CN110607476A - Manufacturing method of cold-rolled hot-galvanized high-strength structural steel with yield strength of 350MPa - Google Patents
Manufacturing method of cold-rolled hot-galvanized high-strength structural steel with yield strength of 350MPa Download PDFInfo
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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
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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
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
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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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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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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- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- 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
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- 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
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- 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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Abstract
The invention relates to a manufacturing method of cold-rolled hot-galvanized high-strength structural steel with 350 MPa-grade yield strength, which sequentially comprises the following process routes: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, slab continuous casting, hot continuous rolling, acid washing, cold continuous rolling, annealing hot galvanizing, finishing and straightening.
Description
Technical Field
The invention belongs to the field of steel production and manufacturing, and particularly relates to a manufacturing method of cold-rolled hot-galvanized high-strength structural steel with yield strength of 350 MPa.
Background
The cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa is mainly applied to the fields of buildings and the like, such as the production of products such as encaustic tiles, goods shelves, welded pipes and the like, and is required to have good coating and surface quality, higher tensile strength, lower yield ratio and certain cold-working forming performance.
At present, the common production process of cold-rolled hot-galvanized high-strength structural steel with yield strength of 350MPa at home and abroad comprises the following steps: 1) the process mainly adds Mn element to steel grade to control the content of Mn element to be more than 1.0%, then obtains fine crystal grains by controlling the technological parameters of hot rolling, cold rolling and annealing process, and mainly realizes the improvement of product strength by solid solution strengthening and fine crystal strengthening. The main problems of the process are that the production load of a rolling mill in steel is large, the yield ratio is low, the high Mn content easily causes the center segregation of products, the alloy cost is high, and the market competitiveness is not strong. 2) The Nb and V microalloying series is produced by adding certain amount of Nb and V elements into steel, controlling Nb and V content to over 0.02%, and raising product strength mainly through solid solution strengthening, fine grain strengthening and precipitation strengthening. The main problems of the process are that the control difficulty of the surface crack problem of the continuous casting billet in the steel is high, the yield ratio of the product is low due to fine grain and precipitation strengthening, the alloy cost of Nb, V and the like is high, and the market competitive advantage is insufficient.
In the process of implementing the invention, the applicant finds that at least the following problems exist in the prior art: the product produced by the conventional production process of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa at home and abroad has the problems of defective continuous casting surface cracks, large production load of a rolling mill, low yield ratio, serious center segregation, high alloy cost, low market competitiveness and the like.
Disclosure of Invention
The embodiment of the invention provides a manufacturing method of cold-rolled hot-galvanized high-strength structural steel with 350 MPa-grade yield strength, and aims to solve the problems of surface crack defects of continuous casting of the steel, large production load of a rolling mill, low yield ratio, serious center segregation, low alloy cost, high market competitiveness and the like.
In order to achieve the purpose, the embodiment of the invention provides a manufacturing method of a cold-rolled hot-galvanized high-strength structural steel with yield strength of 350MPa, which comprises the following steps:
the manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa comprises the following process routes in sequence: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, slab continuous casting, hot continuous rolling, acid washing, cold continuous rolling, annealing hot galvanizing, finishing and straightening.
Further, in the converter molten steel smelting process: controlling S to be less than or equal to 0.0050 Wt% in molten iron entering the furnace and controlling the binary alkalinity of slag RCaO/Al2O3Controlling the temperature to be 2.5-3.5, and adopting bottom blowing argon in the whole smelting process.
Further, in the LF molten steel refining treatment process: performing deoxidation and alloying processes of Al, Mn, Ti and the like, refining the top slag with binary alkalinity RCaO/Al2O3Controlling the molten steel to be 8-12, carrying out Ca treatment on the molten steel, controlling the Ca/Als to be 0.10-0.14, carrying out soft argon blowing on the steel ladle for 8-15 min after the Ca treatment is finished, and controlling the steel ladle molten steel calming time between the soft argon blowing end and the continuous casting ladle casting to be 15-30 min.
Further, in the slab continuous casting: the automatic slag discharging detection control of the ladle is required, the superheat degree of pouring of the tundish is 10-30 ℃, the alkali covering agent is used in the tundish, the plain carbon steel covering slag is used, the casting blank drawing speed is 1.10-1.50 m/min, the liquid level fluctuation of the crystallizer is automatically controlled, and the fluctuation range is controlled to be +/-3 mm.
