CN115558855B - Cold-rolled sheet for battery shell by hood-type annealing and production method thereof - Google Patents

Cold-rolled sheet for battery shell by hood-type annealing and production method thereof Download PDF

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CN115558855B
CN115558855B CN202211197768.3A CN202211197768A CN115558855B CN 115558855 B CN115558855 B CN 115558855B CN 202211197768 A CN202211197768 A CN 202211197768A CN 115558855 B CN115558855 B CN 115558855B
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CN115558855A (en
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汤亨强
杨平
张宜
汪建威
王占业
李进
吴浩
俞波
裴东扬
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Maanshan Iron and Steel Co Ltd
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Maanshan Iron and Steel Co Ltd
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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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0025—Adding carbon material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/068—Decarburising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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

Abstract

The invention discloses a cold-rolled sheet for a battery shell by adopting hood annealing and a production method thereof, belonging to the field of manufacturing of power battery shell steel. The cold-rolled sheet comprises the following chemical components in percentage by weight: c:0.004 to 0.010 percent, si is less than or equal to 0.030 percent, mn:0.30 to 0.40 percent, P is less than or equal to 0.018 percent, S is less than or equal to 0.012 percent, ti:0.035 to 0.055 percent, alt: 0.030-0.060 percent, [ N ] < 0.004 percent, [ O ] < 0.004 percent, and the balance of Fe and unavoidable impurities. The invention produces the cold-rolled sheet for the low-carbon deep-drawing battery case by precisely controlling the steel components and matching with the special production process, the yield strength is 180 MPa-230 MPa, the tensile strength is 300 MPa-350 MPa, the elongation is more than or equal to 33%, the HR30T is more than or equal to 48 and less than or equal to 55, the r value is more than or equal to 1.5,0.5 mu m and less than or equal to 1.0 mu m, and the cold-rolled sheet has the characteristics of excellent punching performance, surface quality, uniform full-section performance, fine dispersion of inclusions and the like.

Description

Cold-rolled sheet for battery shell by hood-type annealing and production method thereof
Technical Field
The invention belongs to the field of manufacturing and using of power battery shell steel, and particularly relates to a cold-rolled sheet for a battery shell by adopting cover annealing and a production method thereof.
Background
In recent years, as the popularity of new energy automobiles in the market is higher, the demand of steel storage batteries for new energy automobiles is also increasing. Meanwhile, as the safety performance of the steel battery is also paid more attention to by a host factory, the steel battery is required to be subjected to higher and higher requirements. The steel battery case has extremely high molten steel purity, the size and the number of inclusions need to be strictly controlled, the defects of cracking, sand holes, wrinkling, pits and the like on the surface of the battery case after stamping forming are avoided, and the battery case has certain compression resistance. Currently, battery case steel in the market has two component systems of aluminum killed steel and IF steel.
The patent with publication number CN1174109C discloses an ultrathin steel strip for a battery shell and a manufacturing method thereof, wherein the ultrathin steel strip comprises the following chemical components in percentage by weight: c is less than or equal to 0.0050%, si is less than or equal to 0.020%, mn:0.15 to 0.30 percent, P:0.010% -0.030%, S: less than or equal to 0.015 percent, N less than or equal to 0.0040 percent, al:0.020% -0.07%, ti:0.010% -0.030%, nb: 0.010-0.025% and the balance of Fe, the technology mainly adds Ti and Nb elements to obtain good stamping performance, but the cost is higher, and meanwhile, the head and tail thickness difference is large in single-frame rolling, cutting is needed, and the yield is low.
The patent publication No. CN100560770C discloses a steel for battery case excellent in plane isotropy and a method for producing the same, the steel comprising the following chemical components in weight percent: c:0.01 to 0.05 percent, si is less than or equal to 0.03 percent, mn:0.10 to 0.50 percent, P is less than or equal to 0.020 percent, S is less than or equal to 0.015 percent, als:0.010 to 0.10 percent of N:0.0020 to 0.0070 percent, ti:0.0050% -0.020% and the balance Fe and unavoidable impurities. The production steps comprise molten iron pretreatment, converter smelting, furnace refining, hot rolling, acid washing, cold rolling and rolling, cover annealing, leveling and finishing to form a finished coil. In the scheme, the steel is an aluminum killed steel system, and has poor plasticity and toughness.
