CN116987848A - Hot dip galvanized steel and preparation method thereof - Google Patents

Hot dip galvanized steel and preparation method thereof Download PDF

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Publication number
CN116987848A
CN116987848A CN202310915893.1A CN202310915893A CN116987848A CN 116987848 A CN116987848 A CN 116987848A CN 202310915893 A CN202310915893 A CN 202310915893A CN 116987848 A CN116987848 A CN 116987848A
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China
Prior art keywords
temperature
annealing
steel
hot dip
dip galvanized
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Chinese (zh)
Inventor
张天越
李润昌
李钊
尹文亚
张士杰
安方亮
潘明
胡开艳
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Shougang Jingtang United Iron and Steel Co Ltd
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Shougang Jingtang United Iron and Steel Co Ltd
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Priority to CN202310915893.1A priority Critical patent/CN116987848A/en
Publication of CN116987848A publication Critical patent/CN116987848A/en
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • 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
    • C21D1/34—Methods of heating
    • C21D1/42—Induction heating
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • 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
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Coating With Molten Metal (AREA)

Abstract

The application relates to the field of steel manufacturing, in particular to hot dip galvanized steel and a preparation method thereof. The method comprises the following steps: annealing the cold-rolled steel coil with the set chemical composition, and controlling the annealing process parameters; the annealing comprises an aging section, and the cold-rolled steel coil is subjected to heating treatment in the aging section; and hot galvanizing the annealed cold rolled steel coil, and finishing to obtain hot galvanized steel. The hot dip galvanized high-strength steel with tensile strength of over 980MPa, yield strength of over 600MPa, elongation of over 11% and hole expansion rate of over 30% at the gauge length of 80mm is obtained by the method, the forming performance is improved, and the stamping cracking is improved.

Description

Hot dip galvanized steel and preparation method thereof
Technical Field
The application relates to the field of steel manufacturing, in particular to hot dip galvanized steel and a preparation method thereof.
Background
High-strength steel is an important material for a vehicle body structural member, development of higher-strength steel is an important direction for realizing weight reduction of a vehicle body, but the higher-strength steel is poor in forming performance, easy to crack during stamping forming, and is not suitable for increasingly complex dies. The cooling temperature in the traditional hot galvanizing process is limited by the temperature of a pot to obtain good plating property, so that the formation of a tissue which is beneficial to the improvement of the forming property is limited, the good forming property can be obtained only by adding the alloy element, the manufacturing cost is high, and the property is easy to fluctuate.
Therefore, there is a need for developing a method for producing a hot dip galvanized steel excellent in formability.
Disclosure of Invention
The application provides hot dip galvanized steel and a preparation method thereof, which aim to solve the technical problem that the existing hot dip galvanized steel is poor in forming performance.
In a first aspect, the present application provides a method for preparing hot dip galvanized steel, the method comprising:
annealing the cold-rolled steel coil with the set chemical composition, and controlling the annealing process parameters; the annealing comprises an aging section, and the cold-rolled steel coil is subjected to heating treatment in the aging section;
and hot galvanizing the annealed cold rolled steel coil, and finishing to obtain hot galvanized steel.
Optionally, the annealing process parameters include:
annealing temperature, slow cooling temperature, quick cooling temperature, aging temperature, annealing atmosphere and strip steel running speed.
Optionally, the annealing temperature is 800-870 ℃, the slow cooling temperature is 670-730 ℃, the rapid cooling temperature is 300-360 ℃, and the aging temperature is 300-360 ℃.
Optionally, the annealing atmosphere includes: hydrogen, the content of the hydrogen is 50-75%.
Optionally, the running speed of the strip steel is 75-100m/min.
Optionally, the heating treatment includes:
1-3 induction heaters are arranged, and the power of the induction heaters is 200-1700 KW/one.
Optionally, the setting chemical composition includes:
C. mn, si, al, P, S, mo, nb, ti and Fe; wherein, the weight percentage is calculated,
the alloy comprises 0.1-0.2% of C, 2-2.5% of Mn, 0.2-0.5% of Si, 0.02-0.07% of Al, less than or equal to 0.02% of P, less than or equal to 0.002% of S, 0.05-0.3% of Mo, 0.02-0.07% of Nb and 0.02-0.07% of Ti.
