WO2011087109A1 - Tôle d'acier laminée à froid présentant une excellente aptitude au formage et à la conservation de forme après vieillissement - Google Patents

Tôle d'acier laminée à froid présentant une excellente aptitude au formage et à la conservation de forme après vieillissement Download PDF

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WO2011087109A1
WO2011087109A1 PCT/JP2011/050588 JP2011050588W WO2011087109A1 WO 2011087109 A1 WO2011087109 A1 WO 2011087109A1 JP 2011050588 W JP2011050588 W JP 2011050588W WO 2011087109 A1 WO2011087109 A1 WO 2011087109A1
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temperature
aging
cold
less
rolling
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PCT/JP2011/050588
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English (en)
Japanese (ja)
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木津太郎
安原英子
花澤和浩
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Ｊｆｅスチール株式会社
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Priority to CN201180006115.6A priority Critical patent/CN102712974B/zh
Priority to MX2012007914A priority patent/MX353920B/es
Publication of WO2011087109A1 publication Critical patent/WO2011087109A1/fr

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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
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0436—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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0473—Final recrystallisation 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • 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
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
    • 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
    • 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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel
    • 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

Definitions

  • the present invention relates to a cold-rolled steel sheet excellent in formability and shape freezing property after aging, which is optimal as a member of a large flat plate-like component such as a backlight chassis of a large-sized liquid crystal television, and a manufacturing method thereof.
  • Thin plate LCD TVs and OA equipment, etc. use many flat plate parts formed by processing mainly bending / extrusion molding. And in manufacturing the member (thin steel plate) used for these parts, in order to correct the shape of the plate or to eliminate the yield point elongation, a light reduction of about several percent elongation is performed in the temper rolling. .
  • a characteristic called so-called strain aging is deteriorated, such as recovery of yield point elongation and reduction of ductility.
  • strain aging has become unavoidable. Yes.
  • Strain aging is known to be caused by C or N dissolved in the steel sheet, and IF steel in which C and N are added as carbonitride-generating elements such as Ti and Nb and fixed as precipitates is Known as a steel plate that is less susceptible to strain aging.
  • conventional IF steel has a high manufacturing cost and a high r value, which is disadvantageous when it includes bending. From the above, there is a great demand for an inexpensive member (thin steel plate) having a low r value, low yield point elongation and high elongation even after aging.
  • Patent Document 1 discloses that in finish rolling in hot rolling, the reduction ratio of Ar3 to (Ar3 + 100) is 25% or more, and the friction coefficient during rolling is 0.
  • the finish rolling is finished with Ar3 or more as 2 or less, or the rolling reduction direction of Ar3 or less is 25% or more and the friction coefficient during rolling is 0.2 or less, thereby controlling the texture and rolling direction.
  • a steel sheet is disclosed in which at least one of the r values in the direction perpendicular to the rolling is 0.7 or less.
  • Patent Document 2 discloses a ferritic thin steel sheet for automobiles having a good shape freezing property in which the ratio of ⁇ 100 ⁇ plane and ⁇ 111 ⁇ plane parallel to the plate surface is 1.0 or more.
  • Patent Document 3 in order to obtain a ferritic steel sheet having excellent shape freezing property, the strength of ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation group and ⁇ 112 ⁇ ⁇ 110>, ⁇ 554 ⁇ ⁇ 225>, ⁇ 111 ⁇ ⁇ 112>, ⁇ 111 ⁇ ⁇ 110>, controlling the strength of each direction, at least one of the r value in the rolling direction and the r value in the direction perpendicular to the rolling direction is 0.7. The following is disclosed.
  • Patent Documents 1 to 3 are deteriorated in workability after aging, and problems such as press cracking occur.
  • an object of the present invention is to provide a cold-rolled steel sheet excellent in formability and shape freezing property after aging, and a method for producing the same.
  • the average r value in the rolling direction, the 45 ° direction of rolling and the direction perpendicular to the rolling is 1.2 or less, the elongation after aging is 40% or more, and the yield point elongation after aging is 1.0% or less. It was found that a cold-rolled steel sheet having excellent formability and shape freezing property even after aging can be obtained.
