JP4788030B2 - Steel plate for lightweight two-piece can and manufacturing method thereof - Google Patents

Description

【００６５】
【表２】

【００６６】
【表３】

【００６７】
また、これら鋼板を用いて表４に示す条件で鋼板に各種めっき処理を施した後１stカップ成形、ＤＩ成形、４段ネック成形を行って350ml ＤＩ缶とし、各種缶体特性を評価した。評価した結果をあわせて表４に示す。
製缶後蓋を取付け、空気で内圧をかけ、ドーム部にバックリングが発生した時の圧力を求め、缶耐圧強度とした。ネックしわは、ネックイン成形後に目視で、また、フランジ割れは、磁気センサを用いて調査した。
【００６８】
【表４】

【００６９】
本発明例は、板厚が薄いにも関らず、缶底耐圧強度を高くでき、多段ネック、フランジ加工を施しても、ネックしわやフランジ割れの発生もなく、しかも缶強度が確保できる特性を有する極薄冷延鋼板となっている。これに対し、本発明の範囲を外れる比較例は、１stカップでの耳立ち、耳切れが発生したり、缶底耐圧強度が小さかったり、ネックしわやフランジ割れが発生する。
【００７０】
【発明の効果】
本発明によれば、空缶重量25g 以下というような軽量飲料缶用として好適な、耳発生も少なく、所望の缶体の耐圧強度を有し、多段ネック加工も容易であり、さらにフランジ加工性に優れた極薄の２ピース缶用鋼板を、安価に製造でき、産業上格段の効果を奏する。また、無菌充填法にも適応できるという効果もある。
【００７１】
さらに、３ピース缶といえども軽量化が進み、極薄鋼板を使用し多段ネック加工や拡缶加工を施されており、２ピース缶同様にしわの問題がある。本発明の缶用鋼板は、このような用途にも使用でき、缶体の軽量化を促進できるという効果もある。
また、２ピース缶用でもＤＷＩ缶（Drawn and wall ironed can ）製法に限らず、ＳＤ缶（Shallow −Drawn can ）製法、ＤＲＤ缶（Drawn and Redrawn can ）製法、ＤＴＲ缶（Drawn and Thin Redrawn can）製法、ＤＴＲにwall ironed を組み合わせた製法、あるいは缶底ドーム加工を施されないものに使っても何ら差し支えなく、缶体の軽量化を促進できる。
【図面の簡単な説明】
【図１】鋼板の降伏応力ＹＳと加工付与歪量と缶体要求強度との関係を示す説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel plate for a two-piece can, and is particularly excellent in cup formability (deep drawing workability), has a moderately large can bottom strength after processing, and does not generate wrinkles even when multi-stage neck processing is performed. The present invention relates to a steel sheet for ultra-thin cans having a thickness of 0.20 mm or less, which has excellent neck workability and stretch flangeability.
[0002]
[Prior art]
Soft drinks, beverage cans such as beer, and various can containers such as food cans are divided into two-piece cans consisting of a can body and top lid, and three-piece cans consisting of a can body, top lid, and bottom lid. Separated. In particular, the steel plate used for the can body of a two-piece can is a variety of harsh processes such as deep drawing (cup forming), subsequent ironing to obtain the can height, neck diameter reduction processing, flange processing, dome processing, etc. Characteristics that can withstand proper molding are required. Furthermore, recently, for the purpose of reducing the weight of the can, the thinning of the steel plate, which is a material, has been directed.
[0003]
Even when the steel plate as the material is thinned, it is necessary to maintain a predetermined strength or higher as the can strength. Therefore, it is a premise that the strength of the steel plate as the material is increased.
The can bottom that can be greatly reduced in thickness in the general can shape is the bottom of the can where there is almost no variation in the plate thickness. At the bottom of the can, the thickness of the material can be further reduced by changing the can shape such as reducing the dome grounding diameter or increasing the dome depth, and by improving can manufacturing technology. However, if the material of the neck portion and the flange portion is thinned, the thickness varies during can manufacturing processing, and the thickness becomes further thin, resulting in insufficient can strength after can manufacturing. In order to achieve thinning at the neck and flange, it is necessary to increase the blank diameter so that the wall thickness at the top of the can does not decrease. However, when the blank diameter is increased, deep drawing becomes difficult, and there is a problem that troubles such as fracture occur. For this reason, in order to reduce the weight of the can, a steel plate for cans that is thin and excellent in deep drawability is desired.
[0004]
In addition, when deep drawing a raw steel plate into a cup shape, if a thin steel plate is used, even if a high strength steel plate is used, the rigidity is insufficient and wrinkles are likely to occur. This tendency becomes more remarkable as the limit drawing ratio (LDR) increases, that is, as the blank diameter increases. In order to reduce the generation of wrinkles, it is conceivable to increase the wrinkle restraining force (BHF). However, there is a problem that when the BHF becomes large, the tip of the ear is easily cut. In order to solve this problem, a steel sheet having a small in-plane anisotropy of r value, that is, a small Δr is desired.
[0005]
In order to obtain a thin steel plate for cans, there are two possible methods: (1) increasing the cold rolling reduction ratio, and (2) reducing the thickness of the cold rolled base plate, that is, the thickness of the hot rolled plate. It is done. However, the increase in the cold rolling reduction increases the in-plane anisotropy of the r value, and increases the generation of ears during drawing. Further, when the thickness of the hot-rolled sheet is reduced, there is a problem that the variation in hot rolling temperature in the width direction and the length direction is increased and the productivity of hot rolling is also reduced.
[0006]
For such a problem, for example, in Japanese Patent No. 2689148 (Japanese Patent Laid-Open No. 2-141535), C: 0.010 to 0.040%, Si: 0.03% or less, Mn: 0.05 to 0.35%, P: 0.015% Hereinafter, a steel slab containing S: 0.015% or less, solAl: 0.03-0.15%, N: 0.0025% or less, Al / N ≧ 30, Ar_ThreeHot rolling is performed at a finishing temperature of less than 630 to 750 ° C., cold rolled at a reduction of 85 to 95%, annealed at a recrystallization temperature of 670 ° C. or less, and then re-reduced to 8 to 30%. A manufacturing method of a steel plate for a drawing can with a small ear generation that performs cold rolling is disclosed.
[0007]
Japanese Patent Laid-Open No. 9-241756 discloses that a hot rolled steel sheet having an average crystal grain size before cold rolling of 30 μm or more is subjected to cold rolling at a cold rolling reduction ratio of 70 to 98%, and a recrystallization temperature of 800 or more. After annealing for 3 min or more at ℃ or lower, re-rolling is further performed with a cold rolling reduction ratio of 1 to 70% and the total cold rolling reduction ratio to the final product is 88 to 98%. Discloses a method for producing a steel plate for containers, which is extremely small.
