CN115491570A - Production method of thick ultra-deep drawing hot-dip galvanized steel plate - Google Patents
Production method of thick ultra-deep drawing hot-dip galvanized steel plate Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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- C21D1/26—Methods of annealing
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- 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
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- 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
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
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- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
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- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
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Abstract
The invention discloses a production method of a thick ultra-deep drawing hot-dip galvanized steel sheet, which comprises the following steps: controlling the steel components according to the following weight percentages: c:0.0010 to 0.005%, si:0.01 to 0.03%, mn:0.10 to 0.30%, P: less than or equal to 0.015 percent, S: less than or equal to 0.015 percent, nb:0.010 to 0.030%, ti: 0.040-0.080%, als: 0.010-0.070%, and the balance of Fe and inevitable impurities, and continuously casting the components after smelting into a continuous casting billet; 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; and continuously annealing and hot galvanizing the cold-rolled coil to obtain the thick ultra-deep drawing hot galvanized steel plate. The method can be used for stably producing the thick hot-dip galvanized steel plate with high formability and high surface quality in batch on a continuous hot-dip galvanizing production line.
Description
Technical Field
The invention belongs to the technical field of steel production, and particularly relates to a production method of a thick ultra-deep drawing hot-dip galvanized steel plate.
Background
With the continuous iterative update of the product structure design in the household appliance and hardware industries, more and more products with complex structures are produced, the molding difficulty of materials used by the products is high, and the improvement of molding requirements also puts higher and higher requirements on raw materials. The hot galvanizing product has wide application in household appliances and automobile industry, and has good forming performance due to good ductility of the zinc layer material, good corrosion resistance and low cost. The extra-deep drawing hot-dip galvanized sheet has low yield strength, high elongation, high formability and excellent corrosion resistance, and is widely applied to the industries of household appliances, automobile parts and the like.
However, the existing extra-deep drawing hot-dip galvanized sheet has high production cost, difficult implementation of manufacturing process and poor product stability, and is difficult to meet the low-cost and high-efficiency manufacturing target to be realized by enterprises.
Therefore, how to stably produce thick ultra-deep drawing galvanized steel sheets at low cost becomes a technical problem to be solved urgently in the field of the production of the galvanized steel sheets.
Disclosure of Invention
The invention provides a method for manufacturing a thick hot-dip galvanized steel sheet, aiming at solving one of the prior technical problems. The method can manufacture the thick hot-dip galvanized steel sheet meeting the requirement with lower cost and smaller implementation difficulty, and can stably produce the thick hot-dip galvanized steel sheet with high formability and high surface quality in batch on a continuous hot-dip galvanizing production line.
According to the invention, the production method of the thick ultra-deep drawing hot-dip galvanized steel plate comprises the following steps:
step 1): controlling the steel components according to the following weight percentages: c:0.0010 to 0.005%, si:0.01 to 0.03%, mn:0.10 to 0.30%, P: less than or equal to 0.015 percent, S: less than or equal to 0.015%, nb:0.010 to 0.030%, ti: 0.040-0.080%, als: 0.010-0.070%, and the balance of Fe and inevitable impurities, and smelting the components and then continuously casting the components into a continuous casting billet;
step 2): heating, rough rolling, finish rolling and cooling the continuous casting billet, and then coiling to obtain a hot rolled coil;
step 3): cold rolling the hot rolled coil to obtain a cold rolled coil;
step 4): and continuously annealing and hot galvanizing the cold-rolled coil to obtain the thick ultra-deep drawing hot galvanized steel plate.
According to one embodiment of the invention, in the step 1), desulfurization and decarburization treatment are performed during smelting, and the carbon content in the molten steel is strictly controlled.
According to one embodiment of the invention, the heating and rough rolling in the step 2) comprises heating the continuous casting blank to 1220-1250 ℃, carrying out rough rolling in a furnace for 200-260 min, wherein the rough rolling adopts 5-pass rolling, the phosphorus is removed from the whole length, and a heat-insulating cover is used in the rolling process.