Optionally, the technological parameters of hot galvanizing include:
the temperature of the zinc pot and the temperature of the cooling tower top; wherein the temperature of the zinc entering pot is 440-460 ℃, and the temperature of the cooling tower top is 170-250 ℃.
Optionally, the elongation of the finish is 0.1-0.7%.
In a second aspect, the application provides a hot dip galvanized steel prepared by a method according to any one of the embodiments of the first aspect.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
according to the preparation method of the hot dip galvanized steel, provided by the embodiment of the application, a hot dip galvanized steel forming performance control component-annealing-finishing process strategy is designed; and the strategy of controlling the forming performance of the high-strength steel is designed through annealing process parameters, and the strip steel is heated back through induction heating in the aging section to replace a large amount of alloy elements to be added, so that the high-strength steel with good forming performance is obtained. In addition, compared with the traditional 980 MPa-level hot dip galvanized high-strength steel production method, the steel plate produced by the method has higher hole expansion rate, better local forming performance and advantages when being applied to complex dies. The method has good practical application effect, defines the temperature control points of each region, improves the strip steel forming performance, has wide application range and can be popularized.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a schematic flow chart of a preparation method of hot dip galvanized steel according to an embodiment of the application.
FIG. 2 is a surface quality chart of a hot dip galvanized steel provided in example 2 of the present application;
fig. 3 is a surface view of a hot dip galvanized steel after reaming experiments provided in example 2 of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Various embodiments of the application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
In the present application, unless otherwise specified, terms such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present specification, the terms "include", "comprising" and the like mean "including but not limited to". Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.
In a first aspect, the present application provides a method for preparing hot dip galvanized steel, referring to fig. 1, the method includes:
s1, annealing a cold-rolled steel coil with set chemical components, and controlling annealing process parameters; the annealing comprises an aging section, and the cold-rolled steel coil is subjected to heating treatment in the aging section;
in some embodiments, the process parameters of the annealing include:
annealing temperature, slow cooling temperature, quick cooling temperature, aging temperature, annealing atmosphere and strip steel running speed.
In some embodiments, the annealing temperature is 800-870 ℃, the slow cooling temperature is 670-730 ℃, the rapid cooling temperature is 300-360 ℃, and the aging temperature is 300-360 ℃.
In the embodiment of the application, the thickness of the cold-rolled steel coil is 1.2-2.0mm, and the width is 900-1560mm. The positive effect of controlling the annealing temperature to be 800-870℃ is that: and the strip steel work hardening is completely eliminated, and meanwhile, the austenitic phases with different proportions are regulated and controlled. When the annealing temperature is less than 800 ℃, the strip steel still has work hardening, the strength is increased, and the formability is reduced; when the annealing temperature is higher than 870 ℃, the austenitizing degree of the strip steel is too high, more tempered martensite is formed after cooling and tempering, the content of fresh martensite is reduced, and the matrix strength is reduced. Specifically, the annealing temperature may be 800 ℃, 830 ℃, 870 ℃, or the like.
The positive effect of controlling the slow cooling temperature to 670-730℃ is that: the ferrite ratio is controlled. When the slow cooling temperature is less than 670 ℃, the ferrite proportion is low, and the tensile strength of the strip steel is insufficient; when the slow cooling temperature is higher than 730 ℃, the tensile strength of the strip steel of the embodiment of the application is increased. Specifically, the slow cooling temperature may be 670 ℃, 700 ℃, 730 ℃, or the like.
The positive effect of controlling the quick cooling temperature to 300-360℃ is that: the proportion of primary martensite is controlled. When the rapid cooling temperature is lower than 300 ℃, the primary martensite content in the structure is too high, a large amount of tempered martensite is formed after tempering, and the tensile strength is reduced; when the quick cooling temperature exceeds 360 ℃, the primary martensite content is insufficient, and the tensile strength and the hole expansion rate are reduced. Specifically, the rapid cooling temperature may be 300 ℃, 330 ℃, 360 ℃, or the like.
