CN115404326A - Production method of hot-dip galvanized steel plate - Google Patents

Production method of hot-dip galvanized steel plate Download PDF

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Publication number
CN115404326A
CN115404326A CN202211149058.3A CN202211149058A CN115404326A CN 115404326 A CN115404326 A CN 115404326A CN 202211149058 A CN202211149058 A CN 202211149058A CN 115404326 A CN115404326 A CN 115404326A
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hot
rolling
steel
cooling
temperature
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王敏莉
郑之旺
陈容
靳阳
周伟
郑昊青
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Pangang Group Research Institute Co Ltd
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Pangang Group Research Institute Co Ltd
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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
    • 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
    • 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
    • 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
    • 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
    • C21D8/0236—Cold 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
    • C21D8/0247—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
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • 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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  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Heat Treatment Of Sheet Steel (AREA)
  • Coating With Molten Metal (AREA)

Abstract

The invention discloses a production method of a hot-dip galvanized steel sheet, which comprises the following steps: desulfurizing molten iron, smelting, alloying, and casting into a blank; heating, rough rolling, finish rolling and cooling the continuous casting billet, and then coiling to obtain a hot rolled coil; cold rolling the hot rolled coil to obtain a cold rolled coil; continuously annealing and hot-galvanizing the cold-rolled coil, controlling the running speed of the continuously annealed strip steel to be 100-150 m/min, controlling the soaking temperature of hot-galvanizing annealing to be 810-840 ℃, controlling the cooling end point temperature to be 440-470 ℃, controlling the temperature of a zinc pot to be 460-470 ℃, and taking the strip steel out of the zinc pot to carry out rapid cooling on the galvanized steel sheet. The method realizes the production of high-strength hot-dip galvanized steel sheets on a conventional hot-dip galvanizing unit, the yield strength of the mechanical property of the finished product can reach 440-470 MPa, the tensile strength reaches 490-520 MPa, the elongation is more than or equal to 30.0%, the mechanical property meets the requirement, and meanwhile, the surface coating has a compact structure and strong coating adhesion.

Description

Production method of hot-dip galvanized steel plate
Technical Field
The invention belongs to the technical field of steel production, and particularly relates to a production method of a hot-dip galvanized steel plate.
Background
The high-strength hot-dip galvanized sheet can improve the strength of parts, reduce the weight of the parts and reduce the cost. With the vigorous development of electric power, traffic, communication, energy and city infrastructure in China and the start of the market of construction steel structures, high-strength hot-dip galvanized steel faces unprecedented opportunities and huge markets. With the trend of users pursuing maintenance of service performance and reduction of cost, demand for high-strength hot-dip galvanized steel sheets is more urgent.
At present, the main means for improving the strength of a steel plate matrix is to add alloy elements into the steel plate to strengthen the matrix. However, in the case of hot-dip galvanized steel sheets, there is a contradiction between the addition of alloying elements and the platability of the steel sheets, and particularly when hot working and the galvanization process are not properly controlled, the adhesion of the plated layer is reduced and the surface quality is deteriorated.
Therefore, how to obtain a galvanized steel sheet with high strength and excellent surface quality is an urgent technical problem to be solved in the field of production of galvanized steel sheets.
Disclosure of Invention
In order to solve one of the prior technical problems, the invention provides a production method of a hot-dip galvanized steel plate. The method realizes the production of high-strength hot-dip galvanized steel sheets on a conventional hot-dip galvanizing unit, the yield strength of the mechanical property of the finished product can reach 440-470 MPa, the tensile strength reaches 490-520 MPa, the elongation is more than or equal to 30.0%, the mechanical property meets the requirement, and meanwhile, the surface coating has a compact structure and strong coating adhesion.
