CN113897540A - High-strength cold-rolled steel plate for precisely-stamped automobile seat adjuster fluted disc - Google Patents
High-strength cold-rolled steel plate for precisely-stamped automobile seat adjuster fluted disc Download PDFInfo
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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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
- C21D8/0226—Hot rolling
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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
- C21D8/0236—Cold rolling
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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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- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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Abstract
The invention discloses a high-strength cold-rolled steel plate for a precision stamping automobile seat adjuster fluted disc, which solves the technical problems of low strength and low hardness of the existing cold-rolled steel plate for the precision stamping automobile seat adjuster fluted disc. The technical scheme is that a high-strength cold-rolled steel plate for a precise stamping automobile seat adjuster fluted disc comprises the following chemical components in percentage by weight: c: 0.20 to 0.26%, Si: 0.10 to 0.30%, Mn: 0.90-1.20%, B: 0.001-0.003%, Ti: 0.02-0.04%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities; tensile strength R of 3.0-5.0 mm thicknessm420 to 470MPa, and 70 to 76HRB Rockwell hardness. The cold-rolled steel sheet has low cost and can be usedAnd (3) manufacturing parts such as the fluted disc of the automobile seat adjuster and the like by high-speed precision stamping.
Description
Technical Field
The invention relates to a cold-rolled steel plate for precision stamping, in particular to a high-strength cold-rolled steel plate for a precision stamping automobile seat adjuster fluted disc and a manufacturing method thereof, and specifically relates to a cold-rolled steel plate for a 420 MPa-level tensile strength precision stamping automobile seat adjuster fluted disc and a manufacturing method thereof, belonging to the technical field of iron-based alloys.
Background
The automobile seat adjusting system part is produced in an early stage always through a machining mode due to the fact that the structure is complex and the size precision is high, the used traditional raw materials are bar products produced by an electric furnace steel mill, but the yield in the machining process is low, the stability of the raw materials is poor, and the consumption of the raw materials is large.
In recent years, with the rapid development of the domestic fine blanking industry, the plate coiled material with stable service performance replaces a plate bar material to perform high-speed precise stamping, which is a trend of industry development. The fine blanking process is complex in forming and has strict requirements on the internal quality, performance, precision and the like of the material. Generally, the low hardness of the material is beneficial to processing and fine blanking forming, so that the hot rolled steel strip produced by the hot continuous rolling mill needs to be subjected to cold deformation and spheroidizing annealing treatment to improve the internal structure, so that the strength and the toughness of the material are well matched; therefore, the method can be well applied to the precision stamping industry, such as manufacturing precision parts of automobiles, machinery, hardware, instruments and the like.
The early automobile seat adjusting system parts have certain strength and higher toughness in order to meet the requirement of high-speed fine blanking, but have the problems of low hardness, low wear resistance and short service life after heat treatment. In order to improve the service performance of parts after heat treatment, the development of fine blanking materials with higher strength (hardness) becomes the key of the development of fine blanking technology. Meanwhile, the material has high toughness, uniform internal structure and good pearlite spheroidization after cold rolling and annealing, meets the requirement of high-speed fine blanking, and realizes the renewal of fine blanking materials.
The patent application with the application publication number of CN106498297A discloses a cold-rolled steel plate for a fluted disc of a precision stamping automobile seat adjuster and a manufacturing method thereof, wherein the cold-rolled steel plate comprises the following chemical components in percentage by weight: c: 0.15 to 0.20%, Si: less than or equal to 0.05 percent, Mn: 0.6-0.8%, P: less than or equal to 0.018%, S: less than or equal to 0.008 percent, Al: 0.03-0.07 percent of N, less than or equal to 0.0060 percent of N; the balance of Fe and inevitable impurities. The low-carbon-content and conventional Mn and Al deoxidizing element design is adopted, and the obtained material is low in strength and hardness, and only has the tensile strength of 350-390 MPa and the hardness of HRB 60-68. Although the material can meet the requirement of fine blanking forming, the strength and the hardness of the material cannot meet the use requirement of high strength load.