The positive effect of controlling the aging temperature to 300-360℃ is that: controlling the proportion of tempered martensite. When the time effect temperature is lower than 300 ℃, the primary martensite tempering in the matrix is insufficient, the strength is high, and the hole expansion rate is low; when the aging temperature is higher than 360 ℃, the primary martensite is excessively tempered, and the tensile strength is insufficient. Specifically, the aging temperature may be 300 ℃, 330 ℃, 360 ℃, or the like.
In some embodiments, the annealing atmosphere comprises: hydrogen, the content of the hydrogen is 50-75%.
In the embodiment of the application, the positive effect of controlling the content of the hydrogen to be 50-75 percent is that: and controlling the cooling speed in the quick cooling range. When the hydrogen content is lower than 50%, the cooling capacity of the quick cooling section is insufficient, and the requirement of cooling the strip steel from the target slow cooling temperature to the target quick cooling temperature cannot be met; when the hydrogen content exceeds 75%, the hydrogen is easy to diffuse to the aging section, bringing potential safety hazard. Specifically, the content of the hydrogen gas may be 50%, 65%, 75%, or the like.
In some embodiments, the strip is run at a speed of 75-100m/min.
In the embodiment of the application, the positive effect of controlling the running speed of the strip steel to be 75-100m/min is that: and controlling the cooling speed of the strip steel. When the running speed of the strip steel is lower than 75m/min, the cooling speed of the strip steel is insufficient, and the formed primary martensite is reduced, so that the hole expansion rate is influenced; when the running speed of the strip steel is higher than 100m/min, the heating speed of the strip steel is too high, and the tensile strength and the yield strength are increased. Specifically, the running speed of the strip steel can be 75m/min, 90m/min, 100m/min and the like.
In some embodiments, the heat treatment comprises: 1-3 induction heaters are arranged, and the power of the induction heaters is 200-1700 KW/one.
In the embodiment of the application, 1-3 induction heaters are arranged, and the power of the induction heaters is 200-1700 KW/positive effects: the aging temperature of the strip steel is convenient to control. At least 1 induction heater is arranged in the furnace area to control the temperature rise of the strip steel after cooling, so that the aging temperature is ensured to reach a set value, and meanwhile, the power of the induction heater is controlled within the numerical range, so that the heating speed can be controlled according to different specifications and strip speeds. The induction heater heats the strip steel to 0-205 ℃.
In some embodiments, the setting the chemical composition comprises:
C. mn, si, al, P, S, mo, nb, ti and Fe; wherein, the weight percentage is calculated,
the alloy comprises 0.1-0.2% of C, 2-2.5% of Mn, 0.2-0.5% of Si, 0.02-0.07% of Al, less than or equal to 0.02% of P, less than or equal to 0.002% of S, 0.05-0.3% of Mo, 0.02-0.07% of Nb and 0.02-0.07% of Ti.
In the embodiment of the application, the positive effect of controlling the content of C to be 0.1-0.2 percent is as follows: ensure that the strip steel obtains enough tensile strength. Too high a carbon content adversely affects hole expansibility and weldability; when the carbon content is insufficient, the tensile strength of the strip steel is insufficient. Specifically, the content of C may be 0.1%, 0.15%, 0.2%, or the like.
The positive effect of controlling the Mn content to be 2-2.5 percent: the tensile strength of the strip steel is ensured. When the Mn content is insufficient, the tensile strength is insufficient. Specifically, the Mn content may be 2.0%, 2.2%, 2.5%, etc.
The positive effect of controlling the content of Si to be 0.2-0.5 percent: the tensile strength of the strip steel is ensured, the hardenability is improved, and the steel-making regulation and control of the other components are facilitated. When the Si content is too high, red rust is generated, and the quality of hot galvanizing is affected. Specifically, the content of Si may be 0.2%, 0.3%, 0.5%, or the like.
The positive effect of controlling the content of Al to be 0.02-0.07 percent: is convenient for regulating and controlling the content of other components. Too high an Al content causes difficulties in steelmaking. Specifically, the Al content may be 0.02%, 0.05%, 0.07%, or the like.
The positive effect of controlling the content of P to be less than or equal to 0.02 percent is that: too high a P content reduces the strip plasticity. Specifically, the content of P may be 0.02%, 0.015%, 0.01%, or the like.