According to the invention, the production method of the hot dip galvanized steel sheet comprises the following steps:
step 1): molten iron is desulfurized, smelted and alloyed, wherein the steel components are controlled according to the following weight percentages: c:0.050 to 0.10%, si:0.050 to 0.150%, mn:0.60 to 1.10%, P: less than or equal to 0.020%, S: less than or equal to 0.012%, nb:0.02 to 0.05 percent, ti:0.01 to 0.05%, als:0.020 to 0.070 percent, and the balance of Fe and inevitable impurities;
step 2): carrying out continuous casting on the molten steel with up-to-standard components to prepare a continuous casting blank;
and step 3): heating the continuous casting billet and carrying out multi-pass rough rolling to obtain an intermediate plate blank with a preset thickness;
step 4): carrying out finish rolling on the intermediate plate blank to obtain a hot rolled plate with required thickness;
step 5): cooling the hot rolled plate and then curling to obtain a hot rolled coil;
step 6): cold rolling the hot rolled coil to a predetermined thickness to obtain a cold rolled sheet;
step 7): continuously annealing and hot galvanizing the cold-rolled sheet, controlling the running speed of the continuously annealed strip steel to be 100-150 m/min, controlling the soaking temperature of hot galvanizing annealing to be 810-840 ℃, controlling the cooling end point temperature to be 440-470 ℃, controlling the temperature of a zinc pot to be 460-470 ℃, and taking the strip steel out of the zinc pot to carry out rapid cooling on the galvanized steel sheet.
According to one embodiment of the invention, the heating and rough rolling in the step 3) comprises the steps of heating the continuous casting blank to 1210-1270 ℃, performing rough rolling for 230-280 min, performing full-length complete scale removal, and applying a heat-insulating cover in the rolling process.
According to an embodiment of the invention, the multi-pass rough rolling is more than 3 passes.
According to one embodiment of the invention, the thickness of the intermediate slab in step 3) is 30 to 34mm.
According to an embodiment of the invention, the start rolling temperature of the finish rolling in the step 4) is 1160-1190 ℃, the finish rolling temperature is 840-890 ℃, and the thickness of the hot rolled plate after the finish rolling is 2.5mm.
According to one embodiment of the invention, the cooling in the step 5) adopts laminar front-end cooling.
According to one embodiment of the invention, the curling temperature in step 5) is 530-570 ℃.
According to one embodiment of the invention, the cold rolling reduction in step 6) is 70 to 80%.
According to one embodiment of the invention, the withdrawal and straightening elongation in step 7) is controlled to be 0.2 to 0.5 percent, and the finishing elongation is controlled to be 0.2 to 0.8 percent.
According to one embodiment of the invention, the cooling rate of the rapid cooling in step 7) is controlled to be 25-45 ℃/s.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages:
the method realizes the production of high-strength hot-dip galvanized steel sheets on a conventional hot-dip galvanizing machine set, the mechanical property yield strength of finished products can reach 440-470 MPa, the tensile strength reaches 490-520 MPa, the elongation is more than or equal to 30.0%, the mechanical property meets the requirements, the surface coating layer has a compact structure, the occupied area ratio of holes is less than or equal to 5%, and the coating layer has strong adhesion.
Drawings
Fig. 1 is a flowchart of a method for manufacturing a galvanized steel sheet according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a production method of a hot-dip galvanized steel sheet. As shown in fig. 1, the method generally comprises a number of steps described below.
Step S1: molten iron desulphurization, smelting and alloying treatment
Controlling the steel components according to the following weight percentages: c:0.050 to 0.10%, si:0.050 to 0.150%, mn:0.60 to 1.10%, P: less than or equal to 0.020%, S: less than or equal to 0.012%, nb:0.02 to 0.05%, ti:0.01 to 0.05%, als:0.020 to 0.070 percent, and the balance of Fe and inevitable impurities.
C is the traditional strengthening element of steel and is also the most economic element. Increasing the C content increases the pearlite quantity and increases the strength and hardness of the steel. However, the C content in steel has a significant influence on hot dip galvanizing, and as the C content increases, the iron-zinc reaction becomes more and more severe, the mass loss of iron becomes large, the substrate of steel reacts more and more violently, and at this time, the iron-zinc alloy layer becomes thick, and the adhesiveness of the galvanized layer deteriorates. Therefore, controlling the C content within an appropriate range can improve the adhesiveness of the zinc plating layer. Therefore, the C content is controlled to 0.050 to 0.10% in the present application.