The patent publication No. CN102286699B discloses a steel for a battery case formed by rapid stamping and a preparation method thereof, wherein the steel for the battery case comprises the following chemical components in percentage by weight: c:0.0001 to 0.005 percent of Mn:0.10% -0.20%, al:0.010% -0.050%, N:0.00010% -0.0040%, nb:0.010 to 0.030 percent, and controlling P to be less than or equal to 0.020 percent, S to be less than or equal to 0.0150 percent, cu to be less than or equal to 0.050 percent, ni to be less than or equal to 0.050 percent, cr to be less than or equal to 0.080 percent, mo to be less than or equal to 0.050 percent, si to be less than or equal to 0.02 percent, and the balance of Fe and unavoidable impurities. The production steps are as follows: smelting and continuously casting pure steel to form a blank; heating the continuous casting billet; rough rolling; finish rolling in a single-phase austenite region; coiling; acid washing; cold rolling; degreasing; annealing in a full hydrogen bell furnace; leveling and waiting for use. In the scheme, the steel belongs to a Nb-IF steel system, the cost is higher, and the rolling performance fluctuation is larger due to the adoption of hood annealing, and the final yield strength is low and the pressure resistance capability is not realized due to the adoption of an ultralow C and low Mn component system design.
The patent of publication No. CN106148803A discloses a method for producing steel for deep-drawing battery cases, which comprises the following chemical components in percentage by weight: c:0.0150% -0.0350%, si less than or equal to 0.020%, mn:0.15% -0.25%, P: less than or equal to 0.018 percent, S: less than or equal to 0.015 percent, N less than or equal to 0.0030 percent, alt:0.030% -0.060%, ti:0.008 to 0.015 percent and the balance of Fe. The scheme steel adopts an aluminum killed steel system, has relatively poor stamping performance, and is difficult to meet the requirement of quick stamping of battery case steel.
Disclosure of Invention
1. Problems to be solved
Aiming at the problem that the whole performance of the prior battery case steel is still difficult to meet the practical requirement, the invention aims to provide the cold-rolled sheet for the battery case, which adopts the hood annealing, and the production method thereof, and the cold-rolled sheet for the battery case, provided by the invention, has good deep drawing and surface quality, the yield strength of the steel plate is 180 MPa-230 MPa, the tensile strength is 300-350 MPa, the elongation is more than or equal to 33%, the HR30T is more than or equal to 48 and less than or equal to 55, the r value is more than or equal to 1.6,0.5 mu m and less than or equal to 1.0 mu m, the distribution of inclusions is tiny and dispersion, and the fluctuation of the rolling performance is less than 20MPa, so that the high standard requirement of the cold-rolled sheet for the battery case at present can be met.
2. Technical proposal
In order to solve the problems, the invention adopts the following technical scheme.
The cold-rolled sheet for the ultra-low carbon deep drawing battery case comprises the following chemical components in percentage by weight: c:0.004 to 0.010 percent, si is less than or equal to 0.030 percent, mn:0.30 to 0.40 percent, P is less than or equal to 0.018 percent, S is less than or equal to 0.012 percent, ti:0.035 to 0.055 percent, alt: 0.030-0.060 percent, [ N ] < 0.004 percent, [ O ] < 0.004 percent, and the balance of Fe and unavoidable impurities.
The steel grade alloy elements of the invention have the following functions:
carbon: as the C element is reduced, the strength of the steel sheet is reduced, the elongation, n value and r value are increased, and the deep drawability of the steel sheet is gradually improved. Therefore, the ultra-low carbon is a precondition for producing the battery case steel, and the trace C element is helpful for improving the strength and the hardness of the steel, so that the battery case is not easy to deform. The invention adopts the design of ultra-low carbon components to control C:0.004 to 0.010 percent.
Silicon: the Si content is too high, oxide scales on the surface of the steel plate are not easy to remove, microcracks pressed by oxides are easy to form on the surface, and the microcracks can be used as crack sources to cause the cracking of the steel plate in the high-speed deep drawing process of the steel belt. In addition, the plating performance of the steel plate is affected by the excessively high content of Si, and Si is less than or equal to 0.030 percent in the invention.
Manganese: mn can reduce the transformation temperature of austenite and ferrite, can compensate the transformation temperature rise of austenite and ferrite caused by the reduction of the content of C element, expands the hot working temperature range and is beneficial to refining the grain size of ferrite; however, the Mn content is too high, which is unfavorable for plasticity, stamping performance and fatigue performance, and the Mn percentage control range in the invention is 0.30-0.40%.
