CN114525448A - 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof - Google Patents

780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof Download PDF

Info

Publication number
CN114525448A
CN114525448A CN202210060467.XA CN202210060467A CN114525448A CN 114525448 A CN114525448 A CN 114525448A CN 202210060467 A CN202210060467 A CN 202210060467A CN 114525448 A CN114525448 A CN 114525448A
Authority
CN
China
Prior art keywords
phase steel
hot
steel
galvanized dual
percent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210060467.XA
Other languages
Chinese (zh)
Inventor
宋志超
张才华
韩健
于晓飞
武智猛
张玉杰
翟景阳
韩雄超
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Handan Iron and Steel Group Co Ltd
HBIS Co Ltd Handan Branch
Original Assignee
Handan Iron and Steel Group Co Ltd
HBIS Co Ltd Handan Branch
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Handan Iron and Steel Group Co Ltd, HBIS Co Ltd Handan Branch filed Critical Handan Iron and Steel Group Co Ltd
Priority to CN202210060467.XA priority Critical patent/CN114525448A/en
Publication of CN114525448A publication Critical patent/CN114525448A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D8/0221—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
    • 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
    • C22C38/06—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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • 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
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • 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
    • 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
    • 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
    • C21D2211/001—Austenite
    • 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

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

The invention provides 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and a preparation method thereof, wherein the dual-phase steel comprises the following chemical components in percentage by mass: c: 0.14% -0.18%, Si: 0.15-0.30%, Mn: 2.0% -2.3%, Al: 0.5-0.7%, P: less than or equal to 0.015 percent, Nb: 0.02 to 0.03%, Ti: 0.015-0.025%, Cr: 0.1-0.4%, B: 0.007 to 0.0015 percent, and the balance of Fe and inevitable impurity elements; the production method comprises the working procedures of converter smelting, hot rolling, acid pickling and cold rolling, annealing and hot galvanizing, wherein the hot rolling working procedure controls the heating temperature of a plate blank to 1180-1210 ℃, the heating time to 180-220min and the hot rolling coiling temperature to 500-550 ℃. The dual-phase steel provided by the invention has higher surface quality.