The solid solution strengthening effect of Si on steel is obvious, but the harmful effect of Si on continuous hot galvanizing is very obvious. The influence of Si in a steel matrix on hot galvanizing is mainly determined by SiO 2 When the steel sheet is subjected to recrystallization annealing in a continuous annealing furnace, si enrichment and SiO formation on the strip surface may be caused 2 . Therefore, the steel strip for hot dip galvanizing is required to have as low Si content as possible. Therefore, the Si content is controlled to 0.050 to 0.150% in the present application.
Mn and Fe are mutually dissolved in the middle of the steel to form a solid solution, and the solid solution has an obvious effect on improving the strength. Mn can also play a role in reducing the phase transition temperature and is beneficial to fine grain strengthening. However, if the Mn content is too high, the toughness of the matrix is lowered, and the steel plate has a band-shaped structure, which significantly increases the anisotropy. Further, too high Mn content may adversely affect the zinc layer adhesion of the galvanized sheet. In the present application, the Mn content is controlled to 0.60 to 1.10%.
Nb forms a solid solution with Fe in the middle of steel, can prevent austenite grains from growing in the heating crystallization process, and can precipitate niobium carbide on dislocation, subboundary and grain boundary in the rolling process to prevent austenite from dynamically recrystallizing. Therefore, the addition of Nb is advantageous for refining the crystal grains. However, the cost of Nb is high, and the amount of Nb should be controlled appropriately to reduce the cost. In the present application, the content of Nb is controlled to 0.02 to 0.05%.
Ti may form a titanium carbide compound with C in the steel. During heating, undissolved titanium carbide particles are distributed at the austenite grain boundaries, which can hinder the growth of austenite grains during heating of the steel before hot working. Furthermore, addition of Ti to Nb-containing steel can further improve the solid solubility of Nb in the austenitic state, and exhibit grain refinement and precipitation strengthening effects of Nb. In addition, the addition of Ti fixes C, which has important effect on the anti-aging of steel. In the present application, the content of Ti is controlled to 0.01 to 0.05%.
S is a harmful element in steel, and FeS can be formed in the steel to influence the quality of the steel plate. Therefore, in the present application, the S content is controlled to 0.012% or less.
P can reduce the plasticity and toughness of steel and influence the welding performance. If the content of P is too high, P is dissolved in ferrite, so that the strength of the steel is increased, the toughness is reduced rapidly, and the service performance is influenced. The P content in the steel is therefore reduced as much as possible. In the present application, the P content is controlled to 0.020% or less.
A1 is added as a deoxidizer, and the deoxidizer has the function of removing oxygen in molten steel, so that the low-temperature plasticity can be improved, and slip lines can be prevented from being generated in the machining process. In the application, the content of A1s is controlled to be 0.020-0.070%.
Step S2: continuously casting molten steel with up-to-standard components to prepare continuous casting billets
Specifically, molten iron is refined and then is continuously cast to obtain a continuous casting billet, and the content of C and Si is carefully controlled in the refining process.
And step S3: heating the continuous casting blank and carrying out multi-pass rough rolling to obtain an intermediate plate blank with a preset thickness
Various parameters of the hot rolling process have a significant influence on the type, composition, quantity and particle size distribution of precipitated phases. The hot rolling process needs to be determined in conjunction with the composition of the steel, and the proper hot rolling process is designed to obtain uniform and fine grains and uniformly distributed dispersed phases. For this purpose, the hot rolling according to the invention is first of all carried out using a multi-pass rough rolling. Specifically, the continuous casting blank can be heated to 1210-1270 ℃, the furnace time is controlled to be 230-280 min, and the rough rolling is carried out for more than 3 times, preferably 5 times. The niobium-containing high-strength steel can be subjected to multi-pass rough rolling in an austenite recrystallization region, and austenite grains are refined by utilizing the dynamic deformation and dynamic recrystallization of austenite in the temperature region. The whole length is descaled, and a heat-insulating cover is used in the rolling process. The thickness of the intermediate slab is 30-34 mm.
