JP2016160438A - Steel sheet for can and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel sheet for can hardly generating buckling deformation of a can body part and excellent in mechanical strength of a can bottom part even when sheet thickness is ultrathin and a manufacturing method therefor.SOLUTION: A steel sheet contains, by mass%, C:0.0100% or less, Si:0.01 to 0.10%, Mn:0.10 to 1.00%, P:0.020% or less, N:0.0050% or less, S:0.03% or less, Al:0.02 to 0.10% and further Nb:0.01 to 0.10% and/or Ti:0.01 to 0.20% and the balance Fe with inevitable impurities and has a ferrite structure, an aspect ratio of a ferrite crystal particle of 1.1 to 2.0, a ratio of integration degree of (001)<1-10> direction to (integration degree of (111)<1-10> direction+integration degree of (111)<-1-12> direction) of 0.30 or less, an average Young rate of 210 GPa or more, a Rockwell hardness of 50 or more and |Δr| of 0.50 or less.SELECTED DRAWING: Figure 1

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.

  In recent years, thinning of steel plates for steel cans has been promoted from the viewpoint of reducing the cost of steel cans. Development of steel plate with improved can body paneling strength to prevent deformation and buckling of can body due to increased pressure applied from outside of can during heat sterilization treatment of contents while reducing plate thickness Is required.

  Since buckling of cans occurs due to elastic deformation, it has been conventionally thought that buckling can be avoided by increasing the Young's modulus of the material and improving the can paneling strength.

  For example, in Patent Document 1, a hot-rolled sheet of ultra-low carbon steel is cold-rolled at a rolling rate of 85% or more, annealed at a recrystallization temperature of 780 ° C. or less to form a strong texture, and rolled. A method of improving the buckling strength (paneling strength) of the can body by increasing the Young's modulus in the direction of 90 ° from the direction and the rolling direction is disclosed.

  Further, in Patent Document 2, a hot rolled sheet of ultra-low carbon steel is cold-rolled at a rolling rate of 87% or more to form a strong texture, and in the 0 °, 45 °, and 90 ° directions with respect to the rolling direction. A method for increasing the buckling strength (paneling strength) of the can body by increasing the Young's modulus is disclosed.

JP 2013-139626 A JP 2012-233255 A

  However, the steel sheet obtained by the technique described in Patent Document 1 tends to have large anisotropy, and the circumferential thickness distribution of the can body becomes uneven, and the can body is broken during drawing. There was a problem that it became easy to torso.

  Moreover, the steel plate obtained by the technique described in Patent Document 2 is not considered for ensuring the strength when thinned. This steel plate uses soft ultra-low carbon steel, and when the plate thickness is thin, the strength of the bottom of the can decreases, so that the can may be deformed and broken during transportation.

  Therefore, the present invention has been made to solve the above-described problems, and even for a can having a high can bottom mechanical strength at the bottom of the can body, even when the plate thickness is extremely thin. It aims at providing a steel plate and its manufacturing method.

  In order to achieve the above object, the present inventors have noted that it is not sufficient to increase the Young's modulus of the steel sheet. It was also noted that the anisotropy generated during molding is desirably as small as possible. As the anisotropy increases, | Δr | increases and the can height in the can circumferential direction after molding becomes uneven. Therefore, the plate thickness of the can body becomes uneven, the paneling strength decreases, and the seat Bends easily. In addition, ultra-low carbon steel is soft because of its low carbon content, especially when the plate thickness is thin, the mechanical strength of the bottom of the can is low, and even if the paneling strength is high, the can may be deformed and damaged. I also focused on that.

  From the above, component composition of Ti and Nb addition, finishing temperature in hot rolling, coiling temperature, rolling reduction of cold rolling, line tension during cold rolling, annealing temperature, rolling reduction of temper rolling are optimized. As a result, it was found that the can body part is less likely to buckle and deform, and a steel plate having a high mechanical strength at the bottom part of the can can be manufactured, and the present invention has been completed. The gist of the present invention is as follows.