According to one embodiment of the invention, the hot rolled intermediate slab has a thickness of 32 to 36mm.
According to an embodiment of the invention, the start rolling temperature of the finish rolling in the step 2) is 1120-1150 ℃, and the finish rolling temperature is 830-880 ℃.
According to an embodiment of the invention, the coiling after cooling in the step 2) comprises the coiling after the finish rolling by adopting a front-stage cooling mode to cool to 600-650 ℃.
According to one embodiment of the invention, the cold rolling in the step 3) comprises the step of carrying out cold rolling after cleaning the hot rolled plate by alkali washing, wherein the cold rolling reduction rate is 65-80%.
According to one embodiment of the invention, the running speed of the continuous annealing strip steel in the continuous annealing of the step 4) is controlled to be 80-110 m/min.
According to one embodiment of the invention, the annealing soaking temperature in the hot galvanizing in the step 4) is 840-860 ℃, and the temperature of a zinc pot is controlled at 450-470 ℃.
According to one embodiment of the invention, the withdrawal and straightening elongation in step 4) is controlled to be 0.1-0.3% and the finishing elongation is controlled to be 0.2-0.4%.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages:
(1) The method has low cost and small implementation difficulty of the manufacturing process, and can stably produce the thick hot-dip galvanized steel plate with high formability and high surface quality in batch on a continuous hot-dip galvanizing production line;
(2) The method comprehensively controls the components of the hot-dip galvanized steel sheet, the annealing process parameters of hot rolling, cold rolling and continuous hot-dip galvanizing, obtains a product with excellent mechanical property, and has the yield strength of 140-170 MPa, the tensile strength of 290-310 MPa, the elongation of more than or equal to 46.0 percent and r 90 ≥2.5，n 90 ≥0.24。
Drawings
Fig. 1 is a flowchart of a method for manufacturing a thick hot-dip 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 thick ultra-deep drawing hot-dip galvanized steel sheet. As shown in fig. 1, the method generally comprises a number of steps described below.
Step S1: casting blank
Controlling the steel components according to the following weight percentages: c:0.0010 to 0.005%, si:0.01 to 0.03%, mn:0.10 to 0.30%, P: less than or equal to 0.015 percent, S: less than or equal to 0.015 percent, nb:0.010 to 0.030%, ti: 0.040-0.080%, als: 0.010-0.070 percent, and the balance of Fe and inevitable impurities, and the components are smelted and then continuously cast into a continuous casting billet.
The ultra-deep drawing hot-dip galvanized steel plate needs to have excellent deep drawing performance, tensile property and complex deformability. The deep drawing property of the plate material is closely related to the anisotropy of the mechanical properties thereof, and it is required to have high plastic fluidity in the plane of the plate and sufficient resistance to plastic flow in the plate thickness direction.
The content of C and the form of C in steel determine the strength and other properties of the steel, and the high content of C causes the high content of cementite after cold rolling of the steel. The cementite is hard and brittle as compared to ferrite, which increases the strength of the steel and decreases plasticity because the cementite hinders deformation of the ferrite. For extra deep drawing hot dip galvanized steel sheets, a lower yield strength and a higher elongation are required. Researches show that along with the increase of the content of solid solution C in steel, the density of {111} oriented texture vertical to the normal direction of a steel plate is reduced, the aging problem of the steel is obvious, the change of the content of C in the steel has obvious influence on the mechanical property of the steel, particularly has larger influence on the plastic strain ratio, and the plastic strain ratio can be improved by controlling the content of C in a lower range. Therefore, the content of C is controlled to 0.0010 to 0.005% in the present application.
Si has strong affinity with O and can be used as a reducing agent and a deoxidizing agent in the steelmaking process. Si exists in solid solution in steel, and can improve the strength and hardness of steel, thereby playing a role in strengthening the strength of steel. However, as the content of Si increases, scale formed on the surface of the strip steel during hot rolling is difficult to remove, and the surface quality of the steel is deteriorated. Therefore, the content of Si needs to be controlled within a certain range. In the application, the content of Si is controlled to be 0.01-0.03%.