[0008]
However, with the techniques described in Japanese Patent Nos. 2689148 (Japanese Patent Laid-Open No. 2141535) and Japanese Patent Laid-Open No. 9-241756, the generation of ears during drawing is reduced, but the neck that reduces the diameter of the can opening is reduced. There has been a problem that no consideration has been given to the generation of wrinkles in the processing and the decrease in the pressure strength accompanying the thinning of the steel sheet.
Recently, the diameter of the lid has been reduced in order to increase the strength of the can lid, and the can body neck portion of the two-piece can has become a multi-stage neck. In multi-stage neck processing, the wall thickness increases, but it is still necessary to have a certain level of rigidity in order not to generate neck wrinkles, so there is a limit to thinning the material even if high-strength steel plates are used. is there. In addition, the high-tensile steel plate generally has a large yield stress, and there is a problem that it is difficult to obtain a predetermined diameter reduction. When neck wrinkles occur, the contents will leak after the lid is double-tightened. On the other hand, when increasing the tension to increase the rigidity, there is a problem that elongation is insufficient and cracking occurs during flange processing, and there is a conflicting demand that a soft steel sheet is desired from the viewpoint of workability. is there.
[0009]
For the generation of wrinkles in neck processing, for example, JP-A-6-306535 and JP-A-6-306536 include C: 0.0100 to 0.0700%, Si: 0.30% or less, Mn: 0.05 to 1.00%, A slab containing P: 0.030% or less, S: 0.025% or less, solAl: 0.002 to 0.100%, N: 0.0100% or less, B: 0 to (0.0010 + 1.8 × N%)%, is hot-rolled. After that, cold rolling at a reduction ratio of 85 to 95% is performed, and the amount of solute C is adjusted by recrystallization annealing at a temperature higher than the recrystallization temperature and the subsequent cooling, and the elongation rate is further adjusted to perform temper rolling. 3% pre-strain of steel sheet-YP after heat treatment is 34kgf / mm² Above, 50% pre-strain-YP after heat treatment is 62kgf / mm² A method of manufacturing a surface treatment original plate for DI can excellent in necked-in properties to be adjusted below has been proposed.
[0010]
Japanese Patent Application Laid-Open No. 10-280095 has excellent neck wrinkle resistance in which a slab containing C: 0.01 to 0.05% and N: 0.004% or less is cast and the slab heating temperature in hot rolling is 1100 ° C. or less. In addition, a method of manufacturing a two-piece container steel sheet has been proposed.
However, the steel plates obtained by the techniques described in JP-A-6-306535 and JP-A-10-280095 are not only so hard that the steel plate is hard, but also the in-plane anisotropicity of the r value. May increase. For this reason, there was a problem that the drawability was not stable and the steel plate was not stable as a steel plate for cans. In addition, although the pressure resistance at the bottom of the can is large, the neck and flange workability is poor, and it is difficult to achieve a plate thickness of 0.20 mm or less.
[0011]
Further, in the technique described in Japanese Patent Application Laid-Open No. 10-280095, the heating temperature for hot rolling is too low, and the finish rolling finish temperature FDT is set to Ar over the entire width of the steel sheet._ThreeIt is difficult to make the temperature higher than the transformation point. For this reason, there is a problem that the r value of the steel sheet is low and the drawability is lowered.
[0012]
[Problems to be solved by the invention]
On the other hand, in order to counter the pressure in the can, the can bottom needs to have a pressure strength higher than a predetermined level. The pressure strength of the bottom of the can is determined by the material thickness, yield strength (yield stress), and the shape of the bottom of the can.²X It is said to be proportional to the yield strength, and an increase in the yield strength is required to increase the pressure resistance. However, since processing such as deep drawing into a cup shape is required, the material is required to be soft (equivalent to tinning tempering T2 to T3) during can manufacturing. In the can making process, heat treatment such as hot water washing, painting, printing by baking, etc. is applied. Therefore, it is soft at the time of processing. That is, a steel plate (equivalent to tinning tempering T4 to T5) having a large strain age hardening after baking is desired. However, since the neck and flange processing is after paint baking, there is an upper limit to the degree of strain age hardening after paint baking, which is about the same as when a conventional soft material with a refining degree of T2 to T3 can be made. It is desired to be workability.
[0013]
Steel plates manufactured with conventional technology can be made rigorously in response to the weight reduction (thickness of 0.20 mm or less) of the two-piece can as described above, and the shape and can of each desired portion of the can. There was a problem that the strength could not be sufficiently achieved. That is, the same steel plate is made of a material having a tempering degree of T2 to T3 at the time of cup processing, and the can bottom pressure strength becomes a material equivalent to a tempering degree of T4 to T5 when it becomes an empty can. In addition, the flange workability is required to have, for each process, a characteristic that provides the same level of workability as when a steel sheet having a conventional tempering degree T2 to T3 can be made.
[0014]
The present invention solves the above-mentioned problems of the prior art, is suitable for lightweight beverage cans having an empty can weight of 25 g or less, is relatively soft with a tempering degree of T2 to 3, and has a deep drawing workability. An object of the present invention is to propose a steel sheet for an ultra-thin two-piece can having a thickness of 0.20 mm or less, which is excellent in multi-stage neck workability and flange workability, and a manufacturing method thereof.
[0015]
[Means for Solving the Problems]
In order to achieve the above-described problems, the present inventors first examined factors affecting the neck portion strength and the can bottom strength. FIG. 1 shows the relationship between the amount of strain and the yield strength during each can manufacturing process.
In the case of a two-piece can, the steel sheet is first deep-drawn and formed into a cup shape. As shown in FIG. 1, at a working strain of 0%, the yield stress (also called yield strength, YS) of the steel sheet should be low from the viewpoint of deep drawing workability, and is adjusted from the viewpoint of wrinkling during deep drawing. It is preferable to use a relatively soft steel plate having a grade of T2 to 3 (with a yield stress of 370 MPa or less). Wrinkles during deep drawing are more likely to occur as the drawing ratio increases and the yield strength increases. For this reason, from the viewpoint of deep drawing workability, an upper limit is required for the yield strength of the steel plate as the material.
[0016]
On the other hand, when the material is thin, the bending rigidity is lowered and the flange wrinkle is likely to occur. In order to prevent the generation of wrinkles on the flange, it is necessary to increase the wrinkle restraining force. However, if the wrinkle restraining force is increased, the punch shoulders are easily broken during processing, and the ears generated in the circumferential direction of the cup Among them, a problem occurs in which the larger one is stretched (ear standing) or torn (ear cut). Such a problem of the ear standing / ear cutting becomes more prominent as the material steel plate becomes softer. For this reason, it is necessary to set a lower limit to the yield stress (yield strength) of the steel plate as the material, and it is preferable to set it to 250 MPa or more.
[0017]
Further, the present inventors have found that the in-plane anisotropy Δr of the r value needs to be reduced to 0 ± 0.2 in order to reduce the generation of ears. As Δr increases, the ear rate increases and the ears in a specific direction become extremely large, causing troubles such as tearing the inside of the cup holder or being caught by a processing machine, resulting in reduced productivity. It has been found that in order to reduce Δr, it is important to optimize the steel composition, the hot rolling temperature, the cold reduction rate, and the annealing temperature.