Phosphorus: the diffusion speed of P in gamma-Fe and alpha-Fe is small, segregation is easy to form, and the forming performance of the steel plate is unfavorable, and the P content is reduced as much as possible in the steelmaking process, so that the P content is less than or equal to 0.018 percent.
Sulfur: the S element is a harmful element in the battery case steel, so that the steel generates hot brittleness, the ductility and toughness of the steel are reduced, and cracks are easily caused during rolling. S is also detrimental to welding performance and reduces corrosion resistance. The invention controls the S content in the steel within the range of S less than or equal to 0.012 percent.
Aluminum: al is used as a main deoxidizer, and aluminum plays a role in refining grains, and has the disadvantage of affecting hot workability, weldability and machinability of steel. The invention controls the percentage content of Al within the range of 0.030-0.060 percent.
Titanium: ti element is a strong carbide, sulfide and nitride forming element, and the compound is not easy to dissolve in austenite at high temperature, and plays roles in preventing austenite grains from growing, refining the grains and improving the deep drawing performance of the steel plate. However, too much second phase precipitate can affect the deep drawing performance of the steel plate, and the invention controls the Ti element of the steel grade to be in the range of 0.035-0.055 percent.
Nitrogen: n element easily forms TiN with Ti in steel, and excessive N element can cause trace Ti element failure. The invention controls the N content within the range of [ N ] < 0.004%.
Oxygen: the O element and Al easily form alumina inclusion in the steel, and the inclusion can influence the stamping performance of the battery case steel, so that the stamping cracking and the trachoma quantity are increased. The invention controls the [ O ] to be less than or equal to 0.004 percent.
The manufacturing method for the cold-rolled sheet for the battery shell with ultra-low carbon comprises the steps of molten iron smelting, slab continuous casting, hot rolling, laminar cooling, coiling, pickling cold rolling, continuous annealing and leveling, wherein the molten iron smelting comprises molten iron pretreatment, a converter, an alloy fine tuning station and RH, and the continuous casting temperature of the converter is as follows: 1675-1685 ℃, adding carbon powder and small lime at the same time, and controlling the end point oxygen to be less than or equal to 500ppm; carbon powder is added into an RH furnace for decarburization, the decarburization time is 8-10min, and the deoxidization target is less than or equal to 250ppm. Through the scheme, inclusions in the steel can be effectively reduced, and the risk of sand holes in the battery case steel in the subsequent stamping process is reduced. After continuous casting, the casting blank is subjected to flame skinning treatment, each surface is cleaned by flame for 4-5mm, surface bubbles and floating inclusions in molten steel are eliminated, and the surface quality of a final finished product is improved.
Furthermore, the heating temperature in the hot rolling stage is controlled to be 1210-1230 ℃, so that the steel billet can be ensured to be fully austenitized, and the compound is fully dissolved; the final rolling temperature is controlled to 880-920 ℃, and the temperature can ensure that the final rolling temperature is controlled to be higher than the austenite temperature, so that the mixed crystal phenomenon caused by rolling in a two-phase zone is avoided. Meanwhile, the hot rolling convexity is controlled to be 0-40 mu m, the wedge shape is controlled to be minus 20 mu m-20 mu m, and the thin edge condition of a final finished product can be effectively improved.
Furthermore, the invention adopts laminar cooling, and after the laminar cooling, the coiling temperature is controlled at 560 ℃ to 580 ℃, and the coiling temperature is favorable for refining the hot rolled coil grains.
Furthermore, in the pickling cold rolling process, the total rolling reduction is controlled to be 75% -85%, and the large rolling reduction can improve the deformation energy of crystal grains in steel, reduce the recrystallization temperature, be favorable for refining the crystal grains, improve the deep drawing performance of the steel plate and be favorable for improving the hardness of the battery shell.
Further, the continuous annealing is carried out in a hood-type annealing furnace with an all-hydrogen atmosphere, and when the temperature in the furnace is lower than 500 ℃, the heating temperature is increased by 25-30 ℃/hour; when the temperature in the furnace is 500-600 ℃, the heating temperature is increased according to 15-20 ℃/h; when the temperature in the furnace is 600-650 ℃, the heating temperature is slowly heated and raised according to 10-15 ℃/hour, the heating speed can effectively ensure the uniform performance of the strip steel in the furnace after the strip steel is covered and removed, and the working efficiency can be effectively improved; when the temperature reaches 650 ℃, heating is stopped, heat is not preserved, and cooling is started by using a cooling cover.