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 dissolved in ferrite during annealing of deep drawing steel hinders the growth of {111} oriented grains that are preferentially nucleated. In the deep drawn sheet, as the Mn content increases, the strength of the material increases and the plasticity decreases, so that the content thereof should be controlled to an appropriate range. In the application, the content of Mn is controlled to be 0.01-0.03%.
S is a harmful element in steel, is particularly serious for deep drawing steel with complex processing deformation, and sulfide is mixed in the rolling process and distributed in a strip or chain shape along the rolling direction, so that the transverse cold bending performance of the steel plate is deteriorated, and anisotropy is generated. In addition, S causes hot shortness of the steel sheet. The S content should be minimized. When the content of S in the steel is low, the content of Mn in the steel can be reduced, so that the content of S element in the steel is reduced as much as possible. However, reducing the content of S element in the steel necessitates an increase in the cost for desulfurization and also an increase in the binding force of the scale. These can reduce the generation of surface defects of the strip steel. The actual amount of S is therefore determined according to the mechanical properties requirements of the material, the surface quality and economic conditions. In the present application, the S content is controlled to 0.015% or less.
P is an element which is effective for improving the strength of the steel material except for C atoms. The deep drawing steel with excellent formability can be obtained by properly adding phosphorus to the low carbon steel. P is one of the most suitable additive elements for producing the deep-drawing high-strength steel. However, the high P content can increase the secondary working embrittlement sensitivity of the material and also can cause the problem of non-uniform alloying of the galvanized product. In the present application, the P content is controlled to 0.015% or less.
A1 is added as a deoxidizer, and the deoxidizer has the function of removing oxygen in molten steel, so that low-temperature plasticity can be improved, and slip lines can be prevented from being generated in the stamping process. In the application, the content of A1s is controlled to be 0.010-0.070%.
Ti fixes C element in steel, precipitates titanium carbide compound, and reduces the amount of C element dissolved in ferrite. The material obtains excellent deep drawing performance. However, ti is expensive and its amount should be properly controlled to reduce the cost. The amount of Ti used is closely related to the C content of the material, and in the present application, the Ti content is controlled to 0.040 to 0.080% in order to sufficiently fix the C in the material.
Nb can play a role in refining grains, can improve the plane anisotropy of the material, reduce the reheating temperature of the plate blank, coarsen the precipitated particles and increase the elongation and the r value. However, nb is expensive and should be used in a controlled amount to reduce the cost. The amount of Nb is related to the C content in the material, and the Nb content is controlled to be 0.010-0.030 percent in the application.
During smelting, desulfurization and decarburization treatment are carried out, and the carbon content in the molten steel is strictly controlled. Before continuous casting, molten steel may be subjected to desulfurization, decarburization and alloying treatment by external refining. The components and the temperature of the molten steel can be accurately adjusted to ensure the purity of the molten steel and the quality of products. In addition, manganese in the steel was adjusted to a target amount before vacuum decarburization.
Step S2: hot rolling
The hot rolling process has a significant influence on the type, composition, amount and particle size distribution of the precipitated phases. The type, composition and quantity of precipitated phases represent the effect of removing interstitial atoms C, influence on the grain size, texture and the like of the hot rolled plate, and influence on the product performance finally. The hot rolling process can also affect the texture and deep drawing properties of the hot rolled sheet, having an effect on the microstructure of the subsequently cold rolled sheet. By controlling the texture of the hot rolled sheet, the quality of the cold rolled sheet can be improved.
Researches show that the hot rolling process of the extra-deep drawing hot-dip galvanized steel sheet has a dependency relationship with components, and the size and distribution of precipitated phases are determined by the synergistic effect of the hot rolling process and the components, so that the hot rolling process is designed by combining the components of the steel.