The surface ecological pickling technology is preferably adopted for descaling. The technology adopts a method of spraying abrasive to remove scales on the surface of a hot-rolled plate. The traditional acid-washing descaling method has long production process, and the emission of waste acid can have adverse effect on the environment.
And step S4: finish rolling the intermediate plate blank to obtain a hot rolled plate with required thickness
The initial rolling temperature of the finish rolling is 1160-1190 ℃, the final rolling temperature is 840-890 ℃, and the thickness of the hot rolled plate after the finish rolling is 2.5mm. And (3) performing multi-pass finish rolling in an austenite non-recrystallization zone to obtain deformed austenite, and matching with a proper cooling speed and coiling temperature to obtain a hot rolled plate with fine tissue and second phase dispersed distribution. This treatment allows to obtain a better surface quality, ready for obtaining a cold-rolled sheet of high quality.
Step S5: cooling the hot rolled plate and then curling to obtain a hot rolled coil
After finish rolling, adopting laminar flow type front-stage cooling mode to cool to 530-570 ℃ for coiling. The high and low coiling temperature directly affects the precipitation of dispersed phases and the shape, size and distribution of precipitates. The high coiling temperature can cause the coarsening of the crystal grains of the dispersed phase, the distribution of the dispersed phase becomes more and more sparse, and the size of the dispersed phase also becomes more and more large, thus being not beneficial to the dispersion strengthening of the steel. Therefore, the coiling temperature of the hot dip galvanized steel sheet containing the components of the present invention is controlled to 530 to 570 ℃, so that the dispersed phase with uniform distribution and small size can be obtained more favorably.
Step S6: cold rolling the hot rolled coil to a predetermined thickness to obtain a cold rolled sheet
Specifically, after the hot rolled plate is washed clean by alkali, the cold rolling reduction is determined to be 70-80% by combining the capacity of a cold rolling mill. Among them, a cleaning agent generally used in the art can be used for the alkali cleaning. The properties of cold rolled sheet are decisive for the final properties of the galvanized sheet. The biggest influence on the galvanized sheet in the cold rolling process is the cold rolling compression ratio which is too small, and the ferrite deformation in the microstructure of the sheet is not enough, so that the final galvanized product has lower strength; the cold rolling compression ratio is too large, so that the hardness and yield ratio of galvanized products are too high, and the secondary growth rate and formability of the galvanized sheets are not good.
Step S7: continuously annealing and hot galvanizing the cold-rolled sheet
The running speed of the continuous annealing strip steel is controlled to be 100-150 m/min, the soaking temperature of the hot galvanizing annealing is 810-840 ℃, the cooling end point temperature is controlled to be 440-470 ℃, the temperature of the zinc pot is controlled to be 460-470 ℃, and the strip steel is taken out of the zinc pot to carry out rapid cooling on the galvanized steel sheet.
In the cold rolling process, the steel plate is subjected to plastic deformation under the action of rolling force, and the hot rolling equiaxial grain structure is subjected to grain extension, distortion and crushing. Plastic deformation causes work hardening, which is not suitable for work forming, and recrystallization annealing is necessary to recover the plasticity of the cold rolled steel sheet. Since the steel is strengthened by adding alloying elements such as Nb and Ti, the temperature of the continuous annealing is suitably increased. In order to prevent grain growth and reduce the strength of the steel, the continuous annealing time should be shortened. Controlling the continuous annealing time at 80-100 seconds, cooling to 700-740 ℃ at the speed of 5-12 ℃/s, and then cooling to 460-470 ℃ at the speed of 20-40 ℃/s to obtain the strip steel.