Further, in the hot continuous rolling process: the control target of the heating soaking temperature of the casting blank is 1250-1280 ℃, the control target of the rough rolling and final rolling temperature is 1050-1090 ℃, the control target of the finish rolling and final rolling temperature is 850-880 ℃, and the control target of the coiling temperature is 580-620 ℃.
Further, in the pickling and cold continuous rolling process: and the cold rolling reduction rate is 65-80%.
Further, in the annealing and galvanizing process: the temperature control target of the soaking section is 700-730 ℃, the terminal temperature control target of the slow cooling section is 650-680 ℃, the terminal temperature control target of the fast cooling section is 490-500 ℃, the temperature control target of the zinc pot is 470-480 ℃, the temperature control target of the zinc liquid is 460 ℃, and the weight of the zinc coating of the hot-dip galvanized steel coil is 180-280 g/m2。
Further, in the finishing and withdrawal and straightening process: the finishing elongation is controlled according to 1.0-1.6% of the thickness of different strip steels, and the withdrawal and straightening elongation is controlled according to 0.5-1.0%.
Further, the chemical components prepared by the manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa are carbon C: 0.10 Wt% -0.18 Wt%, silicon Si is less than or equal to 0.03 Wt%, manganese Mn: 0.15 Wt% -0.40 Wt%, phosphorus P: 0.060 Wt% to 0.075 Wt%, sulfur S: less than or equal to 0.008 Wt%, aluminum Als: 0.015-0.040 Wt%, Ti: 0.045 Wt% -0.080 Wt%, nitrogen N is less than or equal to 0.0040 Wt%, Si + P is less than or equal to 0.090 Wt%, Mn/S is greater than or equal to 20%, and the balance is Fe and inevitable trace elements;
the technical scheme has the following beneficial effects: according to the invention, through reasonable component design and process control, precious alloys such as Nb and V are not required to be added, the high Mn content in steel is not required to be controlled, meanwhile, the measures such as high reduction rolling, low-temperature coiling, continuous annealing low-temperature rapid cooling and the like are not required to be adopted, through economic chemical component design, the production scheme and the production technology of smelting, continuous casting, hot rolling, cold rolling, annealing, galvanizing and the like are formed by taking a hot continuous rolling production line and a continuous annealing galvanizing production line as core processes, the yield strength Rp0.2 (or ReL) of the obtained cold-rolled high-strength structural steel with the yield strength of 350MPa is 370-460 MPa, the tensile strength Rm is 470-540 MPa, the elongation A80mm is 28-34%, and the weight (double faces) of a galvanizing layer is 180-280 g/m2, so that the defects of continuous casting surface cracks of steel, the production load of a rolling mill, the yield ratio is low, the center segregation is serious, the center segregation is avoided, and, The alloy has the problems of low alloy cost, low market competitiveness and the like, has higher strength, low yield ratio, good coating and surface quality and excellent cold-processing formability, and can be used for producing products such as encaustic tiles, goods shelves, welded pipes and the like.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a manufacturing method of a cold-rolled hot-galvanized high-strength structural steel with yield strength of 350MPa, which comprises the following steps:
the manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa comprises the following process routes in sequence: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, slab continuous casting, hot continuous rolling, acid washing, cold continuous rolling, annealing hot galvanizing, finishing and straightening.
Further, smelting molten steel in a converter: controlling S in molten iron to be less than or equal to 0.0050 Wt%, and easily producing low melting point with Fe element in steel when S content is too highFeS causes edge surface defects in the steel sheet, and S also produces titanium carbosulfide with Ti in the steel, thereby weakening the strengthening effect of Ti, so that the lower the S content, the better. Binary basicity R (CaO/Al) of slag2O3) The alkalinity is controlled to be 2.5-3.5, the alkalinity is a sign of P, S removing capacity of slag, the alkalinity control method can improve P, S removing capacity, and bottom blowing argon and inert gas protection are adopted in the whole smelting process.