The positive effect of controlling the S content to be less than or equal to 0.002 percent is that: too high a content of S reduces the strip plasticity and weldability. Specifically, the content of S may be 0.002%, 0.0015%, or the like.
The positive effect of controlling the content of Mo to be 0.05-0.3 percent: the hardenability of the strip steel is ensured, and the tensile strength is ensured. Insufficient hardenability when Mo is insufficient, resulting in insufficient tensile strength. Specifically, the Mo content may be 0.05%, 0.1%, 0.3%, or the like.
The positive effect of controlling the Nb content to be 0.02-0.07 percent: the grain size and the precipitated phase of the strip steel are regulated and controlled, and the tensile strength is ensured. When Nb is insufficient, the tensile strength is insufficient. Specifically, the Nb content may be 0.02%, 0.05%, 0.07%, or the like.
The positive effect of controlling the Ti content to be 0.02-0.07 percent: the grain size and the precipitated phase of the strip steel are regulated and controlled, and the tensile strength is ensured. When Ti is insufficient, the tensile strength is insufficient. Specifically, the Ti content may be 0.02%, 0.05%, 0.07%, etc.
S2, hot galvanizing the annealed cold rolled steel coil, and finishing to obtain hot galvanized steel.
In some embodiments, the process parameters of hot dip galvanizing include:
the temperature of the zinc pot and the temperature of the cooling tower top; wherein the temperature of the zinc entering pot is 440-460 ℃, and the temperature of the cooling tower top is 170-250 ℃.
In the embodiment of the application, the temperature of the zinc pot is controlled to be 440-460 ℃, and the temperature of the cooling tower top is controlled to be 170-250 ℃, which has the positive effects that: the temperature of the zinc pot is used for controlling the coating quality of the strip steel, when the temperature is too low, dezincification and plating omission defects are generated, and when the temperature is too high, zinc slag is generated. The temperature of the top of the cooling tower controls the final cooling speed of the strip steel, and the content of fresh martensite in the structure is regulated and controlled. When the temperature is too low, more fresh martensite appears in the tissue, so that the tensile strength is increased, and the hole expansion rate is reduced; when the content of fresh martensite is too high, the tensile strength is lowered. Specifically, the temperature of the zinc pot can be 440 ℃, 450 ℃, 460 ℃ and the like, and the temperature of the cooling tower top can be 170 ℃, 190 ℃, 210 ℃, 230 ℃, 250 ℃ and the like.
In some embodiments, the finished product has an elongation of 0.1 to 0.7%.
In the embodiment of the application, the positive effect of controlling the elongation of the finishing to be 0.1-0.7 percent is that: and the strip steel is regulated and controlled to obtain proper yield strength and roughness, and the surface quality of the strip steel is improved. A finishing elongation of less than 0.1% can cause insufficient surface roughness of the strip steel, affecting subsequent stamping performance; the yield strength is improved due to the excessively high, and the stamping is easy to rebound. Specifically, the elongation of the finishing may be 0.1%, 0.3%, 0.5%, 0.7%, or the like.
By the method provided by the embodiment of the application, the hot dip galvanized high-strength steel with tensile strength of over 980MPa, yield strength of over 600MPa, elongation of over 11% at the gauge length of 80mm and hole expansion rate of over 30% is obtained, the forming performance is improved, and the stamping cracking is improved.
In a second aspect, the application provides a hot dip galvanized steel prepared by a method according to any one of the embodiments of the first aspect.
The hot dip galvanized steel is realized based on the preparation method of the hot dip galvanized steel, and specific steps of the hot dip galvanized steel can refer to the embodiment, and as the preparation method of the hot dip galvanized steel adopts part or all of the technical schemes of the embodiment, the hot dip galvanized steel has at least all the beneficial effects brought by the technical schemes of the embodiment, and the detailed description is omitted.
The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.
The application provides a preparation method of hot dip galvanized steel, which comprises the following steps:
s1, annealing a cold-rolled steel coil with set chemical components, and controlling annealing process parameters; the annealing comprises an aging section, and the cold-rolled steel coil is subjected to heating treatment in the aging section.
