JP6164273B2 - Steel plate for cans and method for producing steel plate for cans - Google Patents

Description

  The present invention relates to a steel plate for cans suitable for can container materials used for food cans and beverage cans and a method for producing the same.

  In recent years, from the viewpoint of reducing environmental burdens and reducing costs, there has been a demand for a reduction in the amount of steel sheets used for food cans and beverage cans, and thinning of steel sheets is progressing regardless of 2-piece cans and 3-piece cans. Along with this, not only can deformation due to external forces acting during can manufacturing, transportation processes and handling in the market, but also buckling deformation of the can body due to increase / decrease in pressure inside the can during heat sterilization processing etc. of contents Is being viewed. Furthermore, the thinning makes it easy for processing defects such as cracks in neck processing and flange processing to occur, and the problem that productivity decreases has become apparent.

  Conventionally, the strength of steel sheets has been increased in order to improve the buckling resistance of the can body. However, when the yield strength (YP) is increased by increasing the strength of the steel sheet, the formability is lowered, which causes a problem in the can manufacturing process. In other words, the formability of the steel sheet is usually reduced due to the increase in strength of the steel sheet, and the problem that the incidence of neck wrinkles and flange cracks increases in the necking performed after the can body part molding and then in the flange processing performed easily becomes obvious. turn into.

  In response to the above, for example, in Patent Document 1, the steel components are in mass%, C: 0.0016 to 0.0050%, Si: 0.10% or less, Mn: 0.10 to 0.80%. P: 0.001-0.020%, S: 0.001-0.020%, Al: 0.005-0.100%, N: 0.030% or less, Nb: 0.003-0. 030%, B: 0.0002-0.0050%, the balance is composed of Fe and inevitable impurities, the tensile strength in the rolling direction is 400 MPa or more, the tensile strength in the direction perpendicular to the rolling is 430 MPa, and A steel sheet for a high workability can is disclosed, wherein the breaking elongation in the rolling direction is 15% or more and the breaking elongation in the direction perpendicular to the rolling is 10% or more.

In Patent Document 2, in mass%, C: 0.0050% or more and 0.0100% or less, Si: 0.050% or less, Mn: 0.10% or more and 1.00% or less, P: 0.030% S: 0.020% or less, Al: 0.010% or more and 0.100% or less, N: 0.0010% or more and 0.0050% or less, Nb: 0.020% or more and 0.120% or less The content of C and Nb satisfies the following formula (1), the balance is Fe and inevitable impurities, the Young's modulus in the 90 ° direction from the rolling direction and / or the rolling direction is 220 GPa or more, and the tempering A steel plate for cans characterized in that the degree is T3 to T4 is disclosed.
0.4 ≦ (Nb / C) × (12/93) ≦ 2.5 (1)
However, Nb and C show content (mass%).

Patent Document 3 includes C: 0.01 wt% or less and N: 0.04 wt% or less in a total amount of 0.008 wt% or more, Mn: 0.05 wt% or more, 2.0 wt% Hereinafter, a steel slab containing Al: 0.005 wt% or less and O: 0.01 wt% or less, with the balance being a composition of iron and inevitable impurities, and a temperature range from Ar ₃ transformation point to 950 ° C. After hot rolling at a finish rolling temperature of, wound on a coil in a temperature range of 400 ° C. or higher and 600 ° C. or lower, subjected to cold rolling after pickling, and then subjected to continuous annealing at a temperature higher than the recrystallization temperature, A method for producing a steel plate for high-strength cans is disclosed, which is then subjected to temper rolling with a rolling reduction of 5% or more.

  In Patent Document 4, the composition is by weight, C: 0.01% or less, Si: 0.2% or less, Mn: 0.6 to 0.1%, P: 0.02% or less, S: 0 0.02% or less, Al: 0.005% or less, N: 0.03 to 0.001%, O: 0.003% or less, and the balance is a continuous cast steel slab substantially made of Fe, A method for producing a steel plate for cans is disclosed, wherein after hot rolling, pickling, cold rolling and continuous annealing, temper rolling is further performed to obtain a steel plate for cans.

