JP2017119918A - Steel sheet for can and method for producing thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel sheet for a can excellent in buckling strength of the can body part to an external pressure, and a method for producing thereof.SOLUTION: The steel sheet for a can comprises, 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: 0.010% or less, S: 0.010% or less, Al: 0.010% or more and 0.100% or less, N: 0.0010% or more and 0.0050% or less, and Nb: 0.020% or more and 0.120% or less, wherein C and Nb contents satisfy 2.1≤(Nb/C)×(12/93)≤2.5...(1)(Nb and C represent each content (mass%)), with the balance composed of Fe and inevitable impurities, and has Young's moduli in a rolling direction and in a 90° direction from the rolling direction of 220 GPa or more, and a tempering degree of T3-T4.SELECTED DRAWING: None

Description

  The present invention relates to a steel plate for cans used as a container material for foods and beverages and a method for producing the same, and in particular, a steel plate for cans excellent in buckling strength of a can body against an external pressure when used in cans and the same. It relates to a manufacturing method.

  From the viewpoint of reducing environmental impact and cost in recent years, there is a need to reduce the amount of steel sheets used in food and beverage cans, and thinning of steel sheets is progressing regardless of 2-piece or 3-piece cans. ing. Along with this, deformation of the can body due to external forces acting during can manufacturing, transportation processes and handling in the market, deformation of the can body due to increase or decrease in pressure inside the can during processing of heat sterilization of the contents (buckling) is regarded as a problem Has been.

  Conventionally, the strength of steel sheets has been increased in order to improve the deformation resistance. However, when the strength (YP) is increased by increasing the strength of the steel sheet, the effect of springback is increased, so that the roll foam property is lowered, which causes a problem in the can manufacturing process. In addition, increasing the strength of the steel sheet increases the incidence of neck wrinkles and flange cracks in necking performed after can body part forming and then flange forming performed. Thus, increasing the strength of a steel sheet is not necessarily an appropriate method for compensating for the deterioration of deformation resistance associated with the thinning of the steel sheet.

  On the other hand, the buckling phenomenon of the can body portion is caused by the deterioration of the rigidity of the can body due to the thinning of the plate thickness of the can body portion. Therefore, in order to improve the buckling resistance (paneling strength), a method of optimizing the size and design of the can body and increasing the rigidity of the can body can be considered. As a method for improving the rigidity, a method for increasing the Young's modulus of the steel sheet itself can be considered.

  There is a strong correlation between the Young's modulus of iron and the crystal orientation, and the crystal orientation group (α fiber) whose <110> direction is parallel to the rolling direction increases the Young's modulus in the width direction, which is 90 ° with respect to the rolling direction. By increasing the accumulation of {112} <110> orientation, a steel sheet having a Young's modulus of about 280 GPa can be obtained. In addition, the crystal orientation group (γ fiber) in which the <111> direction is parallel to the normal direction of the plate surface can increase the Young's modulus in the 90 ° direction from the rolling direction and the rolling direction to about 230 GPa. On the other hand, when the crystal orientation of the steel sheet does not show an orientation in a specific orientation, that is, the Young's modulus of the steel sheet with a random texture is about 205 GPa.

  As an example of a steel plate for cans oriented to a high Young's modulus, for example, Patent Document 1 can be mentioned. In Patent Document 1, after cold rolling annealing of ultra-low carbon steel, secondary cold rolling of 50% or more is performed to form a strong rolling texture (α fiber), and the Young's modulus in the 90 ° direction from the rolling direction is increased. Discloses a method for increasing the rigidity of a steel sheet.

  In Patent Document 2, a steel sheet is stiffened by cold rolling a hot rolled sheet of ultra-low carbon steel at a rolling rate of 60% or more, forming a strong rolling texture, and increasing the Young's modulus in the 90 ° direction from the rolling direction. The manufacturing method of the steel plate which does not perform annealing while enabling thinning of the container original plate is disclosed.

Patent Document 3 describes that ultra-low carbon steel is hot-rolled at least 50% at a temperature below the Ar ₃ transformation point, pickled, cold-rolled at 50% or more, and then recrystallized at 400 ° C or more. A method for increasing the Young's modulus in the 90 ° direction from the rolling direction and increasing the rigidity of the steel sheet by annealing at a temperature lower than the temperature is disclosed. The recrystallization temperature refers to a temperature at which the recrystallization rate becomes 10%.