  • the mechanism that can ensure the formability and shape freezing property after aging according to the present invention is considered as follows.
  • a method of introducing strain at a room temperature and applying strain is employed.
  • the amount of strain is small, the movable dislocation is fixed by C and N due to aging, and the yield point elongation is restored.
  • the amount of strain at room temperature is increased, the yield point is increased and the elongation is reduced, so that the formability is lowered. Therefore, in the present invention, attention is paid to the distribution of the ferrite particle diameter.
  • the strain By increasing the distribution of the ferrite grain size, even with a small amount of strain, the strain can be concentrated by making the strain introduction position non-uniform. As a result, yield point elongation can be suppressed even after aging. In addition, since the grains with little strain introduction have little hardening due to aging, a decrease in elongation can be suppressed. Such non-uniform introduction of strain can be achieved by increasing the standard deviation of the ferrite grain size distribution.
  • a cold rolled steel sheet having an r value of 1.2 or less, an elongation after aging of 40% or more, and a yield point elongation after aging of 1.0% or less is finished in the ferrite region in hot rolling. After rolling and winding at low temperature, it is not recrystallized in the hot rolling stage, and it is obtained by controlling the heat history during annealing to control the ferrite grain size and grain size distribution and controlling the strain after cooling. It is done.
  • This invention is made
  • the composition further contains at least one of Ti: 0.005 to 0.02% and B: 0.0003 to 0.0030% by mass%.
  • Cold-rolled steel sheet with excellent formability and shape freezing after aging [3] A cold-rolled steel sheet excellent in formability and shape freezing property after aging, characterized in that in [1] or [2], a zinc-based plating layer is provided on the steel sheet surface.
  • a steel slab having the composition described in [1] or [2] above is hot when the final delivery temperature in finish rolling is (Ar3-100 ° C) to Ar3 ° C, and the winding temperature is less than 550 ° C.
  • the temperature range from 600 ° C to the soaking temperature is 1-30 ° C / s average heating Heated at a rate, soaked at a soaking temperature of 800 to 900 ° C., soaking time of 30 to 200 s, and a temperature range from the soaking temperature to 550 ° C. at an average cooling rate of 3 to 30 ° C./s.
  • Cold-rolled steel sheet excellent in formability and shape-freezing property after aging characterized by cooling, holding at 500 to 300 ° C. for 30 s or more, and applying strain of 0.5 to 2.0% elongation at room temperature Manufacturing method.
  • the temperature range from the soaking temperature to 550 ° C. is cooled at an average cooling rate of 3 to 30 ° C./s, and subsequently cooled to a temperature range of 500 ° C. or lower. Then, reheating to a temperature range of 500 to 550 ° C., holding at 500 to 300 ° C. for 30 s or longer, and applying strain of 0.5 to 2.0% elongation at room temperature
  • % which shows the component of steel is mass% altogether.
  • the cold-rolled steel sheet targeted by the present invention includes a steel sheet for subjecting the cold-rolled steel sheet to a zinc-based plating treatment (for example, electrogalvanizing treatment, hot-dip galvanizing treatment, alloying hot-dip galvanizing treatment). . Further, it includes a steel plate having a film formed thereon by chemical conversion treatment or the like.
  • the steel sheet of the present invention can be widely used as a general member for home appliances that bends, projects, and slightly draws flat surfaces such as a large-screen TV backlight chassis, refrigerator panel, and air conditioner outdoor unit.
  • the backlight chassis about 650x500 mm (32V type) or more can be manufactured, for example with the steel plate of plate
  • a cold-rolled steel sheet having excellent formability and shape freezing property after aging can be obtained.
  • a flat plate shape required for a large component can be secured, and a member such as a backlight chassis of a large liquid crystal television can be manufactured.
  • C 0.01 to 0.05% C forms cementite, can reduce the solid solution C, and can reduce the yield strength.
  • production of cementite is suppressed and it becomes easy to age harden
  • the deformation resistance rapidly decreases, and the rolling becomes unstable. Therefore, C needs to be 0.01% or more.
  • C increases, the grain growth is suppressed and the grain size is reduced, so that the steel sheet becomes hard and the elongation decreases. Therefore, C needs to be 0.05% or less.
  • Si 0.05% or less If a large amount of Si is added, the formability deteriorates due to hardening, and the plating property is hindered due to the generation of Si oxide during annealing. Therefore, Si needs to be 0.05% or less.