Description

780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof
Technical Field
The invention belongs to the field of manufacturing of high-strength steel for automobiles, and relates to 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and a manufacturing method thereof.
Background
With the higher and higher requirements of customers on the formability of the hot-dip galvanized dual-phase steel, the hot-dip galvanized dual-phase steel with improved formability is favored by the customers.
However, the current dual-phase steel with enhanced formability has the problem of surface quality which is gradually paid attention to by customers while satisfying high performance. Because the steel contains more alloy elements, particularly Si and Mn elements, the problems of surface quality such as plating leakage, pitted surface and the like easily occur in the coating process, and the quality of finished products is further influenced.
Patent application publication No. CN 111893379 a discloses a 780MPa grade reinforced forming hot-dip galvanized dual-phase steel and a manufacturing method thereof, and discloses C: 0.16% -0.2%, Si: 0.35-0.65%, Mn: 1.8% -2.3%, Al: 0.7 to 1.0 percent of the total weight of the alloy, less than or equal to 0.03 percent of P, and 0.16 to 0.25 percent of Cr or 0 to 0.3 percent of Mo. In the dual-phase steel, the carbon equivalent is high, adverse effects are generated on welding performance, particularly the welding reject ratio of a narrow lap joint resistance welding machine is high, the Al + Si content is up to more than 1.2%, hot-rolled ferrous silicate red rust is serious, high dephosphorization equipment and pressure are needed, the requirement on equipment capacity is high, and the surface color difference of a finished product is difficult to control; in addition, the alloy contains Cr or Mo element, so the cost of the alloy is higher.
Patent application with publication number CN 111979488A discloses 780 MPa-grade alloying hot-dip galvanizing DH steel and a preparation method thereof, wherein the steel comprises the following chemical components in percentage by mass: c: 0.11-0.17%, Mn: 1.4% -2.4%, Si: 0.15-0.60%, Al: 0.02% -1.0%, Mo: 0.20-0.70%, P is less than or equal to 0.03%, S is less than or equal to 0.03%, B is less than or equal to 0.005%, V: 0-0.05%, Ti: 0-0.05%, and Si + Al: 0.5-1.5 percent, the hot-dip galvanized DH steel that this application provides contains higher Mo element, the cost is higher, and its steel samples along the direction (horizontal) perpendicular to rolling, its sampling direction is inconsistent with existing mainstream standard, national standard GB/T2518-.
Patent application with publication number CN 106119716A discloses a plastic reinforced cold-rolled hot-galvanized dual-phase steel and a production method thereof, and the main chemical components of the steel are as follows: c: 0.12-0.18%, Si: 0.3% -0.6%, Mn: 1.3% -2.3%, Al: 0.4 to 0.9 percent of the total weight of the alloy, less than or equal to 0.01 percent of P and less than or equal to 0.01 percent of S; the cost is reduced under the condition of not adding alloy elements, and a certain amount of residual austenite is introduced to generate a TRIP effect, so that the two-phase elongation is improved; however, the content of Si in the steel is as high as 0.3-0.6%, the high content of Si can cause ferrous silicate and red rust generated in the hot rolling process of the product to be serious, high phosphorus removal equipment and pressure are needed, the requirement on the equipment capacity is high, and otherwise, once the iron scale is not completely removed, the surface of a galvanized finished product can generate serious color difference defects. Meanwhile, alloy elements are not added in the steel plate, so that the steel plate matrix cannot be subjected to fine-grain strengthening, and the plasticity of the steel plate is reduced by higher carbon and manganese elements.
Disclosure of Invention
The invention aims to provide 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and a production method thereof.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel comprises the following chemical components in percentage by mass: c: 0.14% -0.18%, Si: 0.15-0.30%, Mn: 2.0% -2.3%, Al: 0.5 to 0.7 percent of Nb, less than or equal to 0.015 percent of P, less than or equal to 0.008 percent of S, and Nb: 0.02 to 0.03%, Ti: 0.015-0.025%, Cr: 0.1-0.4%, B: 0.007 to 0.0015 percent, and the balance of Fe and inevitable impurity elements.
The dual-phase steel has the following functions of the components:
c: the carbon element guarantees the strength requirement of the steel through solid solution strengthening, and free carbon can play a good stabilizing effect on austenite, so that the forming performance of the steel is improved. The content of the element C is too low, so that a proper amount of residual austenite is difficult to obtain, and the mechanical property index of the steel in the invention cannot be met; too high a content can embrittle the steel, not only increasing the cost, but also having the risk of delayed fracture, and increasing the welding difficulty. Therefore, the content of the C element is controlled to be 0.14-0.18 percent in the invention.
Mn: manganese is an austenite stabilizing element in steel, can expand an austenite phase region, reduce the critical quenching speed of the steel, and can refine grains, thereby being beneficial to solid solution strengthening to improve the strength. The content of Mn element is too low, the super-cooled austenite is not stable enough, and the plasticity, the toughness and other processing performances of the steel plate are reduced; too high content of Mn element results in deterioration of the weldability of the steel sheet. Therefore, the content of the Mn element is controlled to be 2.0-2.3 percent in the invention.