JP-A-6-212353 JP-A-6-248332 JP-A-6-248339

  However, all of the above conventional techniques have problems.

  For example, since Patent Document 1 performs secondary cold rolling, which is an additional process, there is a problem that the number of processes increases and the manufacturing cost increases. Furthermore, a high rolling reduction rate of 50% or more of the secondary cold rolling reduction rate is not realistic in actual operation.

  Patent Document 2 is a method of enhancing the Young's modulus in the 90 ° direction from the rolling direction by strengthening the accumulation in the rolling texture by not annealing at all after cold rolling. However, since the strength is too high and the ductility is low in the raw material as it is cold-rolled, roll formability, neck workability and flange formability are deteriorated.

  Patent Document 3 performs hot rolling at least 50% or more at a temperature below the Ar3 transformation point. Therefore, the edge portion having a higher cooling rate than the center portion tends to have a lower temperature during finish rolling, and during finish rolling. There is a tendency that the introduced strain is not released by recrystallization or recovery and the strength of the edge portion is increased. For this reason, the difference in strength between the center portion and the edge portion becomes large, and it is difficult to obtain a uniform hot-rolled sheet in the width direction, so it is difficult to obtain a uniform one in the current operation. Further, after cold rolling, a method of increasing the Young's modulus in the 90 ° direction from the rolling direction by annealing at 400 ° C. or higher and below the recrystallization temperature to enhance the accumulation in the rolling texture is disclosed. When annealing is performed at a temperature lower than that, there is a problem that a cold-rolled structure, a recovery structure, and a recrystallized structure are mixed, and mechanical property values such as strength and ductility become uneven in the steel sheet.

  That is, without adding a secondary cold rolling process that increases the cost as a manufacturing method to increase the Young's modulus of the steel sheet for the purpose of improving the can body rigidity, or without performing an annealing process at a recrystallization temperature or less that makes the material non-uniform, There has been no high Young's modulus steel plate obtained by the current method for manufacturing steel plates for cans and no technology aimed at the manufacturing method.

  This invention is made | formed in view of this situation, and it aims at providing the steel plate for cans excellent in the buckling strength of the can trunk | drum with respect to the external pressure at the time of using for a can, and its manufacturing method.

The inventors of the present invention have intensively studied to solve the above problems. As a result, the following knowledge was obtained.
By optimizing chemical composition, cold rolling conditions and annealing conditions based on semi- extra low carbon steel, Young's modulus in the rolling direction and / or 90 ° direction from the rolling direction is 220 GPa or more, and the tempering degree is T3 It has been found that it is feasible to produce a steel plate for cans of ~ T4.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] By 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% or less, S: 0.020% or less, Al: 0.010% or more, 0.100% Below, 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 consists of Fe and inevitable impurities, rolling A steel plate for cans, wherein the Young's modulus in the 90 ° direction from the direction and / or the rolling direction is 220 GPa or more, and the tempering degree is T3 to T4.
0.4 ≦ (Nb / C) × (12/93) ≦ 2.5 (1)
However, Nb and C show content (mass%).
[2] By 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% or less, S: 0.020% or less, Al: 0.010% or more, 0.100% N: 0.0010% or more and 0.0030% or less, Nb: 0.020% or more and 0.120% or less, B: At least one selected from 0.0005% or more and 0.0070% or less, and the contents of C and Nb Satisfies the following formula (1), the contents of N and B satisfy the following formula (2), the balance consists of Fe and inevitable impurities, and the Young's modulus in the rolling direction and / or 90 ° direction from the rolling direction Is over 220GPa,
A steel sheet for cans characterized by a tempering degree of T3 to T4.
0.4 ≦ (Nb / C) × (12/93) ≦ 2.5 (1)
1.0 ≦ (B / N) × (14/11) ≦ 3.5 (2)
However, Nb, C, B, N shows content (mass%).
[3] A steel slab having the chemical composition described in [1] or [2] above is hot-rolled, pickled, and then cold-rolled at a rolling rate of 85% or higher, and subsequently at a recrystallization temperature or higher. A method for producing a steel plate for cans, comprising annealing at a temperature of 780 ° C or lower and then performing temper rolling.
In addition, in this specification,% which shows the component of steel is mass% altogether.