  • Mn 0.1 to 0.5% Since Mn detoxifies harmful S in steel as MnS, it is necessary to make it 0.1% or more. On the other hand, a large amount of Mn deteriorates formability due to solid solution strengthening or hardening by generation of a low temperature transformation phase. Moreover, Mn lowers the transformation point and makes rolling in the ferrite region in hot rolling difficult. In addition, the structure becomes finer by suppressing the recrystallization of ferrite during annealing. Therefore, Mn needs to be 0.5% or less, preferably 0.3% or less.
  • P 0.05% or less P needs to be 0.05% or less because it segregates at grain boundaries and deteriorates ductility and toughness. Preferably it is 0.03% or less.
  • S 0.02% or less S causes the hot cracking by remarkably reducing the hot ductility, and significantly deteriorates the surface properties. Furthermore, S hardly contributes to the strength, but also reduces the ductility by forming coarse MnS as an impurity element. These problems become significant when the S content exceeds 0.02%, and it is desirable to reduce them as much as possible. Therefore, the S amount needs to be 0.02% or less.
  • Al 0.02 to 0.10% Al can suppress age hardening due to solute N by fixing N as a nitride. In order to obtain such an effect, Al needs to be 0.02% or more. On the other hand, the addition of a large amount of Al not only increases strength and decreases formability, but also increases costs. Therefore, Al needs to be 0.10% or less.
  • N 0.005% or less If N is contained in a large amount, surface cracks may occur due to slab cracking during hot rolling. Moreover, when it exists as solid solution N after cold rolling and annealing, age hardening will be caused. Therefore, N needs to be 0.005% or less.
  • one or more of Ti and B is added to Ti: 0.005 to 0.02% and B: 0.0003 for the purpose of improving aging and shape freezing property. It can be contained within a range of ⁇ 0.0030%.
  • Ti 0.005 to 0.02% Ti combines with N at high temperature to form a nitride, and the aging can be improved by reducing the solid solution N. In order to obtain such an effect, Ti needs to be 0.005% or more. On the other hand, when the content of Ti is large, it is further combined with C to form carbides and carbonitrides, so that the strength is increased and the moldability is lowered. Therefore, when Ti is contained, the content is made 0.005% or more and 0.02% or less.
  • B 0.0003 to 0.0030% B combines with N at a high temperature to form a nitride, and by reducing the solid solution N, aging can be improved. Furthermore, B can improve the shape freezing property by controlling the r value by suppressing the grain growth of ferrite in the annealing process after cold rolling. In order to obtain such an effect, B needs to be 0.0003% or more. On the other hand, when B is present in a large amount, the recrystallization of ferrite during annealing is suppressed, and the structure becomes finer. Therefore, when it contains B, it is set as 0.0003% or more and 0.0030% or less.
  • the other components are composed of iron and inevitable impurities.
  • the inevitable impurities include 0.05% or less of Cu and Cr that are easily mixed from scrap, and 0.01% or less of Sn, Mo, W, V, Nb, Ni, and the like.
  • the structure of the steel sheet of the present invention is mainly composed of a ferrite phase.
  • the average particle size of the ferrite phase is 10 to 20 ⁇ m.
  • ⁇ A ⁇ 0.30, where ⁇ A is the standard deviation of the natural logarithm of the value obtained by dividing the individual ferrite grain size by the average value.
  • a soft ferrite phase is mainly used.
  • “mainly composed of a ferrite phase” refers to a case where the ratio of the ferrite phase to the entire structure is 95% or more in terms of area ratio.
  • the ferrite structure is 100% because elongation is improved.
  • the second phase other than the main phase is a cementite phase or a pearlite phase, and can be contained in an area ratio of 5% or less. If it exceeds 5%, the ductility will be significantly reduced.
  • the area ratio of the ferrite phase can be obtained by image processing after identifying the ferrite phase and the other phases by structure observation.
  • the average particle diameter is 10 ⁇ m or more in order to ensure moldability.
  • the upper limit of the average particle size is 20 ⁇ m.
  • the average particle diameter is measured by a cutting method, and is calculated by 2 / [(1 / Ll) + (1 / Lc)] from the average section lengths Ll and Lc in the rolling direction and the sheet thickness direction.
  • the strain introduction position is made non-uniform so that the strain is concentrated, and the occurrence of yield point elongation is suppressed even after aging.
  • the grains with less strain introduction are less hardened by aging, they suppress the decrease in elongation.
  • FIG. 1 is a graph showing the effect of ⁇ A on yield elongation (YP-El) and elongation (El) when aged at 20 ° C. for 6 months.
  • YP-El yield elongation
  • El elongation
  • the wall angle at the time of overhanging molding can be molded without cracking to about 45 °, and it can cope with most press moldings.
  • ⁇ A is set to 0.30 or more.
  • the steel slab having the above composition is hot-rolled at a final delivery temperature of finish rolling (Ar3-100 ° C) to Ar3 ° C, a winding temperature of less than 550 ° C, and then pickled.
  • finish rolling Ar3-100 ° C
  • a winding temperature of less than 550 ° C