And hot galvanizing the annealed strip steel through a zinc pot at the speed of 100-150 m/min, and controlling the temperature of the zinc pot at 460-470 ℃. And (4) discharging the galvanized steel sheet from the zinc pot, and rapidly cooling the galvanized steel sheet at the cooling speed of 25-45 ℃/s. The rapid cooling after the hot galvanizing unit is hot-plated out of a zinc pot is utilized, so that the zinc liquid adhered to the surface of the steel plate can be rapidly solidified, the nucleation rate is increased, and the initial pure zinc coating structure with smaller grain size, uniform size distribution and compact coating structure is obtained.
And then, the galvanized strip steel is subjected to finishing by a finishing machine and then is curled into a finished product. Wherein the stretch-leveling elongation is controlled to be 0.2-0.5%, and the finishing elongation is controlled to be 0.2-0.8%.
The invention can produce high-strength galvanized sheet with excellent surface quality by adjusting the addition of C, mn, nb and Ti elements and strictly controlling Si content and rolling, continuous annealing and hot galvanizing processes.
The following is a specific example of the method for producing thick ultra-deep drawing galvanized steel sheet according to the present invention. Unless otherwise indicated, raw materials, equipment, consumables and the like used in the following examples are available by conventional commercial means.
For the part relating to the numerical range, the skilled person can select any value in the numerical range defined by the present invention according to the actual needs, and the value is not limited to the value listed in the specific embodiment.
Example 1
Step 1: and desulfurizing molten iron, smelting and alloying. Wherein the steel components are controlled according to the following weight percentages: c:0.08%, si:0.110%, mn:0.89%, P:0.015%, S:0.009%, nb:0.025%, ti:0.015%, als:0.032%, and the balance Fe and unavoidable impurities.
Step 2: and continuously casting the molten steel with up-to-standard components to prepare a continuous casting billet.
And step 3: the continuous casting billet is heated to 1229 ℃ and the furnace time is controlled to be 260min. The intermediate slab was roughly rolled in 4 passes to obtain an intermediate slab having a thickness of 34mm. The whole scale is removed in the whole length, and a heat preservation cover is used in the rolling process.
And 4, step 4: and (3) carrying out finish rolling on the intermediate plate blank, wherein the start rolling temperature of the finish rolling is 1165 ℃, and the finish rolling temperature is 865 ℃, so that a hot rolled plate with the thickness of 2.5mm is obtained.
And 5: and after finish rolling, cooling to 548 ℃ by adopting a laminar flow type front-stage cooling mode, and coiling to obtain a hot rolled coil.
And 6: and (3) after the hot rolled sheet is washed clean by alkali, cold rolling treatment is carried out to obtain the cold rolled sheet, wherein the cold rolling reduction rate is determined to be 80% by combining the capability of a cold rolling mill.
And 7: and carrying out continuous annealing and hot galvanizing treatment on the cold-rolled sheet. The running speed of the continuous annealing strip steel is controlled at 150m/min, the soaking temperature of the hot galvanizing annealing is 816 ℃, the annealing time is controlled at about 80s, and then the strip steel is cooled to 740 ℃ at the speed of 12 ℃/s and then to 464 ℃ at the speed of 40 ℃/s to obtain the strip steel. And (3) hot galvanizing the annealed strip steel through a zinc pot at the speed of 150m/min, controlling the temperature of the zinc pot at 465 ℃, taking the strip steel out of the zinc pot to rapidly cool the galvanized steel sheet, and controlling the cooling speed at 45 ℃/s. And then, the galvanized strip steel is subjected to finishing by a finishing machine, the finishing elongation is 0.3 percent, the withdrawal and straightening elongation is controlled to be 0.26 percent, and then the strip steel is curled into a finished product.
Example 2
Step 1: and desulfurizing molten iron, smelting and alloying. Wherein the steel components are controlled according to the following weight percentages: c:0.07%, si:0.120%, mn:0.90%, P:0.020%, S:0.008%, nb:0.028%, ti:0.018%, als:0.049%, and the balance of Fe and unavoidable impurities.
Step 2: and continuously casting the molten steel with up-to-standard components to prepare a continuous casting billet.
