WO2021009966A1 - Box-type annealed dr steel sheet and method for manufacturing same - Google Patents
Box-type annealed dr steel sheet and method for manufacturing same Download PDFInfo
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- WO2021009966A1 WO2021009966A1 PCT/JP2020/010173 JP2020010173W WO2021009966A1 WO 2021009966 A1 WO2021009966 A1 WO 2021009966A1 JP 2020010173 W JP2020010173 W JP 2020010173W WO 2021009966 A1 WO2021009966 A1 WO 2021009966A1
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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
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
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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
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
Definitions
- the present invention relates to a box-type annealed DR steel sheet having an excellent surface appearance and a method for manufacturing the same.
- temper color is a surface defect caused by an oxide film formed on the surface of a steel sheet due to oxidation of components (for example, Mn, Al, Si) in the steel that are concentrated on the surface of the steel sheet during annealing, and gives the surface appearance of the steel sheet. Deteriorate.
- Patent Document 1 proposes a technique for improving expand moldability by using a box-type annealed DR steel sheet.
- Patent Document 1 investigates the presence or absence of stretcher strain after expand molding, but does not mention uneven color tone.
- the technique of Patent Document 1 has a problem that Si and Mn, which are steel sheet elements, are concentrated on the surface layer during box annealing, and a temper color is generated. Further, even if it is not recognized as a temper color, it is considered that an oxide film (surface oxide) on the surface layer due to oxidized Si or Mn is inevitably formed.
- secondary cold rolling is performed after annealing.
- the present inventors have repeatedly studied the steel sheet composition and the manufacturing method in order to improve the surface appearance of the box-type annealed DR steel sheet. Then, it was found that the surface appearance of the box-type annealed DR steel sheet is improved by setting the rolling reduction ratio at the time of secondary cold rolling (DR rolling) to 25% or less at the time of manufacturing the steel sheet. On the other hand, since the strength cannot be expected by keeping the rolling reduction during the secondary cold rolling low, the components were repeatedly examined in order to secure the strength of the steel sheet. Then, it was found that the strength of the steel sheet can be secured by limiting the content of Mn, which is easily oxidized, and increasing the content of Nb as a reinforcing element.
- the gist of the present invention is as follows. [1] In terms of mass%, C: 0.020 to 0.080%, Si: 0.05% or less, Mn: 0.10 to 0.50%, P: 0.020% or less, S: 0.020 % Or less, Al: 0.001 to 0.100%, N: 0.014 to 0.020%, Nb: 0.014 to 0.020%, Mn + 25Nb ⁇ 0.85, and the balance is Fe.
- a box-type annealed DR steel sheet having a component composition consisting of unavoidable impurities, a yield point of 450 to 650 MPa, and a total elongation of 4% or more.
- Mn and Nb refer to the content (mass%) of each element.
- the steel material having the component composition described in [1] is subjected to hot rolling and then primary cold rolling, and then box-shaped annealing at 650 to 750 ° C. for 2 to 16 hours.
- a box-type annealed DR steel sheet having excellent desired mechanical properties and surface appearance can be obtained.
- the desired mechanical properties in the present invention are a yield point of 450 to 650 MPa and a total elongation of 4% or more.
- the box-type annealed DR steel sheet of the present invention has a mass% of C: 0.020 to 0.080%, Si: 0.05% or less, Mn: 0.10 to 0.50%, P: 0.020%.
- C 0.020 to 0.080% C is an element that improves the strength of the steel sheet.
- the C content is set to 0.020% or more. Preferably, it is 0.025% or more.
- the C content is set to 0.080% or less. Preferably, it is 0.050% or less.
- the Si content is set to 0.05% or less. Preferably, it is 0.03% or less. From the viewpoint of refining, the Si content is preferably 0.001% or more because it is necessary to keep the cost within a range that does not increase.
- Mn 0.10 to 0.50%
- Mn is an element that improves the strength of the steel sheet.
- the Mn content is 0.10% or more.
- it is 0.20% or more.
- the Mn content exceeds 0.50%, it is oxidized during box annealing and oxides are deposited on the WR surface during the subsequent secondary cold rolling to deteriorate the surface appearance. It ends up. It also reduces the total elongation of the steel sheet. Therefore, the Mn content is set to 0.50% or less. Preferably, it is 0.35% or less.
- P 0.020% or less
- P is an element that segregates at the grain boundaries in the steel sheet to reduce workability and deteriorate corrosion resistance. Therefore, the P content is set to 0.020% or less. Preferably, it is 0.015% or less.
- S 0.020% or less S precipitates at the grain boundaries as MnS during continuous casting and causes slab cracking. Therefore, the S content is set to 0.020% or less. Preferably, it is 0.015% or less.
- Al 0.001 to 0.100% Al is known to form N and AlN.
- N that does not form AlN exists as a solid solution N.
- the solid solution N contributes to the improvement of the strength of the steel sheet.
- the Al content is 0.100% or less in order to secure the required solid solution N amount. Preferably, it is 0.08% or less.
- the Al content is set to 0.001% or more because it is necessary to keep the cost within a range that does not increase the cost from the viewpoint of refining.
- N 0.014-0.020% N forms Al and AlN, and N that does not form AlN exists as a solid solution N.
- the solid solution N contributes to the improvement of the strength of the steel sheet. Therefore, the N content is set to 0.014% or more. Preferably, it is 0.015% or more.
- the N content is set to 0.020% or less. Preferably, it is 0.019% or less.
- Nb 0.014-0.020%
- Nb is an element that improves the strength of the steel sheet.
- the Nb content is 0.014% or more. Preferably, it is 0.015% or more.
- the Nb content is set to 0.020% or less. Preferably, it is 0.018% or less.
- Mn + 25Nb ⁇ 0.85 Both Mn and Nb are elements necessary for ensuring the strength of the steel sheet. However, as described above, since Mn is easily oxidized, it forms a surface oxide during annealing and deteriorates the surface appearance of the final product. Therefore, it is necessary to appropriately control the upper limit amount of Mn according to the amount of Nb. From various experimental results, it was found that when Mn + 25Nb ⁇ 0.85, there is no deterioration in the surface appearance and the strength can be ensured. In addition, Mn and Nb indicate the content (mass%) of each element, respectively.
- the rest is Fe and unavoidable impurities.
- unavoidable impurities include Ni and Cu, and Ni is 0.1% or less and Cu is 0.1% or less, which is acceptable.
- the above components are the basic components of the present invention.
- elements generally present in known container steel sheets may be added depending on the purpose.
- one or more selected from Ti, B, Cr, and Mo may be added.
- a plating layer may be provided on the surface of the steel sheet.
- the type of plating method for forming a plating layer on the surface is not particularly limited, and may be electroplating or hot-dip galvanizing.
- a tin-free steel may be obtained by providing two layers of metallic chromium and chromium hydrated oxide on the surface of the steel sheet.
- a slab (steel material) having the above-mentioned composition is hot-rolled and then primary cold-rolled. Then, the primary cold-rolled cold-rolled coil is subjected to box-shaped annealing at 650 to 750 ° C. for 2 to 16 hours, and then secondary cold rolling (DR rolling) is performed at a reduction ratio of 10 to 25%.
- DR rolling secondary cold rolling
- molten steel which is the raw material for box-type annealed DR steel sheets
- the steel is melted in a general converter or electric furnace to have the above-mentioned composition.
- refining may be carried out by degassing treatment.
- the steel having the above-mentioned composition is made into a slab by continuous casting, ingot-bulk rolling, or the like. This slab becomes the material (steel material) for the box-type annealed DR steel sheet.
- Hot rolling it is preferable that the slab is reheated to a temperature of 1050 to 1300 ° C. and then finish-rolled at an Ar3 transformation point or higher.
- the winding temperature after hot rolling is preferably between 450 and 750 ° C.