[0018]
Furthermore, in order to prevent the problem of the ear standing / ear cutting, the inventors suppress the upper limit of the r value while maintaining the lower limit of the r value, and further set the yield stress after deep drawing to a predetermined value. It has been found that by making it higher than (ear stand-off / ear-cut prevention strength), the thickness of the upper end of the cup (can) after deep drawing becomes thick, and tearing of the ear can be prevented. Then, it has been found that it is effective to work and harden to some extent by temper rolling after recrystallization annealing in order to suppress the upper limit value of r value and to increase the yield strength to a level higher than the strength of preventing ears and ears.
[0019]
Therefore, in order to have a desired range of yield stress and a good deep drawing workability and to reduce the occurrence of ears, the average r value is set to an appropriate value of 1.0 to 1.5 as a lightweight two-piece steel plate. In addition, it is necessary to use a steel plate having an in-plane anisotropy Δr of r value as small as 0 ± 0.2.
The steel sheet that has been drawn and formed into a cup shape is then subjected to ironing in order to set the can height to a predetermined height. Subsequently, the bottom of the can is subjected to dome processing that gives a processing strain of about 10%. In addition, as the plate thickness of the material decreases, the processing strain increases by decreasing the ground contact diameter or increasing the dome depth. Therefore, the strength of the steel plate at the bottom after the baking coating after dome processing is determined determines the pressure strength of the two-piece can. Conventionally, after filling the can, the retort treatment (heat treatment of about 120 ° C. × 90 min) was performed as a sterilization treatment. The steel plate strength of the bottom part was determined on the assumption that it could withstand this retort treatment. If the strength of the bottom steel plate is less than 400 MPa, the pressure resistance of the can is insufficient, and buckling occurs during retort processing or when the can of a positive pressure can that has been filled with nitrogen and applied internal pressure is dropped. . Therefore, as a result of investigating the relationship between processing strain and can bottom pressure strength, steel plate properties that yield a steel plate yield stress (YS) of 400 MPa or more after processing strain equivalent to 10%-paint baking equivalent treatment (210 ° C x 20 min heat treatment) I found that the problem could be solved.
[0020]
However, recent advances in filling technology have enabled aseptic filling and do not need to withstand retorting. Therefore, it is only necessary to consider deformation during transportation after filling the contents, and the required pressure strength is lower than in the past. For this reason, the strength required for the steel plate at the bottom is also the pressure resistance for aseptic filling cans lower than the pressure resistance for retort processing cans (see FIG. 1). Therefore, the steel plate as a raw material attaches importance to the improvement of workability, and a steel plate whose strength after dome processing is softer than before may be used. As a result of investigations by the present inventors, in order to satisfy this characteristic, there is no problem if the YS of the steel sheet after 10% processing strain is applied and baking coating equivalent treatment (210 ° C x 20 min heat treatment) is 370 MPa or more. I found it.
[0021]
Furthermore, the present inventors can manufacture a steel sheet having a strength after dome processing that is equal to or higher than the pressure resistance strength for aseptic filling cans by performing box annealing (circle mark in FIG. 1) following continuous annealing. I found. Further, a steel plate having a strength after dome processing that is equal to or higher than the pressure resistance strength for a conventional retort processing can is₁Combining continuous annealing at a high temperature above the transformation point and subsequent overaging treatment (marked with □ in FIG. 1) can achieve appropriate precipitation of solute C and appropriate coarsening of crystal grains, and can be manufactured. I found out that
[0022]
Further, in the can neck portion, after deep drawing processing and ironing processing, after being baked and coated, the neck diameter is further reduced. By deep drawing and ironing, a maximum processing strain of 35% is given, and post-processing paint baking is performed. Therefore, when the neck diameter is reduced, the inventors have paid attention to the fact that the strength of the steel sheet after 35% processing and paint baking is the strength at the time of neck diameter reduction processing. It has been found that when the YS of the steel sheet exceeds 620 MPa during the diameter reduction process, wrinkling is generated. If wrinkles occur in the neck, the contents leak and the can is rejected and eliminated.
[0023]
For this reason, the inventors of the present invention are appropriately soft at the time of drawing, and imparting 10% processing strain--after the baking process, yield stress of 370 MPa or more, or 400 MPa or more, and 35% processing strain imparting-painting. It has been found that a steel sheet having a yield stress of 620 MPa or less after baking is suitable for a lightweight can.
The present invention has been completed based on the above findings and further studies.
[0024]
  That is, the first aspect of the present invention isIn mass%, C: 0.01 to 0.06%, N: 0.0060% or less, Si: 0.03% or less, Mn: 0.6% or less, P: 0.02% or less, S: 0.02% or less, Al: 0.03-0.20%, O: Contains 0.01% or less, and has a composition consisting of the balance Fe and inevitable impuritiesLow-carbon aluminum killed steel sheet with yield stress: 250 to 370 MPa, average r value: 1.0 to 1.5, r value in-plane anisotropy Δr value of 0 ± 0.2, tempering degree T2 to T3 In addition, the yield stress after applying 20% heat treatment at 210 ° C with 10% processing strain is 370MPa or more, and the yield stress after applying heat treatment at 210 ° C and 20min at 210 ° C is 620MPa or less. It is characterized byCup moldingSteel plate for lightweight two-piece cans with a thickness of 0.20mm or less, which has excellent workability, multi-stage neck workability and flange workability,Further, in addition to the above composition, in terms of mass%, Nb: 0.10% or less, Ti: 0.20% or lessunder1 or 2 selected fromseedIt may be a composition containingFurthermore, it is good also as a composition which contains 1 type or 2 types chosen from Nb: 0.10% or less and Ti: 0.20% or less, and B: 0.005% or less by the mass%.
[0025]
  In the first aspect of the present invention, it is preferable to have a surface treatment layer on at least one surface of the steel sheet, and the surface treatment layer is preferably tin plating or chrome plating.
  Also,steelIt comprises a rough rolling process in which a material is heated to form a sheet bar by hot rolling, a finish rolling process in which the sheet bar is hot rolled by hot rolling, and a winding process to wind the hot rolled sheet In the method for producing a hot-rolled steel sheet, the composition of the steel material is, in mass%, C: 0.01 to 0.06%, N: 0.0060% or less, Si: 0.03% or less, Mn: 0.6% or less, P: 0.02% or less, S: 0.02% or less, Al: 0.03-0.20%, O: 0.01% or less, and the composition comprising the balance Fe and inevitable impurities, and the finish rolling finish temperature FDT of the finish rolling process is (Ar_ThreeAn ultra-thin hot-rolled steel sheet with a thickness of 2 mm or less (base plate for ultra-thin cold-rolled steel sheet for cans), characterized by having a transformation point + 10 ° C. or higher and a winding temperature CT in the winding process of 600 to 750 ° C. In addition to the composition described above, the composition may further contain one or two selected from mass%, Nb: 0.10% or less, Ti: 0.20% or less, or In addition to the composition, Nb: 0.10% or less and Ti: 0.20% or less may be contained, and B: 0.005% or less may be contained in addition to the composition. Also,in frontAfter the rough rolling process and before the finish rolling process, it is preferable to perform the finish rolling process after joining the leading end of the sheet bar and the trailing end of the sheet bar preceding the seat bar.