Further, LF molten steel refining treatment: performing deoxidation and Al, Mn, Ti and other alloying processes to refine the top slag with binary basicity R (calcium oxide/aluminum oxide CaO/Al)2O3) The alkalinity is controlled to be 8-12, and the P, S removing capacity can be improved by controlling the alkalinity. The molten steel is treated with Ca, calcium/aluminium [ Ca ]]/[Als][ Ca ] of the present invention controlled at 0.10 to 0.14]/[Als]The proportion control can improve the casting performance of the molten steel and can not bring adverse effects to the solidification behavior of the molten steel in the crystallizer. After the Ca treatment is finished, soft argon blowing is carried out on the steel ladle for 8-15 min, the argon blowing time is mainly related to the capacity of the steel ladle and the steel type, the argon blowing time is not too long, otherwise, the temperature drop is too large, the refractory material is seriously scoured, but generally not less than 3min, if the argon blowing time is not enough, the carbon-oxygen reaction cannot be fully carried out, non-metallic inclusions and gases cannot be effectively removed, and the argon blowing effect is not obvious. The steel ladle molten steel calming time between the soft argon blowing end and the continuous casting steel ladle casting is controlled to be 15-30 min, the steel liquid calming time in the furnace is too long, and the temperature loss in the furnace is large from the energy consumption perspective, so that the heat utilization of the converter is not facilitated; from the quality of steel grades, nitrogen is easy to absorb in the furnace sedation process, which leads to the reduction of the quality of the steel grades, and the energy consumption is low under the condition of not influencing the quality of the steel grades by the time control of the invention.
Further, slab continuous casting: the automatic slag discharging detection control of the ladle is required to be put into use, the superheat degree of pouring of the tundish is 10-30 ℃, the alkali covering agent is used in the tundish, the plain carbon steel covering slag is used, the casting blank drawing speed is 1.10-1.50 m/min, the drawing speed of the invention is improved under the condition that no crack is generated in the steel, the liquid level fluctuation of the crystallizer is automatically controlled, and the fluctuation range is controlled to be +/-3 mm.
Further, hot continuous rolling: controlling the heating soaking temperature of the casting blank to 1250-1280 ℃, so that the steel blank is fully austenitized and most alloying elements are fully dissolved, and preparing for obtaining uniformly refined tissues and second-phase particles; the control target of the rough rolling finishing temperature is 1050-1090 ℃, the control target of the finish rolling finishing temperature is 850-880 ℃, enough deformation in an austenite low-temperature region is ensured, and meanwhile, the deformation in a two-phase region is avoided to obtain mixed crystals, so that a hot rolled plate obtains a uniformly refined structure; the coiling temperature is controlled to be 580-620 ℃, so that second phase particles of Ti in the steel can be fully precipitated, and meanwhile, the structure refinement is ensured as much as possible.
Further, acid pickling and cold continuous rolling: the cold rolling reduction rate is 65-80%, and the large cold deformation degree can enable the steel plate to obtain fine grain size and less dispersedly distributed cementite in the subsequent annealing and galvanizing process, so that the strength of the product is improved.
Further, the annealing galvanizing process comprises the following steps: the proper annealing process parameters can ensure that the steel plate is fully recrystallized, crystal grains are equiaxial, cementite is dispersed and precipitated, and second phase particles are fine and uniformly precipitated, so that the product has good mechanical property and surface quality. The annealing process is mainly divided into hood annealing and continuous annealing. The temperature control target of the soaking section is 700-730 ℃, the terminal temperature control target of the slow cooling section is 650-680 ℃, the terminal temperature control target of the fast cooling section is 490-500 ℃, the temperature control target of the zinc pot is 470-480 ℃, the temperature control target of the zinc liquid is 460 ℃, and the weight (double surfaces) of the zinc coating of the hot-dip galvanized steel coil is 180-280 g/m 2.
Further, the finishing and withdrawal and straightening process comprises the following steps: the finishing elongation is controlled according to 1.0-1.6% of the thickness of different strip steels, and the straightening elongation is controlled according to 0.4-1.0%, mainly aiming at eliminating the tensile yield platform of the strip steels after recrystallization annealing, eliminating the wave shape and improving the surface quality of the galvanized sheet.
Further, the steel manufactured by the manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa comprises the following chemical components in percentage by weight: 0.10 Wt% -0.18 Wt%, silicon Si is less than or equal to 0.03 Wt%, manganese Mn: 0.15 Wt% -0.40 Wt%, phosphorus P: 0.060 Wt% to 0.075 Wt%, sulfur S: less than or equal to 0.008 Wt%, aluminum Als: 0.015-0.040 Wt%, Ti: 0.045 Wt% -0.080 Wt%, nitrogen N is less than or equal to 0.0040 Wt%, Si + P is less than or equal to 0.090 Wt%, Mn/S is greater than or equal to 20%, and the balance is Fe and inevitable trace elements.