- the Ar3 transformation point can be measured by the Formaster test.
- the slab after casting may be directly rolled without being reheated.
- Primary cold rolling in primary cold rolling can be performed by a conventional method.
- the reduction rate is not particularly limited, but is preferably 70 to 98%.
- Box-shaped annealing 2 to 16 hours at 650 to 750 ° C.
- the cold-rolled primary cold-rolled coil is box-shaped annealed at 650 to 750 ° C. for 2 to 16 hours.
- the annealing time is less than 2 hours or the annealing temperature is less than 650 ° C.
- recrystallization does not proceed sufficiently and total elongation of 4% or more cannot be obtained.
- the annealing time exceeds 16 hours or the annealing temperature exceeds 750 ° C. oxides are likely to be formed on the surface of the steel sheet, and the surface appearance is deteriorated.
- the annealing time is preferably 3 hours or more, and the annealing temperature is 680 ° C. or more. Further, from the viewpoint of suppressing the formation of oxides, the annealing time is preferably 12 hours or less, and the annealing temperature is 740 ° C. or less.
- Secondary cold rolling rolling ratio 10 to 25% Secondary cold rolling is performed at a rolling reduction of 10 to 25%. If the reduction rate is less than 10%, the strength at the yield point of 450 to 650 MPa cannot be obtained. On the other hand, when the reduction ratio exceeds 25%, oxides on the surface of the steel sheet are deposited on the work roll and transferred to the steel sheet to deteriorate the surface appearance of the steel sheet. From the viewpoint of ensuring strength, the reduction rate is preferably 15% or more.
- the box-type annealed DR steel sheet obtained as described above may be passed through an electroplating line or the like to be electroplated.
- tinplate may be applied to make tinplate.
- the box-type annealed DR steel sheet may be subjected to electrolytic chromic acid treatment to obtain tin-free steel having two layers of metallic chromium and chromium hydrated oxide on the surface.
- a box-type annealed DR steel sheet having the above-mentioned composition, a yield point of 450 to 650 MPa, and a total elongation of 4% or more can be obtained.
- the cold-rolled primary cold-rolled coil was subjected to box-type annealing and secondary cold-rolling (DR rolling) under the conditions shown in Table 1 to obtain a box-type annealed DR steel sheet having a plate thickness of 0.20 mm.
- DR rolling secondary cold-rolling
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Abstract
Provided are a box-type annealed DR steel sheet having excellent surface appearance and a method for manufacturing same. This box-type annealed DR steel sheet has a component composition including, in mass%, 0.020-0.080% of C, not more than 0.05% of Si, 0.10-0.50% of Mn, not more than 0.020% of P, not more than 0.020% of S, 0.001-0.100% of Al, 0.014-0.020% of N, and 0.014-0.020% of Nb, Mn+25Nb≤0.85 being satisfied, the remaining portion being Fe and unavoidable impurities, and has a yield point of 450-650 MPa and a total elongation not less than 4%. Here, in Mn+25Nb, Mn and Nb represent the contents (mass%) of the respective elements.
Description
本発明は、表面外観に優れた箱型焼鈍ＤＲ鋼板およびその製造方法に関する。
The present invention relates to a box-type annealed DR steel sheet having an excellent surface appearance and a method for manufacturing the same.
近年、容器用等の鋼板について、所望の機械的特性を有するとともに、優れた表面外観を有することがますます求められている。めっき処理前の鋼板の色調がめっき処理後の外観にも表れる製品においては、めっき処理前の鋼板の色調むらが、製品の品質劣化につながる。このため、めっき処理前の鋼板の表面外観を向上させる技術が求められている。
In recent years, steel sheets for containers, etc. are increasingly required to have desired mechanical properties and excellent surface appearance. In a product in which the color tone of the steel sheet before the plating treatment appears in the appearance after the plating treatment, the color tone unevenness of the steel sheet before the plating treatment leads to deterioration of the quality of the product. Therefore, there is a demand for a technique for improving the surface appearance of a steel sheet before plating.
容器用の鋼板等、加工性が要求される鋼板の製造工程においては、冷間圧延後の鋼板に対し、軟質化を目的として箱型焼鈍による焼鈍処理が一般的に行われている。しかし、箱型焼鈍を経た鋼板には、テンパーカラーと呼ばれる色調むらが発生する場合がある。テンパーカラーは、焼鈍中に鋼板表面に濃化する鋼中の成分（例えば、Ｍｎ、Ａｌ、Ｓｉ）が酸化することにより鋼板表面に生じる酸化被膜に起因する表面欠陥であり、鋼板の表面外観を劣化させる。
In the manufacturing process of steel sheets that require workability, such as steel sheets for containers, the steel sheets after cold rolling are generally annealed by box-type annealing for the purpose of softening. However, the steel sheet that has undergone box-type annealing may have color unevenness called temper color. Temper color is a surface defect caused by an oxide film formed on the surface of a steel sheet due to oxidation of components (for example, Mn, Al, Si) in the steel that are concentrated on the surface of the steel sheet during annealing, and gives the surface appearance of the steel sheet. Deteriorate.
特許文献１では、箱型焼鈍ＤＲ鋼板によりエキスパンド成形性を改善する技術が提案されている。
Patent Document 1 proposes a technique for improving expand moldability by using a box-type annealed DR steel sheet.
特許文献１は、エキスパンド成形後のストレッチャーストレインの発生有無について調査しているものの、色調むらに関して言及していない。特許文献１の技術では、箱型焼鈍時に鋼板元素であるＳｉやＭｎが表層に濃化して、テンパーカラーが生じる課題がある。また、テンパーカラーとして認知されなかった場合でも、酸化したＳｉやＭｎによる表層の酸化膜（表層酸化物）が不可避的に形成されていると考えられる。箱型焼鈍ＤＲ鋼板の製造においては焼鈍後に二次冷間圧延が行われる。このため、特許文献１の技術では、二次冷間圧延時に、上述の表層酸化物がワークロール（ＷＲ）に転写し、ＷＲ表面上に蓄積した酸化物が再度鋼板表面に転写することで表面外観を劣化させるという課題があった。
Patent Document 1 investigates the presence or absence of stretcher strain after expand molding, but does not mention uneven color tone. The technique of Patent Document 1 has a problem that Si and Mn, which are steel sheet elements, are concentrated on the surface layer during box annealing, and a temper color is generated. Further, even if it is not recognized as a temper color, it is considered that an oxide film (surface oxide) on the surface layer due to oxidized Si or Mn is inevitably formed. In the production of box-type annealed DR steel sheets, secondary cold rolling is performed after annealing. Therefore, in the technique of Patent Document 1, the above-mentioned surface oxide is transferred to the work roll (WR) during the secondary cold rolling, and the oxide accumulated on the WR surface is transferred to the surface of the steel sheet again. There was a problem of deteriorating the appearance.
上述の事情に鑑み、本発明は、所望の機械的特性および表面外観に優れた箱型焼鈍ＤＲ鋼板およびその製造方法を提供することを目的とする。
In view of the above circumstances, it is an object of the present invention to provide a box-type annealed DR steel sheet having excellent desired mechanical properties and surface appearance and a method for producing the same.
本発明者らは、箱型焼鈍ＤＲ鋼板の表面外観を改善すべく、鋼板成分および製造方法についての検討を重ねた。そして、鋼板の製造時において、二次冷間圧延（ＤＲ圧延）時の圧下率を２５％以下とすることにより箱型焼鈍ＤＲ鋼板の表面外観が改善されることを突き止めた。一方で、二次冷間圧延時の圧下率を低く抑えることにより強度が期待できなくなるため、鋼板の強度を確保するために成分について検討を重ねた。そして、強化元素として、易酸化性であるＭｎの含有量を制限し、Ｎｂの含有量を増加させることで鋼板の強度も確保できるとの知見を得た。
The present inventors have repeatedly studied the steel sheet composition and the manufacturing method in order to improve the surface appearance of the box-type annealed DR steel sheet. Then, it was found that the surface appearance of the box-type annealed DR steel sheet is improved by setting the rolling reduction ratio at the time of secondary cold rolling (DR rolling) to 25% or less at the time of manufacturing the steel sheet. On the other hand, since the strength cannot be expected by keeping the rolling reduction during the secondary cold rolling low, the components were repeatedly examined in order to secure the strength of the steel sheet. Then, it was found that the strength of the steel sheet can be secured by limiting the content of Mn, which is easily oxidized, and increasing the content of Nb as a reinforcing element.
