JPH09310150A - Steel sheet for can excellent in workability, nonearing property and resistance to surface roughening and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a workability, nonearing property and resistance to surface roughening of a steel sheet by incorporating specified amounts of C, Si, Mn, P, S, Al, N and Fe into a steel sheet and regulating the crystal grain size and crystal grain aspect ratio in the surface layer and internal layer of a steel sheet. SOLUTION: This steel sheet for a can has a compsn. contg., by weight, 0.001 to 0.015% C, <=0.1% Si, 0.1 to 0.6% Mn, <=0.02% P, <=0.02% S, 0.015 to 0.15% Al and <=0.02% N, furthermore contg. one or more kinds selected from <=0.02% Nb and <=0.02% Ti and 0.002% B, and the balance substantial Fe. The surface layer region to 1/10 of the sheet thickness from the surface of the steel sheet has a fine equi-axed crystal grain structure in which the crystal grain size is regulated to No. >=10 by ASTM an the crystal grain aspect ratio is regulated to <=1.5. The internal layer of the steel sheet excluding the surface layer has a coarse equi-axed crystal grain structure in which the crystal grain size is regulated to No <=9 by ASTM and the crystal grain aspect ratio is regulated to <=1.5. The steel slab is heated at the Ar3 point or above, and rough rolling is finished at (the Ar3 point + 150 deg.C) to (the Ar3 point + 50 deg.C).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel sheet for cans used for foods, beverage cans and the like, and particularly to workability (press workability), non-earring property (hardness of ear generation),
The present invention relates to a steel sheet for cans having excellent resistance to surface roughening after pressing and a method for manufacturing the same.

[0002]

2. Description of the Related Art Deep drawing cans, DRD (Drawn and Redrawn) cans, DIs made by press forming such as deep drawing.
(Drawn and Ironined) The properties required for cold-rolled steel sheets used for cans are: 1) Press workability; Can be formed without causing defects such as cracks during processing, 2) Rough skin resistance; The surface roughness of the steel sheet after pressing is small, and the finished appearance and corrosion resistance are good. 3) Earring resistance; The material has small anisotropy and little ears after deep drawing. To be

A proposal for developing a steel sheet having these characteristics is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-267242. This technology adjusts the surface layer after annealing to equiaxed fine grains and the inner layer to equiaxed coarse grains by box annealing in nitrogen after cold rolling a low carbon steel material. To improve the rough skin resistance.

[0004]

However, the technique disclosed in Japanese Unexamined Patent Publication No. 2-267242 is used for shallow drawing cans whose drawing conditions are relatively strict and three-piece cans without drawing. Since the r is only 1.2 at the most and the press workability is not sufficient, when it is used as the deep-draw can, DRD can, and DI can described above, defects such as cracks occur during processing. However, it was not suitable for practical use. On the other hand, in order to improve press workability, it is widely known that the component composition of the material is made extremely low carbon. Therefore, in order to have both rough skin and press workability, it is conceivable that the material is ultra low carbon steel and the above technique is applied to this material.
However, in this case, since grain growth is increased due to extremely low carbonization, grain refinement in the steel sheet surface layer cannot be achieved, and as a result, it is impossible to improve the rough surface resistance. there were. Therefore, a main object of the present invention is to provide a steel sheet for a can, which is excellent in press workability, resistance to surface roughening after press work, and earring property, and can withstand deep drawing work, and a method for producing the same. Another object of the present invention is to provide a Rankford value (r value) of 1.5 or more, Δr (absolute value) representing the in-plane anisotropy of the r value of 0.16 or less, and a surface roughness after 20% tensile processing. It is an object of the present invention to provide a steel plate for a can having a characteristic Ra of 0.65 μm or less and a method for manufacturing the same.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the inventors investigated the influence of the size (grain size) and morphology of crystal grains on press workability, earring resistance, and rough skin resistance. . First, focusing on the fact that press workability has a strong correlation with the elongation of steel sheets, the relationship between the size of crystal grains and elongation was investigated. As a result, as shown in FIG. 1, it was found that the larger the steel plate crystal grains, the better the elongation of the steel plate. Further, as shown in FIG. 2, the Δr was found to be smaller in the equiaxed structure as compared with the stretched structure Al killed steel, and was excellent in non-earring property. And, as shown in FIG. 3, the rough skin resistance was better as the grain size of the steel sheet was smaller as opposed to the press workability.