JP 2010-180423 A JP 2013-139626 A JP-A-5-345926 JP-A-6-116647

  However, the techniques disclosed in Patent Documents 1 to 4 include the following problems. For example, in the technology disclosed in Patent Document 1, due to the addition of B, the formability is insufficient, and the ferrite phase has a relatively large crystal grain size of 7 to 12 μm. There is a problem that it tends to occur.

  In patent document 2, only the hardness to tempering degree T3-T4 is obtained, and when the steel plate intensity exceeding T4 is requested | required, such as when further thinning or a higher can body strength is required. There is a problem that it cannot be applied.

  In patent document 3, since there is little Al amount, it is difficult to deoxidize stably and there exists a subject that a moldability falls by the inclusion increasing.

  In patent document 4, similarly to patent document 3, since there is little Al amount, it is difficult to deoxidize stably, and there exists a subject that a moldability falls by the inclusion increasing.

  This invention is made | formed in view of this situation, and it aims at providing the steel plate for cans which has favorable moldability and was excellent in the buckling-proof characteristic, and its manufacturing method.

  The present inventors have intensively studied to solve the above problems. As a result, the inventors found that an excellent steel plate for cans can be obtained by setting the component composition, hardness, and Young's modulus in the direction perpendicular to the rolling to be in a specific range, and completed the present invention.

1st invention for solving the said subject is the mass%, C: more than 0.0030% 0.0100% or less, Si: 0.05% or less, Mn: 0.10% or more and 1.00% or less, P: 0.030% or less, S: 0.020% or less, Al: 0.010% or more and 0.100% or less, N: 0.0050% or less, Nb: 0.010% or more and 0.080% or less And the content of C and Nb satisfies the following formula (1), the remainder has a component composition composed of Fe and inevitable impurities, the HR30T hardness is more than 64, and the Young's modulus in the direction perpendicular to the rolling is 230 GPa. It is the steel plate for cans characterized by the above.
0.15 ≦ ([Nb] /92.9) / ([C] / 12) ≦ 1.50 (1)
In the formula (1), [Nb] and [C] are the contents (mass%) of Nb and C, respectively.

  A second invention for solving the above-mentioned problems is the steel plate for cans according to the first invention, wherein the elongation in the direction perpendicular to the rolling is 10% or more.

  3rd invention for solving the said subject is a steel plate for cans as described in 1st invention or 2nd invention, Comprising: A ferrite phase is contained as steel structure, A ferrite average crystal grain diameter is 7.0 micrometers or less. It is characterized by that.

  4th invention for solving the said subject is a manufacturing method of the steel plate for cans in any one of 1st invention-3rd invention, Comprising: Heating temperature of the steel slab which has a component composition as described in 1st invention After heating at 1100 ° C or higher, hot rolling at a hot rolling finish temperature of 850 ° C or higher and 950 ° C or lower, winding at a winding temperature of 500 ° C or higher and 700 ° C or lower, and primary cold rolling at a rolling reduction of 85% or higher, and annealing. A method for producing a steel plate for cans, comprising annealing at a temperature of 700 ° C. to 800 ° C. and performing secondary cold rolling at a rolling reduction of more than 6.0% and not more than 20%.

  In the present invention, the buckling resistance is a characteristic evaluated by paneling strength and dent strength.

  The steel plate for cans of the present invention has good formability and excellent buckling resistance.

  If the steel plate for cans of the present invention is used, the paneling strength of the can body against the external pressure is higher than the reference value (about 0.150 MPa) provided by the can and beverage manufacturers, and a can body having better dent strength can be easily obtained. Can be manufactured. Therefore, according to the present invention, the rigidity of the can used for food cans, beverage cans, and the like is improved, and the steel sheet can be further thinned to achieve resource saving and cost reduction. It has a remarkable industrial effect.