本発明の要旨は以下の通りである。
［１］ 質量％で、Ｃ：０．０２０～０．０８０％、Ｓｉ：０．０５％以下、Ｍｎ：０．１０～０．５０％、Ｐ：０．０２０％以下、Ｓ：０．０２０％以下、Ａｌ：０．００１～０．１００％、Ｎ：０．０１４～０．０２０％、Ｎｂ：０．０１４～０．０２０％を含有し、Ｍｎ＋２５Ｎｂ≦０．８５であり、残部がＦｅおよび不可避的不純物からなる成分組成を有し、降伏点が４５０～６５０ＭＰａ、全伸びが４％以上である、箱型焼鈍ＤＲ鋼板。
ここで、前記Ｍｎ＋２５Ｎｂにおいて、ＭｎおよびＮｂは各元素の含有量（質量％）を指す。
［２］ ［１］に記載の成分組成を有する鋼素材に対し、熱間圧延の後、一次冷間圧延を施し、次いで、６５０～７５０℃で２～１６ｈの箱型焼鈍を施し、前記箱型焼鈍の後、圧下率１０～２５％で二次冷間圧延を行う、箱型焼鈍ＤＲ鋼板の製造方法。 The gist of the present invention is as follows.
[1] In terms of mass%, C: 0.020 to 0.080%, Si: 0.05% or less, Mn: 0.10 to 0.50%, P: 0.020% or less, S: 0.020 % Or less, Al: 0.001 to 0.100%, N: 0.014 to 0.020%, Nb: 0.014 to 0.020%, Mn + 25Nb ≦ 0.85, and the balance is Fe. A box-type annealed DR steel sheet having a component composition consisting of unavoidable impurities, a yield point of 450 to 650 MPa, and a total elongation of 4% or more.
Here, in the Mn + 25Nb, Mn and Nb refer to the content (mass%) of each element.
[2] The steel material having the component composition described in [1] is subjected to hot rolling and then primary cold rolling, and then box-shaped annealing at 650 to 750 ° C. for 2 to 16 hours. A method for producing a box-type annealed DR steel sheet, in which secondary cold rolling is performed at a rolling reduction of 10 to 25% after mold annealing.
［１］ 質量％で、Ｃ：０．０２０～０．０８０％、Ｓｉ：０．０５％以下、Ｍｎ：０．１０～０．５０％、Ｐ：０．０２０％以下、Ｓ：０．０２０％以下、Ａｌ：０．００１～０．１００％、Ｎ：０．０１４～０．０２０％、Ｎｂ：０．０１４～０．０２０％を含有し、Ｍｎ＋２５Ｎｂ≦０．８５であり、残部がＦｅおよび不可避的不純物からなる成分組成を有し、降伏点が４５０～６５０ＭＰａ、全伸びが４％以上である、箱型焼鈍ＤＲ鋼板。
ここで、前記Ｍｎ＋２５Ｎｂにおいて、ＭｎおよびＮｂは各元素の含有量（質量％）を指す。
［２］ ［１］に記載の成分組成を有する鋼素材に対し、熱間圧延の後、一次冷間圧延を施し、次いで、６５０～７５０℃で２～１６ｈの箱型焼鈍を施し、前記箱型焼鈍の後、圧下率１０～２５％で二次冷間圧延を行う、箱型焼鈍ＤＲ鋼板の製造方法。 The gist of the present invention is as follows.
[1] In terms of mass%, C: 0.020 to 0.080%, Si: 0.05% or less, Mn: 0.10 to 0.50%, P: 0.020% or less, S: 0.020 % Or less, Al: 0.001 to 0.100%, N: 0.014 to 0.020%, Nb: 0.014 to 0.020%, Mn + 25Nb ≦ 0.85, and the balance is Fe. A box-type annealed DR steel sheet having a component composition consisting of unavoidable impurities, a yield point of 450 to 650 MPa, and a total elongation of 4% or more.
Here, in the Mn + 25Nb, Mn and Nb refer to the content (mass%) of each element.
[2] The steel material having the component composition described in [1] is subjected to hot rolling and then primary cold rolling, and then box-shaped annealing at 650 to 750 ° C. for 2 to 16 hours. A method for producing a box-type annealed DR steel sheet, in which secondary cold rolling is performed at a rolling reduction of 10 to 25% after mold annealing.
本発明によれば、所望の機械的特性および表面外観に優れた箱型焼鈍ＤＲ鋼板が得られる。
According to the present invention, a box-type annealed DR steel sheet having excellent desired mechanical properties and surface appearance can be obtained.
なお、本発明における所望の機械的特性とは、降伏点が４５０～６５０ＭＰａ、全伸びが４％以上をいう。
The desired mechanical properties in the present invention are a yield point of 450 to 650 MPa and a total elongation of 4% or more.
＜箱型焼鈍ＤＲ鋼板の成分組成＞
本発明の箱型焼鈍ＤＲ鋼板は、質量％で、Ｃ：０．０２０～０．０８０％、Ｓｉ：０．０５％以下、Ｍｎ：０．１０～０．５０％、Ｐ：０．０２０％以下、Ｓ：０．０２０％以下、Ａｌ：０．００１～０．１００％、Ｎ：０．０１４～０．０２０％、Ｎｂ：０．０１４～０．０２０％を含有し、Ｍｎ＋２５Ｎｂ≦０．８５であり、残部がＦｅおよび不可避的不純物からなる成分組成を有する。 <Component composition of box-type annealed DR steel sheet>
The box-type annealed DR steel sheet of the present invention has a mass% of C: 0.020 to 0.080%, Si: 0.05% or less, Mn: 0.10 to 0.50%, P: 0.020%. Hereinafter, S: 0.020% or less, Al: 0.001 to 0.100%, N: 0.014 to 0.020%, Nb: 0.014 to 0.020% are contained, and Mn + 25Nb ≦ 0. It is 85 and has a component composition in which the balance is composed of Fe and unavoidable impurities.
本発明の箱型焼鈍ＤＲ鋼板は、質量％で、Ｃ：０．０２０～０．０８０％、Ｓｉ：０．０５％以下、Ｍｎ：０．１０～０．５０％、Ｐ：０．０２０％以下、Ｓ：０．０２０％以下、Ａｌ：０．００１～０．１００％、Ｎ：０．０１４～０．０２０％、Ｎｂ：０．０１４～０．０２０％を含有し、Ｍｎ＋２５Ｎｂ≦０．８５であり、残部がＦｅおよび不可避的不純物からなる成分組成を有する。 <Component composition of box-type annealed DR steel sheet>
The box-type annealed DR steel sheet of the present invention has a mass% of C: 0.020 to 0.080%, Si: 0.05% or less, Mn: 0.10 to 0.50%, P: 0.020%. Hereinafter, S: 0.020% or less, Al: 0.001 to 0.100%, N: 0.014 to 0.020%, Nb: 0.014 to 0.020% are contained, and Mn + 25Nb ≦ 0. It is 85 and has a component composition in which the balance is composed of Fe and unavoidable impurities.
以下に、本発明の箱型焼鈍ＤＲ鋼板が有する成分組成の範囲の限定理由を説明する。なお、成分の含有量に関する％は「質量％」を意味する。
The reason for limiting the range of the component composition of the box-type annealed DR steel sheet of the present invention will be described below. In addition,% regarding the content of a component means "mass%".