Si: the silicon element has a certain solid solution strengthening effect in ferrite, so that the steel has enough strength, and meanwhile, the Si can inhibit the decomposition of residual austenite and the precipitation of carbide, thereby reducing the inclusion in the steel. The Si element content is too low to play a role in strengthening; the content of Si element is too high, ferrous silicate iron scale is generated in the hot rolling process, and phosphorus removal is difficult to remove, so that the strip steel has color difference defect after subsequent acid washing, and the galvanized finished product also has color difference defect. Meanwhile, the excessive silicon content causes enrichment on the surface of the strip steel in the galvanizing annealing furnace, and a layer of oxidation film is formed on the surface of the steel plate, thereby influencing the surface quality after plating. Therefore, the content of the Si element is controlled to be 0.15 to 0.3 percent in the invention.
Al: the aluminum element contributes to deoxidation of molten steel and can also suppress decomposition of residual austenite and precipitation of carbide. Al and Si are also insoluble in cementite, so that the formation of the cementite can be inhibited, the accumulation of carbon elements into residual austenite is promoted, meanwhile, Al is used for replacing Si to effectively reduce the defect of surface color difference of a galvanized finished product, but the content of Al is too high, so that the production cost is increased, the continuous casting production is difficult, and the like. Therefore, the content of the Al element is controlled within the range of 0.5 to 0.7 percent in the invention.
P: the P element is a harmful element in steel, seriously reduces the plasticity and the deformability of the steel, and the lower the content, the better the content. In the invention, the content of the P element is controlled to be less than or equal to 0.015 percent in consideration of the cost.
S: the S element is a harmful element in steel, seriously affects the formability of steel, and the lower the content, the better the formability. In consideration of cost, the content of the S element is controlled to be less than or equal to 0.008 percent.
Nb: the microalloying element Nb is used for improving the comprehensive performance of the material through fine grain strengthening, and 0.02-0.03% of Nb is added in the invention in consideration of comprehensive cost.
Ti: the microalloying element Ti improves the comprehensive performance of the material through fine grain strengthening, and 0.015-0.025 percent of Ti is added in the invention in consideration of comprehensive cost.
Cr: the chromium element can increase the hardenability of the steel to ensure the strength of the steel and stabilize the retained austenite, the hardenability of the steel is influenced by too low content of the Cr, and the production cost is increased by too high content of the Cr. Therefore, the content of Cr element is controlled within the range of 0.1 to 0.40 percent in the invention.
B: the main function of boron is to increase the hardenability of the steel, since the addition of very small amounts of boron (0.0007% -0.0015%) increases the hardenability of the steel. Boron is taken as a surface active element, is adsorbed on an austenite crystal boundary, delays the change of gamma-a, and the segregation of the boron on the austenite crystal boundary hinders the nucleation of ferrite and is beneficial to the formation of bainite, so that the delay of the generation of the ferrite is much larger than that of the bainite, thereby improving the hardenability and further being beneficial to the formation of residual austenite in steel.
In order to improve the surface quality of a galvanized finished product and reduce the content of silicon element, Al is used for replacing silicon to ensure the stability of austenite, but the Al element basically does not have the solid solution strengthening effect, so the strength of the steel is often lower. Therefore, it is also necessary to enhance the strength of the steel by the fine grain strengthening effect of the added Nb and Ti.
The invention also provides a production method of the 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel, which comprises the working procedures of converter smelting, hot rolling, acid pickling and cold rolling, annealing and hot galvanizing; wherein the hot rolling step: heating the plate blank at 1180-1210 ℃ for 180-220min, carrying out dephosphorization and 3-pass rough rolling, carrying out 7-pass finish rolling, carrying out finish rolling at the beginning of the finish rolling at 1000-1030 ℃ and the outlet temperature of 880-920 ℃, carrying out laminar cooling to 500-550 ℃, and then coiling and air cooling;
the hot rolling coiling temperature is 500-550 ℃.
The converter smelting process adopts an LF single refining process.
In the pickling and cold rolling process, the cold rolling reduction is 50-60%, and the pickling speed is less than or equal to 150 m/min.
In the annealing process, the conductivity of a cleaning section is more than or equal to 50ms, the reflectivity after cleaning is more than 95, a pre-oxidation device is used in a heating section of the annealing furnace, and the dew point is set to be-20 to-10 ℃.
According to the annealing process, a steel coil is heated to 810-830 ℃, heat preservation and slow cooling are carried out, the steel coil is cooled to 700-720 ℃ at a cooling rate of 6-16 ℃/s, and then the steel coil is cooled to 450-460 ℃ at a cooling rate of 30-65 ℃/s.
