CN112795731A - Cold-rolled steel plate for lampshade and production method thereof - Google Patents
Cold-rolled steel plate for lampshade and production method thereof Download PDFInfo
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0203—Cooling
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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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
- B21B2001/225—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length by 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
- 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
Abstract
The invention discloses a lamp shade cooling deviceA rolled steel plate and a production method thereof mainly solve the technical problems of high manufacturing cost and unstable material performance of the existing cold-rolled steel plate for the lampshade. The invention provides a cold-rolled steel sheet for a lampshade, which comprises the following chemical components in percentage by weight: c: 0.026-0.049%, Si is less than or equal to 0.034%, Mn: 0.15-0.25%, P is less than or equal to 0.020%, S is less than or equal to 0.0154%, N is less than or equal to 0.0035%, Al: 0.025 to 0.05 percent, B: 0.001 to 0.002%, and the balance of Fe and inevitable impurity elements. Yield strength R of cold-rolled steel sheet with thickness of 0.25-0.40 mmP0.2220 to 260MPa, tensile strength Rm330 to 380MPa, elongation after break A50mm35 to 45 percent. The product of the invention is mainly suitable for cold-rolled steel plates for lampshades.
Description
Technical Field
The invention relates to a cold-rolled steel plate and a production method thereof, in particular to a cold-rolled steel plate for a lampshade and a production method thereof, and belongs to the technical field of iron-based alloys.
Background
The cold-rolled steel sheet for the lamp shade's main function is the lamp shade with the steel sheet punching press becomes the desk lamp, and its key performance requirement is that the steel sheet performance is even, has good punching press performance. Steel plate yield strength R required by steel for cold-rolled lampshadeP0.2220 to 260MPa, tensile strength Rm330 to 380MPa, elongation after break A50mm35 to 45%, and the surface roughness Ra of the steel plate is 0.50 to 0.80 μm.
The key of the production process of the cold-rolled steel plate is to obtain the final product performance by matching the product components with a hot rolling process, a cold rolling process and a continuous annealing process.
In the prior art, cold-rolled steel sheets with higher stamping performance requirements are generally produced by adopting a cover annealing process or ultra-low carbon steel components. Because the bell-type annealing time is longer, the steel plate can obtain lower strength, but because the temperature difference between the edge part and the middle part of the steel plate is larger in the bell-type annealing process, the performance uniformity of the annealed product is poorer, and meanwhile, the production efficiency of the bell-type annealing is lower. The ultra-low carbon steel is adopted for production, Ti element is required to be added in the product components, and a deep decarburization process is carried out to obtain the final product performance.
Chinese patent publication No. CN102943164A discloses a cold rolling and continuous annealing process method for SPCC steel sheet with high yield ratio. The technical scheme is as follows: the hot-rolled SPHC steel plate with the thickness of 2.5-3.0 mm is firstly cold-rolled into a steel plate with the thickness of 0.6-2.0 mm, annealing treatment is carried out through a hood-type annealing furnace, secondary cold rolling reduction is carried out to 0.15-0.2 mm after annealing treatment, and the cold rolling reduction rate is ensured to be changed within the range of 75-90%; and then carrying out continuous annealing treatment on the cold-rolled steel sheet by using a continuous annealing furnace, wherein the parameters of the continuous annealing process are as follows: the heating temperature of the thin steel plate is 580-620 ℃, the heating rate is maintained within the range of 10-15 ℃/s, the heat preservation time of the soaking section is 30-80 s, and the cooling rate is maintained within the range of 15-40 ℃/s. The average grain size distribution of the steel sheet subjected to continuous annealing treatment is within the range of 5.0-6.8 microns, and the yield ratio of the SPCC steel sheet subjected to leveling treatment with constant elongation of 0.5-1.5% is 0.94-0.98. The key process of the patent is that the steel plate is subjected to secondary cold rolling and secondary annealing treatment, so that the production cost is obviously increased, and the production efficiency is lower.