Ｃ：０．０２０～０．０８０％
Ｃは、鋼板の強度を向上させる元素である。降伏点が４５０～６５０ＭＰａの強度を得るために、Ｃ含有量は０．０２０％以上とする。好ましくは、０．０２５％以上である。一方で、Ｃ含有量が過剰となると、素材の高強度化により、冷間圧延時の変形抵抗が大きくなり、全伸びが低下する。このため、Ｃ含有量は０．０８０％以下とする。好ましくは、０．０５０％以下である。 C: 0.020 to 0.080%
C is an element that improves the strength of the steel sheet. In order to obtain a strength with a yield point of 450 to 650 MPa, the C content is set to 0.020% or more. Preferably, it is 0.025% or more. On the other hand, if the C content is excessive, the strength of the material is increased, so that the deformation resistance during cold rolling increases and the total elongation decreases. Therefore, the C content is set to 0.080% or less. Preferably, it is 0.050% or less.
Ｃは、鋼板の強度を向上させる元素である。降伏点が４５０～６５０ＭＰａの強度を得るために、Ｃ含有量は０．０２０％以上とする。好ましくは、０．０２５％以上である。一方で、Ｃ含有量が過剰となると、素材の高強度化により、冷間圧延時の変形抵抗が大きくなり、全伸びが低下する。このため、Ｃ含有量は０．０８０％以下とする。好ましくは、０．０５０％以下である。 C: 0.020 to 0.080%
C is an element that improves the strength of the steel sheet. In order to obtain a strength with a yield point of 450 to 650 MPa, the C content is set to 0.020% or more. Preferably, it is 0.025% or more. On the other hand, if the C content is excessive, the strength of the material is increased, so that the deformation resistance during cold rolling increases and the total elongation decreases. Therefore, the C content is set to 0.080% or less. Preferably, it is 0.050% or less.
Ｓｉ：０．０５％以下
Ｓｉは鋼板の表面性状を劣化させる。このため、Ｓｉ含有量は０．０５％以下とする。好ましくは、０．０３％以下である。なお、精錬の観点でコストアップにならない範囲にする必要性から、Ｓｉ含有量は０．００１％以上が好ましい。 Si: 0.05% or less Si deteriorates the surface texture of the steel sheet. Therefore, the Si content is set to 0.05% or less. Preferably, it is 0.03% or less. From the viewpoint of refining, the Si content is preferably 0.001% or more because it is necessary to keep the cost within a range that does not increase.
Ｓｉは鋼板の表面性状を劣化させる。このため、Ｓｉ含有量は０．０５％以下とする。好ましくは、０．０３％以下である。なお、精錬の観点でコストアップにならない範囲にする必要性から、Ｓｉ含有量は０．００１％以上が好ましい。 Si: 0.05% or less Si deteriorates the surface texture of the steel sheet. Therefore, the Si content is set to 0.05% or less. Preferably, it is 0.03% or less. From the viewpoint of refining, the Si content is preferably 0.001% or more because it is necessary to keep the cost within a range that does not increase.
Ｍｎ：０．１０～０．５０％
Ｍｎは、鋼板の強度を向上させる元素である。所望の強度を得るために、Ｍｎ含有量は０．１０％以上とする。好ましくは、０．２０％以上である。一方で、Ｍｎ含有量が０．５０％超えである場合、箱型焼鈍の際に酸化して酸化物がその後の二次冷間圧延の際にＷＲ表面に堆積して表面外観を劣化してしまう。また、鋼板の全伸びも低下させる。このため、Ｍｎ含有量は０．５０％以下とする。好ましくは、０．３５％以下である。 Mn: 0.10 to 0.50%
Mn is an element that improves the strength of the steel sheet. In order to obtain the desired strength, the Mn content is 0.10% or more. Preferably, it is 0.20% or more. On the other hand, when the Mn content exceeds 0.50%, it is oxidized during box annealing and oxides are deposited on the WR surface during the subsequent secondary cold rolling to deteriorate the surface appearance. It ends up. It also reduces the total elongation of the steel sheet. Therefore, the Mn content is set to 0.50% or less. Preferably, it is 0.35% or less.
Ｍｎは、鋼板の強度を向上させる元素である。所望の強度を得るために、Ｍｎ含有量は０．１０％以上とする。好ましくは、０．２０％以上である。一方で、Ｍｎ含有量が０．５０％超えである場合、箱型焼鈍の際に酸化して酸化物がその後の二次冷間圧延の際にＷＲ表面に堆積して表面外観を劣化してしまう。また、鋼板の全伸びも低下させる。このため、Ｍｎ含有量は０．５０％以下とする。好ましくは、０．３５％以下である。 Mn: 0.10 to 0.50%
Mn is an element that improves the strength of the steel sheet. In order to obtain the desired strength, the Mn content is 0.10% or more. Preferably, it is 0.20% or more. On the other hand, when the Mn content exceeds 0.50%, it is oxidized during box annealing and oxides are deposited on the WR surface during the subsequent secondary cold rolling to deteriorate the surface appearance. It ends up. It also reduces the total elongation of the steel sheet. Therefore, the Mn content is set to 0.50% or less. Preferably, it is 0.35% or less.
Ｐ：０．０２０％以下
Ｐは、鋼板中の結晶粒界に偏析し加工性を低下させるほか、耐食性を劣化させる元素である。このため、Ｐ含有量は０．０２０％以下とする。好ましくは、０．０１５％以下である。 P: 0.020% or less P is an element that segregates at the grain boundaries in the steel sheet to reduce workability and deteriorate corrosion resistance. Therefore, the P content is set to 0.020% or less. Preferably, it is 0.015% or less.
Ｐは、鋼板中の結晶粒界に偏析し加工性を低下させるほか、耐食性を劣化させる元素である。このため、Ｐ含有量は０．０２０％以下とする。好ましくは、０．０１５％以下である。 P: 0.020% or less P is an element that segregates at the grain boundaries in the steel sheet to reduce workability and deteriorate corrosion resistance. Therefore, the P content is set to 0.020% or less. Preferably, it is 0.015% or less.
Ｓ：０．０２０％以下
Ｓは、連続鋳造時にＭｎＳとして粒界に析出し、スラブ割れを起こす。このため、Ｓ含有量は０．０２０％以下とする。好ましくは、０．０１５％以下である。 S: 0.020% or less S precipitates at the grain boundaries as MnS during continuous casting and causes slab cracking. Therefore, the S content is set to 0.020% or less. Preferably, it is 0.015% or less.
Ｓは、連続鋳造時にＭｎＳとして粒界に析出し、スラブ割れを起こす。このため、Ｓ含有量は０．０２０％以下とする。好ましくは、０．０１５％以下である。 S: 0.020% or less S precipitates at the grain boundaries as MnS during continuous casting and causes slab cracking. Therefore, the S content is set to 0.020% or less. Preferably, it is 0.015% or less.
Ａｌ：０．００１～０．１００％
ＡｌはＮとＡｌＮを形成することが知られている。ＡｌＮを形成しないＮは固溶Ｎとして存在する。固溶Ｎは鋼板の強度向上に寄与する。固溶Ｎとして存在するＮ量をコントロールするためには、Ａｌ量をコントロールする必要がある。必要な固溶Ｎ量を確保するため、Ａｌ含有量は０．１００％以下とする。好ましくは、０．０８％以下である。一方で、精錬の観点でコストアップにならない範囲にする必要性から、Ａｌ含有量は０．００１％以上とする。 Al: 0.001 to 0.100%
Al is known to form N and AlN. N that does not form AlN exists as a solid solution N. The solid solution N contributes to the improvement of the strength of the steel sheet. In order to control the amount of N existing as the solid solution N, it is necessary to control the amount of Al. The Al content is 0.100% or less in order to secure the required solid solution N amount. Preferably, it is 0.08% or less. On the other hand, the Al content is set to 0.001% or more because it is necessary to keep the cost within a range that does not increase the cost from the viewpoint of refining.