In the invention, the specific hot rolling treatment comprises heating the continuous casting slab to 1220-1250 ℃, carrying out rough rolling for 200-260 min in a furnace, wherein the rough rolling adopts 5-pass rolling, the whole-length and total-number phosphorus removal, and a heat-preserving cover is used in the rolling process. The thickness of the hot-rolled intermediate slab is controlled to be 32-36 mm, the start rolling temperature of finish rolling is 1120-1150 ℃, and the finish rolling temperature range is 830-880 ℃. After finish rolling, adopting a front-section cooling mode to cool to 600-650 ℃ for coiling. The thickness of the hot rolled plate was about 5.0mm.
For the ultra-deep drawing hot-dip galvanized steel sheet with the components, the heating at 1220-1250 ℃ can lead the steel to generate coarse and large two-phase particles and fine ferrite grains after hot rolling, and generate a recrystallization texture with uniform distribution and strong strength in the subsequent cold rolling and continuous annealing treatment processes, thereby improving the deep drawing performance.
For the ultra-deep drawing hot-dip galvanized steel sheet containing the components, the finishing rolling temperature range is set to be 830-880 ℃, so that the steel has obvious influence on Ti and Nb stabilized steel, and a uniform equiaxial microstructure is favorably formed.
In the extra deep drawing hot dip galvanized steel sheet of the composition of the present invention, the TiC particles are greatly affected by a change in the coiling temperature. The high-temperature coiling is beneficial to the precipitation and growth of TiC particles and the growth of ferrite grains. The high and low coiling temperature directly affects the precipitation of the second phase particles and the morphology, size and distribution of precipitates, and the higher the coiling temperature is, the more favorable the precipitation of the second phase particles and the coarsening of crystal grains are, the more favorable the deep drawability of the steel is. However, with the increase of coiling temperature, the distribution of two-phase particles becomes more and more sparse, and the size of the two-phase particles also becomes larger and larger, so that the crystal grains of the hot-rolled strip steel in the coiling and cooling process can well grow, the coarse grain structure can be reserved in the subsequent cold rolling, but the excessively coarse crystal grains are not favorable for the deep drawing performance of the steel. Therefore, the coiling temperature of the extra deep drawing hot dip galvanized steel sheet containing the component of the present invention is controlled to 600 to 650 ℃.
And step S3: cold rolling
After the hot rolled plate is cleaned by alkali washing, the cold rolling reduction rate is determined to be 65-80% 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.
Cold rolling stored energy is the driving force for recrystallization annealing, and the texture strength is much higher than that of a hot rolled plate because recrystallization does not exist in the cold rolling process. The deformation texture is mainly related to the reduction rate. The plastic strain ratio r increases with the cold rolling reduction, and as the cold rolling reduction increases, the ferrite grains near isotropy in the original hot-rolled sheet increase in elongation in the direction of deformation, and the degree of fracture of cementite increases. However, when the value reaches a certain value, the texture orientation density increases disadvantageously, and the r value decreases. Therefore, the cold rolling reduction of the extra deep drawing hot dip galvanized steel sheet containing the component of the present invention is determined to be 65 to 80%.
And step S4: continuous annealing and hot galvanizing
During continuous annealing, the running speed of the continuously annealed strip steel is controlled to be 80-110 m/min, the soaking temperature of hot galvanizing annealing is 840-860 ℃, the temperature of a zinc pot is controlled to be 450-470 ℃, the straightening elongation is controlled to be 0.1-0.3 percent, and the finishing elongation is controlled to be 0.2-0.4 percent.
The annealing process has important influence on the recrystallization texture, the texture orientation and the performance of the finished product of the extra-deep drawing hot-dip galvanized steel sheet, and is an important process for ensuring the performance of the finished product. The annealing temperature is one of the key factors influencing the formation of the annealing recrystallization structure of the extra-deep drawing hot dip galvanized steel sheet, the annealing temperature is high, and annealing recrystallization grains are large; the annealing temperature is low, and the annealing recrystallization is incomplete, so that the reasonable annealing temperature is a precondition for ensuring that the material has good performance indexes. In the invention, the soaking temperature of the hot galvanizing annealing is set to be 840-860 ℃.