[0026]
  Also,in frontAfter the rough rolling step and before the finish rolling step, either or both of heating and heating the longitudinal end of the sheet bar or heating and heating the widthwise end of the sheet bar Preferably it is done.
  The second2In the present invention, a steel raw material is heated and subjected to a hot rough rolling process in which the sheet bar is formed by hot rolling, a hot finish rolling process in which the sheet bar is formed by hot rolling, and the hot rolling. A winding step for winding the plate, and further cold-rolling the hot-rolled plate into a cold-rolled plate, annealing the cold-rolled plate into a cold-rolled annealed plate, and In the method for producing an ultra-thin cold-rolled steel sheet for cans having a sheet thickness of 0.20 mm or less having a temper rolling process for temper rolling a cold-rolled annealed sheet, the composition of the steel material is expressed by mass%, C: 0.01 to 0.06 %, N: 0.0060% or less, Si: 0.03% or less, Mn: 0.6% or less, P: 0.02% or less, S: 0.02% or less, Al: 0.03-0.20%, O: 0.01% or less, the balance Fe and The composition is composed of inevitable impurities, and the finish rolling finish temperature FDT of the finish rolling process is (Ar_ThreeTransformation point + 10 ° C) or higher, the winding temperature CT in the winding process is 600 to 750 ° C, and the annealing temperature is set to Ac.₁Continuous annealing at a transformation point or higher, quenching treatment for quenching from the annealing temperature, and a step of performing overaging treatment after the quenching treatment, or setting the annealing temperature to Ac₁It is a method for producing an ultra-thin cold-rolled steel sheet for cans having excellent cup formability, multi-stage neck workability and flange workability, characterized by continuous annealing at a transformation point or higher and subsequent box annealing. . Further, in addition to the above composition, the composition may further contain one or two kinds selected from Nb: 0.10% or less, Ti: 0.20% or less in mass%, or in addition to the composition, Furthermore, it may contain 1 type or 2 types selected from Nb: 0.10% or less and Ti: 0.20% or less, and B: 0.005% or less in mass%. The second2In the present invention, the 0.2% proof stress target value (σ) corresponding to the target value of the thickness (t mm) of the cold-rolled steel sheet and the yield stress of the cold-rolled steel sheet._0.2, MPa) and (t)² × σ_0.2 However, in the case of 8.0 or less, after the continuous annealing, box annealing with an annealing temperature of 500 to 600 ° C. is performed, and the sheet thickness (t mm) of the cold-rolled steel sheet and the 0.2% yield strength target value (σ_0.2, MPa) and (t)² × σ_0.2 However, if it exceeds 8.0, it is preferable to perform an overaging treatment at 400 to 550 ° C. for 40 seconds or longer after the rapid cooling treatment.
[0027]
  The second2In the present invention, it is preferable that the rolling reduction of the temper rolling in the temper rolling step is 1% or more and less than 15%. The first2In the present invention, after the rough rolling step and before the finish rolling step, the leading end of the sheet bar and the trailing end of the sheet bar preceding the sheet bar are joined.didAfter that, it is preferable to perform a finish rolling process.
[0028]
  The second2In the present invention, after the rough rolling step and before the finish rolling step, either heating the temperature of the longitudinal end of the sheet bar or heating the temperature of the widthwise end of the sheet bar. Preferably, either or both are performed. The second2In the present invention, after the temper rolling step, it is preferable to perform a surface treatment for forming a surface treatment layer on at least one surface of the steel sheet, and the surface treatment is preferably a tin plating treatment or a chrome plating treatment. .
[0029]
DETAILED DESCRIPTION OF THE INVENTION
  First, the reason for limitation of the steel sheet of the present invention will be described.
  The steel plate of the present invention is a low carbon aluminum killed steel plate. The composition is as follows:.
  C:0.01 ~0.06%
  C is an important element that refines the crystal grains and increases the strength of the steel by solid solution strengthening. On the other hand, it forms carbides and lowers the ductility of the steel sheet and thus the workability. For this reason, C is limited to 0.06% or less. In order to secure r value and reduce variation in r value in the width direction and length direction, FDT is changed to Ar_ThreeIt is important to make the transformation point + 10 ° C. or higher. From these viewpoints, C is suitably 0.01 to 0.05%. From the viewpoint of moderate bake hardenability, it is important to finely distribute the carbide after continuous annealing (CAL), and C is 0.01% or more.The
[0030]
N: 0.0060% or less
N is an element that increases age hardenability when it remains in the steel sheet as solute N. In the present invention, it is desirable to reduce it as much as possible, but 0.0060% is acceptable. In addition, Preferably it is 0.003% or less.
Si: 0.03% or less
Si is an element that increases the strength of steel by solid solution strengthening, but addition of a large amount causes problems such as deterioration in workability, surface treatment property, and corrosion resistance. For this reason, it is desirable to reduce as much as possible in the present invention, but it is acceptable up to 0.03%.
[0031]
Mn: 0.6% or less
Mn is an effective element for preventing hot cracking due to S, but if contained in a large amount, it is uneconomical and tends to deteriorate corrosion resistance and increase strength variation. For this reason, in the present invention, Mn is limited to 0.6% or less. In addition, Preferably it is 0.2 to 0.4%.
[0032]
P: 0.02% or less
P significantly hardens the steel, deteriorates flange workability and neck workability, and further deteriorates corrosion resistance. For this reason, in the present invention, P is preferably limited to 0.02% or less.
S: 0.02% or less
S is an element that exists as an inclusion in steel and lowers the ductility of the steel sheet and further degrades the corrosion resistance. In the present invention, S is preferably reduced as much as possible, but up to 0.02% is acceptable. Therefore, in the present invention, S is preferably 0.02% or less. In addition, Preferably it is 0.015% or less.
[0033]
Al: 0.03-0.20%
Al acts as a deoxidizer and combines with solid solution N to form AlN and has the effect of reducing the amount of solid solution N. Such an effect is noticeable when the content is 0.03% or more. On the other hand, a large content exceeding 0.20% increases the oxide inclusions and deteriorates the surface properties, increases the production cost, and is economically disadvantageous. For this reason, Al was limited to the range of 0.03-0.20%. In addition, Preferably, it is 0.03-0.10%.
[0034]
O: 0.01% or less
O exists as an oxide in steel and causes reduction in ductility and deterioration in corrosion resistance. Therefore, it is necessary to reduce O as much as possible. In the present invention, it is acceptable up to 0.01%. In particular, in order to obtain a thin steel plate, the content is preferably 0.005% or less.