ＡｌはＮとＡｌＮを形成することが知られている。ＡｌＮを形成しないＮは固溶Ｎとして存在する。固溶Ｎは鋼板の強度向上に寄与する。固溶Ｎとして存在するＮ量をコントロールするためには、Ａｌ量をコントロールする必要がある。必要な固溶Ｎ量を確保するため、Ａｌ含有量は０．１００％以下とする。好ましくは、０．０８％以下である。一方で、精錬の観点でコストアップにならない範囲にする必要性から、Ａｌ含有量は０．００１％以上とする。 Al: 0.001 to 0.100%
Al is known to form N and AlN. N that does not form AlN exists as a solid solution N. The solid solution N contributes to the improvement of the strength of the steel sheet. In order to control the amount of N existing as the solid solution N, it is necessary to control the amount of Al. The Al content is 0.100% or less in order to secure the required solid solution N amount. Preferably, it is 0.08% or less. On the other hand, the Al content is set to 0.001% or more because it is necessary to keep the cost within a range that does not increase the cost from the viewpoint of refining.
Ｎ：０．０１４～０．０２０％
ＮはＡｌとＡｌＮを形成し、ＡｌＮを形成しないＮは固溶Ｎとして存在する。固溶Ｎは鋼板の強度向上に寄与する。このため、Ｎ含有量は０．０１４％以上とする。好ましくは、０．０１５％以上である。一方で、Ｎ含有量が０．０２０％を超えると、鋼板の脆化につながり、４％以上の全伸びが確保できなくなる。このため、Ｎ含有量は０．０２０％以下とする。好ましくは、０．０１９％以下である。 N: 0.014-0.020%
N forms Al and AlN, and N that does not form AlN exists as a solid solution N. The solid solution N contributes to the improvement of the strength of the steel sheet. Therefore, the N content is set to 0.014% or more. Preferably, it is 0.015% or more. On the other hand, if the N content exceeds 0.020%, the steel sheet becomes embrittled and the total elongation of 4% or more cannot be secured. Therefore, the N content is set to 0.020% or less. Preferably, it is 0.019% or less.
ＮはＡｌとＡｌＮを形成し、ＡｌＮを形成しないＮは固溶Ｎとして存在する。固溶Ｎは鋼板の強度向上に寄与する。このため、Ｎ含有量は０．０１４％以上とする。好ましくは、０．０１５％以上である。一方で、Ｎ含有量が０．０２０％を超えると、鋼板の脆化につながり、４％以上の全伸びが確保できなくなる。このため、Ｎ含有量は０．０２０％以下とする。好ましくは、０．０１９％以下である。 N: 0.014-0.020%
N forms Al and AlN, and N that does not form AlN exists as a solid solution N. The solid solution N contributes to the improvement of the strength of the steel sheet. Therefore, the N content is set to 0.014% or more. Preferably, it is 0.015% or more. On the other hand, if the N content exceeds 0.020%, the steel sheet becomes embrittled and the total elongation of 4% or more cannot be secured. Therefore, the N content is set to 0.020% or less. Preferably, it is 0.019% or less.
Ｎｂ：０．０１４～０．０２０％
Ｎｂは鋼板の強度を向上させる元素である。所望の強度を得るため、Ｎｂ含有量は０．０１４％以上とする。好ましくは、０．０１５％以上である。一方で、Ｎｂ含有量が０．０２０％超えの場合、Ｎｂの添加により再結晶温度が上昇するため、再結晶が十分に進まず、全伸びが低下する。このため、Ｎｂ含有量は０．０２０％以下とする。好ましくは、０．０１８％以下である。 Nb: 0.014-0.020%
Nb is an element that improves the strength of the steel sheet. In order to obtain the desired strength, the Nb content is 0.014% or more. Preferably, it is 0.015% or more. On the other hand, when the Nb content exceeds 0.020%, the recrystallization temperature rises due to the addition of Nb, so that the recrystallization does not proceed sufficiently and the total elongation decreases. Therefore, the Nb content is set to 0.020% or less. Preferably, it is 0.018% or less.
Ｎｂは鋼板の強度を向上させる元素である。所望の強度を得るため、Ｎｂ含有量は０．０１４％以上とする。好ましくは、０．０１５％以上である。一方で、Ｎｂ含有量が０．０２０％超えの場合、Ｎｂの添加により再結晶温度が上昇するため、再結晶が十分に進まず、全伸びが低下する。このため、Ｎｂ含有量は０．０２０％以下とする。好ましくは、０．０１８％以下である。 Nb: 0.014-0.020%
Nb is an element that improves the strength of the steel sheet. In order to obtain the desired strength, the Nb content is 0.014% or more. Preferably, it is 0.015% or more. On the other hand, when the Nb content exceeds 0.020%, the recrystallization temperature rises due to the addition of Nb, so that the recrystallization does not proceed sufficiently and the total elongation decreases. Therefore, the Nb content is set to 0.020% or less. Preferably, it is 0.018% or less.
Ｍｎ＋２５Ｎｂ≦０．８５
ＭｎおよびＮｂは、ともに鋼板の強度を確保するために必要な元素である。しかし、前述のとおり、Ｍｎは易酸化性であるがゆえに焼鈍の際に表層酸化物を形成し、最終製品の表面外観を劣化させる。そのため、Ｎｂ量に応じてＭｎ上限量を適正に制御する必要がある。種々の実験結果から、Ｍｎ＋２５Ｎｂ≦０．８５であれば、表面外観の劣化が無く、強度の確保も可能であることが分かった。
なお、ＭｎおよびＮｂは、それぞれ各元素の含有量（質量％）を指す。 Mn + 25Nb ≦ 0.85
Both Mn and Nb are elements necessary for ensuring the strength of the steel sheet. However, as described above, since Mn is easily oxidized, it forms a surface oxide during annealing and deteriorates the surface appearance of the final product. Therefore, it is necessary to appropriately control the upper limit amount of Mn according to the amount of Nb. From various experimental results, it was found that when Mn + 25Nb ≦ 0.85, there is no deterioration in the surface appearance and the strength can be ensured.
In addition, Mn and Nb indicate the content (mass%) of each element, respectively.
ＭｎおよびＮｂは、ともに鋼板の強度を確保するために必要な元素である。しかし、前述のとおり、Ｍｎは易酸化性であるがゆえに焼鈍の際に表層酸化物を形成し、最終製品の表面外観を劣化させる。そのため、Ｎｂ量に応じてＭｎ上限量を適正に制御する必要がある。種々の実験結果から、Ｍｎ＋２５Ｎｂ≦０．８５であれば、表面外観の劣化が無く、強度の確保も可能であることが分かった。
なお、ＭｎおよびＮｂは、それぞれ各元素の含有量（質量％）を指す。 Mn + 25Nb ≦ 0.85
Both Mn and Nb are elements necessary for ensuring the strength of the steel sheet. However, as described above, since Mn is easily oxidized, it forms a surface oxide during annealing and deteriorates the surface appearance of the final product. Therefore, it is necessary to appropriately control the upper limit amount of Mn according to the amount of Nb. From various experimental results, it was found that when Mn + 25Nb ≦ 0.85, there is no deterioration in the surface appearance and the strength can be ensured.
In addition, Mn and Nb indicate the content (mass%) of each element, respectively.
残部はＦｅおよび不可避的不純物である。不可避的不純物としては、例えばＮｉやＣｕが挙げられ、Ｎｉは０．１％以下、Ｃｕは０．１％以下であれば許容できる。
The rest is Fe and unavoidable impurities. Examples of unavoidable impurities include Ni and Cu, and Ni is 0.1% or less and Cu is 0.1% or less, which is acceptable.