C of the present invention: 0.10 Wt% -0.18 Wt%, carbon is the cheapest strengthening element in the steel, C can promote the formation of cementite and pearlite and the precipitation of other carbides, the strength of the steel is improved through solid solution strengthening, structure strengthening and precipitation strengthening, particularly, the tensile strength can be obviously improved so as to reduce the yield ratio of the steel, but the plasticity of the steel is also reduced, therefore, the content of C is improved as much as possible on the premise of ensuring no problem of forming performance, the addition amount of other precious alloy elements can be reduced, and the production cost is reduced.
According to the invention, Si is less than or equal to 0.03%, the high content of Si brings difficulty to hot galvanizing, deteriorates the quality of a zinc layer, and forms oxide inclusions with poor ductility to reduce the plasticity (cold forming property) of steel, so that the lower the content of Si is, the better the control is.
Mn of the present invention: 0.15 Wt% -0.40 Wt%, S: less than or equal to 0.008 Wt%. Mn can play a role in refining grains in steel, and can play a role in solid solution strengthening, but the problem of product center segregation is caused by excessively high Mn content, and the production cost is also higher. The high S content is easy to produce FeS with low melting point with Fe element in steel, so that the problem of edge surface defect of the steel plate is caused, and the Mn/S in the steel is required to be more than or equal to 20; meanwhile, S and Ti in steel produce titanium carbosulfide, so that the strengthening effect of Ti is weakened. Therefore, the lower the S content control, the better.
P of the present invention: 0.060 Wt% -0.075 Wt%, P is very cheap as alloying element in steel, and the solid solution strengthening effect of P can obviously improve the strength of the product. However, P deteriorates the quality of the zinc coating and has an effect similar to that of Si, so that Si + P in the steel must be strictly controlled to 0.090 Wt% to ensure good quality of the zinc coating.
Als of the present invention: 0.015 to 0.040%. Al can play a role in deoxidizing and refining grains in steel, and the microalloying effect of Ti is ensured.
Ti of the present invention: 0.045 Wt% -0.080 Wt%. Compared with noble alloys such as Nb, V and the like, the Ti has lower cost and remarkable precipitation strengthening effect.
The N is less than or equal to 0.0040 Wt%. N in steel can form large-particle TiN in Ti to deteriorate the plasticity of the product and reduce effective Ti in the steel so as to weaken the precipitation strengthening effect of Ti; in addition, N causes aging of product properties, so that the lower the N content, the better the N content control.
The invention specifically discloses a production method of a cold-rolled hot-galvanized high-strength structural steel with 350 MPa-grade yield strength, which adopts the following component proportions and specific processes. Wherein, Table 1 shows the compositions (in weight%) of the steels of the respective examples. Tables 2 and 3 are the process parameters corresponding to the example steels described in table 1. Table 4 shows the properties of the steel compositions according to the examples of Table 1.
TABLE 1 product chemistry (Wt%)
TABLE 2 specific Process parameters for the examples
TABLE 3 specific Process parameters for the examples
TABLE 4 comprehensive properties of the cold-rolled hot-dip galvanized high-strength structural steel obtained in each example
The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa has the yield strength Rp0.2 (or ReL) of 370-460 MPa, the tensile strength Rm of 470-540 MPa and the elongation A80mm28 to 34 percent, and the weight (double surfaces) of the zinc coating is 180 to 280g/m2Through reasonable component design and process controlThe method does not need to add noble alloys such as Nb, V and the like, does not need to control the high Mn content in the steel, meanwhile, the measures of rolling with large reduction, low-temperature coiling, continuous annealing low-temperature rapid cooling and the like are not required, the production method has the advantages that through economic chemical component design, the production scheme and the production technology of smelting, continuous casting, hot rolling, cold rolling, annealing and galvanizing by taking a hot continuous rolling production line and a continuous annealing galvanizing production line as core processes are formed, the problems of surface crack defects of continuous casting, large production load of a rolling mill, low yield ratio, serious center segregation, low alloy cost, low market competitiveness and the like of the series of products are solved, the produced cold-rolled hot-galvanized high-strength structural steel with 350 MPa-grade yield strength has high strength, low yield ratio, good coating and surface quality and excellent cold-working forming performance, and can be used for producing products such as color tiles, goods shelves, welded pipes and the like.