[1] By mass%
C: 0.0100% or less, Si: 0.01 to 0.10%, Mn: 0.10 to 1.00%, P: 0.020% or less, N: 0.0050% or less, S: 0.00. Containing not more than 03%, Al: 0.02-0.10%,
Furthermore, Nb: 0.01 to 0.10% and / or Ti: 0.01 to 0.20%, the balance is a steel plate for cans made of Fe and inevitable impurities,
Having a ferrite structure,
The aspect ratio of the ferrite crystal grain size is 1.1 to 2.0,
Accumulation of (001) <1-10> orientation with respect to (accumulation degree of (111) <1-10> orientation + integration degree of (111) <-1-12> orientation) expressed by the following formula (1): Degree ratio (f) is 0.30 or less,
The average Young's modulus (E _ave ) represented by the following formula (2) is 210 GPa or more,
Rockwell hardness (HR30T) is 50 or more,
A steel plate for a can, wherein | Δr | represented by the following formula (3) is 0.50 or less.

Ｅ_ａｖｅ＝（Ｅ_０＋Ｅ_９０＋２Ｅ_４５）／４ ・・・（２）
ここで、Ｅ_０、Ｅ_９０、Ｅ_４５：圧延方向に対してそれぞれ０°、４５°、９０°方向のヤング率である。
｜Δｒ｜＝｜（ｒ_０＋ｒ_９０−２ｒ_４５）／２｜ ・・・（３）
ここで、ｒ_０、ｒ_９０、ｒ_４５：圧延方向に対してそれぞれ０°、４５°、９０°方向のランクフォード値である。

E _ave = (E ₀ + E ₉₀ + 2E ₄₅ ) / 4 (2)
Here, E ₀ , E ₉₀ , E ₄₅ : Young's moduli of 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively.
| Δr | = | (r ₀ + r ₉₀ −2r ₄₅ ) / 2 | (3)
Here, r ₀ , r ₉₀ , r ₄₅ : Rankford values in 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively.

  [2] The ferrite average crystal grain size is 3.0 to 15.0 μm, the average Young's modulus is 215 GPa or more, and the | Δr | is 0.40 or less. Steel plate for cans.

  [3] The steel plate for cans according to [1] or [2], wherein the plate thickness is 0.300 mm or less.

[4] A method for producing a steel plate for cans according to any one of [1] to [3], wherein the steel slab is hot-rolled at a finishing temperature of 840 ° C. or higher, and at a winding temperature of 500 ° C. or higher. Winding, pickling, rolling reduction: 80% or more, maximum value of line tension: cold rolling at 20 kg / mm ² or less, annealing at a temperature of 790 ° C. or less, 0.6 to 6.0% A method for producing a steel plate for cans, characterized by performing temper rolling at a rolling reduction.

  According to the present invention, even when the plate thickness is extremely thin, the can body portion is unlikely to buckle and the can bottom portion can have high mechanical strength.

It is a graph which shows the relationship between the aspect-ratio of a crystal grain, and | (DELTA) r |. It is a graph which shows the relationship between the aspect-ratio of a crystal grain, and an average Young's modulus.

The steel plate for cans according to the present invention is in mass%, C: 0.0100% or less, Si: 0.01 to 0.10%, Mn: 0.10 to 1.00%, P: 0.020% or less. N: 0.0050% or less, S: 0.03% or less, Al: 0.02-0.10%, and Nb: 0.01-0.10% and / or Ti: 0.0. Containing 0.1 to 0.20%, with the balance being a component composition consisting of Fe and inevitable impurities, having a ferrite structure, and the ferrite crystal grains having an aspect ratio of 1.1 to 2.0, (( 111) <11-0> orientation integration degree + (111) <-1-12> orientation integration degree)) (001) <1-10> orientation integration ratio (f) is 0.30 or less, mean Young's modulus _{(E ave) (= (E} 0 + E 90 + 2E 45) / 4) is more than 210 GPa, Rock E le hardness (HR30T) of 50 or _{more, | Δr | (= | (} r 0 + r 90 -2r 45) / 2 |) is 0.50 or less. Hereinafter, the steel plate for cans of the present invention will be described.

<C: 0.0100% or less>
In order to develop a crystal orientation that is advantageous for increasing the Young's modulus of a steel sheet, the C content is reduced, and C is fixed as a carbide (NbC or TiC) with Nb or Ti to reduce the amount of dissolved C. Is effective. If the C content exceeds 0.0100%, the development of the texture is suppressed and a high Young's modulus cannot be obtained, so the C content is set to 0.0100% or less. In order to secure the paneling strength of the can body portion of the steel plate and the mechanical strength of the bottom portion of the can, the C content is preferably 0.0020% or more.