ADVANTAGE OF THE INVENTION According to this invention, the steel plate for cans excellent in the buckling strength of the can trunk | drum with respect to the external pressure at the time of using for a can is obtained. In other words, a steel plate for cans is obtained in which the buckling strength of the can body with respect to external pressure is higher than a reference value (about 1.5 kgf / cm ² ) provided by the can and beverage manufacturers.
Therefore, by using the steel plate for cans of the present invention, the rigidity of the can used for food cans, beverage cans, etc. is improved, the steel plate can be made thinner, and resource saving and cost reduction are achieved. can do.
Moreover, the steel plate of this invention can be used suitably as a steel plate for 3 piece cans. Moreover, the application range of the steel plate of the present invention can be expected to be applied not only to various metal cans but also to a wide range of can battery interior cans, various home appliances / electrical parts, automotive parts and the like.

Hereinafter, the present invention will be described in detail.
The steel plate for cans of the present invention has a component composition of 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% or less, 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), and the balance is Fe And the inevitable impurities, the Young's modulus in the rolling direction and / or 90 ° direction from the rolling direction is 220 GPa or more, and the tempering degree is T3 to T4. Or, 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% or less, S: 0.020% or less, Al: 0.010% or more and 0.100% or less , N: 0.0010% or more and 0.0030% or less, Nb: 0.020% or more and 0.120% or less, B: 0.0005% or more and 0.0070% or less, at least one selected from C, Nb content The following formula (1) is satisfied, the contents of N and B satisfy the following formula (2), the balance is composed of Fe and inevitable impurities, and the Young's modulus in the rolling direction and / or 90 ° direction from the rolling direction is It is 220 GPa or more, and the tempering degree is T3 to T4.
And such a steel plate for cans is hot-rolled to a steel slab having the above component composition, pickled, then cold-rolled at a rolling rate of 85% or higher, and then at a recrystallization temperature of 780 ° C. or higher. It can be manufactured by annealing at a temperature and temper rolling. These are the most important requirements of the present invention.
0.4 ≦ (Nb / C) × (12/93) ≦ 2.5 (1)
1.0 ≦ (B / N) × (14/11) ≦ 3.5 (2)
However, Nb, C, B, N shows content (mass%).

The component composition of the steel plate for cans of this invention is demonstrated.
C: 0.0050% to 0.0100%, Nb: 0.020% to 0.120%
C and Nb are elements having the most important role in the present invention. Grain boundaries of hot-rolled sheets become the nucleation sites of γ-fiber recrystallized grains during recrystallization annealing because of the effect of suppressing recrystallization of γ grains by solute Nb during hot rolling The area increases. As a result, γ fibers develop, and the Young's modulus can be increased in the rolling direction, 45 ° from the rolling direction, and 90 ° from the rolling direction.
Further, the steel sheet can be hardened by utilizing the refinement of the steel sheet structure and precipitation strengthening by increasing the amount of precipitates of NbC.
And C is 0.0050% or more and 0.0100% or less, Nb is 0.020% or more and 0.120% or less, so that the Young's modulus of 90 ° from the rolling direction and / or rolling direction is 220 GPa or more and the tempering degree is T3 to T4. A steel plate can be obtained.
If C is less than 0.0050%, the precipitation amount of NbC decreases, and the effect of refinement of the steel sheet structure and precipitation strengthening cannot be obtained sufficiently, and the desired tempering degree cannot be obtained. If C exceeds 0.0100%, C dissolves in the ferrite, the matrix becomes excessively hard, and formability deteriorates. Further, if Nb is less than 0.020%, the hot rolled plate crystal grains cannot be sufficiently refined. If Nb exceeds 0.120%, the recrystallization completion temperature is excessively raised, and it becomes difficult to industrially produce steel plates for cans, especially those with many thin materials, in a continuous annealing process or the like.
Furthermore, in this invention, content of C and Nb shall satisfy following formula (1).
0.4 ≦ (Nb / C) × (12/93) ≦ 2.5 (1)
However, Nb and C show content (mass%).
If (Nb / C) × (12/93) is less than 0.4, the effect of fine graining and precipitation strengthening by NbC is insufficient, and the desired tempering degree cannot be obtained. If (Nb / C) x (12/93) exceeds 2.5, the recrystallization delay due to the solute drag effect of solute Nb becomes excessive, making it difficult to manufacture and reducing the pinning effect due to the coarsening of NbC. The ferrite grain size becomes coarse and the effect of grain refinement cannot be obtained.

Si: 0.050% or less
When Si is added in a large amount, problems such as deterioration of the surface treatment property of the steel sheet and a decrease in corrosion resistance occur, so 0.050% or less, preferably 0.020% or less.