Hereinafter, the present invention will be described in detail.
The steel plate for cans of the present invention is, by mass%, C: more than 0.0030% and 0.0100% or less, Si: 0.05% or less, Mn: 0.10% or more and 1.00% or less, P: 0.00. 030% or less, S: 0.020% or less, Al: 0.010% or more and 0.100% or less, N: 0.0050% or less, Nb: 0.010% or more and 0.080% or less, C And the content of Nb satisfies the following formula (1), the balance has a component composition consisting of Fe and inevitable impurities, the HR30T hardness is more than 64, and the Young's modulus in the direction perpendicular to the rolling is 230 GPa or more.
0.15 ≦ ([Nb] /92.9) / ([C] / 12) ≦ 1.50 (1)
In the formula (1), [Nb] and [C] are the contents (mass%) of Nb and C, respectively.
And the steel plate for cans of this invention heats the steel slab which has the said component composition at the heating temperature of 1100 degreeC or more, and hot-rolls at the hot rolling finishing temperature of 850 degreeC or more and 950 degrees C or less, Then, coiling temperature 500 degreeC Winding at 700 ° C. or lower, primary cold rolling at a rolling reduction of 85% or higher, annealing at an annealing temperature of 700 ° C. or higher and 800 ° C. or lower, and performing secondary cold rolling at a rolling reduction of 6.0% or higher and 20% or lower. It is preferable to manufacture by a manufacturing method.

  The component composition of the present invention will be described. % Means mass% with respect to the content of each component.

C: more than 0.0030% and 0.0100% or less C is an especially important element in the present invention. The hardness increases due to the presence of solute C and the refinement of the ferrite crystal grain size due to the pinning effect of NbC, and further the texture of the steel sheet develops, in the direction perpendicular to the rolling direction (hereinafter also referred to as C direction). Young's modulus is improved. C itself is also effective in reducing the ferrite crystal grain size. In order to obtain these effects, the C content needs to exceed 0.0030%. In particular, from the viewpoint of preventing the weld from being softened and increasing the hardness by reducing the ferrite crystal grain size, the content is preferably 0.0040% or more, and more preferably more than 0.0050%. On the other hand, if the content exceeds 0.0100%, the development of the texture is inhibited and the Young's modulus decreases. Furthermore, since elongation decreases and as a result moldability falls, the upper limit is made 0.0100%. In particular, it is preferably 0.0080% or less from the viewpoint of improving the flange workability.

Nb: 0.010% or more and 0.080% or less Nb is an element having the most important role together with C in the present invention. That is, not only NbC is generated and contributes to the improvement in hardness, but also the refinement of the ferrite crystal grain size of the annealed plate by the pinning effect contributes to the increase in hardness. At the same time, the refinement of the ferrite crystal grain size of the hot-rolled sheet develops a texture of the steel sheet and improves the C-direction Young's modulus. In order to obtain these effects, Nb needs to be 0.010% or more. Furthermore, it is preferable to set it as 0.015% or more. On the other hand, if it exceeds 0.080%, NbC tends to be coarsened and the hardness is lowered. In addition, the pinning effect is reduced and the ferrite crystal grain size is also coarsened, so that the hardness is lowered. For this reason, the upper limit is made 0.080%. Preferably it is 0.060% or less.

0.15 ≦ ([Nb] /92.9) / ([C] / 12) ≦ 1.50 ([Nb] and [C] are Nb and C contents (mass%), respectively)
In the present invention, the content of C and Nb can be adjusted within a predetermined range, and by adjusting the balance, the hardness, C-direction Young's modulus, and moldability can be improved in a balanced manner. When ([Nb] /92.9) / ([C] / 12) is lower than 0.15, the solute C becomes excessive, the texture development is inhibited, and the C-direction Young's modulus decreases. In addition, wrinkles are likely to occur during neck processing, and flange workability is reduced.
When ([Nb] /92.9) / ([C] / 12) exceeds 1.50, NbC becomes coarse and the hardness decreases, and in addition, the pinning effect is reduced, resulting in a reduction in the annealing plate. The ferrite crystal grain size becomes coarse and the hardness further decreases. Further, since the solid solution C is remarkably reduced, the (001) [1-10] to (112) [1-10] orientation is not developed, and the C-direction Young's modulus is reduced. ([Nb] /92.9) / ([C] / 12) is preferably less than 0.4.

Si: 0.05% or less When Si is added in a large amount, surface treatment properties are deteriorated due to surface concentration, and the corrosion resistance is lowered. Preferably it is 0.02% or less.