<Si: 0.01-0.10%>
Si is an element having an effect of increasing the hardness of the steel sheet by solid solution strengthening. In order to stably secure the tensile strength, Si needs to be contained by 0.01% or more. On the other hand, since Si is an element that deteriorates the corrosion resistance of the steel plate for cans, the upper limit of the Si content is 0.10%.

<Mn: 0.10 to 1.00%>
Mn is an element having an effect of increasing the hardness of the steel sheet by solid solution strengthening. Mn needs to be contained in an amount of 0.10% or more in order to ensure the tensile strength stably and to refine the ferrite grains. On the other hand, if the Mn content increases, the cost of the raw material increases, so the upper limit of the Mn content is 1.00%. However, since the upper limit of Mn of the tin plate used for the food container is defined as 0.60% or less, when used as a food container, the Mn content is preferably 0.60% or less.

<P: 0.020% or less>
P segregates at the grain boundaries and lowers the ductility and toughness of the steel sheet. It is also a harmful element that reduces corrosion resistance. Therefore, the upper limit of the P content is 0.020%. On the other hand, P is an element having an effect of increasing the hardness of the steel sheet by solid solution strengthening. Therefore, the lower limit of the P content is preferably 0.010%.

<N: 0.0050% or less>
When N is contained in a large amount, excess nitride is generated, and the ductility and toughness of the steel sheet are lowered. Moreover, workability is deteriorated. Therefore, the upper limit of the N content is 0.0050%.

<S: 0.03% or less>
S combines with Mn to form coarse MnS, deteriorates the surface properties and lowers the ductility in hot rolling, so the upper limit of the S content is 0.03%.

<Al: 0.02-0.10%>
Al is a useful element that acts as a deoxidizer, and in order to obtain the effect, it is necessary to contain 0.02% or more. On the other hand, if the Al content exceeds 0.10%, surface defects of the steel sheet are induced, so the upper limit of the Al content is 0.10%.

<Nb: 0.01 to 0.10% and / or Ti: 0.01 to 0.20%>
Nb combines with C, precipitates as carbide NbC, fixes a part of the solid solution C present in the steel, develops the texture of the steel sheet, improves Young's modulus, and reduces the absolute value of the r value Contribute. Nb fine carbonitride is effective in increasing hardness. In order to acquire this effect, when it contains Nb, the content needs to be 0.01% or more. On the other hand, if the Nb content exceeds 0.10%, not only the cost of the alloy increases, but also the recrystallization end temperature rises and the texture does not develop. Moreover, since the rolling load is increased, it is difficult to produce a stable steel sheet. Therefore, when Nb is contained, the Nb content is limited to a range of 0.01 to 0.10%.

  Ti, like Nb, binds with C, precipitates as carbide TiC, fixes a part of solid solution C present in the steel, develops a texture of the steel sheet, improves Young's modulus, and increases r value. Contributes to reduction of absolute value. Further, the fine carbonitride of Ti is effective in increasing the hardness. In order to acquire this effect, when it contains Ti, the content needs to be 0.01% or more. On the other hand, if the Ti content exceeds 0.20%, not only the cost of the alloy increases, but also the recrystallization end temperature rises and the texture does not develop. Moreover, since the rolling load is increased, it is difficult to produce a stable steel sheet. Therefore, when Ti is contained, the Ti content is limited to a range of 0.01 to 0.20%.

  The balance other than the above-described components is Fe and inevitable impurities.

  The steel plate for cans of the present invention has a structure having ferrite as a main phase. Moreover, the steel plate for cans of this invention can have a pearlite, a martensite, a bainite, and a cementite in a total amount 5 area% or less in a steel plate other than a ferrite. For the structure, take a structure photograph of the thickness cross section parallel to the rolling direction of the steel sheet, extract the desired region by image analysis in the obtained structure photograph data, and use commercially available image analysis software to check the dark contrast The area to have is determined to be ferrite, and the other area is determined to be pearlite, martensite, bainite or cementite.

  As described above, the component composition range of the steel sheet has been described. However, to obtain the effect expected in the present invention, it is not sufficient to adjust the component composition to the above range, and the aspect ratio of the ferrite crystal grains will be described below. Thus, it is important to control within a range that satisfies the specific conditions.

<Aspect ratio of ferrite crystal grains: 1.1 to 2.0>
In the steel plate for cans of the present invention, the aspect ratio of the ferrite crystal grains is in the range of 1.1 to 2.0. When the aspect ratio is less than 1.1 or when the aspect ratio exceeds 2.0, | Δr | exceeds 0.50 and anisotropy increases. In addition, since the degree of texture accumulation decreases and the Young's modulus decreases, the paneling strength decreases.