Patent application with application publication number CN103160738A discloses a low-cost boron-containing steel and a manufacturing method thereof, which comprises the following chemical components: c: 0.05-0.08%, Si: 0.10 to 0.25%, Mn: 1.6-1.8%, Al: 0.03-0.045%, Ti: 0.030-0.045%, B: 0.003 to 0.009 percent, P is less than or equal to 0.025 percent, S is less than or equal to 0.015 percent, and O is less than or equal to 0.0015 percent; n is less than or equal to 0.0025 percent; the balance of Fe and inevitable impurities. The patent relates to manufacturing low-carbon boron-containing hot-rolled structural steel, adopts a low-carbon cold forming processing design, and belongs to the application of common structural steel; the material can not be subjected to complex fine blanking processing and can not be used for heat treatment, and the content of alloy elements such as manganese, boron and the like is high, so that the production and manufacturing cost is high.
Disclosure of Invention
The invention aims to provide a high-strength cold-rolled steel plate for a precision stamping automobile seat adjuster fluted disc and a manufacturing method thereof, which solve the technical problems of low strength and low hardness of the existing cold-rolled steel plate for the precision stamping automobile seat adjuster fluted disc; the fluted disc of the automobile seat regulator manufactured by the cold-rolled steel sheet precision stamping process has the advantages of high hardness, good wear resistance, long service life and low cost.
The technical idea of the invention is that a component design method of improving the content of C, Mn alloy elements in steel and adding a certain amount of element B with high hardenability is adopted to further control P, S harmful elements, and a small amount of micro-alloy element Ti is added to fix the element N in the steel, so that the added element B is completely converted into solid solution B in the steel, and the aim of improving the hardenability of parts after heat treatment is achieved. Meanwhile, the temperature in the hot rolling process and the cold rolling annealing process are controlled, the spheroidizing annealing effect of pearlite is improved, the hardness in the material process is reduced, and the steel strip for the automobile safety system parts meeting the requirement of high-speed fine blanking is obtained.
The invention has the technical scheme that a high-strength cold-rolled steel plate for a fluted disc of a precision stamping automobile seat adjuster comprises the following chemical components in percentage by weight: c: 0.20 to 0.26%, Si: 0.10 to 0.30%, Mn: 0.90-1.20%, B: 0.001-0.003%, Ti: 0.02-0.04%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities.
The metallographic structure of the cold-rolled steel plate is massive ferrite and granular pearlite, and the grain size of the ferrite in the metallographic structure is I7.0-9.0 grade; the spheroidization rate is more than or equal to 92 percent; yield strength R of cold-rolled steel sheet with thickness of 3.0-5.0 mmP0.2250 to 300MPa, tensile strength Rm420 to 470MPa, a yield ratio of 0.50 to 0.65 and a post-fracture elongation A50mm34-40% and 70-76 HRB Rockwell hardness.
The reason why the chemical composition of the cold rolled steel sheet for the toothed disc of the high-strength precision press-formed automobile seat adjuster is limited to the above range is as follows:
c: carbon is the main alloying element for pearlite formation and affects the hardness of the material after hot rolling, cold rolling, annealing and quenching of parts. The C content is too low, the hardenability of steel is reduced, and the final high hardness requirement of parts cannot be met; if the content of C is too high, the plastic toughness is obviously reduced, and the complex forming is not facilitated. The range of carbon addition in the present invention is 0.20 to 0.26%.
Si: silicon is used as a solid solution strengthening element, has a certain strengthening effect when being dissolved in a steel strip matrix, and plays a role in deoxidation and desulfurization as a deoxidizer during smelting. However, when the amount is large, the ferrite phase is hardened, and the workability is remarkably lowered. Si promotes the generation of the rust red iron oxide skin defect on the surface of the steel coil in the hot rolling process, and the appearance of a finished product is influenced; therefore, the Si content in the invention is designed to be between 0.1 and 0.3 percent.
Mn: manganese is a good deoxidizer and desulfurizer. The steel contains a certain amount of manganese, so that the hot workability of the steel can be eliminated or improved, and the hardenability can be obviously improved. However, when the content is too large, the composition segregation is caused, the structure is not uniform, and the moldability of the material is rapidly lowered. Therefore, in the present invention, Mn is limited to 0.9 to 1.2%.