And 3, step 3: the continuous casting billet is heated to 1225 ℃, and the furnace time is controlled to be 230min. And 5-pass rough rolling is carried out to obtain an intermediate plate blank with the thickness of 32 mm. The whole scale is removed in the whole length, and a heat preservation cover is used in the rolling process.
And 4, step 4: and (3) carrying out finish rolling on the intermediate plate blank, wherein the start rolling temperature of the finish rolling is 1155 ℃, and the finish rolling temperature is 882 ℃, so that a hot rolled plate with the thickness of 2.5mm is obtained.
And 5: after finish rolling, cooling to 550 ℃ by adopting a laminar flow type front-stage cooling mode, and coiling to obtain a hot-rolled coil.
And 6: and (3) cleaning the hot rolled sheet by alkali, determining the cold rolling reduction rate to be 75% by combining the capacity of a cold rolling mill, and performing cold rolling treatment to obtain the cold rolled sheet.
And 7: and carrying out continuous annealing and hot galvanizing treatment on the cold-rolled sheet. The running speed of the continuous annealing band steel is controlled at 130m/min, the soaking temperature of the hot galvanizing annealing is 815 ℃, the annealing time is controlled at about 90s, and then the band steel is cooled to 720 ℃ at the speed of 13 ℃/s and then cooled to 465 ℃ at the speed of 35 ℃/s to obtain the band steel. And (3) hot galvanizing the annealed strip steel through a zinc pot at the speed of 130m/min, controlling the temperature of the zinc pot at 460 ℃, taking the strip steel out of the zinc pot to rapidly cool the galvanized steel plate, and controlling the cooling speed at 35 ℃/s. And then, the galvanized strip steel is subjected to finishing by a finishing machine, the finishing elongation is 0.55 percent, the withdrawal and straightening elongation is controlled to be 0.25 percent, and then the strip steel is curled into a finished product.
Example 3
Step 1: and desulfurizing, smelting and alloying the molten iron. Wherein the steel components are controlled according to the following weight percentages: c:0.09%, si:0.10%, mn:0.92%, P:0.014%, S:0.007%, nb:0.024%, ti:0.020%, als:0.042%, and the balance of Fe and inevitable impurities.
Step 2: and continuously casting the molten steel with up-to-standard components to prepare a continuous casting billet.
And 3, step 3: heating the continuous casting slab to 1223 ℃, and controlling the furnace time to be 200min. And 5 times of rough rolling is carried out to obtain an intermediate plate blank with the thickness of 30 mm. The whole length is descaled, and a heat-insulating cover is used in the rolling process.
And 4, step 4: and (3) carrying out finish rolling on the intermediate plate blank, wherein the start rolling temperature of the finish rolling is 1156 ℃, and the finish rolling temperature is 866 ℃, so that a hot rolled plate with the thickness of 2.5mm is obtained.
And 5: after finish rolling, the steel is cooled to 552 ℃ by adopting a laminar front-end cooling mode and coiled to obtain a hot-rolled coil.
Step 6: and (3) cleaning the hot rolled sheet by alkali, determining the cold rolling reduction rate to be 70% by combining the capacity of a cold rolling mill, and performing cold rolling treatment to obtain the cold rolled sheet.
And 7: and carrying out continuous annealing and hot galvanizing treatment on the cold-rolled sheet. The running speed of the continuous annealing strip steel is controlled at 100m/min, the soaking temperature of the hot galvanizing annealing is 818 ℃, the annealing time is controlled at about 90s, then the strip steel is cooled to 730 ℃ at the speed of 12 ℃/s and then is cooled to 460 ℃ at the speed of 38 ℃/s, and the strip steel is obtained. And (3) carrying out hot galvanizing on the annealed strip steel through a zinc pot at the speed of 100m/min, controlling the temperature of the zinc pot at 462 ℃, taking the strip steel out of the zinc pot, and carrying out rapid cooling on the galvanized steel sheet at the cooling speed of 35 ℃/s. And then, the galvanized strip steel is subjected to finishing by a finishing machine, the finishing elongation is 0.68 percent, the withdrawal and straightening elongation is 0.26 percent, and then the strip steel is curled into a finished product.