Mn: 0.10% to 1.00%
Mn needs to be added in an amount of 0.10% or more in order to prevent a decrease in hot ductility due to the impurity S contained in the steel. In addition, Mn is one of the elements that lowers the Ar ₃ transformation point, and can reduce the hot rolling finish rolling temperature, thereby suppressing the recrystallized grain growth of γ grains during hot rolling, and further after transformation Α grains can be refined. On the other hand, Mn interacts with solute C to affect the formation of recrystallized texture, and has the effect of reducing accumulation in γ-fiber as the amount of Mn added increases. Therefore, considering these, the content is made 1.00% or less. If Mn exceeds 1.00%, the Young's modulus in the 90 ° direction from the rolling direction is less than 220 GPa, and the steel sheet is excessively hardened, resulting in deterioration in can-making characteristics such as roll formability. Therefore, Mn is set to 0.10% or more and 1.00% or less.

P: 0.030% or less
When P is added in a large amount, it causes hardening of the steel and deterioration of corrosion resistance. Therefore, the upper limit of P is 0.030%.

S: 0.020% or less
S combines with Mn in steel to form MnS and precipitate a large amount, thereby reducing the hot ductility of the steel. Therefore, S is set to 0.020% or less.

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 solute N in the steel. However, when the Al content is less than 0.010%, a sufficient deoxidizing effect or a solid solution N reducing effect cannot be obtained. On the other hand, if it exceeds 0.100%, not only is the above effect saturated, but also inclusions such as alumina increase, which is not preferable. Therefore, Al is made 0.010% or more and 0.100% or less.

N: 0.0010% to 0.0050%, B: 0.0005% to 0.0070%
N is preferably as small as possible because it combines with Al, Nb, or the like to form nitrides or carbonitrides and impairs hot ductility. N is one of the solid solution strengthening elements, and when added in a large amount, it leads to hardening of the steel sheet, and the elongation is remarkably lowered to deteriorate the formability. On the other hand, it is difficult to stabilize the operation to less than 0.0010%, and the manufacturing cost increases. Therefore, N is set to be 0.0010% or more and 0.0050% or less. Further, the upper limit of N in the case of adding B is set to 0.0030% in order to efficiently obtain the effect of solid solution B after being precipitated as BN as described below.
N and B are elements having an important role in the present invention, like C and Nb. When B is added in an amount more than necessary for the precipitation of BN, excessively added B during hot rolling segregates as a solid solution B at the grain boundary and suppresses grain growth of the crystal grain. Due to the effect of suppressing the recrystallization of the grains, the crystal grains of the hot-rolled sheet become finer, and the crystal grain interface area of the hot-rolled sheet that becomes the nucleation site of the γ-fiber recrystallized grains during the recrystallization annealing increases. As a result, γ fibers develop, and the Young's modulus can be increased in the rolling direction, 45 ° from the rolling direction, and 90 ° from the rolling direction. In order to exert such a refinement effect of crystal grains, it is necessary to precipitate BN and further to have B as a solid solution B. Results of various tests conducted by the present inventors From this, it was found that B is required to be 0.0005% or more. From the above, in the present invention, 0.0005% is set as the lower limit of B. On the other hand, the increase in solid solution B excessively raises the recrystallization completion temperature in the continuous annealing process, and the risk of occurrence of in-furnace breakage and buckling increases. For this reason, 0.0070% is made the upper limit of B. N is an irreversible impurity. The higher the amount of N, the more B should be added to fix it. Since a significant increase in the amount of B added leads to an increase in cost, the upper limit of N is set to 0.0030%.
Furthermore, in this invention, content of N and B shall satisfy following formula (2).
1.0 ≦ (B / N) × (14/11) ≦ 3.5 (2)
However, if B and N indicate the content (mass%) (B / N) × (14/11) is less than 1.0, the effect of refining hot-rolled sheet by solid solution B is insufficient, (B If / N) × (14/11) exceeds 3.5, the recrystallization delay due to the solid solution B becomes excessive, and the production becomes difficult.

  The balance is Fe and inevitable impurities.