[0035]
  Nb: 0.10% or less, Ti: 0.20% or lessUnderOne or two selected from our houseSpecies or Nb: 0.10% or less, Ti: In addition to one or two selected from 0.20% or less, B: 0.005% or less
  Nb, Ti, and B are all elements that form carbides and nitrides and are effective in improving workability, and can be selected and contained as necessary.
  Nb is an effective element that forms carbides and nitrides, reduces the residual amount of solute C and solute N, and improves workability. However, if it contains more than 0.10%, it depends on Nb-based precipitates. The recrystallization temperature rises due to the pinning effect of the crystal grain boundaries, the workability of the continuous annealing furnace is lowered, and the grains become finer. For this reason, it is preferable to limit Nb to 0.10% or less. In order to obtain such an effect, Nb is desirably contained in an amount of 0.002% or more.
[0036]
Ti is an effective element that forms carbides and nitrides, reduces the residual amount of solid solution C and solid solution N, and improves workability. However, if it exceeds 0.20%, it is hard to precipitate. Products are generated, corrosion resistance is lowered, and scabs are easily generated during press working. For this reason, Ti is preferably limited to 0.20% or less. In addition, in order to acquire such an effect, it is desirable to contain Ti 0.01% or more.
[0037]
B is an effective element that forms carbides and nitrides and softens to improve workability. However, when it exceeds 0.005%, it segregates at the recrystallization grain boundary during continuous annealing and delays recrystallization. For this reason, B is preferably limited to 0.005% or less. In addition, in order to acquire such an effect, it is desirable to contain B 0.0003% or more. B is also an element effective in improving grain boundary embrittlement, and has a relatively low C content. In particular, when a carbide forming element is added, the strength of the recrystallized grain boundary is increased and embrittlement cracking is prevented. Have the effect of
[0038]
Remaining Fe and inevitable impurities
The balance other than the above components is Fe and inevitable impurities. As unavoidable impurities, Cr: 0.04% or less, Cu: 0.06% or less, Ni: 0.04% or less, Mo: 0.05% or less are acceptable.
The steel sheet of the present invention has the above composition range, yield stress: 250 to 370 MPa, average r value: 1.0 to 1.5, r value in-plane anisotropy Δr value of 0 ± 0.2, and tempering degree. It is a steel plate of T2 to T3.
[0039]
Yield stress YS of steel sheet: 250 to 370 MPa, tempering degree: T2 to T3
When YS and tempering degree of steel sheet increase and become hard, it becomes difficult to draw and iron into cans of predetermined dimensions. Therefore, yield stress YS of steel sheet is 370 MPa or less, and tempering degree is T3 or less. There is a need to. On the other hand, when deep drawing is performed with a thin-walled steel plate, the wrinkle restraining force increases, and the larger one of the ears generated in the cup circumferential direction is stretched or torn off. If the steel plate is too soft, this phenomenon is promoted, so that it is necessary to set the yield stress YS of the steel plate to 250 MPa or more and the tempering degree to T2 or more.
[0040]
Average r value: 1.0 to 1.5, Δr: 0 ± 0.2
The steel sheet of the present invention is a steel sheet having a small in-plane anisotropy having an average r value: 1.0 to 1.5 and Δr: 0 ± 0.2. If the average r value is less than 1.0, there is a problem that the deep drawing processability deteriorates and it is difficult to obtain the required can height. On the other hand, if the average r value exceeds 1.5, the elongation in the can height direction is large. The thickness of the side wall of the cup becomes thin, and there is a problem that the formed large ear part is easily torn or stretched. In order to suppress the generation of ears, it is preferable to reduce Δr in the range of 0 ± 0.2 and the in-plane anisotropy of the r value.
[0041]
The average r value and Δr are the r value (r) for the rolling direction (L direction), 45 ° from the rolling direction (D direction), and the perpendicular direction from the rolling direction (C direction), respectively._L, R_D, R_C) And average r value = (r_L+ R_C+ 2r_D) / 4, Δr = (r_L+ R_C-2r_D) / 2. For steel sheets with large temper rolling reduction and small elongation El, the average r value is measured using the natural vibration method specified in JIS G 3135 or JIS Z 2254. Further, as shown in Steel. Met. Ind., 50 (1973), 328, the following relationship is recognized between Δr and Young's modulus. Assume that Δr is also measured using the method.
[0042]
The average r value, Δr, is an average value E in each direction in the in-plane Young's modulus E from the obtained frequency by applying a high frequency to the strip-shaped test piece with the excitation coil and detecting the frequency with the detection coil.^*And anisotropy ΔE
Average r value = 101.44 / (145.0 × E^*× 10^-6-38.83)²−0.564
Δr = 0.031 −0.323 (145.0 × ΔE × 10^-6)
Where E^*= (E_L+ E_C+ 2 E_D) / 4
ΔE = (E_L+ E_C-2 E_D) / 2
Calculate using. E_L, E_C, E_DAre Young's modulus (N / mm) in the rolling direction (L direction), the direction perpendicular to the rolling direction (C direction), and 45 ° (D direction) from the rolling direction, respectively.²).
[0043]
Furthermore, the steel sheet of the present invention has a yield stress of 370 MPa or more after applying 10% processing strain and heat treatment at 210 ° C for 20 minutes, and after applying 35% processing strain and heat treatment at 210 ° C for 20 minutes. Yield stress is 620 MPa or less. By having such an appropriate bake hardenability (BH property), the can body has a high pressure resistance, can be reduced in multi-stage neck diameter, and can be an ultra-thin steel plate that can achieve weight reduction.
[0044]
According to the study by the present inventors, the processing strain introduced during can making can be evaluated by replacing with rolling strain. That is, by applying rolling with a rolling reduction of 10% or 35% to the steel sheet, it is possible to give a strain corresponding to 10% processing strain and 35% processing strain introduced at the time of can making as described above. Therefore, in the present invention, the yield stress after heat treatment at 210 ° C. for 20 min is the yield stress after rolling the steel plate at a reduction rate of 10% and heat treatment at 210 ° C. for 20 min, or the steel plate has a reduction rate of 35%. % Yield stress after heat treatment at 210 ° C for 20 min.
[0045]
Below, the manufacturing method of this invention steel plate which has the above-mentioned characteristic is demonstrated.
The steel material having the above composition is melted by a generally known melting method to obtain a steel material such as a slab having a high cleanliness by a known casting method such as a continuous casting method.
In the present invention, a steel material is heated and subjected to a rough rolling step for forming a sheet bar by hot rolling, a finish rolling step for forming the sheet bar by hot rolling, and a winding for winding the hot rolled plate. It is set as the hot-rolled board wound up in the coil shape by the removal process.