The hot galvanizing process comprises the following steps: galvanizing at the temperature of 450-460 ℃, and cooling to the temperature of 200-250 ℃ after galvanizing; and (3) leveling the steel coil after the steel coil is discharged from the furnace, wherein the leveling elongation is 0.2-0.3%, and the straightening elongation is 0.1%.
Compared with the prior art, the invention has the following beneficial effects:
the steel smelting components of the invention mainly comprise C, Mn and Al, a small amount of Si and trace amounts of Nb and Ti are added, and a small amount of Cr is added to improve the strength of the steel.
The invention adopts a low-temperature coiling process to coil the steel grade in a bainite single-phase region, thereby avoiding the substrate from forming microcracks due to the substrate rolling cracks in the cold rolling process and further avoiding the pitted surface defect from forming on the surface of a galvanized finished product.
The DH780 produced by the method introduces 6-8% of residual austenite and a very small amount of bainite on the basis of the traditional dual-phase steel, and realizes the characteristics of high strength, high plasticity and high hole expanding performance under the coupling action of transformation induced plasticity (TRIP) effect and bainite coordinated deformation.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.
FIG. 1 shows the metallographic structure of 780MPa grade reinforced formable hot-dip galvanized dual-phase steel obtained in example 1.
FIG. 2 is a gold phase diagram of the retained austenite content by Electron Back Scattering Diffraction (EBSD) measurement of the 780 MPa-grade reinforced formable hot-dip galvanized dual-phase steel obtained in example 1.
FIG. 3 shows the surface quality of 780MPa grade enhanced forming hot dip galvanized dual phase steel obtained in example 1.
Detailed Description
The 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel provided by the invention has the following production steps and process parameter control ranges:
1) smelting and pouring into a blank according to a process route of molten iron pretreatment → converter smelting → alloy fine adjustment → LF furnace refining → continuous casting;
2) heating the plate blank to 1180-1210 ℃, heating for 180-220min, carrying out 7-pass finish rolling after dephosphorization and 3-pass rough rolling, carrying out finish rolling at the finish rolling start temperature of 1000-1030 ℃, carrying out outlet temperature of 880-920 ℃, carrying out laminar cooling to 500-550 ℃, and then coiling and air cooling;
3) carrying out cold rolling after conventional pickling, wherein the cold rolling reduction rate is 50-60%, and the pickling speed is controlled to be less than or equal to 150 m/min;
4) annealing and galvanizing are carried out, the conductivity of the cleaning section is more than or equal to 50ms, the reflectivity after cleaning is more than 95, a pre-oxidation device is used in the heating section of the annealing furnace, the dew point setting value is-20 to-10 ℃, the steel coil is heated to 810 to 830 ℃, slow cooling is carried out after heat preservation, the steel coil is cooled to 700 to 720 ℃ at the cooling rate of 6 to 16 ℃/s, then the steel coil is cooled to 450 to 460 ℃ at the cooling rate of 30 to 65 ℃/s, galvanizing is carried out at 450 to 460 ℃, the steel coil is cooled to 250 ℃ quickly after galvanizing, the steel coil is discharged from the furnace and leveled, the leveling elongation is 0.3%, and the straightening elongation is 0.1%.
The method specifically comprises the following steps:
the chemical compositions of 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel of examples 1-8 are shown in Table 1, and the production process parameters are shown in Table 2.
TABLE 1 chemical composition (wt%) of the dual phase steel of each example
Figure DEST_PATH_IMAGE002
TABLE 2 Rolling Process parameters for the examples
Figure DEST_PATH_IMAGE004
TABLE 3 annealing and galvanizing process parameters of each example
Figure DEST_PATH_IMAGE006
TABLE 4 mechanical Properties of the Dual-phase steels of the examples
Figure DEST_PATH_IMAGE008
Note: the method for measuring the mechanical properties (yield strength, tensile strength and elongation after fracture) adopts the national standard GB/T2518-2019, the type number of the sample is P6, and the direction of the sample is longitudinal.
The result shows that the technical scheme of the invention has good adaptability, and the prepared dual-phase steel has uniform elongation of 19-23% on the premise that the strength meets the national standard requirement.
The metallographic structure of the high-surface dual-phase steel prepared in example 1 is shown in fig. 1, the metallographic structure of the high-surface dual-phase steel is shown in fig. 2, the residual austenite content is measured by Electron Back Scattering Diffraction (EBSD), and the residual austenite content in the metallographic structure is calculated to be about 6% to 8% by using statistical software. As shown in FIG. 3, the surface of the product of example 1 was found to have good surface quality, no color difference, landscape painting, and selective oxidation skip plating defects.
The above detailed description of a 780MPa grade enhanced forming hot dip galvanized dual phase steel and its production method with reference to the examples is illustrative and not restrictive, several examples are listed according to the limited scope, therefore changes and modifications without departing from the general concept of the present invention shall fall within the protection scope of the present invention.