Comparative example 1
Step 1: and desulfurizing, smelting and alloying the molten iron. Wherein the steel components are controlled according to the following weight percentages: c:0.09%, si:0.26%, mn:0.95%, P:0.015%, S:0.015%, als:0.052 percent, and the balance of Fe and inevitable impurities.
Step 2: and continuously casting the molten steel with up-to-standard components to prepare a continuous casting billet.
And step 3: heating the continuous casting slab to 1220 ℃, and controlling the in-furnace time to be 260min. And carrying out 2-pass rough rolling to obtain an intermediate plate blank with the thickness of 36 mm. The whole length is descaled, and a heat-insulating cover is used in the rolling process.
And 4, step 4: and (3) carrying out finish rolling on the intermediate plate blank, wherein the start rolling temperature of the finish rolling is 1290 ℃, and the finish rolling temperature is 980 ℃, so that a hot rolled plate with the thickness of 2.5mm is obtained.
And 5: after finish rolling, adopting a laminar flow front-end cooling mode to cool to 670 ℃ for coiling, and obtaining a hot rolled coil.
And 6: and (3) after the hot rolled sheet is washed clean by alkali, performing cold rolling treatment to obtain the cold rolled sheet after the cold rolling reduction is determined to be 60% by combining the capacity of a cold rolling mill.
And 7: and carrying out continuous annealing and hot galvanizing treatment on the cold-rolled sheet. The running speed of the continuously annealed strip steel is controlled at 150m/min, the soaking temperature of the hot galvanizing annealing is 840 ℃, the annealing time is controlled at about 80s, then the strip steel is cooled to 740 ℃ at the speed of 12 ℃/s and then cooled to 470 ℃ at the speed of 20 ℃/s to obtain the strip steel. And (3) hot galvanizing the annealed strip steel through a zinc pot at the speed of 150m/min, controlling the temperature of the zinc pot at 430 ℃, and slowly cooling the galvanized steel plate after being taken out of the zinc pot. And then, the galvanized strip steel is subjected to finishing by a finishing machine, the finishing elongation is 0.8%, and then the strip steel is curled into a finished product.
Comparative example 2
Step 1: and desulfurizing, smelting and alloying the molten iron. Wherein the steel components are controlled according to the following weight percentages: c:0.09%, si:0.26%, mn:0.98%, P:0.015%, S:0.015%, nb:0.037%, als:0.052 percent, and the balance of Fe and inevitable impurities.
And 2, step: and continuously casting the molten steel with up-to-standard components to prepare a continuous casting billet.
And step 3: heating the continuous casting slab to 1229 ℃, and controlling the furnace time to be 260min. The intermediate slab was roughly rolled in 4 passes to obtain an intermediate slab having a thickness of 34mm. The whole scale is removed in the whole length, and a heat preservation cover is used in the rolling process.
And 4, step 4: and (3) carrying out finish rolling on the intermediate plate blank, wherein the start rolling temperature of the finish rolling is 1165 ℃, and the finish rolling temperature is 865 ℃, so that a hot rolled plate with the thickness of 2.5mm is obtained.
And 5: and after finish rolling, cooling to 648 ℃ by adopting a laminar flow type front-stage cooling mode, and coiling to obtain a hot-rolled coil.
Step 6: and (3) cleaning the hot rolled sheet by alkali, determining the cold rolling reduction rate to be 50% by combining the capacity of a cold rolling mill, and performing cold rolling treatment to obtain the cold rolled sheet.
And 7: and carrying out continuous annealing and hot galvanizing treatment on the cold-rolled sheet. The running speed of the continuous annealing strip steel is controlled at 150m/min, the soaking temperature of the hot galvanizing annealing is 816 ℃, the annealing time is controlled at about 80s, and then the strip steel is cooled to 740 ℃ at the speed of 12 ℃/s and then to 464 ℃ at the speed of 40 ℃/s to obtain the strip steel. And (3) hot galvanizing the annealed strip steel through a zinc pot at the speed of 150m/min, controlling the temperature of the zinc pot at 465 ℃, and slowly cooling the galvanized steel plate after being taken out of the zinc pot. And then, the galvanized strip steel is subjected to finishing by a finishing machine, the finishing elongation is 0.3 percent, the withdrawal and straightening elongation is controlled to be 0.26 percent, and then the strip steel is curled into a finished product.