P: phosphorus is an impurity element, segregates in a grain boundary to reduce the processing performance, and hopefully reduces the content of the phosphorus as much as possible to improve the forming performance; but considering the control capability of process equipment and dephosphorization cost, the invention limits P to be less than or equal to 0.015 percent.
S: sulfur is an impurity element, and forms inclusions such as MnS and the like in steel, thereby affecting fine blanking performance. It is desirable to reduce the content thereof as much as possible; considering the practical control capacity and desulfurization cost, the invention limits S to be less than or equal to 0.005 percent.
B: boron can obviously improve the hardenability of the material, and the hardenability of the material can be obviously improved only by lower content. Further increases in boron content do not significantly increase hardenability, and too high a boron content can reduce the toughness of the material and also increase the alloy cost of the material. Therefore, the content of B is limited to 0.001-0.003%.
Ti: titanium is a strong deoxidizer in steel, and can make the internal structure of steel compact and refine grains. And is also an effective element for fixing N in steel. The effective Ti content needs to be determined according to the N content in the steel; if the titanium content is too high, the hot rolling strength of the material is obviously increased, and the performance fluctuation is large, so that the subsequent processing of a user is not facilitated. Therefore, the content of Ti is limited to 0.02-0.04%.
N: nitrogen is a BN-forming element, which in combination with boron hinders the hardenability effect of boron. The smaller the amount of N, the more preferable, the more expensive the steel refining cost is. The present invention defines the upper limit as 0.0030%.
A manufacturing method of a high-strength and precise stamping cold-rolled steel plate for a fluted disc of an automobile seat adjuster comprises the following steps:
continuously casting molten steel to obtain a continuous casting plate blank, wherein the molten steel comprises the following components in percentage by weight: c: 0.20 to 0.26%, Si: 0.10 to 0.30%, Mn: 0.90-1.20%, B: 0.001-0.003%, Ti: 0.02-0.04%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities;
heating the continuous casting plate blank at 1170-1210 ℃ for 180-270 min, and then carrying out hot rolling, wherein the hot rolling is a two-stage rolling process, the rough rolling is 5-pass continuous rolling, and the rolling is carried out at the austenite recrystallization temperature or above; the finish rolling is 7-pass continuous rolling, and the finish rolling finishing temperature is 800-860 ℃; after finish rolling, controlling the thickness of the steel plate to be 4.5-8.0 mm, adopting front-section cooling for laminar cooling, and coiling at 540-600 ℃ to obtain a hot-rolled steel coil;
the hot rolled steel coil is uncoiled again, then is subjected to acid cleaning, cold rolling and annealing in a hood-type annealing furnace, and is coiled to obtain a finished cold rolled steel plate with the thickness of 3.0-5.0 mm; the cold rolling reduction rate is 30-45%, the annealing temperature of the cold-rolled hard steel strip in the soaking section of the hood-type annealing furnace is 690-710 ℃, and the annealing time of the steel strip in the soaking section is 16-20 h.
The production process adopted by the invention has the following reasons:
1. setting of heating temperature and heating time of continuous casting slab
The heating temperature and time of the continuous casting slab are set to ensure that alloy elements such as C, Si, Mn and the like in the continuous casting slab are fully diffused and dissolved, and coarse carbide particles are dissolved and uniformly distributed in steel. Both too low a temperature and too short a heating time do not achieve the above objectives. The medium slab heating temperature is adopted, the target temperature is 1200 ℃, if the temperature is too high, the heating time is too long, the oxidation and decarburization on the surface of the slab are serious, the final performance and the surface quality of a steel strip are not facilitated, and energy is consumed at the same time. Therefore, the heating temperature of the continuous casting slab is set to 1180-1220 ℃, and the heating time is set to 180-240 min.
2. Setting of finish Rolling finishing temperature
The finish rolling temperature of the invention is set to have two functions, on one hand, flat austenite grains with deformation zones inside are obtained by rolling the material in an austenite non-recrystallization area and are converted into fine ferrite grains in the subsequent laminar cooling process, thus playing the roles of refining the grains and reducing the zonal segregation; on the other hand, if the finish rolling temperature is too low, the rolling load becomes too large, and the rolling stability is impaired. Therefore, the finish rolling finishing temperature is set to be 800-860 ℃.