  The method for measuring the aspect ratio of the ferrite crystal grain is to take a structure photograph of the cross section of the sheet thickness parallel to the rolling direction of the steel sheet at a magnification of 400 times, and to actually add six lines in the thickness direction and the rolling direction. Then, the distance between the grain boundaries and the lines is counted at an interval of 50 μm or more, and the total line length in the rolling direction divided by the number of intersections is defined as the line segment length per ferrite crystal grain. Is obtained by dividing the total line length by the number of intersections to obtain the line segment length in the rolling direction per ferrite crystal grain. The ratio of the line segment length in the rolling direction and the line segment length in the sheet thickness direction (the line segment length in the rolling direction / the line segment length in the sheet thickness direction) is defined as the aspect ratio.

<Ferrite average crystal grain size: 3.0 to 15.0 μm>
If the average grain size of ferrite exceeds 15.0 μm, the mechanical strength of the bottom of the steel plate may be lowered. In addition, the paneling strength of the can body may be reduced. When the ferrite average crystal grain size is less than 3.0 μm, the anisotropy increases and the paneling strength may decrease. Therefore, the ferrite average crystal grain size is preferably set to 3.0 to 15.0 μm.

  Here, the ferrite average crystal grain size is obtained by taking a structure photograph of a cross section of the plate thickness parallel to the rolling direction of the steel sheet at a magnification of 400, and cutting in accordance with the steel-crystal grain size microscopic test method of JIS G 0552. The average ferrite particle diameter measured by the method.

  The aspect ratio of the ferrite crystal grains and the average crystal grain diameter of the ferrite are the steel having the predetermined components of the present invention, the hot rolling finishing temperature is 840 ° C. or higher, and the annealing temperature is 790 ° C. or lower. Thus, the desired range can be controlled.

<Texture: Ratio of (001) <1-10> orientation integration degree to (001) <1-10> orientation integration degree + (111) <-1-12> orientation integration degree) (f) Is 0.30 or less>
Next, the texture of the steel plate for cans of the present invention will be described. In the steel sheet for cans of the present invention, (001) <1-10 with respect to (the degree of integration in the (111) <1-10> orientation + the degree of integration in the (111) <-1-12> orientation) shown in Formula (1). The ratio (f) of the degree of integration of orientation is set to 0.30 or less.

  The Young's modulus of iron is strongly controlled by the texture, and the (001) <1-10> orientation is an orientation that decreases the average Young's modulus. Since the (111) <1-10> orientation and the (111) <-1-12> orientation are orientations that increase the average Young's modulus, the ((111) <1-10> orientation accumulation degree + (111) < The ratio (f) of the (001) <1-10> orientation accumulation degree to the (1-12> orientation accumulation degree) is an index for controlling the average Young's modulus. In the present invention, as a condition for obtaining a desirable Young's modulus, the ratio (f) needs to be 0.30 or less. To measure the degree of integration, first, an X-ray diffractometer is used, and (110), (200), (211), (222) pole figures are created by the Schulz reflection method. Then, a crystal orientation distribution function (ODF: Orientation Distribution Function) is calculated from these pole figures by a series expansion method, and (001) <1-10> orientation, (111) <1-10> orientation, (111) The degree of integration of <-1-12> orientation can be obtained.

<The average Young's modulus (E _ave ) is 210 GPa or more>
The average Young's modulus (E _ave ) greatly affects the improvement of paneling strength. In order to improve paneling strength and prevent buckling deformation of the can body and damage to the bottom of the can, the average Young's modulus (E _ave ) needs to be 210 GPa or more. The average Young's modulus (E _ave ) is preferably 215 GPa or less.

The Young's modulus can be measured according to the American Society for Testing Materials standard (C1259) using a transverse vibration type resonance frequency measuring device. Then, the average Young's modulus (E _ave ) can be calculated based on the following formula (2).
E _ave = (E ₀ + E ₉₀ + 2E ₄₅ ) / 4 (2)
Here, E ₀ , E ₉₀ , E ₄₅ : Young's moduli of 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively.

<| Δr | is 0.50 or less>
In the steel sheet of the present invention, Δr shown in the following formula (3) is used as an anisotropy index.
Δr = (r ₀ + r ₉₀ −2r ₄₅ ) / 2 (3)
Here, r ₀ , r ₉₀ , r ₄₅ : Rankford values in 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively.