What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or".
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A manufacturing method of cold-rolled hot-galvanized high-strength structural steel with 350 MPa-grade yield strength is characterized by comprising the following steps of:
the manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa comprises the following process routes in sequence: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, LF molten steel refining treatment, slab continuous casting, hot continuous rolling, acid washing, cold continuous rolling, annealing hot galvanizing, finishing and straightening.
2. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
the converter molten steel smelting process comprises the following steps: controlling S to be less than or equal to 0.0050 Wt% in molten iron entering the furnace and controlling the binary alkalinity of slag RCaO/Al2O3Controlling the temperature to be 2.5-3.5, and adopting bottom blowing argon in the whole smelting process.
3. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
in the LF molten steel refining treatment process: performing deoxidation and alloying processes of Al, Mn, Ti and the like, refining the top slag with binary alkalinity RCaO/Al2O3Controlling the molten steel to be 8-12, carrying out Ca treatment on the molten steel, controlling the Ca/Als to be 0.10-0.14, carrying out soft argon blowing on the steel ladle for 8-15 min after the Ca treatment is finished, and controlling the steel ladle molten steel calming time between the soft argon blowing end and the continuous casting ladle casting to be 15-30 min.
4. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
in the slab continuous casting: the automatic slag discharging detection control of the ladle is required, the superheat degree of pouring of the tundish is 10-30 ℃, the alkali covering agent is used in the tundish, the plain carbon steel covering slag is used, the casting blank drawing speed is 1.10-1.50 m/min, the liquid level fluctuation of the crystallizer is automatically controlled, and the fluctuation range is controlled to be +/-3 mm.
5. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
the hot continuous rolling process comprises the following steps: the control target of the heating soaking temperature of the casting blank is 1250-1280 ℃, the control target of the rough rolling and final rolling temperature is 1050-1090 ℃, the control target of the finish rolling and final rolling temperature is 850-880 ℃, and the control target of the coiling temperature is 580-620 ℃.
6. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
the pickling and cold continuous rolling process comprises the following steps: and the cold rolling reduction rate is 65-80%.
7. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
in the annealing galvanizing process: the temperature control target of the soaking section is 700-730 ℃, the terminal temperature control target of the slow cooling section is 650-680 ℃, the terminal temperature control target of the fast cooling section is 490-500 ℃, the temperature control target of the zinc pot is 470-480 ℃, the temperature control target of the zinc liquid is 460 ℃, and the weight of the zinc coating of the hot-dip galvanized steel coil is 180-280 g/m2。
8. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
the finishing and withdrawal and straightening process comprises the following steps: the finishing elongation is controlled according to 1.0-1.6% of the thickness of different strip steels, and the withdrawal and straightening elongation is controlled according to 0.5-1.0%.
9. The manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa according to claim 1, characterized by comprising the following steps:
the steel manufactured by the manufacturing method of the cold-rolled hot-galvanized high-strength structural steel with the yield strength of 350MPa comprises the following chemical components in percentage by weight: 0.10 Wt% -0.18 Wt%, silicon Si is less than or equal to 0.03 Wt%, manganese Mn: 0.15 Wt% -0.40 Wt%, phosphorus P: 0.060 Wt% to 0.075 Wt%, sulfur S: less than or equal to 0.008 Wt%, aluminum Als: 0.015-0.040 Wt%, Ti: 0.045 Wt% -0.080 Wt%, nitrogen N is less than or equal to 0.0040 Wt%, Si + P is less than or equal to 0.090 Wt%, Mn/S is greater than or equal to 20%, and the balance is Fe and inevitable trace elements.
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| CN114525392A (en) * | 2022-02-22 | 2022-05-24 | 新疆八一钢铁股份有限公司 | Preparation method of titanium-carbon bistable carbon structural steel cold-rolled sheet |
| CN116219278A (en) * | 2022-12-21 | 2023-06-06 | 本钢板材股份有限公司 | Hot galvanizing low-carbon high-strength steel for ton barrels and manufacturing method thereof |
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