3. Setting of laminar cooling mode after finish rolling
The laminar cooling after the finish rolling adopts a front-stage cooling process, so that austenite in the material structure after the finish rolling can be promoted to be rapidly converted into ferrite, the grains are refined, and the structure is uniform.
4. Setting of coiling temperature in Hot Rolling
The hot rolling coiling temperature mainly influences the structure and the performance of the material and the subsequent spheroidizing annealing effect. The lower coiling temperature is adopted, so that the crystal grains can be refined, the structure is uniform, and the subsequent spheroidizing annealing is facilitated. However, the excessively low coiling temperature can obviously increase the strength of the hot rolled material, and the brittleness of the steel coil is increased, so that the further uncoiling and splitting and cold rolling processing are not facilitated. Therefore, the hot rolling coiling temperature is set to be 540-600 ℃.
5. Setting of Cold Rolling reduction
The cold rolling deformation is an important means for improving the dimensional precision of the steel strip and meets the requirement of continuous fine blanking processing. Meanwhile, the increase of the cold rolling deformation can also promote the fracture of lamellar pearlite, so that the dislocation density in the material is greatly increased, and more energy is provided for spheroidization transformation of the pearlite. However, too high deformation will cause too large load on the cold rolling mill, increase the number of cold rolling passes, and greatly increase the cost of cold rolling. Comprehensively, the cold rolling reduction rate is preferably 30-45%.
6. Setting of annealing temperature and annealing time
The invention adopts the cover type annealing furnace for annealing, and the thermodynamic calculation shows that the material A of the invention1The point (equilibrium pearlite transformation) transformation temperature is 712.8 ℃. In consideration of the effect of cold rolling deformation accumulation in the preceding step, the advance spheroidization of lamellar pearlite is promoted, and generally, the spheroidization is carried out at A1Annealing is performed below the point temperature. Too high annealing temperature can cause coarse ferrite grains and obvious decarburization on the surface of the steel strip, and the final service performance of the material is influenced. In order to improve the spheroidizing annealing effect, the annealing temperature of the steel strip in the soaking section of the hood-type annealing furnace is set to be 690-710 ℃.
The heat preservation time of the soaking section is also very critical during annealing; if the heat preservation time is too short, the lamellar pearlite chains cannot be completely fused and disconnected; fine spherical particles cannot be generated, and the dispersion distribution is formed; if the heat preservation time is too long, the granular pearlite can grow up again and agglomerate together to form lamellar segregation, so that the toughness of the material is reduced, and the subsequent fine blanking processing is not facilitated. In order to improve the spheroidizing annealing effect, the annealing time of the steel strip in the soaking section is 16-20 h.
The metallographic structure of the cold-rolled steel plate produced by the method is massive ferriteThe ferrite plus the granular pearlite, wherein the grain size of the ferrite in the metallographic structure is I7.0-9.0 grade; the spheroidization rate is more than or equal to 92 percent; yield strength R of Cold rolled Steel sheetP0.2250 to 300MPa, tensile strength Rm420 to 470MPa, a yield ratio of 0.50 to 0.65 and a post-fracture elongation A50mm34-40% and 70-76 HRB Rockwell hardness.
Compared with the prior art, the invention has the following positive effects: 1. the hardness of the material is improved by adopting higher carbon content in the component design, and the hardenability and hardness of the material are obviously improved by adding a small amount of microalloy element B, Ti; obtaining a high-hardness cold-rolled fine-stamped steel plate for the fluted disc of the high-strength automobile seat device, wherein the yield strength R of the cold-rolled steel plateP0.2250 to 300MPa, tensile strength Rm420 to 470MPa, a yield ratio of 0.50 to 0.65 and a post-fracture elongation A50mm34-40% and 70-76 HRB Rockwell hardness. The method is suitable for complex fine blanking and forming, can meet the requirement of high hardness of parts after heat treatment, and has the advantages of low alloy consumption and low manufacturing cost. 2. According to the invention, the effects of Mn and Ti alloy elements are exerted by controlling the hot rolling coiling temperature and the cooling process after rolling; obtaining the hot-rolled steel coil with refined grains and uniform structure, wherein the structure is as follows: ferrite + fine lamellar pearlite; the toughness is moderate, which is beneficial to the subsequent cold rolling and annealing. 3. The invention adopts the large cold rolling reduction rate and the reasonable annealing process, so that the strength of the cold-rolled steel strip is greatly reduced, and the toughness is excellent; the annealed steel coil is fully spheroidized and uniformly distributed; the requirement of high-speed fine blanking is met.