Next, the mechanical properties of the steel plate for cans of the present invention will be described.
In the container in which the roll foam is applied so that the Young's modulus in the rolling direction and / or the 90 ° direction from the rolling direction is 220 GPa or more and the 90 ° direction from the rolling direction is the circumferential direction of the can body portion, From the viewpoint of increasing rigidity, the Young's modulus in the rolling direction and / or 90 ° direction from the rolling direction is set to 220 GPa or more. By setting it to 220 GPa or more, the paneling strength is remarkably improved, and buckling deformation of the can body due to increase / decrease of pressure outside the can in the heat sterilization treatment of the contents accompanying thinning of the steel plate can be prevented. Either the rolling direction only, the 90 ° direction from the rolling direction, or both the rolling direction and the 90 ° direction from the rolling direction may be 220 GPa or more, but the direction with the highest Young's modulus is the circumference of the can body part. It is preferable to apply the roll form so that it is in the direction.
The Young's modulus in the rolling direction and / or 90 ° direction from the rolling direction can be measured by a transverse vibration type resonance frequency measuring device.

Tempering degree is T3 ~ T4
Buckling deformation of the can body due to increase or decrease in pressure outside the can during processing such as heat sterilization of the contents can be prevented by increasing the Young's modulus of the steel sheet. However, it is necessary to harden the steel plate in order to prevent plastic deformation due to dropping of the can, contact with the conveying device in the vending machine, and stacking of the cans. On the other hand, excessive hardening significantly reduces can-making characteristics such as roll foam properties. From the above, the refining degree is T3 to T4. In the present invention, the tempering degree T3 to T4 is an index indicating the hardness of tin or tin-free steel used as a steel plate for cans. In JIS G3303 and JIS G3315, Rockwell hardness (HR30T) is used. T3 is defined as 57 ± 3 and T4 is defined as 61 ± 3.

Next, the manufacturing method of the steel plate for cans of this invention is demonstrated.
The steel plate for cans of the present invention is a steel slab having the above composition, hot-rolled, pickled, cold-rolled at a rolling rate of 85% or higher, and subsequently at a recrystallization temperature of 780 ° C. or lower. Manufactured by annealing and temper rolling.

  It can be melted by a generally known melting method using a converter or the like. Moreover, it can be set as a rolling raw material with the casting methods used normally, such as a continuous casting method. At this time, the slab reheating temperature is preferably 1050 to 1300 ° C. If the heating temperature is too high, problems such as defects on the product surface and increased energy costs may occur. On the other hand, if it is too low, it will be difficult to ensure the final finish rolling temperature.

Hot finish rolling temperature: 860-950 ° C, winding temperature 500-640 ° C (preferred conditions)
From the viewpoint of grain refinement of the hot-rolled steel sheet and uniformity of precipitate distribution, the final finishing rolling temperature is preferably in the range of 860 to 950 ° C and the winding temperature is in the range of 500 to 640 ° C. When the final finish rolling temperature is higher than 950 ° C., γ grain growth after rolling occurs more violently, and the accompanying coarse γ grains may cause coarsening of the α grains after transformation. On the other hand, when the temperature is lower than 860 ° C., the rolling becomes below the Ar3 transformation point, which may lead to coarsening of α grains. When the coiling temperature is higher than 640 ° C, the amount of precipitation of Nb-based precipitates increases, but the precipitate particle size becomes coarse, and the pinning effect of the precipitate is reduced and the α particle size becomes coarse. is there. In addition, in the temperature range lower than 500 ° C., the amount of Nb-based precipitates decreases, so that the α phase may not be refined due to the pinning effect.
More preferably, the final finishing rolling temperature is in the range of 860 to 930 ° C, and the winding temperature is in the range of 500 to 600 ° C.
The subsequent pickling process is not particularly limited as long as the surface scale can be removed. Pickling can be performed by a commonly performed method.

Next, cold rolling, annealing, and temper rolling are performed.
Rolling ratio: 85% or more The rolling ratio of cold rolling is 85% or more in order to achieve the tempering degree defined by the present invention. If it is less than 85%, the crystal grains become coarse and the material softens. By storing a large amount of strain energy in the steel sheet at a rolling rate of 85% or more, Nb remaining in solid solution without precipitation during hot rolling is used as the precipitation site, and fine at many sites during annealing in the next process. Nb-based precipitates can be deposited to achieve crystal grain refinement by the pinning effect.
Annealing temperature: Recrystallization temperature or higher and 780 ° C. or lower An annealing method is preferably a continuous annealing method from the viewpoint of material uniformity and high productivity. The annealing temperature in continuous annealing must be higher than the recrystallization temperature, but if the annealing temperature is too high, the crystal grains become coarse and the material becomes soft, and in the case of thin materials such as steel plates for cans, The risk of breakage and buckling increases. For this reason, the upper limit of annealing temperature shall be 780 degreeC.
Temper rolling elongation: 0.5 to 5% (preferred conditions)
The elongation ratio of temper rolling is appropriately determined depending on the tempering degree of the steel sheet, but it is preferable to perform rolling at an elongation ratio of 0.5% or more in order to suppress the occurrence of stretcher strain. On the other hand, if rolling is performed at an elongation rate exceeding 5%, the workability and elongation decrease due to the steel plate becoming hard. Therefore, the upper limit is preferably 5%.