Chinese patent publication No. CN105838991A discloses a cold-rolled steel sheet for home appliances and a production method thereof. The chemical components of the material by weight percentage are as follows: c: 0.020-0.035%, Si is less than or equal to 0.03%, Mn: 0.10% -0.35%, P: 0.008% -0.020%, S: 0.008% -0.015%, Als: 0.010% -0.050%, B: 0.001 to 0.002 percent of the total weight of the alloy, and the balance of Fe and inevitable impurities. The production method comprises the steps of sequentially carrying out hot rolling, coiling, cold rolling, annealing, finishing and straightening on the plate blank. The core technology of the patent is that a high hot rolling coiling temperature and a high annealing heating temperature are adopted, the hot rolling coiling temperature is high, thick iron scales are easily formed on the surface of a hot rolled steel plate, and the difficulty of subsequent cleaning is increased; higher annealing temperatures inevitably lead to increased energy consumption and increased risk of buckling of the steel sheet in the annealing furnace.
Disclosure of Invention
The invention aims to provide a cold-rolled steel plate for a lampshade and a production method thereof, and mainly solves the technical problems of high manufacturing cost and unstable material performance of the existing cold-rolled steel plate for the lampshade.
According to the invention, the low-carbon steel component design is adopted, P, S harmful elements are further controlled, the high-performance requirements of the cold-rolled steel plate for the lampshade are met by optimizing the hot rolling process control temperature, the finish rolling post-laminar cooling mode and cooling rate, the reduction rate of the pickling line set and the vertical continuous annealing process, and meanwhile, the production efficiency of each line set is higher, and the production cost of the product is low.
The invention adopts the technical scheme that a cold-rolled steel plate for a lampshade comprises the following chemical components in percentage by weight: c: 0.026-0.049%, Si is less than or equal to 0.034%, Mn: 0.15-0.25%, P is less than or equal to 0.020%, S is less than or equal to 0.0154%, N is less than or equal to 0.0035%, Al: 0.025-0.050%, B: 0.001 to 0.002%, and the balance of Fe and inevitable impurity elements.
The metallographic structure of the cold-rolled steel plate is ferrite and a small amount of pearlite, and the grain size grade of the ferrite is I8.0-I9.0 grade; yield strength R of cold-rolled steel sheet with thickness of 0.25-0.40 mmP0.2220 to 260MPa, tensile strength Rm330 to 380MPa, elongation after break A50mm35 to 45%, and the surface roughness Ra of the cold-rolled steel sheet is 0.50 to 0.80 μm.
The reason why the chemical composition of the cold rolled steel sheet for a lamp cover of the present invention is limited to the above range is as follows:
carbon: because C exists in the form of interstitial atoms and cementite in the material, the C has a stronger strengthening effect in steel, the element is too high, the plastic deformation resistance of the material is increased, and the C is not beneficial to product punch forming; however, if the carbon content is too low, deep decarburization is required in the steel-making process, and the production cost is increased. Therefore, the carbon content is controlled to be 0.026-0.049% of C.
Silicon: silicon is an element that improves the strength of the material, but Si easily generates scales during hot rolling, is difficult to remove by high-pressure water for hot rolling, remains on the hot-rolled steel sheet as red scales, and such deep-seated scale is difficult to wash out by pickling on the hot-rolled steel sheet, which causes defects in the surface of the steel sheet after cold rolling, and affects the appearance. Therefore, in the present invention, the lower the Si content, the better, the content is controlled to 0.034% or less as much as possible.
Manganese: mn and C are the same as reinforcing elements of the material, a small amount of Mn is properly added into the material to be combined with S to generate MnS, so that the surface hot brittleness is reduced, the surface quality problem is avoided, but the excessive addition can improve the plastic deformation resistance of the material and is not beneficial to the stamping performance of the product. Therefore, the Mn content is controlled to be 0.15-0.25%.
Sulfur and phosphorus: sulfur forms sulfide inclusions in the steel, reducing its ductility and toughness. When a steel sheet is rolled, MnS inclusions extend along the rolling direction, so that the anisotropy of the steel is increased, and the steel sheet is delaminated in a severe case. Phosphorus can improve the strength of the material and reduce the stamping performance of the product. Therefore, the lower the two elements, the better, but in view of the actual process control capability, the invention limits P to 0.020% and S to 0.0154%.