  • pickled After performing cold rolling at a rolling reduction of 40 to 80%, when annealing, the temperature range from 600 ° C. to the soaking temperature is heated at an average heating rate of 1 to 30 ° C./s. Is 800-900 ° C., soaking time is 30-200 s, the temperature range from the soaking temperature to 550 ° C. is cooled at an average cooling rate of 3-30 ° C./s, and 500-300 ° C.
  • the ferrite grain size distribution can be increased, and a low yield point strength after aging, a low r value and excellent elongation can be obtained. .
  • Finishing rolling finish temperature (Ar3-100 ° C.) to Ar3
  • Ar3 Ar3-100 ° C.
  • the amount of reduction at Ar 3 or less is not particularly limited, but is preferably 10% or more, more preferably 20% or more.
  • Winding temperature less than 550 ° C. If the winding temperature after finish rolling is high, ferrite will recrystallize and it will not be possible to introduce non-uniform strain, so the winding temperature should be less than 550 ° C. There is.
  • the lower limit of the coiling temperature is not particularly specified, but if the temperature is too low, the coil winding shape is deteriorated.
  • the cooling rate from the finish rolling to the winding is not particularly specified, but is preferably 10 ° C./S or more, more preferably 30 ° C./s or more, and further preferably 100 ° C./s or more.
  • Rolling ratio during cold rolling 40-80%
  • the rolling reduction in cold rolling after pickling hot-rolled sheet is large, the introduction of strain is made uniform, the ferrite grain size distribution after annealing is reduced, and the strength is increased by refinement by increasing the amount of strain. And formability is reduced.
  • the r value increases and the shape freezing property decreases. From the above, the rolling reduction needs to be 80% or less.
  • the rolling reduction when the rolling reduction is small, the amount of strain introduced is small, so that recrystallization at the time of annealing is suppressed and a recovery structure is formed, so that formability is lowered. Therefore, the rolling reduction needs to be 40% or more.
  • Average heating rate from 600 ° C to soaking temperature 1-30 ° C / s
  • the ferrite grain size and grain size distribution are controlled by controlling the thermal history during annealing, and the strain after cooling is controlled. Therefore, the manufacturing conditions for annealing are an important requirement. If the average heating rate from 600 ° C. to the soaking temperature is small, the recovery proceeds and recrystallization is suppressed. Therefore, the average heating rate needs to be 1 ° C./s or more. On the other hand, if the average heating rate is high, recrystallization nucleation during heating is suppressed, and nucleation occurs simultaneously during soaking, resulting in finer grains. Therefore, the average heating rate needs to be 30 ° C./s or less.
  • Soaking temperature 800-900 ° C
  • Soaking time 30-200s
  • the soaking temperature needs to be 800 ° C. or higher.
  • the soaking temperature needs to be 900 ° C. or less.
  • the soaking time is short, recrystallization will not be completed, or even if it is completed, the time for grain growth is short, so that the particles are finely granulated and the moldability is lowered.
  • the soaking time during heating needs to be 30 s or more.
  • the soaking time needs to be 200 s or less.
  • the cooling rate after soaking is small, the growth of ferrite grains is promoted, and large grains grow and grow while eroding the small grains, so the ferrite grain size distribution becomes smaller and the grain size becomes larger. In press molding, it causes poor appearance such as orange peel. Therefore, the average cooling rate in the temperature range from the soaking temperature to 550 ° C. needs to be 3 ° C./s or more.
  • the cooling rate is too high, the strength increases and the moldability decreases, so the average cooling rate needs to be 30 ° C./s or less.
  • cooling from the above-mentioned soaking to 550 ° C. during the holding up to 500 to 300 ° C., it may be appropriately cooled in accordance with the manufacturing equipment.
  • cooling is continued in the same cooling rate range, that is, 3 to 30 ° C./s.
  • the upper limit of the time is not particularly defined, it is preferable that the upper limit of the holding time is about 300 s because holding for a long time decreases the production efficiency.
  • maintenance the said cooling conditions do not need to prescribe
  • strain application at room temperature elongation: 0.5-2.0% After annealing, the yield point can be eliminated by applying strain at room temperature. For this reason, the strain applied at room temperature must be 0.5% or more in terms of elongation. On the other hand, when the elongation increases, the yield point rises and the formability decreases, so it is necessary to make it 2.0% or less. Preferably it is 1.5% or less.
  • the application of strain at room temperature may be rolling with a roll or tension, or a combination of roll and tension. In rolling, it may or may not be lubricated.
  • a melting method can be appropriately applied, such as a normal converter method and an electric furnace method.
  • the molten steel is cast into a slab and then heated as it is or after cooling and hot rolling.