以上の成分が本発明の基本の成分である。本発明では、上記の元素に加え、さらに、公知の容器用鋼板中に一般的に存在する元素を目的に応じて添加してもよい。例えば、Ｔｉ、Ｂ、Ｃｒ、Ｍｏのうちから選ばれた１種類または２種類以上を添加してもよい。
The above components are the basic components of the present invention. In the present invention, in addition to the above elements, elements generally present in known container steel sheets may be added depending on the purpose. For example, one or more selected from Ti, B, Cr, and Mo may be added.
また、箱型焼鈍ＤＲ鋼板に耐食性を付与するために、鋼板表面にめっき層を設けてもよい。表面にめっき層を形成するためのめっき法の種類は特に限定されず、電気めっきでも溶融めっきでもよい。また、鋼板表面に金属クロムとクロム水和酸化物の二層を設け、ティンフリースチールとしてもよい。
Further, in order to impart corrosion resistance to the box-type annealed DR steel sheet, a plating layer may be provided on the surface of the steel sheet. The type of plating method for forming a plating layer on the surface is not particularly limited, and may be electroplating or hot-dip galvanizing. Further, a tin-free steel may be obtained by providing two layers of metallic chromium and chromium hydrated oxide on the surface of the steel sheet.
＜箱型焼鈍ＤＲ鋼板の製造方法＞
次に、本発明の箱型焼鈍ＤＲ鋼板の製造方法について説明する。 <Manufacturing method of box-type annealed DR steel sheet>
Next, a method for manufacturing the box-type annealed DR steel sheet of the present invention will be described.
次に、本発明の箱型焼鈍ＤＲ鋼板の製造方法について説明する。 <Manufacturing method of box-type annealed DR steel sheet>
Next, a method for manufacturing the box-type annealed DR steel sheet of the present invention will be described.
本発明では、上記の成分組成を有するスラブ（鋼素材）を熱間圧延した後、一次冷間圧延する。その後、一次冷間圧延された冷延コイルに対し６５０～７５０℃で２～１６ｈの箱型焼鈍を施し、次いで、圧下率１０～２５％で二次冷間圧延（ＤＲ圧延）を施すことにより、箱型焼鈍ＤＲ鋼板を製造する。以下、各工程について説明する。
In the present invention, a slab (steel material) having the above-mentioned composition is hot-rolled and then primary cold-rolled. Then, the primary cold-rolled cold-rolled coil is subjected to box-shaped annealing at 650 to 750 ° C. for 2 to 16 hours, and then secondary cold rolling (DR rolling) is performed at a reduction ratio of 10 to 25%. , Manufactures box-type annealed DR steel sheets. Hereinafter, each step will be described.
箱型焼鈍ＤＲ鋼板の原材料である溶鋼を溶製する方法について特に制限はなく、一般的な転炉もしくは電気炉で溶製し、上述の成分組成を有する鋼とする。なお、溶製後、脱ガス処理にて精錬を実施してもよい。そして、上述の成分組成を有する鋼を、連続鋳造または造塊－分塊圧延法等でスラブとする。このスラブが、箱型焼鈍ＤＲ鋼板の素材（鋼素材）となる。
There are no particular restrictions on the method of melting molten steel, which is the raw material for box-type annealed DR steel sheets, and the steel is melted in a general converter or electric furnace to have the above-mentioned composition. After melting, refining may be carried out by degassing treatment. Then, the steel having the above-mentioned composition is made into a slab by continuous casting, ingot-bulk rolling, or the like. This slab becomes the material (steel material) for the box-type annealed DR steel sheet.
熱間圧延
熱間圧延では、スラブを１０５０～１３００℃の温度に再加熱した後、Ａｒ３変態点以上で仕上げ圧延するのが好ましい。熱間圧延後の巻取り温度は、４５０～７５０℃の間にするのが好ましい。ここで、Ａｒ３変態点は、フォーマスタ試験により測定することができる。なお、鋳造後のスラブを再加熱することなく、直送圧延してもよい。 Hot rolling In hot rolling, it is preferable that the slab is reheated to a temperature of 1050 to 1300 ° C. and then finish-rolled at an Ar3 transformation point or higher. The winding temperature after hot rolling is preferably between 450 and 750 ° C. Here, the Ar3 transformation point can be measured by the Formaster test. The slab after casting may be directly rolled without being reheated.
熱間圧延では、スラブを１０５０～１３００℃の温度に再加熱した後、Ａｒ３変態点以上で仕上げ圧延するのが好ましい。熱間圧延後の巻取り温度は、４５０～７５０℃の間にするのが好ましい。ここで、Ａｒ３変態点は、フォーマスタ試験により測定することができる。なお、鋳造後のスラブを再加熱することなく、直送圧延してもよい。 Hot rolling In hot rolling, it is preferable that the slab is reheated to a temperature of 1050 to 1300 ° C. and then finish-rolled at an Ar3 transformation point or higher. The winding temperature after hot rolling is preferably between 450 and 750 ° C. Here, the Ar3 transformation point can be measured by the Formaster test. The slab after casting may be directly rolled without being reheated.
一次冷間圧延
一次冷間圧延における冷間圧延は常法にて行うことができる。圧下率に特に制限はないが、７０～９８％とするのが好ましい。 Primary cold rolling Cold rolling in primary cold rolling can be performed by a conventional method. The reduction rate is not particularly limited, but is preferably 70 to 98%.
一次冷間圧延における冷間圧延は常法にて行うことができる。圧下率に特に制限はないが、７０～９８％とするのが好ましい。 Primary cold rolling Cold rolling in primary cold rolling can be performed by a conventional method. The reduction rate is not particularly limited, but is preferably 70 to 98%.
箱型焼鈍：６５０～７５０℃で２～１６ｈ
４％以上の全伸びを確保するため、一次冷間圧延した冷延コイルを６５０～７５０℃で２～１６ｈ箱型焼鈍する。焼鈍時間が２ｈ未満または焼鈍温度が６５０℃未満の場合、再結晶が十分に進まず、４％以上の全伸びが得られない。一方で、焼鈍時間が１６ｈ超えまたは焼鈍温度が７５０℃超えの場合、鋼板表面に酸化物が形成しやすくなり、表面外観が劣化する。なお、再結晶を促進する観点から、好ましくは、焼鈍時間は３ｈ以上であり、焼鈍温度は６８０℃以上である。また、酸化物の形成を抑制する観点から、好ましくは、焼鈍時間は１２ｈ以下であり、焼鈍温度は７４０℃以下である。 Box-shaped annealing: 2 to 16 hours at 650 to 750 ° C.
In order to secure a total elongation of 4% or more, the cold-rolled primary cold-rolled coil is box-shaped annealed at 650 to 750 ° C. for 2 to 16 hours. When the annealing time is less than 2 hours or the annealing temperature is less than 650 ° C., recrystallization does not proceed sufficiently and total elongation of 4% or more cannot be obtained. On the other hand, when the annealing time exceeds 16 hours or the annealing temperature exceeds 750 ° C., oxides are likely to be formed on the surface of the steel sheet, and the surface appearance is deteriorated. From the viewpoint of promoting recrystallization, the annealing time is preferably 3 hours or more, and the annealing temperature is 680 ° C. or more. Further, from the viewpoint of suppressing the formation of oxides, the annealing time is preferably 12 hours or less, and the annealing temperature is 740 ° C. or less.
４％以上の全伸びを確保するため、一次冷間圧延した冷延コイルを６５０～７５０℃で２～１６ｈ箱型焼鈍する。焼鈍時間が２ｈ未満または焼鈍温度が６５０℃未満の場合、再結晶が十分に進まず、４％以上の全伸びが得られない。一方で、焼鈍時間が１６ｈ超えまたは焼鈍温度が７５０℃超えの場合、鋼板表面に酸化物が形成しやすくなり、表面外観が劣化する。なお、再結晶を促進する観点から、好ましくは、焼鈍時間は３ｈ以上であり、焼鈍温度は６８０℃以上である。また、酸化物の形成を抑制する観点から、好ましくは、焼鈍時間は１２ｈ以下であり、焼鈍温度は７４０℃以下である。 Box-shaped annealing: 2 to 16 hours at 650 to 750 ° C.