Mn: 0.10% or more and 1.00% or less Mn is an effect of improving the hardness of a steel sheet by solid solution strengthening, and a decrease in hot ductility due to S contained in steel by forming MnS. There is an effect to prevent. In order to obtain this effect, addition of 0.10% or more is necessary. Further, Mn has the effect of improving the C-direction Young's modulus by refining the ferrite crystal grain size of the hot-rolled sheet and contributing to the development of the texture of the steel sheet. From this point of view, the content is preferably 0.25% or more. More preferably, it is 0.40% or more. On the other hand, if Mn exceeds 1.00%, the texture does not easily develop during annealing and the C-direction Young's modulus decreases, so the upper limit is made 1.00%. Preferably it is 0.60% or less.

P: 0.030% or less When P is added in a large amount, formability is reduced due to excessive hardening or central segregation, and corrosion resistance is reduced. Therefore, the upper limit of P is 0.030%. Preferably it is 0.020% or less. On the other hand, since it has the effect of improving hardness, it is preferable to add 0.010% or more.

S: 0.020% or less S forms sulfides in steel and reduces hot ductility. Therefore, the upper limit of S is 0.020%. Preferably it is 0.015% or less. On the other hand, since it has the effect of suppressing pitting corrosion, it is preferable to add 0.008% or more.

Al: 0.010% or more and 0.100% or less Al is an element added as a deoxidizer. Moreover, by forming N and AlN, it has the effect of reducing the solid solution N in steel and improving the formability and aging resistance. In order to obtain this effect, 0.010% or more must be added. When Nb nitride is generated, the effective amount of Nb is reduced, so that it is preferable to generate AlN preferentially, and from this point of view, it is preferably 0.050% or more. Even if Al is added excessively, not only the above effect is saturated, but also inclusions such as alumina are remarkably increased and formability is lowered. For this reason, the upper limit of Al is 0.100%.

N: 0.0050% or less N is combined with Al, Nb or the like to form nitrides or carbonitrides, and increases hardness, while decreasing hot ductility. Therefore, the smaller the content, the better. A lower N content is preferable, but even if it is less than 0.0010%, not only the effect on the Young's modulus in the C direction is saturated, but also the effect of increasing the hardness due to nitrides may not be obtained, so the lower limit is set to 0. It is preferable to set it to 0010%. Further, when N is added in a large amount, the development of the texture of the steel sheet is inhibited and the C-direction Young's modulus is lowered, so the upper limit needs to be made 0.0050%. Preferably, it is less than 0.0030%.

  The balance of the component composition is Fe and inevitable impurities.

  Next, the material characteristics of the present invention will be described.

HR30T hardness: It is necessary to harden the steel plate in order to prevent plastic deformation when it receives a load due to dropping of over-64 cans, transportation in a vending machine, stacking of cans, and the like. For this reason, Rockwell superficial hardness (scale 30T, HR30T) needs to exceed 64. Preferably it is more than 66. An upper limit is not particularly defined, but if the hardness is excessively high, the moldability may be lowered.

  In the present invention, the Rockwell Superficial 30T hardness (HR30T) at the position defined in JIS G 3315 is measured in accordance with the Rockwell hardness test method of JIS Z 2245.

Young's modulus in the direction perpendicular to rolling (C direction): 230 GPa or more In a three-piece can in which the circumferential direction of the can body is perpendicular to the rolling direction, the paneling strength of the can body can be increased by improving the Young's modulus in the C direction. . For this reason, the C direction Young's modulus needs to be 230 GPa or more. Preferably it is 235 GPa or more. In the above-described component composition, it is preferable that the texture is developed by the manufacturing method described later so that the C-direction Young's modulus is 230 GPa or more.

  In the present invention, Young's modulus is measured by the following method. A 10 × 35 mm test piece with the 90 ° direction as the longitudinal direction with respect to the rolling direction was cut out, and the Young's modulus in the C direction was measured using a lateral vibration type resonance frequency measuring device in accordance with American Society for Testing Materials standard (C1259). (GPa) is measured.

Elongation in the direction perpendicular to the rolling direction (C direction): 10% or more From the viewpoint of preventing wrinkling in necking and cracking in flange processing, that is, from the viewpoint of improving formability, the elongation in the direction perpendicular to rolling should be 10% or more. Is preferred. From the viewpoint of improving canability, the content is more preferably 15% or more.