  In order to ensure a good shape after forming, the anisotropy of the steel sheet is desirably as small as possible. As | Δr | increases, the anisotropy increases and the can height in the circumferential direction of the can becomes uneven. Thereby, the plate | board thickness of a can trunk | drum becomes non-uniform | heterogenous, paneling intensity | strength falls and it becomes easy to carry out buckling deformation. Therefore, | Δr | needs to be 0.50 or less. Further, | Δr | is preferably 0.40 or less.

<Rockwell hardness (HR30T) is 50 or more>
When the steel plate for cans of the present invention is used for a two-piece can, the strength of the material affects the mechanical strength of the bottom of the can. In particular, in the case of a thinner can, in order to prevent deformation of the can body and breakage of the bottom of the can during transportation, the Rockwell hardness needs to be 50 or more. The Rockwell hardness can be measured according to the method of JIS Z 2245.

<Thickness is 0.300mm or less>
The steel plate for cans according to the present invention has a remarkable effect when the plate thickness is thin. Therefore, the plate thickness is preferably 0.300 mm or less. More preferably, the plate thickness is 0.225 mm or less.

[Production method]
Next, an example of the manufacturing method of the steel plate for cans of this invention is demonstrated. In the method for producing a steel plate for cans of the present invention, the slab having the above-described component composition is hot-rolled by rough rolling and finish rolling at a finishing temperature of 840 ° C. or higher, and wound at a winding temperature of 500 ° C. or higher. Pickling, rolling reduction of 80% or more, maximum value of line tension: cold rolling at 20 kg / mm ² or less, annealing at a temperature of 790 ° C. or less, tempering of 0.6 to 6.0% Roll.

<Finishing rolling temperature: 840 ° C or higher>
When the finish rolling temperature is lower than 840 ° C., crystal grains stretched in the rolling direction are likely to be generated, and the development of the texture of the cold-rolled steel sheet is lowered. Moreover, when using the steel plate of this invention as a steel plate for cans with thin plate | board thickness, when the finish rolling temperature is less than 840 degreeC, the temperature on the edge side of a coil will fall easily. Therefore, finish rolling temperature shall be 840 degreeC or more.

  On the other hand, the finish rolling temperature is preferably 950 ° C. or lower and more preferably 930 ° C. or lower in order to make the ferrite average crystal grain size smaller and the ferrite crystal grain aspect ratio to be within a predetermined range. .

<Winding temperature: 500 ° C or higher>
When the coiling temperature is lower than 500 ° C., the anisotropy increases and the moldability decreases. Therefore, the winding temperature is set to 500 ° C. or higher. On the other hand, if the coiling temperature exceeds 750 ° C., the ferrite crystal grains in the hot-rolled sheet stage become coarse, the hardness decreases, the desired texture does not develop, and the Young's modulus may decrease. The temperature is preferably 750 ° C. or lower.

<Draft ratio in cold rolling: 80% or more, maximum value of line tension: 20 kg / mm ² or less>
After the hot rolling process, before the cold rolling, pickling and removing the surface scale. The conditions for pickling are not particularly limited, and the surface scale may be removed by pickling by a conventional method. The surface scale can be suitably removed by pickling, but the surface scale may be removed not only by pickling but also by other methods such as physical removal.

Thereafter, cold rolling is performed at a rolling reduction of 80% or more and a maximum value of the line tension of 20 kg / mm ² or less.

  If the rolling reduction in cold rolling is less than 80%, the texture that improves the Young's modulus is not sufficiently developed. In addition, the anisotropy may be increased. As a result, moldability deteriorates and sufficient paneling strength cannot be obtained when the thickness is reduced. Therefore, the rolling reduction in cold rolling is 80% or more.

When the maximum value of line tension in cold rolling exceeds 20 kg / mm ² , crystal rotation due to cold rolling hardly occurs, and a texture that improves Young's modulus may not develop, in which case the paneling strength decreases. To do. Therefore, the maximum value of line tension in cold rolling is 20 kg / mm ² or less. Further, the maximum value of the line tension in cold rolling is preferably 15 kg / mm ² or less in order to further develop a desired texture and to refine crystal grains. On the other hand, if the line tension in the cold rolling is too small, a problem on the sheet passing may occur. Therefore, the line tension is preferably 4.5 kg / mm ² or more.
In addition, the line tension here refers to the tension per unit area of the line direction (rolling direction) of a steel plate.