Nitrogen: the high nitrogen content can reduce the toughness, welding performance and thermal property of a thermal stress area of steel, increases the brittleness of the steel, can also cause continuous casting billet cracking, and has high nitrogen content and poor timeliness of a final product. Therefore, the invention controls N in the steel to be less than or equal to 0.0035 percent.
Aluminum: the aluminum plays a role in deoxidation in the present invention, and is a strong oxidizing forming element, and forms Al with oxygen in steel2O3When the aluminum is removed during steel making, the aluminum and the N in the steel can be combined into fine AlN second phase particles which are distributed in a dispersed mode, and the aging resistance of the product is improved. Higher aluminum content can result in excessive Al formation2O3And the inclusion is easy to block a pouring water gap during continuous casting pouring. Therefore, the Al content in the steel is controlled to be 0.025-0.050%.
Boron: the addition of proper boron content can effectively coarsen ferrite grains, further realize the reduction of material strength at relatively low annealing temperature and improve the stamping performance of the material. However, the boron content must not be too high, since otherwise a network-like precipitation phase occurs at the austenite grain boundaries, which embrittles the steel, resulting in high-temperature "boron embrittlement". In conclusion, the content of B in the steel is controlled as follows: 0.001 to 0.002%.
A method for producing a cold rolled steel sheet for a lamp cover, comprising:
continuously casting molten steel to obtain a continuous casting plate blank, wherein the molten steel comprises the following components in percentage by weight: c: 0.026-0.049%, Si is less than or equal to 0.034%, Mn: 0.15-0.25%, P is less than or equal to 0.020%, S is less than or equal to 0.0154%, N is less than or equal to 0.0035%, Al: 0.025-0.050%, B: 0.001 to 0.002%, and the balance of Fe and inevitable impurity elements;
heating the continuous casting plate blank at 1180-1220 ℃ for 180-240 min, and then rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 6-pass rolling, and the rolling is carried out at the austenite recrystallization temperature or above; the finish rolling is 7-pass continuous rolling, the finish rolling temperature is 855-895 ℃, the finish rolling reduction rate is more than or equal to 90%, the thickness of the steel plate after finish rolling is 2.0-2.75mm, the laminar cooling adopts post-stage cooling, the cooling speed is 10-30 ℃/s, and the coiling temperature is 620-650 ℃ to coil the hot-rolled steel plate;
the hot-rolled steel coil is uncoiled again, then is subjected to acid cleaning, cold continuous rolling, annealing and leveling in a vertical continuous annealing furnace, and is coiled to obtain a finished cold-rolled steel plate with the thickness of 0.25-0.40 mm, wherein the cold-rolling reduction rate is 80-90%; the temperature of the cold-rolled hard strip steel in the soaking section of the vertical continuous annealing furnace is 710-740 ℃, and the annealing time of the strip steel in the soaking section is 65-145 s; cooling the annealed strip steel to 300-400 ℃ for aging treatment, wherein the cooling speed is 10-35 ℃/s, and the strip steel aging time is 214-478 s; the flat elongation is 1.0-2.0%.
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. The above purpose cannot be achieved by too low temperature and too short heating time; meanwhile, the finish rolling finishing temperature cannot be guaranteed due to too low temperature. 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 surface oxidation of the slab is serious, the performance and the surface quality of the final product of the steel plate are not facilitated, energy is consumed, and the manufacturing cost is increased. Therefore, the heating temperature of the continuous casting plate blank is set to be 1180-1220 ℃, and the heating time is 180-240 min.
2. Setting of finish Rolling finishing temperature
The finish rolling finishing temperature of the invention has two functions, on one hand, flat austenite crystal grains with deformation zones inside are obtained by rolling the material in an austenite non-recrystallization area and are converted into fine ferrite crystal grains in the subsequent laminar cooling process, thus playing the roles of refining the crystal grains and reducing the zonal segregation; on the other hand, if the finish rolling finishing temperature is lower, the strength of the hot rolled product is higher, which affects the strength of the product after cold rolling and continuous annealing to a certain extent and is not favorable for meeting the deep drawing performance of the final product. Therefore, the finish rolling finishing temperature is set to 855-895 ℃.