  • hot rolling after finishing under the above-mentioned finishing conditions, winding is performed at the above-described winding temperature.
  • the above-mentioned cold rolling is performed.
  • plating with molten zinc may be performed at around 480 ° C. Further, after plating, the plating may be alloyed by reheating to 500 ° C. or higher.
  • the holding time at 300 ° C. it is about 460 degreeC. That is, when hot dip galvanization is performed after the soaking and further alloying is performed, the heat history may be as follows. After the soaking, the temperature range from the soaking temperature to 550 ° C.
  • temper rolling is performed at an elongation of about 0.5 to 2.0%. Preferably, it is 0.5 to 1.5%.
  • a film may be formed on the cold-rolled steel plate or the plated steel plate by chemical conversion treatment or the like. From the above, a cold-rolled steel sheet having excellent formability and shape freezing property after aging can be obtained. And the cold-rolled steel sheet obtained by the above has an average r value of 1.2 or less in the rolling direction, the 45 ° direction of rolling, and the direction perpendicular to the rolling, the elongation after aging is 40% or more, and the yield point elongation after aging is 1.0% or less. These characteristics are the average r value, elongation, and yield point elongation after aging treatment at 20 ° C. for 6 months.
  • the r value correlates with the warp that occurs after bending. In bending, the r value in the bending direction is increased, so that saddle-shaped warpage occurs remarkably along the bending line. Therefore, in order to improve the shape freezing property after press molding by lowering the r value, the average r value is set to 1.2 or less in the present invention.
  • Elongation has a good correlation with moldability, and the larger the elongation, for example, the higher the stretch molding. Therefore, the larger the required elongation, the better, and by setting the elongation after aging to 40% or more, drawing or overhanging can be performed, and the shape required for the part can be ensured.
  • the steel sheet of the present invention has a yield point elongation after aging of 1.0% or less.
  • specimen No. No. 4 was subjected to a hot dip galvanizing treatment at 480 ° C., and the surface was hot dip galvanized (GI).
  • Specimen No. 3 was plated with hot dip zinc at 480 ° C. in the middle, and then reheated to 540 ° C. to make the surface alloyed hot dip galvanized (GA).
  • Specimen No. No. 2 was electroplated and the surface was electroplated (EG). In addition, it cooled at the same cooling rate as CR shown in Table 1 continuously from 550 degreeC to 500 degreeC except sample material No4. The structure and mechanical properties of the specimens obtained as described above were investigated.
  • the structure was obtained by observing the thickness cross section in the rolling direction with an optical microscope, and obtaining the average particle size and particle size distribution of the structure by a cutting method.
  • the structure of all the test materials had a ferrite phase of 99% or more.
  • a JIS No. 5 tensile test piece with the rolling direction as the tensile direction was cut out from the test material, subjected to an aging treatment at 20 ° C. for 6 months, a tensile test was performed at a tensile rate of 10 mm / min, and the yield point elongation (YP) -El) and total elongation (El) were measured.
  • the r value is obtained by cutting out a JIS No. 5 tensile test piece from each of the rolling direction of the test material, the rolling 45 ° direction, and the direction perpendicular to the rolling direction, measuring with a pre-strain of 15%, and the r value (r L ) in the rolling direction.
  • the rolling direction of 45 ° of the r value (r d), perpendicular to the rolling direction C in r values from (r C), average of r values (r m) at r m (r L + 2r D + r C) / 4 Asked.
  • the obtained results are shown in Table 1 together with the component composition and production conditions.
  • the steel sheet (invented steel) having the composition of the present invention and manufactured by the manufacturing method of the present invention has a ferrite average particle diameter in the range of 10 to 20 ⁇ m and a standard deviation ( ⁇ A ). Is 0.30 or more.
  • the average r value in the rolling direction, the 45 ° direction of rolling, and the direction perpendicular to the rolling direction is 1.2 or less
  • the elongation at yield point after aging is 1.0% or less
  • the elongation (Elm) after aging is 40% or more.
  • the steel sheet (comparative steel) whose manufacturing method is outside the range of the present invention has an average ferrite value or standard deviation ( ⁇ A ) outside the range, and the average r value, yield point after aging. Either elongation or elongation after aging (El) was inferior.
  • FIG. 1 to 8 the effect of (FT-Ar3) on ⁇ A is shown in FIG.
  • FIG. 2 shows that the standard deviation ( ⁇ A ) can be set to 0.30 or more by setting the final delivery temperature (FT) to (Ar3-100 ° C.) to Ar3.
  • FIG. 3 shows that the standard deviation ( ⁇ A ) can be set to 0.30 or more by setting the coiling temperature (CT) to less than 550 ° C.