Drawings
FIG. 1 is a photograph of a metallographic structure of a hot-rolled steel sheet according to example 3 of the invention, at a magnification of 500.
FIG. 2 is a photograph of a metallographic structure of a cold-rolled and annealed steel sheet according to example 3 of the present invention at a magnification of 500.
Detailed Description
The present invention is further illustrated in the following examples 1 to 5, which are shown in tables 1 to 4.
Table 1 shows the chemical composition (in weight%) of the steels of the examples of the invention, the balance being Fe and unavoidable impurities.
Table 1 chemical composition of the steels of the examples of the invention, in units: weight percent.
Molten steel meeting the basic requirements of chemical components is obtained by smelting in a converter, after the molten steel is subjected to deep desulfurization and fine adjustment of alloy components in an LF ladle refining furnace, a RH furnace is subjected to vacuum cycle degassing treatment, the RH pure degassing time is more than 8 minutes, and a continuous casting slab is obtained by casting in a continuous casting machine; the thickness of the continuous casting slab is 210-230 mm, the width is 1000-1500 mm, and the length is 8500-11000 mm.
The fixed-length slab produced by steel making is directly sent to a heating furnace to be reheated, taken out of the furnace to be descaled and then sent to a hot continuous rolling mill set to be rolled. Controlling rolling by a rough rolling and finish rolling continuous rolling unit, carrying out coiling after laminar cooling, and producing a hot rolled steel coil by adopting a front-section cooling mode through the laminar cooling; the thickness of the hot rolled steel plate is 4.5-8.0 mm, referring to fig. 1, the metallographic structure of the hot rolled steel plate is ferrite and fine pearlite; the hot rolling process control parameters are shown in Table 2.
TABLE 2 Hot Rolling Process control parameters of the inventive examples
The hot rolled steel coil is uncoiled again and then is pickled, and is subjected to multi-pass cold rolling on a reversible rolling mill or a single-stand cold rolling mill after being split according to the width specification, wherein the cold rolling reduction rate is 30-45%; annealing the cold-rolled hard steel coil through a hood-type annealing furnace to obtain a finished cold-rolled steel plate with the thickness of 3.0-5.0 mm, wherein the annealing process comprises the following steps: the annealing temperature of the cold-rolled hard-state steel strip in the soaking section of the hood-type annealing furnace is 690-710 ℃, and the annealing time (soaking section) is 16-20 h. The control parameters of the cold rolling and annealing processes are shown in Table 3.
TABLE 3 control parameters of the cold rolling and annealing processes of the present invention
| Cold rolling and annealing parameters | Cold rolling reduction/%) | Annealing temperature/. degree.C | Annealing time/h | Thickness/mm of cold-rolled steel sheet |
| The invention | 30～45 | 690～710 | 16～20 | 3.0～5.0 |
| Example 1 | 36.0 | 700 | 20.0 | 4.8 |
| Example 2 | 38.5 | 705 | 18.5 | 4.0 |
| Example 3 | 33.3 | 695 | 18.0 | 3.0 |
| Example 4 | 41.7 | 705 | 17.0 | 3.5 |
| Example 5 | 34.0 | 700 | 19.0 | 3.3 |
Referring to fig. 2, the cold-rolled steel sheet obtained by the method has a metallographic structure of bulk ferrite and granular pearlite, and the grain size of the ferrite in the metallographic structure is in the grade of I7.0 to 9.0; the spheroidization rate is more than or equal to 92 percent; yield strength R of Cold rolled Steel sheetP0.2250 to 300MPa, tensile strength Rm420 to 470MPa, a yield ratio of 0.50 to 0.65 and a post-fracture elongation A50mm34-40% and 70-76 HRB Rockwell hardness.