S2, hot galvanizing the annealed cold rolled steel coil, and finishing to obtain hot galvanized steel. Specific process parameters are shown in the examples below
Example 1
The specification of the cold-rolled steel coil is 1.3mm multiplied by 1060mm, and the weight percentage of the steel coil components is as follows: c:0.11%, mn:2.3%, si:0.3%, P:0.01%, S:0.002%, al:0.04%, mo:0.1%, cr:0.4%, nb:0.02%, ti:0.02% >. Annealing temperature 813 ℃, slow cooling temperature 714 ℃, quick cooling temperature 321 ℃, hydrogen content 58%, aging temperature 327 ℃, running speed 80, number of induction heaters 3, induction heater power 897KW, 314KW, 294KW, induction heater heating strip steel 6 ℃, pan temperature 448 ℃, overhead temperature 191 ℃ and finishing elongation 0.16%.
Mechanical properties: the tensile strength is 1010MPa, the yield strength is 655MPa, the elongation at gauge length is 13 of 80mm, and the hole expansion rate is 33%.
Example 2
The specification of the cold-rolled steel coil is 1.4mm multiplied by 990mm, and the weight percentage of the steel coil components is as follows: c:0.12%, mn:2.2%, si:0.33%, P:0.01%, S:0.002%, al:0.04%, mo:0.09%, cr:0.41%, nb:0.02%, ti:0.02% >. Annealing temperature 819 ℃, slow cooling temperature 709 ℃, quick cooling temperature 325 ℃, hydrogen content 56%, aging temperature 330 ℃, running speed 79m/min, induction heater number 3, induction heater power 911KW, 297KW, 301KW, induction heater to heat strip steel 5 ℃, entering boiler temperature 451 ℃, tower top temperature 187 ℃ and finishing elongation 0.61%.
Mechanical properties: tensile strength 1020MPa, yield strength 744MPa, elongation 12% at gauge length 80mm and hole expansion ratio 41%.
Example 3
The specification of the cold-rolled steel coil is 1.5mm multiplied by 1075mm, and the weight percentage of the components of the steel coil is as follows: c:0.13%, mn:2.3%, si:0.35, P:0.01%, S:0.002%, al:0.04%, mo:0.11%, cr:0.42%, nb: nb:0.021%, ti:0.025%. Annealing temperature 824 ℃, slow cooling temperature 727 ℃, quick cooling temperature 300 ℃, hydrogen content 58%, aging temperature 324 ℃, running speed 80m/min, induction heater number 3, induction heater power 1003KW, 347KW, 255KW, induction heater heating strip steel 45 ℃, pan feeding temperature 447 ℃, tower top temperature 182 ℃ and finishing elongation 0.13%.
Mechanical properties: the tensile strength is 1030MPa, the yield strength is 879MPa, the elongation at the gauge length is 80mm is 12.5%, and the reaming ratio is 59%.
Example 4
The specification of the cold-rolled steel coil is 2.0mm multiplied by 960mm, and the weight percentage of the steel coil components is as follows: c:0.12%, mn:2.2%, si:0.35, P:0.01%, S:0.002%, al:0.04%, mo:0.1%, cr:0.42%, nb:0.022%, ti:0.024%. Annealing temperature 800 ℃, slow cooling temperature 670 ℃, quick cooling temperature 310 ℃, hydrogen content 53%, aging temperature 324 ℃, running speed 75m/min, induction heater quantity 2, induction heater power 925KW, 378KW, induction heater heating strip steel 14 ℃, pan temperature 440 ℃, tower top temperature 170 ℃ and finishing elongation 0.50%.
Mechanical properties: tensile strength 1020MPa, yield strength 776MPa, elongation 13% at gauge length 80mm and hole expansion 36%.
Example 5
The specification of the cold-rolled steel coil is 2.2mm multiplied by 1073mm, and the weight percentage of the steel coil components is as follows: c:0.11%, mn:2.4%, si:0.39, P:0.009%, S:0.0021%, al:0.045%, mo:0.08%, cr:0.45%, nb:0.023%, ti:0.023%. Annealing temperature 870 ℃, slow cooling temperature 730 ℃, quick cooling temperature 310 ℃, hydrogen content 75%, aging temperature 350 ℃, running speed 95m/min, induction heater number (2, induction heater power 1156KW, 422KW, 204KW, induction heater heating band steel 40 ℃, entering pot temperature 460 ℃, tower top temperature 250 ℃ and finishing elongation 0.7%).