3. Setting of reduction ratio of finish rolling
The finish rolling reduction rate is controlled to be more than or equal to 90 percent, the main reason is that the heat dissipation can be reduced by the thickness of a larger intermediate blank, the internal heat storage of a plate blank is increased, meanwhile, more deformation energy is generated by the larger finish rolling reduction rate, the finish rolling outlet material is ensured to be rolled in an austenite non-recrystallization region, the tissue and performance uniformity of the hot rolled steel plate is improved, and therefore the performance uniformity of the steel plate after cold rolling and annealing is improved.
4. Method of laminar cooling and setting of cooling rate
The laminar cooling mode set by the invention adopts the back-end cooling and the lower cooling speed, mainly aims to obtain the coarser ferrite and pearlite structures, is favorable for reducing the strength of a hot-rolled product, improves the deep drawing performance of the cold-rolled annealed product, and can ensure the higher finish rolling finishing temperature. Therefore, the laminar cooling of the invention adopts the back-end cooling, and the cooling speed is 10-30 ℃/s.
5. Setting of coiling temperature in Hot Rolling
The coiling temperature mainly influences the structure and the performance of the strip steel, the higher coiling temperature can promote the growth of crystal grains, the effect of reducing the strength of a hot-rolled product is achieved, and the deep drawing performance of the product after cold rolling and annealing is favorably improved. However, the hot rolling coiling temperature is too high, which increases the thickness of scale on the surface of the steel sheet, and also makes pearlite too coarse, which increases the brittleness of the material and deteriorates the uniformity of the structure. Therefore, the coiling temperature is set to 620-650 ℃ comprehensively.
6. Setting of cold continuous rolling reduction
The cold continuous rolling reduction rate is controlled to be 80-90%, the cold continuous rolling reduction rate is improved, more deformation energy can be stored in the steel plate, the recrystallization driving force is increased, the structure is fully recrystallized in the subsequent annealing process, a larger uniform recrystallized structure is obtained, and the deep drawing performance of the steel plate is improved; but when the reduction rate exceeds 90%, the load of the rolling mill is obviously increased, and the process stability is poor. The actual production capacity of the five-stand rolling mill is comprehensively considered, and the reduction rate of cold rolling is set to be 80-90%.
7. Setting of annealing temperature and post-annealing cooling process
The invention adopts vertical continuous annealing, the continuous annealing is mainly used for eliminating the work hardening generated in the cold rolling process, various defects in crystals, anisotropy in mechanical property and the like, and the setting of the heat preservation temperature in the continuous annealing process mainly considers the recrystallization temperature and the product performance requirements of a steel plate. The heat preservation temperature and the heat preservation time of the continuous annealing process are improved, the growth and the homogenization of recrystallized grains are facilitated, and the deep drawing performance of the steel plate is improved, so that the performance requirements of products are comprehensively considered, the heat preservation temperature range of the steel plate in the vertical continuous annealing process is set to be 710-740 ℃, and the heat preservation time is set to be 65-145 s;
after the heat preservation of the steel plate in the continuous annealing process is finished, the steel plate needs to be cooled from a higher heat preservation temperature to a lower aging temperature in time for aging treatment, and a nozzle is adopted in the cooling process to spray nitrogen-hydrogen mixed gas to the surface of the steel plate. If the cooling speed is too high, the steel plate is rapidly cooled from high temperature to lower temperature, the surface temperature of the steel plate is uneven, the shape of the steel plate is easy to be poor, and the consumption of nitrogen-hydrogen mixed gas energy is increased; but the cooling rate is too low, and the steel plate cannot be cooled to the temperature required by aging, so that the cooling speed is controlled to be 10-35 ℃/s after the annealing heat preservation is set to be finished;
the steel plate is cooled from a higher heat preservation temperature to a lower aging temperature in the continuous annealing process, and is subjected to aging treatment, wherein the aging treatment process is mainly used for ensuring that carbides in the steel plate structure are fully precipitated, so that the aging resistance of the steel plate is improved, and the problem that the performance of the steel plate changes after the steel plate is placed for a period of time is solved. Therefore, the aging temperature is set to be 300-400 ℃, and the aging time is controlled to be 214-478 s;
the metallographic structure of the cold-rolled steel sheet produced by the method is ferrite and a small amount of pearlite, and the grain size grade of the ferrite is I8.0-I9.0 grade; yield strength R of cold-rolled steel sheet with thickness of 0.25-0.40 mmP0.2220 to 260MPa, tensile strength Rm330 to 380MPa, elongation after break A50mm35 to 45%, and the surface roughness Ra of the cold-rolled steel sheet is 0.50 to 0.80 μm.