The cold-rolled steel strip obtained by the invention is subjected to tensile, microstructure and hardness detection according to a metal material tensile test method (GB/T228.1), a steel microstructure evaluation method (GB/T13299) and a metal material Rockwell hardness test method (GB/T230.1), and the mechanical properties of the cold-rolled steel strip are shown in Table 4.
TABLE 4 Performance index of cold-rolled steel sheets according to examples of the present invention
The cold-rolled steel plate obtained by the invention has high strength, higher elongation and plasticity, and pearlite is in a fine granular shape and is uniformly distributed; the requirement of precise stamping is met.
In addition to the above embodiments, the present invention may have other embodiments; all technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (5)
1. A high-strength cold-rolled steel plate for a precisely-punched automobile seat adjuster fluted disc comprises the following chemical components in percentage by weight: c: 0.20 to 0.26%, Si: 0.10 to 0.30%, Mn: 0.90-1.20%, B: 0.001-0.003%, Ti: 0.02-0.04%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities; yield strength R of cold-rolled steel sheet with thickness of 3.0-5.0 mmP0.2250 to 300MPa, tensile strength Rm420 to 470MPa, a yield ratio of 0.50 to 0.65 and a post-fracture elongation A50mm34-40% and 70-76 HRB Rockwell hardness.
2. The cold-rolled steel sheet for a high-strength precision stamped automobile seat adjuster fluted disc as claimed in claim 1, wherein the metallographic structure of the cold-rolled steel sheet is bulk ferrite + granular pearlite, and the grain size of ferrite in the metallographic structure is in the order of I7.0 to 9.0; the spheroidization rate is more than or equal to 92 percent.
3. A manufacturing method of a cold-rolled steel plate for a fluted disc of a high-strength precision stamping automobile seat adjuster is characterized by comprising the following steps:
continuously casting molten steel to obtain a continuous casting plate blank, wherein the molten steel comprises the following components in percentage by weight: c: 0.20 to 0.26%, Si: 0.10 to 0.30%, Mn: 0.90-1.20%, B: 0.001-0.003%, Ti: 0.02-0.04%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities;
heating the continuous casting plate blank at 1170-1210 ℃ for 180-270 min, and then carrying out hot rolling, wherein the hot rolling is a two-stage rolling process, the rough rolling is 5-pass continuous rolling, and the rolling is carried out at the austenite recrystallization temperature or above; the finish rolling is 7-pass continuous rolling, and the finish rolling finishing temperature is 800-860 ℃; after finish rolling, adopting front-section cooling for laminar cooling, and coiling at 540-600 ℃ to obtain a hot-rolled steel coil;
the hot rolled steel coil is uncoiled again, then is subjected to acid cleaning, cold rolling and annealing in a hood-type annealing furnace, and is coiled to obtain a finished cold rolled steel plate with the thickness of 3.0-5.0 mm; the cold rolling reduction rate is 30-45%, the annealing temperature of the cold-rolled hard steel strip in the soaking section of the hood-type annealing furnace is 690-710 ℃, and the annealing time of the steel strip in the soaking section is 16-20 h.
4. The method of manufacturing a high-strength cold rolled steel sheet for a toothed disc of a precisely stamped car seat adjuster as set forth in claim 3, wherein the thickness of the hot rolled steel sheet is controlled to be 4.5 to 8.0mm after the finish rolling.
5. The method for manufacturing a cold-rolled steel sheet for a toothed disc of a high-strength precision-stamped automobile seat adjuster according to claim 3, wherein the metallographic structure of the cold-rolled steel sheet is bulk ferrite + granular pearlite, and the grain size of ferrite in the metallographic structure is in the order of I7.0 to 9.0; the spheroidization rate is more than or equal to 92 percent; yield strength R of Cold rolled Steel sheetP0.2250 to 300MPa, tensile strength Rm420 to 470MPa, a yield ratio of 0.50 to 0.65 and a post-fracture elongation A50mm34-40% and 70-76 HRB Rockwell hardness.
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