[0046]
In the rough rolling process, the heating temperature and rolling conditions are not particularly limited, and it is sufficient that the sheet bar can have a predetermined size and shape. In addition, it is preferable that the heating temperature of a steel raw material shall be 1100-1250 degreeC. When the heating temperature is less than 1100 ° C., the rolling load in the rough rolling increases and it becomes difficult to set the finish rolling end temperature within a predetermined temperature range. On the other hand, when the heating temperature exceeds 1250 ° C., the formation of surface scale becomes remarkable, resulting in large scale loss and economical disadvantage, and a scale that is difficult to remove by finish rolling remains and tends to cause surface defects. Further, the coarsening of crystal grains becomes remarkable.
[0047]
In the present invention, after being formed into a sheet bar in the rough rolling process, before the finish rolling process, the front end of the sheet bar and the rear end of the sheet bar preceding the sheet bar are joined, and then finish rolling. It is preferable to do. By joining the sheet bars in this manner, it is possible to easily prevent the disturbance of the shape in the longitudinal direction, which is a problem particularly in the ultrathin hot-rolled steel sheet as in the present invention, and the yield of products can be improved.
[0048]
Moreover, it is preferable to heat and heat the longitudinal direction edge part of a sheet bar over the full width between rough rolling processes and finish rolling, or to heat and heat the width direction edge part over the full length. The end of the sheet bar in the longitudinal direction or the end in the width direction tends to decrease in temperature, and this part is heated to raise the temperature to make the temperature inside the sheet bar uniform, and the finish regulated in relation to the transformation point It is easy to secure the rolling temperature in the longitudinal direction and the width direction, and the yield is improved. Note that the heating method is preferably an induction heating method.
[0049]
In addition, as described above, after being formed into a sheet bar in the rough rolling process, when the finish rolling is performed after the front end portion of the sheet bar and the rear end portion of the sheet bar are joined before the finish rolling step, they are joined. The yield can be improved by heating and heating the vicinity of the joint corresponding to the longitudinal direction end of the sheet bar before joining, or finishing and rolling after heating and heating the end in the width direction. From the viewpoint of
[0050]
Thus, by performing soaking of the sheet bar before the finish rolling step, the temperature of the end portion in the width direction and the end portion in the length direction of the sheet bar can be increased. Finish rolling finish temperature FDT (Ar_Three(Transformation point + 10 ° C.) or higher.
The sheet bar that has undergone the rough rolling process is then hot-rolled in a finish rolling process to form a hot-rolled sheet. In the finish rolling process, the finish rolling end temperature FDT is set to (Ar_ThreeTransformation point + 10 ° C) or higher. FDT is (Ar_ThreeIf the transformation point is less than + 10 ° C., AlN precipitates and solute N decreases, or the r value after recrystallization annealing decreases, and the in-plane anisotropy increases and Δr increases. For this reason, FDT is (Ar_Three(Transformation point + 10 ° C.) or more is preferable.
[0051]
In order to increase the r value after recrystallization annealing, it is said that it is better to reduce the cold rolling reduction ratio in a steel sheet for cans having a high cold rolling reduction ratio. However, even if the thickness of the hot-rolled sheet is reduced in order to reduce the cold rolling reduction ratio, the increase of the r value was not obtained so much. The reason for this is that by using a thin hot-rolled sheet, the surface layer of the hot-rolled sheet takes a longer time to be lower than the central part of the plate thickness, so the rolled texture of the surface layer decreases the r value after recrystallization annealing. This is probably because the (110) recrystallized texture is easily formed. In order not to form such a rolling texture in the surface layer part, FDT (Ar_ThreeIt was found that the transformation point + 10 ° C or higher is good. Thereby, the effect of reducing the cold rolling reduction ratio for improving the r value becomes significant.
[0052]
Moreover, although a hot-rolled sheet is wound up in a coil shape at a winding-up process, it is preferable that winding-up temperature CT shall be 600-750 degreeC. When CT is less than 600 ° C., the amount of AlN deposited is small and fine, the r value is lowered, and a hard steel sheet with high yield strength is obtained. On the other hand, when the temperature exceeds 750 ° C., the crystal grains of the hot-rolled sheet become coarser as the carbides become coarser, and the distance between carbides as the precipitation site of the solid solution C increases in the continuous annealing-overaging process. Even if the overaging treatment is performed for 40 seconds or longer, the strain aging characteristics necessary for the present invention cannot be obtained, and the effect is not increased. For this reason, CT is preferably 600 to 750 ° C.
[0053]
The cooling after winding is preferably air cooling. Further, after sufficient self-annealing, water cooling may be performed. By cooling with water, it is possible to prevent a decrease in yield due to an increase in surface scale. The water cooling can be a short-time cooling such as watering.
The thickness of the hot-rolled plate is determined depending on the thickness of the cold-rolled plate (product plate) as the base plate of the cold-rolled plate, but to make a thin cold-rolled plate with a thickness of 0.20 mm or less, In consideration of reducing the in-plane anisotropy and improving the r value, it is preferably 2 mm or less.
[0054]
The hot-rolled sheet manufactured by the above-described process is descaled by hydrochloric acid pickling, and then cold-rolled by cold rolling, and annealed to cold-roll and anneal the cold-rolled sheet. A process and a temper rolling step of temper rolling the cold-rolled annealed sheet are performed to obtain a cold-rolled annealed sheet.
In the cold rolling process, it is only necessary to obtain the desired dimension and shape of the cold rolled sheet, and the conditions are not particularly limited. However, in order to obtain a large r value and a small Δr, the reduction ratio of the cold rolling is preferably 93% or less, and preferably 91% or less. In order to obtain such a cold rolling reduction ratio, it is preferable to perform sheet rolling and hot rolling to reduce the thickness of the hot rolled sheet.
[0055]
The cold rolled sheet is then annealed. In the annealing process, the annealing temperature is set to Ac₁It is preferable to perform a continuous annealing at a transformation point or higher, a rapid cooling process for quenching from the annealing temperature, and a process for subsequent overaging, or a process for continuous annealing and subsequent box annealing.
In continuous annealing, in order to ensure the workability required for DI (Drawing & Ironing) for lightweight beverage cans, Ac₁It is preferable to soak at a temperature above the transformation point. Set the annealing temperature to Ac₁By setting the transformation point or more, precipitation of AlN is promoted, carbides aggregate, the crystal grain size grows, and the strain aging necessary for the present invention can be obtained and the r value becomes high (111). A recrystallized texture can be developed. Therefore, the annealing temperature for continuous annealing is Ac.₁It is preferable to set it above the transformation point. It should be noted that the soaking time at the annealing temperature is sufficient if it is 1 s or more in view of operational stability.
[0056]
It is preferable to perform a rapid cooling treatment after the continuous annealing. The rapid cooling treatment is preferably performed at the outlet side of the continuous annealing and is cooled to the overaging temperature at a cooling rate of 40 to 70 ° C./s. Thereby, precipitation of solid solution C is achieved and it becomes a steel plate which has appropriate softness and strain aging.