  By the above, the steel plate for cans of this invention is obtained.

A steel slab was obtained by melting steel containing the component compositions A to P shown in Table 1 and the balance being Fe and inevitable impurities. The obtained steel slab was reheated at 1250 ° C., and then hot rolled at a hot finish rolling temperature of 900 to 920 ° C. and a winding temperature of 580 ° C. Next, after pickling, cold rolling was performed at a rolling rate of 84 to 92.5% to produce a 0.18 mm thin steel plate. The obtained thin steel sheet was annealed at an annealing temperature of 740 to 790 ° C. and an annealing time of 30 seconds in a continuous annealing furnace, and temper rolled at an elongation of 1.5%. Detailed production conditions are shown in Table 2.
Characteristic evaluation was performed by the following method with respect to the steel plate obtained from the above.

  The Young's modulus was evaluated by cutting out a 10 x 35 mm test piece in the rolling direction and 90 ° direction from the rolling direction, and using a transverse vibration type resonance frequency measuring device. ), Young's modulus (GPa) was measured.

  As for Rockwell hardness (HR30T), Rockwell 30T hardness (HR30T) at a position specified in JIS G3315 was measured according to the Rockwell hardness test method of JIS Z2245. The tempering degree T3 is 57 ± 3, and the tempering degree T4 is 61 ± 3.

Furthermore, in order to evaluate the can body characteristics after can manufacturing, 3 piece can molding was performed with respect to the steel plate. The molding method is such that the direction with the higher Young's modulus is the circumferential direction of the can body part among the rolling direction and the 90 ° direction from the rolling direction so that the shape after molding is 52 mm in diameter and the length of the can body is 96 mm. A rectangular plate was rolled and the ends were joined by welding.
The measuring method of the external pressure strength is as follows. The can body was placed inside the pressurizing chamber, and pressurization inside the pressurizing chamber was performed by introducing pressurized air into the chamber at 0.016 MPa / s via an air introduction valve. The pressure inside the 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 critical buckling pressure, that is, the external pressure strength, was the pressure at the pressure change point accompanying buckling. Generally, it is said that the external pressure strength should be 1.5 kgf / cm ² or more with respect to the pressure change caused by the heat sterilization treatment. From this, a single circle (○) indicates that the external pressure strength is 1.5 kgf / cm ² or more (0.147 MPa or more), and a cross indicates that the external pressure strength is less than 1.5 kgf / cm ² (0.147 MPa). .

  The results obtained as described above are shown in Table 2 together with the production conditions.

In the example of the present invention, the refining degree is T3 to T4, and the Young's modulus is 220 GPa or more in both the rolling direction and the 90 ° direction from the rolling direction, and the external pressure strength is excellent.
On the other hand, in the comparative example, any one or more of the above characteristics are inferior. In Table 2, since Experiments Nos. 7, 18, and 28 were not recrystallized, the steel sheet characteristics evaluation and the can body characteristics survey were not performed.

Claims (2)

% By mass, C: 0.0050% or more and 0.0100% or less,
Si: 0.050% or less,
Mn: 0.10% to 1.00%,
P: 0.010% or less,
S: 0.010% 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), and the balance consists of Fe and inevitable impurities,
Young's modulus in the rolling direction and 90 ° direction from the rolling direction is 220 GPa or more,
A steel sheet for cans characterized by a tempering degree of T3 to T4.
2.1 ≦ (Nb / C) × (12/93) ≦ 2.5 (1)
However, Nb and C show content (mass%).   The method for producing a steel plate for can according to claim 1, wherein the steel slab is hot-rolled, pickled, and then cold-rolled at a rolling rate of 85% or more, and subsequently at a recrystallization temperature of 780 ° C or higher. The manufacturing method of the steel plate for cans characterized by performing annealing at the following temperatures and then performing temper rolling.