  In the present invention, the elongation is measured as follows. A JIS No. 5 test piece is taken with the direction perpendicular to the rolling as the longitudinal direction, a tensile test is performed in accordance with JIS Z 2241, and the elongation (total elongation) is measured.

In the present invention, by setting the steel components and production conditions within a predetermined range, good HR30T, Young's modulus in the direction perpendicular to the rolling, and elongation in the direction perpendicular to the rolling can be obtained. In particular, it is important to set C, Nb, and the balance of C and Nb as components ([Nb] /92.9) / ([C] / 12) within a predetermined range.
As production conditions, it is particularly important that the secondary cold rolling reduction is more than 6.0% and not more than 20%. By these, it is possible to obtain a steel sheet having an HR30T hardness of more than 64 and a Young's modulus in the direction perpendicular to the rolling of 230 GPa or more.

Ferrite average crystal grain size: 7.0 μm or less By making the average crystal grain size of the ferrite phase fine, the hardness can be improved and the generation of wrinkles in necking can be prevented. For this reason, it is preferable that the steel plate for cans contains a ferrite phase as a steel structure, and a ferrite average crystal grain diameter shall be 7.0 micrometers or less. From the viewpoint of improving the hardness, it is more preferable that the ferrite average crystal grain size is less than 6.0 μm.

  In the present invention, the average crystal grain size of the ferrite phase is determined according to the cutting method described in JIS G 0551 with respect to the plate thickness section parallel to the rolling direction.

  The steel structure of the steel plate for cans of the present invention may be a single phase of ferrite phase, or may contain a ferrite phase and other phases. When a ferrite phase and other phases are included, the ferrite phase is preferably the main phase. The other phases are preferably about 3% or less in total area ratio.

  Although the plate | board thickness of the steel plate for cans of this invention is not specifically limited, 0.300 mm or less is preferable and 0.225 mm or less is more preferable.

  The steel plate for cans of the present invention is preferably used for the production of 3-piece cans. The steel plate for cans of the present invention is preferably used for the production of cans that undergo welding. Moreover, the steel plate for cans of the present invention is preferably used for production of cans that undergo heat sterilization treatment.

  Next, the manufacturing method of the steel plate for cans of this invention is demonstrated. The production method of the present invention is suitable for the production of a steel plate for cans of the present invention having good formability and excellent buckling resistance.

  The steel plate for cans of the present invention is preferably heated to a steel slab having the above composition at a heating temperature of 1100 ° C. or higher, hot rolled at a hot rolling finish temperature of 850 ° C. or higher and 950 ° C. or lower, and then a winding temperature of 500 Winding at a temperature of not less than 700 ° C and not more than 700 ° C, primary cold rolling at a rolling reduction of 85% or more, annealing at an annealing temperature of 700 ° C to 800 ° C, and secondary cold rolling at a rolling reduction of more than 6.0% but not more than 20%. Manufactured by doing.

Heating temperature: 1100 ° C. or more If the heating temperature before hot rolling is too low, coarse NbC remains and the effect of increasing the hardness due to precipitation strengthening by NbC or the effect of refining the ferrite crystal grain size cannot be obtained. 1100 ° C. The upper limit is not particularly defined, but if the heating temperature is too high, excessive scale is generated and defects on the product surface occur, so the upper limit is preferably 1300 ° C.

Hot-rolling finishing temperature: 850 ° C. or more and 950 ° C. or less When the hot-rolling finishing rolling temperature is higher than 950 ° C., the ferrite crystal grain size of the hot-rolled sheet becomes coarse and inhibits the development of the texture of the steel sheet. As the rate decreases, the ferrite crystal grain size of the annealed plate becomes coarse and the hardness decreases. For this reason, an upper limit shall be 950 degreeC. When the temperature is lower than 850 ° C., the rolling becomes below the Ar ₃ transformation point, and due to the formation of coarse grains and the remaining of the processed structure, the texture does not easily develop and the C-direction Young's modulus decreases, so the lower limit is set to 850 ° C. A preferred lower limit is 870 ° C.