<Annealing temperature: 790 ° C or lower>
When the annealing temperature exceeds 790 ° C., the crystal grains become coarse and the hardness decreases. On the other hand, when the annealing temperature exceeds 790 ° C., the paneling strength decreases. Therefore, annealing temperature shall be 790 degrees C or less. On the other hand, if the annealing temperature is lower than 700 ° C., ferrite crystal grains stretched in the rolling direction may remain and formability may be deteriorated.

  The holding time in annealing is preferably 10 seconds or more so that the ferrite average crystal grain size and the ferrite crystal grain aspect ratio are within the range of the present invention. On the other hand, if this holding time is too long, the ferrite crystal grain size may become too large, and therefore it is preferably 60 seconds or less.

<Rolling ratio of temper rolling: 0.6 to 6.0%>
The temper rolling is performed to adjust the plate shape and the surface roughness and hardness. If the rolling reduction of the temper rolling is less than 0.6%, the effect of the temper rolling is not sufficient, and if it exceeds 6.0%, the elongation decreases due to work hardening, so the formability decreases. Therefore, the rolling reduction of temper rolling is set to 0.6 to 6.0%. Moreover, the rolling reduction of temper rolling is preferably 1.0% or more. Moreover, the rolling reduction of temper rolling is preferably 3.0% or less.

  As described above, the steel plate for cans of the present invention described above has a high Young's modulus and low anisotropy, and increases the paneling strength, which is a buckling strength against the external pressure of the can body, and makes the bottom of the can have a high hardness Can do. The steel plate for cans of the present invention can be applied, for example, for a two-piece can.

  Examples of the present invention will be described below.

  A steel slab having the composition shown in Table 1 and the balance consisting of Fe and inevitable impurities is hot-rolled under the conditions shown in Table 2, and then the scale is removed by pickling. Cold rolling was performed under the conditions, and annealing and temper rolling were performed under the conditions shown in Table 2 to produce steel plates having the thicknesses listed in Table 2. Evaluation methods and evaluation results are as follows.

(1) Structure observation A plate thickness section parallel to the rolling direction of the obtained cold-rolled steel sheet was mirror-polished to expose ferrite crystal grains with a nital corrosion liquid.

  Regarding the ferrite average crystal grain size, a structural photograph of the cross-sectional sample was taken at 400 times, and the ferrite average crystal grain size was measured by a cutting method in accordance with the steel-crystal grain size microscopic test method of JIS G 0552. Table 3 shows the calculated average ferrite grain size.

  Regarding the ratio of the length of the ferrite crystal grains in the rolling direction and the plate thickness direction, the lines drawn in the plate thickness direction and the rolling direction with 6 lines each drawn at an interval of 50 μm or more in the actual length, The number of intersections of the grain boundaries was counted, and the total line length in the rolling direction divided by the number of intersections was taken as the line segment length in the rolling direction per ferrite crystal grain. Similarly, the line segment length in the plate thickness direction per ferrite crystal grain was determined. The ratio of the line segment length in the rolling direction to the line segment length in the sheet thickness direction (the line segment length in the rolling direction / the line segment length in the sheet thickness direction) is shown as the aspect ratio.

(2) Measurement of r value From the obtained cold-rolled steel sheet, a JIS No. 5 tensile test piece was collected so that the tensile direction was the rolling direction (0 °), the oblique direction (45 °), and the vertical direction (90 °). Strain was applied at a pre-strain of 15%, and the r value was measured. | Δr | was calculated according to the following equation. Table 3 shows the calculation results.
| Δr | = | (r ₀ + r ₉₀ −2r ₄₅ ) / 2 |
Here, r ₀ , r ₉₀ , r ₄₅ : Rankford values in 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively.

(3) Measurement of Young's modulus Young's modulus is measured by cutting out a test piece of 10 mm x 35 mm with the rolling direction and 45 ° and 90 ° directions from the rolling direction as longitudinal directions, respectively, and using a transverse vibration type resonance frequency measuring device. The Young's modulus (GPa) was measured in accordance with American Society for Testing Materials Standard (C1259). And average Young's modulus ( _Eave ) was computed according to the following formula _| equation. Table 3 shows the calculation results.
E _ave = (E ₀ + E ₉₀ + 2E ₄₅ ) / 4
Here, E ₀ , E ₉₀ , E ₄₅ : Young's moduli of 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively.