In order to secure a total elongation of 4% or more, the cold-rolled primary cold-rolled coil is box-shaped annealed at 650 to 750 ° C. for 2 to 16 hours. When the annealing time is less than 2 hours or the annealing temperature is less than 650 ° C., recrystallization does not proceed sufficiently and total elongation of 4% or more cannot be obtained. On the other hand, when the annealing time exceeds 16 hours or the annealing temperature exceeds 750 ° C., oxides are likely to be formed on the surface of the steel sheet, and the surface appearance is deteriorated. From the viewpoint of promoting recrystallization, the annealing time is preferably 3 hours or more, and the annealing temperature is 680 ° C. or more. Further, from the viewpoint of suppressing the formation of oxides, the annealing time is preferably 12 hours or less, and the annealing temperature is 740 ° C. or less.
二次冷間圧延（ＤＲ圧延）：圧下率１０～２５％
二次冷間圧延は、圧下率１０～２５％で行われる。圧下率が１０％未満の場合、降伏点４５０～６５０ＭＰａの強度が得られない。一方で、圧下率が２５％超えの場合、鋼板表面の酸化物がワークロールに堆積し、鋼板に転写して鋼板の表面外観が劣化する。なお、強度を確保する観点から、好ましくは、圧下率は１５％以上である。 Secondary cold rolling (DR rolling): rolling ratio 10 to 25%
Secondary cold rolling is performed at a rolling reduction of 10 to 25%. If the reduction rate is less than 10%, the strength at the yield point of 450 to 650 MPa cannot be obtained. On the other hand, when the reduction ratio exceeds 25%, oxides on the surface of the steel sheet are deposited on the work roll and transferred to the steel sheet to deteriorate the surface appearance of the steel sheet. From the viewpoint of ensuring strength, the reduction rate is preferably 15% or more.
二次冷間圧延は、圧下率１０～２５％で行われる。圧下率が１０％未満の場合、降伏点４５０～６５０ＭＰａの強度が得られない。一方で、圧下率が２５％超えの場合、鋼板表面の酸化物がワークロールに堆積し、鋼板に転写して鋼板の表面外観が劣化する。なお、強度を確保する観点から、好ましくは、圧下率は１５％以上である。 Secondary cold rolling (DR rolling): rolling ratio 10 to 25%
Secondary cold rolling is performed at a rolling reduction of 10 to 25%. If the reduction rate is less than 10%, the strength at the yield point of 450 to 650 MPa cannot be obtained. On the other hand, when the reduction ratio exceeds 25%, oxides on the surface of the steel sheet are deposited on the work roll and transferred to the steel sheet to deteriorate the surface appearance of the steel sheet. From the viewpoint of ensuring strength, the reduction rate is preferably 15% or more.
めっき処理
上記のようにして得られた箱型焼鈍ＤＲ鋼板を電気めっきライン等に通板して、電気めっき処理を施してもよい。例えば、電気錫めっき処理を施して、ぶりきとしてもよい。または、箱型焼鈍ＤＲ鋼板に対し電解クロム酸処理を施して、金属クロムとクロム水和酸化物の二層を表面に有するティンフリースチールとしてもよい。 Plating treatment The box-type annealed DR steel sheet obtained as described above may be passed through an electroplating line or the like to be electroplated. For example, tinplate may be applied to make tinplate. Alternatively, the box-type annealed DR steel sheet may be subjected to electrolytic chromic acid treatment to obtain tin-free steel having two layers of metallic chromium and chromium hydrated oxide on the surface.
上記のようにして得られた箱型焼鈍ＤＲ鋼板を電気めっきライン等に通板して、電気めっき処理を施してもよい。例えば、電気錫めっき処理を施して、ぶりきとしてもよい。または、箱型焼鈍ＤＲ鋼板に対し電解クロム酸処理を施して、金属クロムとクロム水和酸化物の二層を表面に有するティンフリースチールとしてもよい。 Plating treatment The box-type annealed DR steel sheet obtained as described above may be passed through an electroplating line or the like to be electroplated. For example, tinplate may be applied to make tinplate. Alternatively, the box-type annealed DR steel sheet may be subjected to electrolytic chromic acid treatment to obtain tin-free steel having two layers of metallic chromium and chromium hydrated oxide on the surface.
以上の製造方法により、上述の成分組成を有し、降伏点が４５０～６５０ＭＰａ、全伸びが４％以上である、表面外観に優れた箱型焼鈍ＤＲ鋼板が得られる。
By the above manufacturing method, a box-type annealed DR steel sheet having the above-mentioned composition, a yield point of 450 to 650 MPa, and a total elongation of 4% or more can be obtained.
以下、本発明の実施例を説明する。なお、本発明は以下の実施例に限定されない。
１．箱型焼鈍ＤＲ鋼板の製造
表１に示す成分組成を有するスラブを鋳造して製造した。スラブを１０５０～１３００℃に再加熱した後、仕上げ圧延終了温度８５０～９５０℃で熱間圧延を行って熱延板とした。熱延板は、４５０～７５０℃の巻取り温度で巻き取った。その後、熱延板を７０～９８％の圧下率で一次冷間圧延した。一次冷間圧延した冷延コイルに対し、表１に示す条件で箱型焼鈍と二次冷間圧延（ＤＲ圧延）を施し、板厚０．２０ｍｍの箱型焼鈍ＤＲ鋼板とした。
２．材質評価
以上のようにして得た鋼板からＪＩＳ５号サイズの引張試験片を切り出し、引張試験（ＪＩＳ Ｚ ２２４１に準拠）を実施して降伏点（ＭＰａ）および全伸び（％）を求めた。結果を表１に示す。
３．外観評価
以上のようにして得た鋼板について、テンパーカラーの混入率により、鋼板の表面外観を評価した。求められた混入率に基づき、外観を、最良（「◎」で示す）：混入率が２％以下、良（「〇」で示す）：２％超え５％以下、不良（「×」で示す）：５％超え、と評価した。このうち、「最良」と「良」を合格とし、「表面外観に優れる」と評価した。結果を表１に示す。 Hereinafter, examples of the present invention will be described. The present invention is not limited to the following examples.
1. 1. Production of Box-Annealed DR Steel Sheet A slab having the composition shown in Table 1 was cast and produced. After reheating the slab to 1050 to 1300 ° C., hot rolling was performed at a finish rolling end temperature of 850 to 950 ° C. to obtain a hot-rolled plate. The hot-rolled plate was wound at a winding temperature of 450 to 750 ° C. Then, the hot-rolled sheet was first cold-rolled at a reduction rate of 70 to 98%. The cold-rolled primary cold-rolled coil was subjected to box-type annealing and secondary cold-rolling (DR rolling) under the conditions shown in Table 1 to obtain a box-type annealed DR steel sheet having a plate thickness of 0.20 mm.
2. 2. Material Evaluation A JIS No. 5 size tensile test piece was cut out from the steel sheet obtained as described above, and a tensile test (based on JIS Z 2241) was carried out to determine the yield point (MPa) and total elongation (%). The results are shown in Table 1.
3. 3. Appearance evaluation With respect to the steel sheet obtained as described above, the surface appearance of the steel sheet was evaluated by the mixing ratio of the temper color. Based on the obtained mixing rate, the appearance is best (indicated by "◎"): mixing rate is 2% or less, good (indicated by "○"): more than 2% and 5% or less, defective (indicated by "x"). ): Evaluated to exceed 5%. Of these, "best" and "good" were passed, and "excellent surface appearance" was evaluated. The results are shown in Table 1.