Winding temperature: 500 ° C. or more and 700 ° C. or less When the winding temperature exceeds 700 ° C., NbC is coarsened and the hardness is reduced, and the pinning effect is reduced, and the ferrite grain size of the annealed plate is coarse. As a result, the hardness decreases. In addition, when the ferrite crystal grain size of the hot-rolled sheet becomes coarse, the development of the texture of the steel sheet is inhibited, and the C-direction Young's modulus decreases. For this reason, an upper limit shall be 700 degreeC. Preferably it is 630 degrees C or less. When the coiling temperature is too low, the precipitation of NbC does not occur sufficiently and the precipitation strengthening decreases, so the hardness of the annealed plate decreases. Moreover, since the solute C becomes excessive, the development of the texture is inhibited and the C-direction Young's modulus is lowered. For this reason, a lower limit shall be 500 degreeC. Preferably it is 530 degreeC or more.

Primary cold rolling reduction ratio: 85% or more The surface scale is removed before the primary cold rolling. The method for removing the surface scale is not particularly limited, and various conventional methods such as pickling and physical removal can be applied, but it can be suitably removed by pickling. The conditions for pickling are not particularly limited, and may be pickled by a conventional method. The reduction ratio of primary cold rolling is set to 85% or more in order to improve the Young's modulus in the C direction due to the development of the texture of the steel sheet. More preferably, it is 87% or more from the viewpoint of texture development. When the rolling reduction is less than 85%, the texture does not develop sufficiently, the C-direction Young's modulus decreases, and the ferrite crystal grain size becomes coarse, so that a predetermined hardness cannot be obtained.

Annealing temperature: 700 ° C. or higher and 800 ° C. or lower Annealing is performed at a recrystallization temperature or higher from the viewpoint of controlling the texture of the steel sheet and improving formability. From this viewpoint, the lower limit of the annealing temperature is 700 ° C. If the annealing temperature is too high, the ferrite crystal grain size becomes coarse, and NbC also becomes coarse and the hardness decreases. Therefore, the annealing temperature is set to 800 ° C. or less. Although the annealing method is not limited, the continuous annealing method is preferable from the viewpoint of material uniformity. From the viewpoint of texture development due to the growth of ferrite crystal grains, it is preferable to perform soaking for 10 seconds or more.

Secondary cold rolling reduction: More than 6.0% and not more than 20% The steel sheet after annealing needs to have sufficient hardness to ensure the strength of the can body. From this point of view, the secondary rolling rate is set to more than 6.0%. In secondary rolling with an excessive reduction, there is a possibility that formability may be lowered, and therefore, it is preferably 20% or less. From the viewpoint of moldability, it is more preferably 15.0% or less.

  In addition to the above, the method for producing a steel plate for cans of the present invention may include other steps as appropriate. For example, there is a resin film coating process such as laminating.

  Examples of the present invention will be described below. The technical scope of the present invention is not limited to the following examples.

  Steel slabs were obtained by melting steel containing the components of steel symbols A to Q shown in Table 1, with the balance being Fe and inevitable impurities. Under the conditions shown in Table 2, the obtained steel slab was heated, hot-rolled and wound up, scales were removed by pickling, primary cold-rolled, and each annealing temperature was adjusted in a continuous annealing furnace. After cooling by soaking for 15 seconds, secondary cold rolling was performed to obtain steel plates (steel plate symbols 1 to 29). The steel sheet obtained above was subjected to a heat treatment at 210 ° C. for 20 minutes as a heat treatment corresponding to paint baking, and then the characteristics were evaluated by the following methods.

  The Young's modulus was evaluated by cutting out a 10 × 35 mm test piece with the 90 ° direction as a longitudinal direction with respect to the rolling direction, and using a transverse vibration type resonance frequency measuring device in accordance with American Society for Testing Materials standards (C1259). The Young's modulus (GPa) in the C direction was measured.

  Based on the Rockwell hardness test method of JIS Z 2245, the Rockwell superficial 30T hardness (HR30T) at the position defined in JIS G 3315 was measured.

  A JIS No. 5 test piece was taken with the direction perpendicular to the rolling as the longitudinal direction, a tensile test was performed in accordance with JIS Z 2241, and the elongation (total elongation) was measured.

  The average crystal grain size of the ferrite phase was determined according to the cutting method described in JIS G 0551 for the plate thickness cross section parallel to the rolling direction.