The magnitude of the finished elongation rate reflects the magnitude of the deformation degree of the steel plate. When the elongation is insufficient, the yield platform is difficult to eliminate, new work hardening occurs on the steel plate with the overlarge elongation, the yield stress slowly rises, and various plasticity indexes are reduced. The elongation required is different for different steel grades, with different concentrations of C atoms. Therefore, the finishing elongation of the extra deep drawing galvanized steel sheet containing the components of the invention is controlled to be 0.2 to 0.4%.
The hot galvanizing method specifically comprises the steps of completing recrystallization of strip steel in an annealing furnace on a continuous annealing unit (the running speed of the continuous annealing strip steel is controlled to be 80-110 m/min, the soaking temperature of the hot galvanizing annealing is controlled to be 840-860 ℃), directly entering a zinc pot from an outlet of the annealing furnace (the temperature of the zinc pot is controlled to be 450-470 ℃), running with tension after galvanizing, then performing finishing and straightening and coiling (the straightening elongation is controlled to be 0.1-0.3%, and the finishing elongation is controlled to be 0.2-0.4%).
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.
Examples 1 to 4 and comparative examples 1 to 2
The components shown in the following table 1 were mixed and smelted, and the molten steel was continuously cast into a continuous casting slab.
Table 1 chemical composition (wt.%)
| Numbering | C | Si | Mn | P | S | Als | Nb | Ti |
| Example 1 | 0.002 | 0.01 | 0.12 | 0.009 | 0.010 | 0.042 | 0.021 | 0.056 |
| Example 2 | 0.002 | 0.01 | 0.13 | 0.010 | 0.011 | 0.039 | 0.022 | 0.058 |
| Example 3 | 0.003 | 0.02 | 0.15 | 0.011 | 0.012 | 0.043 | 0.020 | 0.065 |
| Comparative example 1 | 0.003 | 0.07 | 0.07 | 0.010 | 0.011 | 0.035 | 0.052 | |
| Comparative example 2 | 0.003 | 0.09 | 0.08 | 0.010 | 0.012 | 0.032 | 0.050 |
The continuous casting billet is coiled after being heated, roughly rolled, finely rolled and cooled to obtain a hot rolled coil, and the hot rolling process parameters are shown in the following table 2.
TABLE 2 Hot Rolling Main Process parameters
| Numbering | Heating temperature/. Degree.C | Finish Rolling temperature/. Degree.C | Final Rolling temperature/. Degree.C | Coiling temperature/. Degree.C | Thickness/mm |
| Example 1 | 1220 | 1159 | 845 | 628 | 5.0 |
| Example 2 | 1222 | 1166 | 842 | 630 | 5.0 |
| Example 3 | 1225 | 1170 | 851 | 632 | 5.0 |
| Comparative example 1 | 1230 | 1135 | 920 | 746 | 4.0 |
| Comparative example 2 | 1233 | 1136 | 922 | 745 | 4.0 |
The hot rolled coil was cold rolled to obtain a cold rolled coil, and the cold rolling reductions of examples 1 to 3 and comparative examples 1 to 2 were 70%, 80%, and 80%, respectively.
And carrying out continuous annealing and hot galvanizing on the cold-rolled coil to obtain the thick ultra-deep drawing hot-galvanized steel plate. The continuous annealing and hot galvanizing process parameters are shown in table 3.