Mechanical properties: tensile strength 1100MPa, yield strength 834MPa, elongation 11% at gauge length 80mm and hole expansion 34%.
Comparative example 1
The specification of the cold-rolled steel coil of the comparative example is 1.5mm multiplied by 1070mm, and the weight percentage of the steel coil components is as follows: c:0.13%, mn:2.3%, si:0.35, P:0.01%, S:0.002%, al:0.04%, mo:0.11%, cr:0.42%, nb:0.021%, ti:0.025%. Annealing temperature 790 ℃, slow cooling temperature 701 ℃, quick cooling temperature 300 ℃, hydrogen content 59%, aging temperature 324 ℃, running speed 80m/min, induction heater number 3, induction heater power 1013KW, 325KW, 258KW, induction heater heating strip steel 24 ℃, pan temperature 456 ℃, tower top temperature 185 ℃, finishing elongation 0.14%.
Mechanical properties: tensile strength 972MPa, yield strength 551MPa, elongation at gauge length 80mm 13% and hole expansion rate 14%.
According to the method disclosed by the embodiment of the application, referring to the hot dip galvanized high-strength steel prepared in the embodiments 1-5, the hot dip galvanized high-strength steel with the tensile strength of more than 980MPa, the yield strength of more than 600MPa, the elongation of more than 11% at the gauge length of 80mm and the hole expansion rate of more than 30% is obtained, the forming performance is improved, and the stamping cracking is improved. Referring to the surface quality chart of a hot dip galvanized steel provided in example 2 shown in fig. 2, it is shown that the surface quality of the steel sheet is excellent; referring to the surface chart of the hot dip galvanized steel after the reaming experiment, which is shown in the embodiment 2 in fig. 3, the reaming performance of the steel plate is excellent. In comparative example 1, however, the mechanical properties of the hot-dip galvanized high-strength steel are not satisfactory by changing the annealing temperature.
The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A method of preparing a hot dip galvanized steel, the method comprising:
annealing the cold-rolled steel coil with the set chemical composition, and controlling the annealing process parameters; the annealing comprises an aging section, and the cold-rolled steel coil is subjected to heating treatment in the aging section;
and hot galvanizing the annealed cold rolled steel coil, and finishing to obtain hot galvanized steel.
2. The method of claim 1, wherein the process parameters of the annealing include:
annealing temperature, slow cooling temperature, quick cooling temperature, aging temperature, annealing atmosphere and strip steel running speed.
3. The method of claim 2, wherein the annealing temperature is 800-870 ℃, the slow cooling temperature is 670-730 ℃, the rapid cooling temperature is 300-360 ℃, and the aging temperature is 300-360 ℃.
4. The method of claim 2, wherein the annealing atmosphere comprises: hydrogen, the content of the hydrogen is 50-75%.
5. The method of claim 2, wherein the strip is run at a speed of 75-100m/min.
6. The method of claim 1, wherein the heat treatment comprises:
1-3 induction heaters are arranged, and the power of the induction heaters is 200-1700 KW/one.
7. The method of claim 1, wherein the setting the chemical composition comprises:
C. mn, si, al, P, S, mo, nb, ti and Fe; wherein, the weight percentage is calculated,
the alloy comprises 0.1-0.2% of C, 2-2.5% of Mn, 0.2-0.5% of Si, 0.02-0.07% of Al, less than or equal to 0.02% of P, less than or equal to 0.002% of S, 0.05-0.3% of Mo, 0.02-0.07% of Nb and 0.02-0.07% of Ti.
8. The method of claim 1, wherein the process parameters of hot dip galvanizing include:
the temperature of the zinc pot and the temperature of the cooling tower top; wherein the temperature of the zinc entering pot is 440-460 ℃, and the temperature of the cooling tower top is 170-250 ℃.
9. The method of claim 1, wherein the finish has an elongation of 0.1-0.7%.
10. A hot dip galvanized steel, characterized in that it is produced by the method according to any one of claims 1 to 9.
CN202310915893.1A 2023-07-25 2023-07-25 Hot dip galvanized steel and preparation method thereof Pending CN116987848A (en)

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