Furthermore, laser Mao Huagun is adopted for leveling in the leveling procedure, the leveling elongation is controlled to be 0.6-1.2%, and a leveling roller with Ra of 1.6-2.0 μm is adopted, so that the roughness of the plate surface is ensured to be 0.5-1.0 μm, and the roughness is favorable for the surface finish of the battery shell after electroplating.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
the invention produces the cold-rolled sheet for the low-carbon deep-drawing battery case by precisely controlling the steel type components and matching with the special production process, the yield strength of the produced cold-rolled sheet is 180 MPa-230 MPa, the tensile strength is 300 MPa-350 MPa, the elongation is more than or equal to 33%, the HR30T is more than or equal to 48 and less than or equal to 55, the r value is more than or equal to 1.5,0.5 mu m and less than or equal to Ra is less than or equal to 1.0 mu m; has the characteristics of excellent stamping performance, surface quality, uniform whole-section performance, fine dispersion of inclusions and the like.
Detailed Description
The invention is further described below in connection with specific embodiments.
Example 1
The chemical compositions of the cold rolled sheet for the ultra-low carbon deep drawing battery case of the embodiment are shown in table 1, the manufacturing method comprises the procedures of molten iron smelting, slab continuous casting, hot rolling, laminar cooling, coiling, pickling cold rolling, continuous annealing and leveling, the molten iron smelting comprises molten iron pretreatment, a converter, an alloy fine tuning station and RH, and the continuous casting temperature of the converter is as follows: at 1675 ℃, carbon powder and small lime are added simultaneously, and the end point oxygen is controlled to be less than or equal to 500ppm; adding carbon powder into an RH furnace for decarburization, wherein the decarburization time is 10min, the deoxidization target is less than or equal to 250ppm, and performing flame peeling treatment on a casting blank after continuous casting, wherein each surface is cleaned by flame for 4-5mm; the heating temperature in the hot rolling stage is 1210 ℃, and the final rolling temperature is 882 ℃; after laminar cooling, coiling the temperature to 561 ℃; in the pickling cold rolling process, the total rolling reduction rate is 75%; the continuous annealing is carried out in a cover annealing furnace with full hydrogen atmosphere, and when the temperature in the furnace is lower than 500 ℃, the heating temperature is increased by 25 ℃ per hour; when the temperature in the furnace is higher than 500 ℃, the heating temperature is increased according to 15 ℃/hour; when the temperature in the furnace is higher than 600 ℃, the heating temperature is slowly heated and raised according to 10 ℃/hour, when the temperature reaches 650 ℃, the heating is stopped, the heat is not preserved, and the cooling is started by using a cooling cover; the elongation rate in the leveling process is controlled to be 1.2%, and a leveling roller with Ra of 1.6-2.0 μm is adopted to ensure that the roughness of the plate surface is 0.5-1.0 μm.
Example 2
The chemical compositions of the cold rolled sheet for ultra-low carbon deep drawing battery case of this embodiment are shown in table 1, and the manufacturing method is basically the same as that of embodiment 1, except that the continuous casting temperature of the transfer furnace in this embodiment is: 1685 ℃, decarburization time of 8min, heating temperature of 1230 ℃ in the hot rolling stage and final rolling temperature of 919 ℃; the coiling temperature is 580 ℃; cold rolling total reduction rate is 85%; continuous annealing when the temperature in the furnace is lower than 500 ℃, the heating temperature is increased at 30 ℃/h; when the temperature in the furnace is higher than 500 ℃, the heating temperature is raised according to 20 ℃/hour; when the temperature in the furnace is higher than 600 ℃, the heating temperature is slowly heated and raised according to 15 ℃/hour, and when the temperature reaches 650 ℃, the temperature starts to be lowered; the elongation at flatness is controlled at 0.6%.