On the basis of the above results, the inventors of the present invention have conducted extensive research mainly focusing on the conditions of descaling performed prior to finish rolling, and as a result, have been used so far to achieve the above object. By applying ultra-high pressure descaling that has never been done before, the surface of the hot-rolled steel strip is rapidly cooled and only the surface layer is refined, and the crystal grains after cold rolling and annealing have a fine grain structure. The surface roughness is ensured by the above, the press workability is improved by making the inner layer a coarse grain structure, and the equiaxed grain from the steel plate surface to the center layer results in a small Δr and excellent non-earing property. The present invention has been completed by finding that it is possible to obtain a steel sheet having excellent properties. That is, the gist configuration of the present invention is as follows.

1) C: 0.0010 to 0.0150 wt%, Si: 0.10 wt%
%, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less,
S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.
The content of 02 wt% or less, the balance consisting of Fe and unavoidable impurities, the crystal grains in the surface layer area from the surface of the steel plate to 1/10 of the plate thickness are ASTM grain size No. 10 or more and the crystal grain axis ratio.
It is characterized by having a fine equiaxed grain structure of 1.5 or less, and the inner layer of the steel sheet excluding this surface layer is composed of a coarse equiaxed grain structure of ASTM grain size No. 9 or less and a grain axis ratio of 1.5 or less. A steel plate for cans that has excellent workability, non-earring properties, and resistance to rough skin.

2) C: 0.0010 to 0.0150 wt%, Si: 0.10 wt
%, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less,
S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.
02 wt% or less, Nb: 0.020 wt% or less, Ti: 0.
It contains any one or two selected from 020 wt% or less, the balance is Fe and unavoidable impurities, and the crystal grains in the surface layer region from the surface of the steel plate to 1/10 of the plate thickness are:
It consists of a fine equiaxed grain structure with an ASTM grain size of No. 10 or more and a grain axis ratio of 1.5 or less. The inner layer of the steel sheet excluding this surface layer is a coarse grain with an ASTM grain size of No. 9 or less and a grain axis ratio of 1.5 or less. A steel sheet for cans having excellent workability, non-earring property, and resistance to roughening, which is characterized by having an equiaxed grain structure.

3) C: 0.0010 to 0.0150 wt%, Si: 0.10 wt%
%, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less,
S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.
02 wt% or less and B: 0.0020 wt% or less,
The balance consists of Fe and unavoidable impurities, and the crystal grains in the surface layer area from the surface of the steel plate to 1/10 of the plate thickness are AST.
The inner layer of the steel sheet, excluding this surface layer, consists of a fine equiaxed grain structure with M grain size No. 10 or more and grain axis ratio of 1.5 or less.
A workability characterized by a coarse equiaxed grain structure having an ASTM grain size of 9 or less and a grain axis ratio of 1.5 or less,
Steel sheet for cans with excellent non-earring properties and resistance to rough skin.

4) C: 0.0010 to 0.0150 wt%, Si: 0.10 wt%
%, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less,
S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.
02 wt% or less, Nb: 0.020 wt% or less, Ti: 0.
It contains any one or two kinds selected from 020 wt% or less, further contains B: 0.0020 wt% or less, and the balance is Fe and unavoidable impurities.
Crystal grains in the surface layer area up to / 10 are ASTM grain size No. 1
Coarse equiaxed crystal grains consisting of a fine equiaxed grain structure of 0 or more and a grain axis ratio of 1.5 or less, excluding this surface layer, are ASTM grain size No. 9 or less and a grain axis ratio of 1.5 or less. A steel sheet for cans having excellent workability, non-earring property, and resistance to roughening of the surface, which is characterized by having a structure.