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  • Chemical & Material Sciences (AREA)
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  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Coating With Molten Metal (AREA)

Abstract

L'invention concerne une tôle d'acier laminée à froid qui présente une excellente aptitude au formage et à la conservation de forme après vieillissement, et un procédé pour produire celle-ci. La tôle d'acier présente une structure à base de la phase ferrite qui contient entre 0,01 % et 0,05 % de C, pas plus de 0,05 % de Si, entre 0,1 % et 0,5 % de Mn, pas plus de 0,05 % de P, pas plus de 0,02 % de S, entre 0,02 % et 0,10 % d'Al, pas plus de 0,005 % de N, le reste étant constitué de fer et des inévitables impuretés. La taille de particule moyenne de ladite phase ferrite est comprise entre 10 µm et 20 μm, et l'écart-type σA du logarithme naturel de la valeur obtenue en divisant des tailles de particules de ferrite individuelles par la valeur moyenne est d'au moins 0,30. Pour obtenir la tôle d'acier, lorsque l'on procède à un recuit après le laminage à froid, on chauffe de 600 °C jusqu'à la gamme de la température de maintien à une vitesse de chauffage comprise entre 1 °C/s et 30 °C/s ; le maintien est réalisé à une température de maintien comprise entre 800 °C et 900 °C pendant une période de maintien comprise entre 30 s et 200 s; un refroidissement à partir de la température de maintien jusqu'à la gamme de 550 °C est exécuté à une vitesse de refroidissement moyenne de 3 °C/s à 30 °C/s; et ensuite la tôle d'acier est maintenue à une température comprise entre 500 °C et 300 °C pendant au moins 30 s, et une déformation est appliquée pour obtenir un allongement de l'ordre de 0,5 % à 2,0 % à la température ambiante.
PCT/JP2011/050588 2010-01-15 2011-01-07 Tôle d'acier laminée à froid présentant une excellente aptitude au formage et à la conservation de forme après vieillissement WO2011087109A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN201180006115.6A CN102712974B (zh) 2010-01-15 2011-01-07 时效后的成形性和形状冻结性优良的冷轧钢板及其制造方法
MX2012007914A MX353920B (es) 2010-01-15 2011-01-07 Lamina de acero laminada en frio que tiene excelente moldeabilidad y conservacion de la forma post-envejecimiento.