Example 3
The chemical compositions of the cold rolled sheet for ultra-low carbon deep drawing battery case of this embodiment are shown in table 1, and the manufacturing method is basically the same as that of embodiment 1, except that the continuous casting temperature of the transfer furnace in this embodiment is: 1680 ℃, decarburization time of 9min, heating temperature of the hot rolling stage of 1225 ℃ and finishing temperature of 890 ℃; coiling temperature is 565 ℃; cold rolling total reduction rate is 78.2%; continuous annealing when the temperature in the furnace is lower than 500 ℃, heating the temperature to rise at 28 ℃ per hour; when the temperature in the furnace is higher than 500 ℃, the heating temperature is raised according to 18 ℃/hour; when the temperature in the furnace is higher than 600 ℃, the heating temperature is slowly heated and raised according to 12 ℃/h, and when the temperature reaches 650 ℃, the temperature starts to be lowered; the elongation at flatness is controlled at 0.8%.
Example 4
The chemical compositions of the cold rolled sheet for ultra-low carbon deep drawing battery case of this embodiment are shown in table 1, and the manufacturing method is basically the same as that of embodiment 1, except that the continuous casting temperature of the transfer furnace in this embodiment is: 1678 ℃, decarburizing time is 8min, heating temperature in the hot rolling stage is 1221 ℃, and final rolling temperature is 895 ℃; coiling temperature is 562 ℃; the total rolling reduction rate is 81.2 percent; continuous annealing when the temperature in the furnace is lower than 500 ℃, the heating temperature is increased at 25 ℃ per hour; when the temperature in the furnace is higher than 500 ℃, the heating temperature is raised according to 18 ℃/hour; when the temperature in the furnace is higher than 600 ℃, the heating temperature is slowly heated and raised according to 15 ℃/hour, and when the temperature reaches 650 ℃, the temperature starts to be lowered; the elongation at flatness is controlled at 0.8%.
Example 5
The chemical compositions of the cold rolled sheet for ultra-low carbon deep drawing battery case of this embodiment are shown in table 1, and the manufacturing method is basically the same as that of embodiment 1, except that the continuous casting temperature of the transfer furnace in this embodiment is: 1675 ℃, decarburizing for 8min, heating temperature in the hot rolling stage is 1215 ℃, and final rolling temperature is 892 ℃; coiling temperature is 575 ℃; cold rolling total reduction rate is 82%; continuous annealing when the temperature in the furnace is lower than 500 ℃, the heating temperature is increased at 30 ℃/h; when the temperature in the furnace is higher than 500 ℃, the heating temperature is increased according to 15 ℃/hour; when the temperature in the furnace is higher than 600 ℃, the heating temperature is slowly heated and raised according to 10 ℃/h, and when the temperature reaches 650 ℃, the temperature starts to be lowered; the leveling elongation is controlled at 0.85%.
The chemical compositions of the molten steels of the examples and comparative examples in the present invention are shown in Table 1, and the balance is Fe and unavoidable impurity elements. Wherein comparative example 1 and comparative example 2 were not smelted according to the smelting scheme of the present invention, and comparative examples 3, 4, 5, and 6 were not annealed according to the annealing process of the present invention.
Table 1 chemical compositions of comparative steel sheets of examples, wt%
Category(s) C Si Mn P S Als Ti O N
Example 1 0.0040 0.0130 0.300 0.0120 0.0050 0.0310 0.0350 0.0025 0.0039
Example 2 0.0100 0.0290 0.390 0.0175 0.0060 0.0450 0.0540 0.0039 0.0015
Example 3 0.0055 0.0130 0.350 0.0110 0.0040 0.0590 0.0450 0.0015 0.0035
Example 4 0.0045 0.0120 0.360 0.0100 0.0032 0.0460 0.0470 0.0025 0.0031
Example 5 0.0052 0.0130 0.32 0.0120 0.0042 0.0420 0.0420 0.0026 0.0029
Comparative example 1 0.0210 ≤0.0200 0.200 ≤0.0120 0.0040 0.0350 0.0110 0.0042 0.0017
Comparative example 2 0.0023 ≤0.0200 0.230 ≤0.0120 0.0050 0.0360 0.0550 0.0095 0.0035
Comparative example 3 0.0045 ≤0.0200 0.320 ≤0.0120 0.0050 0.0430 0.0390 0.0056 0.0017
Comparative example 4 0.0045 ≤0.0200 0.320 ≤0.0120 0.0050 0.0430 0.0390 0.0056 0.0017
Comparative example 5 0.0045 ≤0.0200 0.320 ≤0.0120 0.0050 0.0430 0.0390 0.0056 0.0017
Comparative example 6 0.0045 ≤0.0200 0.320 ≤0.0120 0.0050 0.0430 0.0390 0.0056 0.0017
The steel plate production processes of a plurality of groups of examples and comparative examples in the invention are mainly performed with trial production according to the table 2, and the thickness specification of the finished product is 0.5mm.