１．箱型焼鈍ＤＲ鋼板の製造
表１に示す成分組成を有するスラブを鋳造して製造した。スラブを１０５０～１３００℃に再加熱した後、仕上げ圧延終了温度８５０～９５０℃で熱間圧延を行って熱延板とした。熱延板は、４５０～７５０℃の巻取り温度で巻き取った。その後、熱延板を７０～９８％の圧下率で一次冷間圧延した。一次冷間圧延した冷延コイルに対し、表１に示す条件で箱型焼鈍と二次冷間圧延（ＤＲ圧延）を施し、板厚０．２０ｍｍの箱型焼鈍ＤＲ鋼板とした。
２．材質評価
以上のようにして得た鋼板からＪＩＳ５号サイズの引張試験片を切り出し、引張試験（ＪＩＳ Ｚ ２２４１に準拠）を実施して降伏点（ＭＰａ）および全伸び（％）を求めた。結果を表１に示す。
３．外観評価
以上のようにして得た鋼板について、テンパーカラーの混入率により、鋼板の表面外観を評価した。求められた混入率に基づき、外観を、最良（「◎」で示す）：混入率が２％以下、良（「〇」で示す）：２％超え５％以下、不良（「×」で示す）：５％超え、と評価した。このうち、「最良」と「良」を合格とし、「表面外観に優れる」と評価した。結果を表１に示す。 Hereinafter, examples of the present invention will be described. The present invention is not limited to the following examples.
1. 1. Production of Box-Annealed DR Steel Sheet A slab having the composition shown in Table 1 was cast and produced. After reheating the slab to 1050 to 1300 ° C., hot rolling was performed at a finish rolling end temperature of 850 to 950 ° C. to obtain a hot-rolled plate. The hot-rolled plate was wound at a winding temperature of 450 to 750 ° C. Then, the hot-rolled sheet was first cold-rolled at a reduction rate of 70 to 98%. The cold-rolled primary cold-rolled coil was subjected to box-type annealing and secondary cold-rolling (DR rolling) under the conditions shown in Table 1 to obtain a box-type annealed DR steel sheet having a plate thickness of 0.20 mm.
2. 2. Material Evaluation A JIS No. 5 size tensile test piece was cut out from the steel sheet obtained as described above, and a tensile test (based on JIS Z 2241) was carried out to determine the yield point (MPa) and total elongation (%). The results are shown in Table 1.
3. 3. Appearance evaluation With respect to the steel sheet obtained as described above, the surface appearance of the steel sheet was evaluated by the mixing ratio of the temper color. Based on the obtained mixing rate, the appearance is best (indicated by "◎"): mixing rate is 2% or less, good (indicated by "○"): more than 2% and 5% or less, defective (indicated by "x"). ): Evaluated to exceed 5%. Of these, "best" and "good" were passed, and "excellent surface appearance" was evaluated. The results are shown in Table 1.
表１より、ＭｎおよびＮｂの含有量を本発明の範囲内にし、箱型焼鈍およびＤＲ圧延の条件を本発明の範囲内にすることにより、所望の機械的特性および優れた表面外観を有する箱型焼鈍ＤＲ鋼板を提供することができた。
From Table 1, by keeping the contents of Mn and Nb within the range of the present invention and the conditions of box annealing and DR rolling within the range of the present invention, a box having desired mechanical properties and excellent surface appearance. We were able to provide a die-annealed DR steel sheet.
Claims (2)
- 質量％で、
Ｃ：０．０２０～０．０８０％、
Ｓｉ：０．０５％以下、
Ｍｎ：０．１０～０．５０％、
Ｐ：０．０２０％以下、
Ｓ：０．０２０％以下、
Ａｌ：０．００１～０．１００％、
Ｎ：０．０１４～０．０２０％、
Ｎｂ：０．０１４～０．０２０％
を含有し、Ｍｎ＋２５Ｎｂ≦０．８５であり、残部がＦｅおよび不可避的不純物からなる成分組成を有し、
降伏点が４５０～６５０ＭＰａ、全伸びが４％以上である、
箱型焼鈍ＤＲ鋼板。
ここで、前記Ｍｎ＋２５Ｎｂにおいて、ＭｎおよびＮｂは各元素の含有量（質量％）を指す。 By mass%
C: 0.020 to 0.080%,
Si: 0.05% or less,
Mn: 0.10 to 0.50%,
P: 0.020% or less,
S: 0.020% or less,
Al: 0.001 to 0.100%,
N: 0.014-0.020%,
Nb: 0.014-0.020%
Mn + 25Nb ≦ 0.85, and the balance has a component composition of Fe and unavoidable impurities.
The yield point is 450 to 650 MPa, and the total elongation is 4% or more.
Box-type annealed DR steel sheet.
Here, in the Mn + 25Nb, Mn and Nb refer to the content (mass%) of each element. - 請求項１に記載の成分組成を有する鋼素材に対し、
熱間圧延の後、一次冷間圧延を施し、
次いで、６５０～７５０℃で２～１６ｈの箱型焼鈍を施し、
前記箱型焼鈍の後、圧下率１０～２５％で二次冷間圧延を行う、
箱型焼鈍ＤＲ鋼板の製造方法。 For a steel material having the component composition according to claim 1.
After hot rolling, primary cold rolling is performed,
Then, box-shaped annealing was performed at 650 to 750 ° C. for 2 to 16 hours.
After the box-shaped annealing, secondary cold rolling is performed at a rolling reduction of 10 to 25%.
A method for manufacturing a box-type annealed DR steel sheet.
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|---|---|---|---|---|
| JPH0734193A (en) * | 1993-07-14 | 1995-02-03 | Toyo Kohan Co Ltd | Steel sheet suitable for application to thinned deep-drawn can and its production |
| JP2000160289A (en) * | 1998-11-25 | 2000-06-13 | Kawasaki Steel Corp | Steel sheet for can, and its manufacture |
| JP2008138234A (en) * | 2006-11-30 | 2008-06-19 | Jfe Steel Kk | High-strength and high-ductility steel sheet for can, and manufacturing method therefor |
| WO2008102006A1 (en) * | 2007-02-23 | 2008-08-28 | Corus Staal Bv | Packaging steel, method of producing said packaging steel and its use |
| WO2017150066A1 (en) * | 2016-02-29 | 2017-09-08 | Ｊｆｅスチール株式会社 | Steel sheet for cans and manufacturing method therefor |
| JP2018059196A (en) * | 2016-10-04 | 2018-04-12 | Ｊｆｅスチール株式会社 | High strength ultrathin steel sheet and manufacturing method therefor |
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| TW200827460A (en) * | 2006-08-11 | 2008-07-01 | Nippon Steel Corp | DR steel sheet and manufacturing method thereof |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0734193A (en) * | 1993-07-14 | 1995-02-03 | Toyo Kohan Co Ltd | Steel sheet suitable for application to thinned deep-drawn can and its production |
| JP2000160289A (en) * | 1998-11-25 | 2000-06-13 | Kawasaki Steel Corp | Steel sheet for can, and its manufacture |
| JP2008138234A (en) * | 2006-11-30 | 2008-06-19 | Jfe Steel Kk | High-strength and high-ductility steel sheet for can, and manufacturing method therefor |
| WO2008102006A1 (en) * | 2007-02-23 | 2008-08-28 | Corus Staal Bv | Packaging steel, method of producing said packaging steel and its use |
| WO2017150066A1 (en) * | 2016-02-29 | 2017-09-08 | Ｊｆｅスチール株式会社 | Steel sheet for cans and manufacturing method therefor |
| JP2018059196A (en) * | 2016-10-04 | 2018-04-12 | Ｊｆｅスチール株式会社 | High strength ultrathin steel sheet and manufacturing method therefor |
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