Compared with the prior art, the invention has the following positive effects: 1. the invention adopts the chemical components of low-carbon steel, combines the design of hot rolling, cold continuous rolling and vertical continuous annealing process, and obtains the cold-rolled steel plate for the lampshade, and the yield strength R of the rolled steel plateP0.2220 to 260MPa, tensile strength Rm330-380 MPa, and the elongation A50 mm after fracture is 35-45%. The product performance requirements of the cold-rolled steel plate for the lampshade are met, compared with a cover type annealing process and an ultra-low carbon component product, the cost of each ton of steel is reduced by 50-100 yuan, and the manufacturing cost of the product is low. 2. According to the invention, the strength of the hot-rolled steel plate is reduced by controlling the hot-rolling coiling temperature and the cooling process after rolling, and meanwhile, the cold-rolled steel plate with good deep drawing performance is obtained by adopting a large cold-rolling reduction rate and a reasonable vertical continuous annealing process, so that the performance requirements of the steel plate for the lampshade are met; the steel plate has uniform structure performance and higher production efficiency, well solves the technical problems of non-uniform performance of the edge part and the middle part of a product of cover annealing and low production efficiency, and reduces the production cost of the product.
Drawings
FIG. 1 is a metallographic structure photograph of a cold-rolled annealed steel sheet according to example 1 of the present invention.
Detailed Description
The invention is further illustrated with reference to specific examples 1-5, as shown in tables 1-4, 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: and (4) weight percentage.
Molten steel meeting the basic requirements of chemical components is obtained by smelting in a converter, and after the molten steel is subjected to deep desulfurization and fine adjustment of alloy components in an LF ladle refining furnace, a continuous casting slab is obtained by casting in a continuous casting machine; the thickness of the slab is 210-230mm, the width is 900-1400mm, 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. And 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 rear-section cooling mode in the laminar cooling. The thickness of the hot rolled steel plate is 2.0-2.75mm, and the control parameters of the hot rolling process are shown in Table 2.
TABLE 2 Hot Rolling Process control parameters of the inventive examples
Uncoiling the hot-rolled steel coil again, then carrying out acid pickling, cold continuous rolling, annealing and leveling in a vertical continuous annealing furnace, and coiling to obtain a finished cold-rolled steel plate with the thickness of 0.25-0.40 mm, wherein the cold-rolling reduction rate is 80-90%; annealing (soaking section) temperature of the cold-rolled hard strip steel in a vertical continuous annealing furnace is 710-740 ℃, and annealing time of the strip steel in the soaking section is 65-145 s; and cooling the annealed strip steel to 300-400 ℃ by air injection, and carrying out aging treatment, wherein the cooling speed is 10-35 ℃/s, and the aging time of the strip steel is 214-478 s. The control parameters of the cold rolling and annealing processes are shown in Table 3.
TABLE 3 control parameters of the cold rolling, annealing and leveling processes of the examples of the present invention
Referring to fig. 1, the cold-rolled steel sheet obtained by the method has a metallographic structure of ferrite and a small amount of pearlite, and the ferrite grain size is in the grade of I8.0 to I9.0; yield strength R of Cold rolled Steel sheetP0.2220 to 260MPa, tensile strength Rm330 to 380MPa, elongation after break A50mm35 to 45%, and the surface roughness Ra of the cold-rolled steel sheet is 0.50 to 0.80 μm.