Applications Claiming Priority (2)

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JP2010-006553 2010-01-15
JP2010006553A JP5018900B2 (ja) 2010-01-15 2010-01-15 時効後の成形性及び形状凍結性に優れた冷延鋼板およびその製造方法

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MY (1) MY161948A (fr)
TW (1) TWI429758B (fr)
WO (1) WO2011087109A1 (fr)

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KR101461740B1 (ko) * 2012-12-21 2014-11-14 주식회사 포스코 재질 및 두께 편차가 작고 내도금박리성이 우수한 열연강판 및 그 제조방법
CN105378128B (zh) * 2013-07-03 2017-09-19 Posco公司 加工性及抗时效性优异的热轧钢板及其制造方法
CN112553537A (zh) * 2019-09-25 2021-03-26 上海梅山钢铁股份有限公司 屈服强度240MPa级冷轧热镀锌钢板及其制造方法

Citations (6)

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Publication number Priority date Publication date Assignee Title
JPH02263950A (ja) * 1989-04-04 1990-10-26 Kobe Steel Ltd 深絞り用熱延鋼板及びその製法
JP2000045046A (ja) * 1998-07-29 2000-02-15 Nisshin Steel Co Ltd 耐粗粒化性・耐銅浸入性等に優れたシングルパイプ用銅めっき鋼板およびその製造方法
JP2003064446A (ja) * 2001-08-21 2003-03-05 Kawasaki Steel Corp 歪時効硬化特性に優れるとともに室温時効劣化のない冷延鋼板および冷延めっき鋼板ならびにそれらの製造方法
WO2005028693A1 (fr) * 2003-09-24 2005-03-31 Nippon Steel Corporation Tole d'acier laminee a chaud a travailler
JP2010229486A (ja) * 2009-03-27 2010-10-14 Jfe Steel Corp 絞りおよびしごき加工後の表面性状に優れた缶用鋼板およびその製造方法
JP2010265545A (ja) * 2009-04-13 2010-11-25 Jfe Steel Corp 時効性および焼付け硬化性に優れた冷延鋼板およびその製造方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100473742C (zh) * 2006-04-29 2009-04-01 宝山钢铁股份有限公司 静电搪瓷用热轧细晶粒钢及其制造方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02263950A (ja) * 1989-04-04 1990-10-26 Kobe Steel Ltd 深絞り用熱延鋼板及びその製法
JP2000045046A (ja) * 1998-07-29 2000-02-15 Nisshin Steel Co Ltd 耐粗粒化性・耐銅浸入性等に優れたシングルパイプ用銅めっき鋼板およびその製造方法
JP2003064446A (ja) * 2001-08-21 2003-03-05 Kawasaki Steel Corp 歪時効硬化特性に優れるとともに室温時効劣化のない冷延鋼板および冷延めっき鋼板ならびにそれらの製造方法
WO2005028693A1 (fr) * 2003-09-24 2005-03-31 Nippon Steel Corporation Tole d'acier laminee a chaud a travailler
JP2010229486A (ja) * 2009-03-27 2010-10-14 Jfe Steel Corp 絞りおよびしごき加工後の表面性状に優れた缶用鋼板およびその製造方法
JP2010265545A (ja) * 2009-04-13 2010-11-25 Jfe Steel Corp 時効性および焼付け硬化性に優れた冷延鋼板およびその製造方法

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CN102712974B (zh) 2014-06-25
JP2011144427A (ja) 2011-07-28
KR20120094125A (ko) 2012-08-23
TW201134954A (en) 2011-10-16
MX2012007914A (es) 2012-08-01
MY161948A (en) 2017-05-15
JP5018900B2 (ja) 2012-09-05
MX353920B (es) 2018-02-06
CN102712974A (zh) 2012-10-03
TWI429758B (zh) 2014-03-11

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