(Evaluation of formability and measurement of paneling strength and dent strength)
In order to evaluate the neck / flange processability (formability) and the buckling resistance, a can body similar to a three-piece can applied to a beverage can was formed. That is, a can body having an outer diameter of 52.8 mm was formed by seam welding using the obtained steel plate, and the end portion was necked in to an outer diameter of 50.4 mm, and then flanged to an outer diameter of 55.4 mm. Formed body. X is marked when wrinkles are noticed during neck processing or cracks occur in the flanged part, ◎ when there are no wrinkles and no cracks, and wrinkles are practically not a problem The case where there was a crack and it did not generate was evaluated as ○.

  For cans with good neck and flange workability, after buckling the lid, two further buckling resistance properties (dent strength and paneling strength) were evaluated.

  Dento strength: An indenter with a tip radius of 5 mm and a length of 40 mm with respect to the center of the can body opposite to the welded portion, with the indenter length direction parallel to the can height direction, and the indenter in that state The indentation was perpendicular to the body, and the indentation amount and indentation load were measured. The buckling load, that is, the load immediately before the inclination of the indentation load with respect to the indentation amount was reduced, and the load immediately before becoming constant was read as the dent strength. If the thickness t is 1224 × t-130 (N) or more, the dent strength is very good, and ◎, 1224 × t-135 (N) or more and less than 1224 × t-130 (N) If it is less than 1224 × t-135 (N), the dent strength is insufficient.

  Paneling strength: The can body was placed inside the pressurizing chamber, and pressurization inside the pressurizing chamber was performed by introducing pressurized air into the pressurizing chamber at 0.016 MPa per second via an air introduction valve. . The pressure inside the pressurizing chamber was confirmed through a pressure gauge, a pressure sensor, an amplifier that amplifies the detection signal, a signal processing device that performs display of the detection signal, data processing, and the like. The paneling strength was the pressure at the pressure change point accompanying buckling. Generally, the paneling strength is required to be 0.150 MPa or more with respect to the pressure change due to the heat sterilization treatment. From this, a paneling strength of 0.155 MPa or more was marked with ◎, a paneling strength of 0.150 MPa or more and less than 0.155 MPa was marked with ◯, and a paneling strength of less than 0.150 MPa was marked with ×.

  The results are shown in Table 3. In all of the examples of the present invention, HR30T exceeds 64, the C-direction Young's modulus is 230 GPa or more, and the moldability and the buckling resistance as a can body are excellent. On the other hand, in the comparative example, any one or more of the above characteristics are inferior.

Claims (4)

In mass%, C: more than 0.0030% and 0.0100% or less, Si: 0.05% or less, Mn: 0.10% or more and 1.00% or less, P: 0.030% or less, S: 0.00. 020% or less, Al: 0.010% or more and 0.100% or less, N: 0.0050% or less, Nb: 0.010% or more and 0.080% or less, and the content of C and Nb is the following formula (1) is satisfied, and the balance has a component composition consisting of Fe and inevitable impurities,
A steel plate for cans having an HR30T hardness of more than 64 and a Young's modulus in the direction perpendicular to the rolling of 230 GPa or more.
0.15 ≦ ([Nb] /92.9) / ([C] / 12) ≦ 1.50 (1)
In the formula (1), [Nb] and [C] are the contents (mass%) of Nb and C, respectively.   Furthermore, the steel plate for cans according to claim 1, wherein elongation in the direction perpendicular to rolling is 10% or more.   The steel sheet for cans according to claim 1 or 2, wherein the steel structure contains a ferrite phase and has an average ferrite grain size of 7.0 µm or less.   It is a manufacturing method of the steel plate for cans in any one of Claims 1-3, Comprising: The steel slab which has the component composition of Claim 1 is heated with the heating temperature of 1100 degreeC or more, Hot-rolling finishing temperature is 850 degreeC or more. After hot rolling at 950 ° C. or less, winding at a coiling temperature of 500 ° C. or more and 700 ° C. or less, primary cold rolling at a reduction rate of 85% or more, annealing at an annealing temperature of 700 ° C. or more and 800 ° C. or less, and a reduction rate of 6 A method for producing a steel plate for cans, characterized in that secondary cold rolling is performed at more than 0% and not more than 20%.