TABLE 3 main process parameters for continuous annealing
| Numbering | Annealing temperature/. Degree.C | temperature/deg.C of zinc pot | Percent grain ratio of polished elongation% | Withdrawal elongation/%) |
| Example 1 | 842 | 465 | 0.21 | 0.20 |
| Example 2 | 845 | 468 | 0.23 | 0.20 |
| Example 3 | 847 | 455 | 0.22 | 0.20 |
| Comparative example 1 | 821 | 461 | 0.31 | 0.62 |
| Comparative example 2 | 823 | 462 | 0.32 | 0.61 |
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
| Numbering | Thickness/mm | R p0.2 /MPa | Rm/MPa | Elongation A 80 /％ | n 90 | r 90 |
| Example 1 | 1.5 | 157 | 301 | 47.5 | 0.24 | 2.6 |
| Example 2 | 1.5 | 156 | 300 | 46.5 | 0.24 | 2.6 |
| Example 3 | 1.5 | 155 | 299 | 47.0 | 0.25 | 2.5 |
| Comparative example 1 | 0.8 | 153 | 320 | 44.0 | 0.23 | 2.5 |
| Comparative example 2 | 0.8 | 155 | 325 | 44.5 | 0.23 | 2.5 |
As can be seen from the mechanical property analysis of the above examples and comparative examples, the mechanical property of the thick ultra-deep drawing hot-dip galvanized steel sheet finished product obtained by the method of the invention meets the requirements of yield strength 140-170 MPa, tensile strength 290-310 MPa, elongation greater than or equal to 46.0%, r 90 ≥2.5，n 90 More than or equal to 0.24.
The above examples only express embodiments of the present invention, and the description thereof is more 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 shall be subject to the appended claims.
Claims (10)
1. The production method of the thick ultra-deep drawing hot-dip galvanized steel plate is characterized by comprising the following steps of:
step 1): controlling the steel components according to the following weight percentages: c:0.0010 to 0.005%, si:0.01 to 0.03%, mn:0.10 to 0.30%, P: less than or equal to 0.015 percent, S: less than or equal to 0.015 percent, nb:0.010 to 0.030%, ti: 0.040-0.080%, als: 0.010-0.070%, and the balance of Fe and inevitable impurities, and smelting the components and then continuously casting the components into a continuous casting billet;
step 2): heating, rough rolling, finish rolling and cooling the continuous casting billet, and then coiling to obtain a hot rolled coil;
step 3): cold rolling the hot rolled coil to obtain a cold rolled coil;
step 4): and carrying out continuous annealing and hot galvanizing on the cold-rolled coil to obtain the thick ultra-deep drawing hot-galvanized steel plate.
2. The method as claimed in claim 1, wherein the heating and rough rolling in step 2) comprises heating the continuous casting slab to 1220-1250 ℃ for 200-260 min in a furnace, performing rough rolling, wherein the rough rolling adopts 5-pass rolling, phosphorus is removed from the whole length, and a heat preservation cover is used in the rolling process.
3. The method according to claim 2, wherein the hot rolled intermediate slab has a thickness of 32 to 36mm.
4. The method as claimed in claim 1, wherein the finishing rolling in step 2) has a start rolling temperature of 1120 to 1150 ℃ and a finish rolling temperature of 830 to 880 ℃.
5. The method of claim 4, wherein said cooling followed by coiling in step 2) comprises cooling to 600-650 ℃ with front-end cooling after said finish rolling.
6. The method as claimed in claim 1, wherein the cold rolling in the step 3) comprises cold rolling after cleaning the hot rolled plate with alkali, wherein the cold rolling reduction is 65-80%.
7. The method as claimed in claim 1, wherein the running speed of the continuously annealed steel strip in the continuous annealing of step 4) is controlled to be 80 to 110m/min.
8. The method as claimed in claim 1, characterized in that the annealing soaking temperature in the hot galvanizing in the step 4) is 840-860 ℃, and the temperature of the zinc pot is controlled at 450-470 ℃.
9. The method as claimed in claim 1, wherein the withdrawal and straightening elongation in step 4) is controlled to be 0.1 to 0.3% and the finishing elongation is controlled to be 0.2 to 0.4%.
10. The method as claimed in claim 1, wherein in the step 1), desulfurization and decarburization are performed during smelting, and the carbon content in the molten steel is strictly controlled.
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