(4) Measurement of hardness The Rockwell hardness (HR30T) was measured according to the Rockwell hardness test method of JIS Z 2245, and the Rockwell 30T hardness (HR30T) was measured. The results are shown in Table 3.

(5) Measurement of integration degree The integration of (111) <1-10> orientation + (111) <-1-12> orientation integration shown in the formula (1) of the plate surface at a quarter thickness of the steel sheet. The ratio (f) of the degree of integration of (001) <1-10> orientation with respect to (degree) was calculated according to the following calculation formula.

  The steel plate was polished from the surface to a ¼ plate thickness surface and subjected to chemical polishing (oxalic acid etching) to remove the influence of processing strain, and then the integrated strength f was measured. An X-ray diffractometer was used for the measurement, and (110), (200), (211), and (222) pole figures were created by the Schulz reflection method. A crystal orientation distribution function (ODF: Orientation Distribution Function) is calculated from these pole figures by a series expansion method, and (001) <1-10> orientation, (111) <1-10> orientation, (111) <- The degree of integration of 1-12> orientation was determined.

(6) Measurement of paneling strength In order to evaluate the can body characteristics after can-making, a two-piece can was formed on the steel sheet. Specifically, the steel plate was subjected to chromium plating (tin-free) treatment as a surface treatment, and then a laminated steel plate coated with an organic film was produced. Next, after punching into a circle, deep drawing, ironing, etc. were performed to form a can body of a two-piece can (diameter: 52.4 mm, can body length: 100 mm) applied in a beverage can. .

  The method for measuring the paneling strength is as follows. The can body was installed inside the pressurizing chamber, and pressurization inside the pressurizing chamber was performed by introducing pressurized air into the chamber at 0.035 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 paneling strength, was the pressure at the pressure change point inside the pressurized chamber accompanying buckling. In general, it is said that the paneling strength should be 0.147 MPa or more with respect to the pressure change due to the heat sterilization treatment. Therefore, in this invention, paneling strength evaluated less than 0.147 MPa as improper (x), 0.147 MPa or more-less than 0.157 MPa as good ((circle)), and 0.157 MPa or more as especially excellent ((double-circle)). The results are shown in Table 3.

  FIG. 1 shows the relationship between the aspect ratio (= major axis length / minor axis length) and | Δr | of the ferrite crystal grains obtained based on the results of Table 3 above. As shown in FIG. 1, it was found that the smaller the aspect ratio, the smaller | Δr | and the better the anisotropy. Further, when the aspect ratio was 1.1 to 2.0 and | Δr | was 0.50 or less, the paneling strength was 0.147 MPa or more.

FIG. 2 shows the relationship between the aspect ratio and average Young's modulus (E _ave ) of the ferrite crystal grains obtained based on the results of Table 3 above. As shown in FIG. 2, the desired texture develops and the Young's modulus increases as the aspect ratio decreases. When the aspect ratio was 1.1 to 2.0 and the average Young's modulus was 210 GPa or more, the paneling strength was 0.147 MPa or more.

  From Table 3, in the steel plate for cans within the scope of the present invention, the desired paneling strength and hardness could be obtained.

  On the other hand, Comparative Steel No. No. 4, f is beyond the range of the present invention, the aspect ratio of the ferrite crystal grains is beyond the range of the present invention, the average Young's modulus is less than the range of the present invention, and | Δr | Therefore, the paneling strength was low.

  Comparative steel No. No. 7 had an average Young's modulus less than the range of the present invention, and | Δr | was beyond the range of the present invention, so that the paneling strength and hardness were low.

  Comparative steel No. In No. 8, the Mn content was less than the range of the present invention, and the paneling strength and hardness were low.

  Comparative steel No. No. 9, the N content was beyond the range of the present invention, the aspect ratio of the ferrite crystal grains was beyond the range of the present invention, and the average Young's modulus was less than the range of the present invention, so the paneling strength was low.

  Further, the comparative steel 10 had a P content exceeding the range of the present invention, f was beyond the range of the present invention, and the aspect ratio of the ferrite crystal grains was beyond the range of the present invention, so the paneling strength was low. .

  Comparative steel 11 has an S content exceeding the range of the present invention, f exceeding the range of the present invention, an aspect ratio of ferrite crystal grains exceeding the range of the present invention, and an average Young's modulus of the present invention. The paneling strength was low.