The mechanical properties of the hot-dip galvanized steel sheet prepared by the process are shown in the following table 4.
TABLE 4 mechanical properties of hot-dip galvanized steel sheets
Figure BDA0003856085970000111
The production method of the hot-dip galvanized steel sheet realizes the production of the high-strength hot-dip galvanized steel sheet, the mechanical property yield strength of the finished product can reach 440-470 MPa, the tensile strength reaches 490-520 MPa, the elongation is more than or equal to 30.0 percent, the mechanical property meets the requirement, the surface coating layer has a compact structure, the occupied area ratio of holes is less than or equal to 5 percent, and the coating layer has strong adhesion.
The above examples only show the embodiments of the present invention, and the description thereof is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims (10)

1. A method for producing a hot-dip galvanized steel sheet, characterized by comprising the steps of:
step 1): molten iron is desulfurized, smelted and alloyed, wherein the steel components are controlled according to the following weight percentages: c:0.050 to 0.10%, si:0.050 to 0.150%, mn:0.60 to 1.10%, P: less than or equal to 0.020%, S: less than or equal to 0.012%, nb:0.02 to 0.05%, ti:0.01 to 0.05%, als:0.020 to 0.070 percent, and the balance of Fe and inevitable impurities;
step 2): continuously casting the molten steel with the standard composition to prepare a continuous casting billet;
and step 3): heating the continuous casting billet and carrying out multi-pass rough rolling to obtain an intermediate plate blank with a preset thickness;
step 4): performing finish rolling on the intermediate plate blank to obtain a hot rolled plate with required thickness;
and step 5): cooling the hot rolled plate and then curling to obtain a hot rolled coil;
step 6): cold rolling the hot rolled coil to a predetermined thickness to obtain a cold rolled sheet;
step 7): continuously annealing and hot galvanizing the cold-rolled sheet, controlling the running speed of the continuously annealed strip steel to be 100-150 m/min, controlling the soaking temperature of hot galvanizing annealing to be 810-840 ℃, controlling the cooling end point temperature to be 440-470 ℃, controlling the temperature of a zinc pot to be 460-470 ℃, and taking the strip steel out of the zinc pot to carry out rapid cooling on the galvanized steel sheet.
2. The method as claimed in claim 1, wherein the heating and rough rolling in step 3) comprises heating the continuous casting slab to 1210-1270 ℃ for 230-280 min, rough rolling, full-length descaling, and applying a heat-insulating cover during rolling.
3. The method of claim 1, wherein the multi-pass rough rolling is greater than 3 passes.
4. The method according to claim 1, wherein the thickness of the intermediate slab of step 3) is 30 to 34mm.
5. The method according to claim 1, wherein the finish rolling in step 4) is performed at a start rolling temperature of 1160 to 1190 ℃, a finish rolling temperature of 840 to 890 ℃, and a thickness of the hot rolled sheet after the finish rolling is 2.5mm.
6. The method of claim 1, wherein the cooling of step 5) is laminar front-end cooling.
7. The method as claimed in claim 1, wherein the curling temperature in the step 5) is 530 to 570 ℃.
8. The method as claimed in claim 1, wherein the cold rolling reduction in the step 6) is 70 to 80%.
9. The method as claimed in claim 1, wherein the withdrawal and straightening elongation is controlled to be 0.2 to 0.5% and the finishing elongation is controlled to be 0.2 to 0.8% in step 7).
10. The method as claimed in claim 1, wherein the cooling rate of the rapid cooling in step 7) is controlled to be 25-45 ℃/s.
CN202211149058.3A 2022-09-21 2022-09-21 Production method of hot-dip galvanized steel plate Pending CN115404326A (en)

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