링성이 우수한 열연강판 및 그 제조방법
CN105821301A (zh) * 2016-04-21 2016-08-03 河北钢铁股份有限公司邯郸分公司 一种800MPa级热轧高强度扩孔钢及其生产方法
CN106521327B (zh) * 2016-12-27 2018-08-21 首钢集团有限公司 一种具有高扩孔性能的热轧酸洗带钢及其生产方法
CN110291215B (zh) * 2017-01-20 2022-03-29 蒂森克虏伯钢铁欧洲股份公司 由具有大部分为贝氏体的组织结构的复相钢组成的热轧扁钢产品和用于生产这种扁钢产品的方法

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009263685A (ja) * 2008-04-22 2009-11-12 Nippon Steel Corp 切断後の特性劣化の少ない高強度鋼板及びその製造方法
JP6287623B2 (ja) * 2013-06-25 2018-03-07 新日鐵住金株式会社 高強度熱延鋼板とその製造方法
CN103602895A (zh) 2013-11-29 2014-02-26 宝山钢铁股份有限公司 一种抗拉强度780MPa级高扩孔钢板及其制造方法
JP2015199987A (ja) * 2014-04-08 2015-11-12 新日鐵住金株式会社 低温靭性と均一伸びと穴拡げ性に優れた引張強度７８０ＭＰａ以上の高強度熱延鋼板及びその製造方法
CN105483545A (zh) 2014-09-19 2016-04-13 鞍钢股份有限公司 一种800MPa级热轧高扩孔钢板及其制造方法
CN104513930A (zh) * 2014-12-19 2015-04-15 宝山钢铁股份有限公司 弯曲和扩孔性能良好的超高强热轧复相钢板和钢带及其制造方法
JP2017025397A (ja) * 2015-07-28 2017-02-02 新日鐵住金株式会社 熱延鋼板およびその製造方法
CN108570604A (zh) 2018-04-28 2018-09-25 唐山钢铁集团有限责任公司 一种780MPa级热轧酸洗高扩孔钢带及其生产方法
CN109594020A (zh) * 2018-12-28 2019-04-09 首钢集团有限公司 一种抗拉强度1000MPa级冷轧复相钢及其制备方法

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