  Further, the comparative steel 12 has an Nb content exceeding the range of the present invention, f exceeding the range of the present invention, an aspect ratio of ferrite crystal grains exceeding the range of the present invention, and an average Young's modulus of the present invention. The paneling strength and hardness were low because | Δr | was beyond the range of the present invention.

  Further, since the comparative steel 16 has f exceeding the range of the present invention, the aspect ratio of the ferrite crystal grains is beyond the range of the present invention, and the average Young's modulus is less than the range of the present invention, the paneling strength and hardness are It was low.

  Further, since the comparative steel 17 has f exceeding the range of the present invention, the aspect ratio of the ferrite crystal grains exceeds the range of the present invention, and the average Young's modulus is less than the range of the present invention, the paneling strength and hardness are It was low.

  Further, the comparative steel 18 had a low paneling strength and hardness because the Al content exceeded the range of the present invention.

  Comparative steel No. No. 19, Mn content exceeds the range of the present invention, f exceeds the range of the present invention, the aspect ratio of the ferrite crystal grains exceeds the range of the present invention, and the average Young's modulus is less than the range of the present invention Therefore, paneling strength and hardness were low.

  Comparative steel No. No. 22, f is beyond the range of the present invention, the aspect ratio of the ferrite crystal grains is beyond the range of the present invention, the average Young's modulus is less than the range of the present invention, and | Δr | Therefore, paneling strength and hardness were low.

  Comparative steel No. No. 23 had a low paneling strength because the average Young's modulus was less than the range of the present invention.

  Comparative steel No. 24, the C content is beyond the range of the present invention, f is beyond the range of the present invention, the aspect ratio of the ferrite crystal grains is beyond the range of the present invention, and the average Young's modulus is less than the range of the present invention. Yes, | Δr | was beyond the range of the present invention, so the paneling strength was low.

Comparative steel No. 25, the C content is beyond the range of the present invention, f is beyond the range of the present invention, the aspect ratio of the ferrite crystal grains is beyond the range of the present invention, and the average Young's modulus is less than the range of the present invention. Yes, | Δr | was beyond the range of the present invention, so the paneling strength was low.

Claims (4)

% By mass
C: 0.0100% or less, Si: 0.01 to 0.10%, Mn: 0.10 to 1.00%, P: 0.020% or less, N: 0.0050% or less, S: 0.00. Containing not more than 03%, Al: 0.02-0.10%,
Further, Nb: 0.01 to 0.10% and / or Ti: 0.01 to 0.20%, the remainder has a component composition consisting of Fe and inevitable impurities,
Having a ferrite structure,
The aspect ratio of the ferrite crystal grains is 1.1 to 2.0,
Accumulation of (001) <1-10> orientation with respect to (accumulation degree of (111) <1-10> orientation + integration degree of (111) <-1-12> orientation) expressed by the following formula (1): Degree ratio (f) is 0.30 or less,
The average Young's modulus (E _ave ) represented by the following formula (2) is 210 GPa or more,
Rockwell hardness (HR30T) is 50 or more,
A steel plate for a can, wherein | Δr | represented by the following formula (3) is 0.50 or less.

E _ave = (E ₀ + E ₉₀ + 2E ₄₅ ) / 4 (2)
Here, E ₀ , E ₉₀ , E ₄₅ : Young's moduli of 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively.
| Δr | = | (r ₀ + r ₉₀ −2r ₄₅ ) / 2 | (3)
Here, r ₀ , r ₉₀ , r ₄₅ : Rankford values in 0 °, 45 °, and 90 ° directions with respect to the rolling direction, respectively. The ferrite average crystal grain size is 3.0-15.0 μm,
The steel sheet for cans according to claim 1, wherein the average Young's modulus (E _ave ) is 215 GPa or more and the | Δr | is 0.40 or less. The steel plate for cans according to claim 1 or 2, wherein a plate thickness is 0.300mm or less. It is a manufacturing method of the steel plate for cans of any one of Claims 1-3, A steel slab is hot-rolled by the finishing temperature of 840 degreeC or more, and it winds up by the winding temperature of 500 degreeC or more, and acid. Wash, cold rolling: 80% or more, maximum value of line tension: 20 kg / mm ² or less, cold-rolled, annealed at a temperature of 790 ° C. or less, adjusted at a rolling reduction of 0.6 to 6.0% A method for producing a steel plate for cans, characterized by performing quality rolling.

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