Note that the thickness (tmm) of the cold-rolled sheet and the 0.2% yield strength target value (σ_0.2(MPa), also called the yield stress target value), (t)²× σ_0.2However, when it exceeds 8.0, it is preferable to carry out an overaging treatment at 400 to 550 ° C. for 40 seconds or more after a rapid cooling treatment at a cooling rate of 40 to 70 ° C./s on the continuous annealing side. By this overaging treatment, solid solution C is precipitated, and a preferable effect is obtained that a steel sheet having a soft and appropriate strain aging property can be obtained as a continuous annealing material (CAL material). More preferably, an overaging treatment is performed at 400 to 500 ° C.
[0057]
Meanwhile, (t)²× σ_0.2However, in the case of 8.0 or less, it is preferable to anneal by a continuous annealing-box annealing method instead of continuous annealing-rapid cooling treatment-overaging treatment. A rapid cooling process of 40 ° C./s or more is not particularly required between the continuous annealing and the box annealing. In the box annealing, it is preferable that the annealing temperature is 500 ° C. or more and heated to a temperature in the range of 600 ° C. or less, and then slowly cooled while ensuring a residence time in the carbide precipitation temperature range of 500 to 400 ° C. for 1 h or more. No holding time is required at the box annealing temperature. By annealing with the box annealing method under such conditions, a steel plate for cans that is non-aged and soft, has a large r value, a small Δr, and a workability close to that of a box annealed material excellent in deep drawing workability is obtained. This makes it possible to manufacture a two-piece can with a reduced plate thickness. On the other hand, when the annealing temperature of box annealing exceeds 600 ° C., graphite is precipitated, and it is difficult to form a uniform plating layer by subsequent plating treatment.
[0058]
(T)²× σ_0.2However, in the case of 8.0 or less, when continuous annealing-overaging treatment is performed, deep drawing workability may be deteriorated, and it is preferable to perform continuous annealing-box annealing. (T)²× σ_0.2However, in the case of 8.0 or less, the pressure resistance of the can body is 617 kPa or less required for the can body that requires retorting after filling the contents. However, at present, by improving the can shape and can filling method, even if the pressure resistance of the can is 617 kPa or less, it can be applied for aseptic filling treatment.
[0059]
The atmosphere for box annealing is preferably a reducing atmosphere such as HN gas. Note that the heating rate is not particularly limited, and it is preferably a gradual heating.
The cold-rolled annealed plate that has undergone the annealing step is then temper-rolled by cold rolling in the temper rolling step. This temper rolling adds work hardening and increases the strength of the bottom of the can. For this purpose, it is preferable that the rolling reduction is at least 1% and less than 15%. If the temper rolling reduction is less than 1%, the strength of the bottom of the can is not increased. On the other hand, if it is 15% or more, the steel sheet becomes too hard, making it unsuitable as a lightweight two-piece can. More preferably, the rolling reduction is 3% or more. The conventional box annealed material is subjected to SR (single cold-reduced product) with a rolling reduction of 2% or less to introduce movable dislocations.
[0060]
The cold-rolled annealed plate thus manufactured may be shipped as a product plate (coil) as it is after the rust prevention treatment. Alternatively, a pickling treatment is performed, and a surface treatment for forming a surface treatment layer such as tin plating, chromium plating, nickel plating or the like is formed on at least one surface to obtain a product plate. The product plate is further oiled and shipped. The thickness of the surface treatment layer depends on the application, but with tin plating, the tin weight per side is 11 g / m.²(# 100) The following, no reflow finish without applying tinning treatment, preferably hydrated chromium oxide layer 1mg / m²By applying as follows, the effect of solid lubrication in press working can be greatly exhibited. In addition, in the chromium plating (TFS) treatment, the basis weight is 60 mg / m per side.²The following is preferable. Further, as the oil coating agent, DOS (Di-octyl sebacate) and ATBC (Acetyl tri-butyl citrate) are preferable.
[0061]
【Example】
The effect of this invention is demonstrated based on an Example.
The steels with the components shown in Table 1 were melted in a bottom-blowing converter to prevent non-metallic inclusions from entering and remaining, and then rolled into a rolling material (slab) using a large tundish and a vertical bending type continuous casting machine. . Subsequently, these rolled materials were hot rolled under the conditions shown in Table 2 to obtain hot rolled sheets. Thereafter, the hot-rolled sheets are subjected to descaling by pickling, further subjected to cold rolling under the conditions shown in Table 2, and then subjected to annealing and temper rolling under the conditions shown in Table 2, did.
[0062]
Except steel plate No. 4, the slab heating temperature of the steel plate in Table 2 is 1100-1250 ° C, and the finish rolling temperature is (Ar_Three(Transformation point + 10 ° C.) or higher. Steel plate No. 4 has a slab heating temperature of 1040 ° C, and the finish rolling temperature is Ar._ThreeThe transformation point was 870 ° C.
The ultra-thin cold-rolled steel sheet thus obtained was subjected to a tensile test, a hardness test, a bake hardening test, and an r value measurement. In order to evaluate the pressure strength of the bottom of the can, it was rolled as described above to give 10% strain, and for the evaluation of neck / flange workability, 35% strain was applied, and then each was subjected to paint baking treatment. An aging treatment of 210 ° C. × 20 min corresponding to was performed and evaluated by a tensile test. In the tensile test, if no clear yield point phenomenon was observed, the 0.2% proof stress was taken as the yield stress.
(I) Tensile test
JIS No. 5 tensile test specimens were collected from the center in the width direction of these cold rolled steel sheets in the rolling direction, in the direction of 45 ° from the rolling direction and in the direction perpendicular to the rolling direction, and subjected to a tensile test at a strain rate of 40% / min. Yield stress (0.2% yield strength) YS, tensile strength TS, and elongation El were measured, and an average value in three directions was determined.
(Ii) Bake hardenability test
Specimens were taken from the center of the cold rolled steel sheet in the width direction and in the direction perpendicular to the rolling direction, and after cold rolling, a strain of 10% or 35% reduction was applied, followed by coating baking at 210 ° C for 20 min. A heat treatment corresponding to the treatment was performed, and then a tensile test was performed to measure a yield stress, and an average value in two directions was obtained.
(Iii) Hardness test
The tempering degree was determined from the HR30T hardness of these cold-rolled steel sheets and the steel sheets after these cold-rolled steel sheets were subjected to a heat treatment equivalent to a paint baking process in accordance with the provisions of JIS G 3303. In addition, the cross-sectional hardness of the neck flange processing part after can making was measured by Vickers hardness (load 50g).