According to the part 1 of a GB/T228.1-2010 metal material tensile test, the cold-rolled steel plate obtained by the invention is prepared by the following steps: room temperature test method, tensile test, microstructure, and test were performed by a steel microstructure evaluation method (GB/T13299), a metal material vickers hardness test method (GB/T4340.1-2009), and a surface roughness test method (GB/T131), and the properties of cold-rolled steel sheets are shown in table 4.
Table 4 mechanical properties of cold-rolled steel sheets according to examples of the present invention
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 cold-rolled steel plate for a lampshade comprises the following chemical components in percentage by weight: c: 0.026-0.049%, Si is less than or equal to 0.034%, Mn: 0.15-0.25%, P is less than or equal to 0.020%, S is less than or equal to 0.0154%, N is less than or equal to 0.0035%, Al: 0.025 to 0.05 percent, B: 0.001 to 0.002%, and the balance of Fe and inevitable impurity elements; yield strength R of cold-rolled steel sheet with thickness of 0.25-0.40 mmP0.2220 to 260MPa, tensile strength Rm330 to 380MPa, elongation after break A50mm35 to 45%, and the surface roughness Ra of the cold-rolled steel sheet is 0.50 to 0.80 μm.
2. The cold rolled steel sheet for lampshades as claimed in claim 1, wherein the metallographic structure of the cold rolled steel sheet is ferrite + a small amount of pearlite, and the ferrite grain size is in the range of I8.0 to I9.0.
3. A production method of a cold-rolled steel plate for a lampshade 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: 0.026-0.049%, Si is less than or equal to 0.034%, Mn: 0.15-0.25%, P is less than or equal to 0.020%, S is less than or equal to 0.0154%, N is less than or equal to 0.0035%, Al: 0.025 to 0.05 percent, B: 0.001 to 0.002%, and the balance of Fe and inevitable impurity elements;
heating the continuous casting plate blank at 1180-1220 ℃ for 180-240 min, and then rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 6-pass rolling, and the rolling is carried out at the austenite recrystallization temperature or above; the finish rolling is 7-pass continuous rolling, the finish rolling temperature is 855-895 ℃, the finish rolling reduction rate is more than or equal to 90%, after finish rolling, laminar cooling adopts post-stage cooling, the cooling speed is 10-30 ℃/s, and the coiling temperature is 620-650 ℃ to coil the hot-rolled steel plate;
the hot-rolled steel coil is uncoiled again, then is subjected to acid cleaning, cold continuous rolling, annealing and leveling in a vertical continuous annealing furnace, and is coiled to obtain a finished cold-rolled steel plate with the thickness of 0.25-0.40 mm, wherein the cold-rolling reduction rate is 80-90%; the temperature of the cold-rolled hard strip steel in the soaking section of the vertical continuous annealing furnace is 710-740 ℃, and the annealing time of the strip steel in the soaking section is 65-145 s; cooling the annealed strip steel to 300-400 ℃ for aging treatment, wherein the cooling speed is 10-35 ℃/s, and the strip steel aging time is 214-478 s; the flat elongation is 1.0-2.0%.
4. The method of manufacturing a cold rolled steel sheet for a lamp house according to claim 3, wherein the thickness of the hot rolled steel sheet is controlled to be 2.0 to 2.75mm after the hot rolling finish rolling.
5. A method for producing a cold rolled steel sheet for lampshades as claimed in claim 3, characterized in that the metallographic structure of the cold rolled steel sheet is ferrite + a small amount of pearliteThe ferrite grain size grade is I8.0-I9.0 grade; yield strength R of Cold rolled Steel sheetP0.2220 to 260MPa, tensile strength Rm330 to 380MPa, elongation after break A50mm35 to 45%, and the surface roughness Ra of the cold-rolled steel sheet is 0.50 to 0.80 μm.
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