Claims (6)

1. The 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel is characterized by comprising the following chemical components in percentage by mass: c: 0.14% -0.18%, Si: 0.15-0.30%, Mn: 2.0% -2.3%, Al: 0.5% -0.7%, P: less than or equal to 0.015 percent, Nb: 0.02 to 0.03%, Ti: 0.015-0.025%, Cr: 0.1-0.4%, B: 0.007 to 0.0015 percent, and the balance of Fe and inevitable impurity elements.
2. The production method of the 780MPa grade reinforced forming hot galvanized dual-phase steel according to the claim 1, characterized in that the production method comprises the working procedures of converter smelting, hot rolling, acid pickling cold rolling, annealing and hot galvanizing; wherein the hot rolling step: the heating temperature of the plate blank is 1180-1210 ℃, the heating time is 180-20 min, and the hot rolling coiling temperature is 500-550 ℃.
3. The method for producing 780MPa grade enhanced forming hot galvanized dual phase steel according to claim 2, characterized in that the converter smelting process comprises the following steps: adopts LF + RH duplex process.
4. The method for producing 780MPa grade enhanced forming hot galvanized dual phase steel according to claim 2, characterized in that the pickling cold rolling process: the cold rolling reduction rate is 50-60%, and the pickling speed is controlled to be less than or equal to 150 m/min.
5. A method for producing 780MPa grade enhanced forming hot galvanized dual phase steel according to claim 2, characterized in that the annealing process: the conductivity of the cleaning section is more than or equal to 50ms, the reflectivity after cleaning is more than 95, the pre-oxidation device is used in the heating section of the annealing furnace, and the dew point setting value is-20 to-10 ℃.
6. A production method of 780MPa grade enhanced forming hot galvanized dual phase steel according to claim 2, characterized in that the annealing procedure: heating the steel coil to 810-830 ℃, carrying out slow cooling after heat preservation, cooling to 700-720 ℃ at a cooling rate of 6-16 ℃/s, and then cooling to 450-460 ℃ at a cooling rate of 30-65 ℃/s.
CN202210060467.XA 2022-01-19 2022-01-19 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof Pending CN114525448A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210060467.XA CN114525448A (en) 2022-01-19 2022-01-19 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210060467.XA CN114525448A (en) 2022-01-19 2022-01-19 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof

Publications (1)

Publication Number Publication Date
CN114525448A true CN114525448A (en) 2022-05-24

Family

ID=81619991

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210060467.XA Pending CN114525448A (en) 2022-01-19 2022-01-19 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof

Country Status (1)

Country Link
CN (1) CN114525448A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116287957A (en) * 2023-04-11 2023-06-23 攀枝花学院 Vanadium-containing hot dip galvanized steel and smelting method thereof

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006283156A (en) * 2005-04-01 2006-10-19 Nippon Steel Corp High-strength cold rolled steel sheet having excellent formability and weldability, high-strength hot dip galvanized steel sheet, high-strength alloyed galvannealed steel sheet, production method of high-strength cold rolled steel sheet, production method of high-strength hot dip galvanized steel sheet, and production method of high-strength alloyed galvannealed steel sheet
CN102409222A (en) * 2010-09-21 2012-04-11 鞍钢股份有限公司 Cold-rolled phase-change induced plasticity steel plate for continuous annealing or hot galvanizing and preparation method thereof
JP2013234340A (en) * 2012-05-07 2013-11-21 Nippon Steel & Sumitomo Metal Corp High-strength hot-dip galvanized steel plate with excellent moldability in ordinary and intermediate temperature range, and method for manufacturing the same
CN106119716A (en) * 2016-06-17 2016-11-16 首钢总公司 The cold-rolled galvanized duplex steel of a kind of plasticity enhancing and production method thereof
CN109023149A (en) * 2018-06-26 2018-12-18 武汉钢铁有限公司 Low 980MPa grade cold-rolled biphase steel and its manufacturing method are required producing line cooling capacity
CN110172640A (en) * 2019-05-30 2019-08-27 安徽工业大学 500MPa grades high work hardening rate hot dip galvanized dual phase steel plate and preparation method thereof
CN110499457A (en) * 2019-08-07 2019-11-26 邯郸钢铁集团有限责任公司 1200MPa grades of hot dip galvanized dual phase steels of great surface quality and its production method
CN111748745A (en) * 2019-03-29 2020-10-09 宝山钢铁股份有限公司 780 MPa-grade cold-rolled hot-galvanized dual-phase steel with high formability and manufacturing method thereof
CN111748746A (en) * 2019-03-29 2020-10-09 宝山钢铁股份有限公司 780 MPa-grade TRIP type cold-rolled hot-galvanized dual-phase steel and manufacturing method thereof