Table 2 comparative steel sheet main production process of each example
The final mechanical properties of the steel sheets obtained in the above examples and comparative examples are shown in Table 3.
Table 3 mechanical properties of comparative steel sheets of examples
Category(s) Direction R p0.2 /MPa R m /MPa A 50 /％ r value hardness/HR 30T
Example 1 0° 182 312 48 1.82 49
Example 2 0° 227 342 43 1.56 53
Example 3 0° 195 335 45 1.65 51
Example 4 0° 189 326 46 1.68 50
Example 5 0° 198 334 45 1.65 51
Comparative example 1 0° 249 356 36 1.44 55
Comparative example 2 0° 163 275 49 1.73 42
Comparative example 3 0° 168 277 50 1.78 41
Comparative example 4 0° 267 385 38 1.02 62
Comparative example 5 head 0° 204 326 46 1.59 51
Comparative example 5 middle part 0° 249 357 42 1.26 56
Comparative example 6 0° 175 296 49 1.85 46
It can be seen that the performances of the steel plates obtained in the embodiments can meet the requirements of the patent, and the yield strength performance of the comparative example 1 is higher, so that the requirements of high-speed stamping of the battery case steel can not be met. Comparative example 2 has a lower yield strength, and although it can meet the requirements of the press, it has a large number of sand hole defects, and has a lower hardness, and it cannot meet the requirements of the finished product. Comparative examples 3, 4, 5, and 6, although the composition design, hot rolling process, and cold rolling process of the present invention were adopted, only the annealing process was produced according to the conventional process flow, and the battery case steel product satisfying the performance requirement could not be produced. Wherein the yield strength, tensile strength and hardness of comparative example 3 are all lower than the requirements of the invention, the yield strength, tensile strength and hardness of comparative example 4 are all higher than the requirements of the patent, and the r value is lower, and the head and tail performance of comparative example 5 is greatly fluctuated due to the high heating speed, and the middle performance cannot meet the requirements. Comparative example 6 has lower through-roll yield strength, tensile strength, and hardness than the present invention.
The above examples and comparative examples were punched using a battery case punching apparatus, and punching ability thereof was measured, and the results are shown in table 4 below. When the strength exceeds 230MPa, breakage is likely to occur at the time of high-speed stamping, and when the yield strength is lower than 180MPa, the plating damage rate is sharply increased, and defective products are sharply increased. Meanwhile, the patent is not adopted to control the O element in steelmaking, and after the O element content exceeds 0.004%, the proportion of the battery shell with sand holes is also increased rapidly, so that the requirement cannot be met.
Table 4 comparative steel sheet punching results of each example
Category(s) Type of punched battery Stamping speed Results Electroplating situation PPM with sand holes
Example 1 32650 type 40/min Normal stamping Normal electroplating 12
Example 2 32650 type 40/min Normal stamping Normal electroplating 14
Example 3 32650 type 40/min Normal stamping Normal electroplating 9
Example 4 32650 type 40/min Normal stamping Normal electroplating 11
Example 5 32650 type 40/min Normal stamping Normal electroplating 12
Comparative example 1 32650 type 40/min High breakage rate Normal electroplating 105
Comparative example 2 32650 type 40/min Normal stamping High rate of bruise 1985
Comparative example 3 32650 type 40/min Normal stamping High impact injury rate 203
Comparative example 4 32650 type 40/min High breakage rate Normal electroplating 215
Comparative example 5 head 32650 type 40/min Normal stamping Normal electroplating 226
Comparative example 5 middle part 32650 type 40/min High breakage rate Normal electroplating 215
Comparative example 6 32650 type 40/min Normal stamping High rate of bruise 245
The examples of the present invention are merely for describing the preferred embodiments of the present invention, and are not intended to limit the spirit and scope of the present invention, and those skilled in the art should make various changes and modifications to the technical solution of the present invention without departing from the spirit of the present invention.