(Iv) Measurement of r value
Among these cold-rolled steel sheets, those with a temper rolling reduction of 2% or less are from the center in the width direction to the rolling direction (L), from the rolling direction to 45 ° direction (D), and perpendicular to the rolling direction ( C), take a JIS No. 5 tensile specimen, conduct a tensile test at a strain rate of 40% / min, and use the plastic strain method (JIS G 3135-1986 commentary 18p or JIS Z 2254) to determine the width direction and the plate. The r value was determined from the logarithmic strain ratio in the thickness direction. The average r value is the average r value = (r_L+ R_C+ 2r_D) / 4, and Δr is Δr = (r_L+ R_C-2r_D) / 2. Further, when the rolling reduction of the temper rolling exceeded 2%, the average r value and Δr value were calculated by the natural vibration method (JIS G 3135-1986 commentary 22p or JIS Z 2254) as described above.
[0063]
These results are shown in Table 3.
[0064]
[Table 1]

[0065]
[Table 2]

[0066]
[Table 3]

[0067]
Moreover, after performing various plating processes on the steel plate using these steel plates under the conditions shown in Table 4, 1st cup molding, DI molding, and four-stage neck molding were performed to obtain 350 ml DI cans, and various can body characteristics were evaluated. The evaluation results are shown in Table 4.
After the can was made, a lid was attached, internal pressure was applied with air, and the pressure when buckling occurred in the dome was determined to obtain the can pressure resistance. Neck wrinkles were visually observed after neck-in molding, and flange cracks were examined using a magnetic sensor.
[0068]
[Table 4]

[0069]
Although the present invention example has a thin plate thickness, it can increase the pressure resistance of the bottom of the can, and even if it is subjected to multi-stage neck and flange processing, there is no occurrence of neck wrinkles or flange cracks, and can strength can be secured It is an ultra-thin cold-rolled steel sheet. On the other hand, in the comparative example that is out of the scope of the present invention, the ears and ears are cut off at the 1st cup, the can bottom pressure resistance is small, neck wrinkles and flange cracks are generated.
[0070]
【The invention's effect】
According to the present invention, it is suitable for a lightweight beverage can having an empty can weight of 25 g or less, has little ear generation, has a desired pressure resistance of a can body, is easy to perform a multistage neck processing, and further has a flange workability. It is possible to manufacture an extremely thin steel plate for a two-piece can that is excellent in manufacturing at low cost, and has a remarkable industrial effect. In addition, there is an effect that it can be applied to an aseptic filling method.
[0071]
Furthermore, even 3-piece cans have been reduced in weight, and have been subjected to multi-stage neck processing and can-expansion processing using ultra-thin steel plates, and have wrinkling problems similar to 2-piece cans. The steel plate for cans of the present invention can be used for such applications, and has the effect of promoting the weight reduction of the can body.
Also for 2-piece cans, not only DWI can (Drawn and wall ironed can) manufacturing method, but also SD can (Shallow-Drawn can) manufacturing method, DRD can (Drawn and Redrawn can) manufacturing method, DTR can (Drawn and Thin Redrawn can) It can be used for manufacturing methods, manufacturing methods combining DTR with wall ironed, or those that are not subjected to can bottom dome processing, and can reduce the weight of the can body.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a relationship among a yield stress YS of a steel sheet, a strain imparted by processing, and a required strength of a can body.

Claims (8)

% By mass
C: 0.01 to 0.06%, N: 0.0060% or less,
Si: 0.03% or less, Mn: 0.6% or less,
P: 0.02% or less, S: 0.02% or less,
Al: 0.03-0.20%, O: 0.01% or less, low-carbon aluminum killed steel sheet having a composition composed of the balance Fe and inevitable impurities, yield stress: 250-370 MPa, average r value: 1.0-1.5 The in-plane anisotropy of the r value is 0 ± 0.2, the tempering degree is T2 to T3, 10% working strain is applied, and the yield stress after heat treatment at 210 ° C. for 20 minutes is 370 MPa. As described above, the yield stress after applying 35% processing strain and heat treatment at 210 ° C for 20min is 620MPa or less. Thickness 0.20 with excellent cup formability, multi-stage neck workability and flange workability Steel plate for lightweight 2-piece cans up to mm. In addition to the above composition,
The steel plate for lightweight two-piece cans according to claim 1, wherein the steel plate has a composition containing one or two selected from Nb: 0.10% or less and Ti: 0.20% or less. In addition to the above composition,
B: The steel plate for lightweight two-piece cans according to claim 2, having a composition containing 0.005% or less.   The steel plate for lightweight two-piece cans according to any one of claims 1 to 3, further comprising a surface treatment layer on at least one surface of the steel plate.   The lightweight steel plate for a two-piece can according to claim 4, wherein the surface treatment layer is tin plating or chrome plating. A hot rough rolling step in which a steel material is heated to form a sheet bar by hot rolling, a hot finish rolling step in which the sheet bar is hot rolled by hot rolling, and a winding for winding the hot rolled plate A cold rolling process in which the hot-rolled sheet is cold-rolled into a cold-rolled sheet, an annealing process in which the cold-rolled sheet is annealed to form a cold-rolled annealed sheet, and the cold-rolled annealed plate In the method for producing an ultrathin cold-rolled steel sheet for cans having a sheet thickness of 0.20 mm or less having a temper rolling process for temper rolling,
The composition of the steel material in mass%,
C: 0.01 to 0.06%, N: 0.0060% or less,
Si: 0.03% or less, Mn: 0.6% or less,
P: 0.02% or less, S: 0.02% or less,
Al: 0.03-0.20%, O: 0.01% or less, the composition consisting of the balance Fe and inevitable impurities,
The finish rolling finish temperature FDT of the finish rolling process is (Ar ₃ transformation point + 10 ° C.) or higher, and the winding temperature CT of the winding process is 600 to 750 ° C.,
When the thickness of the cold-rolled steel sheet (t mm) and 0.2% yield strength target value (σ _0.2 , MPa), (t) ² × σ _0.2 exceeds 8.0, the annealing step is performed at the annealing temperature. was a continuous annealing to Ac ₁ transformation point or higher, and fast cooling by quenching from該焼blunt temperature, after the quench treatment, a step of performing overaging over 40s at 400 to 550 ° C.,
When the thickness of the cold-rolled steel sheet (t mm) and the 0.2% yield strength target value (σ _0.2 , MPa), (t) ² × σ _0.2 is 8.0 or less, the annealing step is performed at the annealing temperature. Is a step of performing box annealing with an annealing temperature of 500 to 600 ° C., followed by continuous annealing with an Ac ₁ transformation point or higher ,
The method for producing an ultra-thin cold-rolled steel sheet for cans excellent in cup formability, multi-stage neck workability and flange workability, characterized in that the temper rolling has a temper rolling reduction ratio of 1% or more and less than 15%. . In addition to the above composition,
It has a composition containing 1 type or 2 types chosen from Nb: 0.10% or less and Ti: 0.20% or less, The manufacturing method of the ultra-thin cold-rolled steel sheet for cans of Claim 6 characterized by the above-mentioned. In addition to the above composition,
B: It has a composition containing 0.005% or less, The manufacturing method of the ultra-thin cold-rolled steel plate for cans of Claim 7 characterized by the above-mentioned .

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