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006283156A (en) * 2005-04-01 2006-10-19 Nippon Steel Corp High-strength cold rolled steel sheet having excellent formability and weldability, high-strength hot dip galvanized steel sheet, high-strength alloyed galvannealed steel sheet, production method of high-strength cold rolled steel sheet, production method of high-strength hot dip galvanized steel sheet, and production method of high-strength alloyed galvannealed steel sheet
CN102409222A (en) * 2010-09-21 2012-04-11 鞍钢股份有限公司 Cold-rolled phase-change induced plasticity steel plate for continuous annealing or hot galvanizing and preparation method thereof
JP2013234340A (en) * 2012-05-07 2013-11-21 Nippon Steel & Sumitomo Metal Corp High-strength hot-dip galvanized steel plate with excellent moldability in ordinary and intermediate temperature range, and method for manufacturing the same
CN106119716A (en) * 2016-06-17 2016-11-16 首钢总公司 The cold-rolled galvanized duplex steel of a kind of plasticity enhancing and production method thereof
CN109023149A (en) * 2018-06-26 2018-12-18 武汉钢铁有限公司 Low 980MPa grade cold-rolled biphase steel and its manufacturing method are required producing line cooling capacity
CN111748745A (en) * 2019-03-29 2020-10-09 宝山钢铁股份有限公司 780 MPa-grade cold-rolled hot-galvanized dual-phase steel with high formability and manufacturing method thereof
CN111748746A (en) * 2019-03-29 2020-10-09 宝山钢铁股份有限公司 780 MPa-grade TRIP type cold-rolled hot-galvanized dual-phase steel and manufacturing method thereof
CN110172640A (en) * 2019-05-30 2019-08-27 安徽工业大学 500MPa grades high work hardening rate hot dip galvanized dual phase steel plate and preparation method thereof
CN110499457A (en) * 2019-08-07 2019-11-26 邯郸钢铁集团有限责任公司 1200MPa grades of hot dip galvanized dual phase steels of great surface quality and its production method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116287957A (en) * 2023-04-11 2023-06-23 攀枝花学院 Vanadium-containing hot dip galvanized steel and smelting method thereof
CN116287957B (en) * 2023-04-11 2024-05-17 攀枝花学院 Vanadium-containing hot dip galvanized steel and smelting method thereof

Similar Documents

Publication Publication Date Title
CN110129668B (en) 1000 MPa-grade alloying hot-dip galvanizing complex-phase steel and preparation method thereof
JP6052472B2 (en) High-strength hot-dip galvanized steel sheet and manufacturing method thereof
CN109097705A (en) A kind of 800MPa grade cold rolling hot dip galvanizing dual phase steel and its production method
CN110777290B (en) Hot-dip galvanized aluminum-magnesium high-strength steel, preparation method and application
WO2016113788A1 (en) High-strength hot-dip galvanized steel sheet and production method thereof
WO2013114850A1 (en) Hot-dip galvanized steel sheet and production method therefor
KR101461740B1 (en) Hot rolled steel sheet having low deviation of mechanical property and thickness and excellent coating detachment resistance and method for manufacturing the same
WO2010011790A2 (en) Cold rolled dual phase steel sheet having high formability and method of making the same
JP4751152B2 (en) Hot-dip galvanized high-strength steel sheet excellent in corrosion resistance and hole expansibility, alloyed hot-dip galvanized high-strength steel sheet, and methods for producing them
KR101629113B1 (en) High strength hot-dip galvanized steel sheet having excellent deep drawability and method for manufacturing the same
KR20120113791A (en) Method for producing high-strength steel plate having superior deep drawing characteristics
CN113249648B (en) 800 MPa-grade hot-base zinc-aluminum-magnesium coating complex-phase steel and preparation method thereof
CN104726768A (en) High strength hot rolled steel sheet having excellent surface property and method for manufacturing the same
CN113528940B (en) Aluminum-silicon alloy plating layer hot forming steel and preparation method thereof
CN112251668B (en) Forming reinforced complex phase steel and preparation method thereof
CN113403550A (en) High-plasticity fatigue-resistant cold-rolled hot-galvanized DH1180 steel plate and preparation method thereof
CN110527923B (en) High-yield-ratio structural steel for 600 MPa-grade automobile body and production method thereof
JPS6256209B2 (en)
JP4360319B2 (en) High tensile hot dip galvanized steel sheet and its manufacturing method
CN114525448A (en) 780 MPa-grade reinforced forming hot-dip galvanized dual-phase steel and manufacturing method thereof
CN115216688B (en) 800 MPa-grade hot-rolled low-alloy high-strength steel, steel matrix thereof and preparation method thereof
JPH03257124A (en) Production of cold rolled steel sheet for deep drawing having baking hardenability
CN115109994B (en) High-strength cold-rolled hot-dip galvanized microalloy strip steel and manufacturing method thereof
CN115612934A (en) 590 MPa-level high-formability hot-dip galvanized dual-phase steel plate and preparation method thereof
CN114207172A (en) High-strength steel sheet, high-strength member, and method for producing same

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
WD01 Invention patent application deemed withdrawn after publication
WD01 Invention patent application deemed withdrawn after publication

Application publication date: 20220524