Claims (4)

1. A production method of a cold-rolled sheet for a battery shell by hood-type annealing is characterized by comprising the following steps: the cold-rolled sheet comprises the following chemical components in percentage by weight: c:0.004% -0.010%, si is less than or equal to 0.030%, mn:0.30% -0.40%, P is less than or equal to 0.018%, S is less than or equal to 0.012%, ti:0.035% -0.055%, alt: 0.030-0.060 percent, [ N ] < 0.004 percent, [ O ] < 0.004 percent, and the balance of Fe and unavoidable impurities; the yield strength of the cold-rolled sheet is 180-230 MPa, the tensile strength is 300-350 MPa, the elongation is more than or equal to 33%, HR30T is more than or equal to 48 and less than or equal to 55, and the r value is more than or equal to 1.5,0.5 μm and less than or equal to Ra is less than or equal to 1.0 μm;
the production method comprises the steps of molten iron smelting, slab continuous casting, hot rolling, laminar cooling, coiling, pickling cold rolling, continuous annealing and leveling, wherein in the molten iron smelting step, the continuous casting temperature of a converter is as follows: 1675-1685 ℃, adding carbon powder and small lime at the same time, and controlling the end point oxygen to be less than or equal to 500ppm; adding carbon powder into an RH furnace for decarburization, wherein the decarburization time is 8-10min, and the deoxidization target is less than or equal to 250ppm; the heating temperature in the hot rolling process is controlled to be 1210-1230 ℃, and the finishing temperature is controlled to be 880-920 ℃; after laminar cooling, the coiling temperature is controlled to be 560-580 ℃; the total rolling reduction rate of cold rolling is controlled to be 75% -85%; the continuous annealing is carried out in a cover annealing furnace with full hydrogen atmosphere, and when the temperature in the furnace is lower than 500 ℃, the heating temperature is increased by 25-30 ℃/h; when the temperature in the furnace is 500-600 ℃, the heating temperature is increased according to 15-20 ℃/h; when the temperature in the furnace is 600-650 ℃, the heating temperature is increased according to 10-15 ℃/h; when the temperature reaches 650 ℃, heating is stopped, heat is not preserved, and cooling is started by using a cooling cover.
2. The method for producing a cold-rolled sheet for battery cases using cap annealing according to claim 1, wherein: after the slab continuous casting process, the casting blank is required to be subjected to flame peeling treatment, and each surface is cleaned by flame for 4-5mm.
3. The method for producing a cold-rolled sheet for battery cases using cap annealing according to claim 1, wherein: the hot rolling convexity is controlled to be 0-40 mu m, and the wedge shape is controlled to be-20 mu m.
4. The method for producing a cold-rolled sheet for battery cases using cap annealing according to claim 1, wherein: the leveling procedure adopts laser Mao Huagun to level, the leveling elongation is controlled to be 0.6-1.2%, and a leveling roller with Ra of 1.6-2.0 μm is adopted, so that the surface roughness of the plate is ensured to be 0.5-1.0 μm.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4576657A (en) * 1982-02-19 1986-03-18 Kawasaki Steel Corporation Process of manufacturing a cold rolled steel sheet having excellent press formability
JP2002088446A (en) * 2000-09-12 2002-03-27 Toyo Kohan Co Ltd Steel sheet for forming outer cylinder of battery having excellent anisotropy and its production method
CN1940109A (en) * 2005-09-29 2007-04-04 宝山钢铁股份有限公司 Steel for battery shell with excellent planar isotropism and its production
CN108728737A (en) * 2018-04-18 2018-11-02 马鞍山钢铁股份有限公司 A kind of Ultra-low carbon battery case cold-rolled steel sheet and production method

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140261916A1 (en) * 2013-03-15 2014-09-18 Thyssenkrupp Steel Usa, Llc High strength - high ductility cold rolled recovery annealed steel and process for manufacture thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4576657A (en) * 1982-02-19 1986-03-18 Kawasaki Steel Corporation Process of manufacturing a cold rolled steel sheet having excellent press formability
JP2002088446A (en) * 2000-09-12 2002-03-27 Toyo Kohan Co Ltd Steel sheet for forming outer cylinder of battery having excellent anisotropy and its production method
CN1940109A (en) * 2005-09-29 2007-04-04 宝山钢铁股份有限公司 Steel for battery shell with excellent planar isotropism and its production
CN108728737A (en) * 2018-04-18 2018-11-02 马鞍山钢铁股份有限公司 A kind of Ultra-low carbon battery case cold-rolled steel sheet and production method

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