5) C: 0.0010 to 0.0150 wt%, Si: 0.10 wt
%, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less,
S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.
The steel slab containing up to 02wt%, the average temperature is heated so that the above _three points Ac, exit the rough rolling in the temperature range of (Ar ₃ point +150 ℃) ~ (Ar ₃ point + 50 ° C.), to give The seat bar has a collision pressure of 25 kgf / cm ² or more and a liquid density of 0.002.
Ultra high pressure descaling under the condition of liter / cm ² or more is applied to make the temperature difference between the surface of the sheet bar and the center in the thickness direction 400 ° C or more, and then finish rolling is started within 5 seconds, and Ar ₃ points are set. Finished above, within 2 seconds after finishing rolling, cool at 50 ℃ / sec or more and wind at 700 ℃ or less,
Any one of the above 1) to 4), characterized in that it is pickled by a conventional method, cold-rolled, continuously annealed at a recrystallization temperature or higher, and temper-rolled at a rolling reduction of 0.5 to 10%. The method for manufacturing a steel sheet for cans according to.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the reasons why the component composition, manufacturing conditions and the like are limited to the above-mentioned constitution will be explained. (1) Steel composition C: 0.0010 to 0.0150 wt% C is better for elongation and is more advantageous for press workability, but if too little, the steel sheet becomes excessively soft and the strength of the can body is increased. , The lower limit is 0.0010.
wt%. On the other hand, if the amount exceeds 0.015 wt%, the steel plate becomes hard and elongation is significantly reduced and press workability deteriorates, so 0.0010 to 0.0150 wt% is set.

Si: 0.10 wt% or less Si lowers corrosion resistance and extremely hardens the material, and is a harmful element as a can material. Therefore, its upper limit is 0.1 wt%, preferably 0.05 wt%. Below.

Mn: 0.1-0.6 wt% Mn is an element necessary for preventing red hot embrittlement during hot rolling due to S which is an impurity. 0 for this effect.
1 wt% or more is necessary, but if added in excess of 0.6 wt%, cracks will occur during slab rolling and the steel sheet will be excessively hardened, so the addition amount should be in the range of 0.1 to 0.6 wt%.

P: 0.02 wt% or less P exceeds 0.02 wt%, and the corrosion resistance remarkably decreases, so the upper limit is made 0.02 wt%.

S: 0.02 wt% or less S is an impurity component that causes red hot embrittlement during hot rolling, and it is desirable to reduce it as much as possible. However, the unavoidably contained amount is 0.02 wt%, so the upper limit is 0.02 wt%
And

Al: 0.015 to 0.15 wt% Al is added to the steel bath as a deoxidizing agent in steelmaking and removed as slag. If the added amount is too small, a stable deoxidizing effect cannot be obtained, so 0.015 wt% or more must be added. On the other hand, even if added in excess of 0.15 wt%, there is no further effect and it is economically unfavorable, so the upper limit is made 0.15 wt%.

N: 0.02 wt% or less N exceeds 0.02 wt%, since the steel plate is hardened, elongation is remarkably reduced, and press workability is deteriorated, so the upper limit is 0.02 wt%.
%.

Nb: 0.020 wt% or less, Ti: 0.020 wt% or less Nb and Ti are elements that form carbonitrides, and for improving the elongation and r value by reducing the solute C and N. Is added. If the addition amount of each exceeds 0.02 wt%, the recrystallization end temperature rises and Ti further deteriorates the surface properties of the steel sheet, so the upper limit of these is made 0.02 wt%.

B: 0.0020 wt% or less B has the effect of suppressing the grain boundary embrittlement that occurs when the amounts of solid solution C and N decrease, and enhances the hardenability. However, if added in excess of 0.0020 wt%, the steel becomes hard and brittle, so the upper limit is 0.0020 wt.
%. In order to obtain the effect of adding B, 0.0002 wt% or more is preferably added.

(2) Manufacturing conditions: Hot rolling The steel material before hot rolling may be heated as long as it is completely solutionized, and may be heated to Ac ₃ point or more. Specifically from 1050
1350 ° C is suitable. After the heating, hot rolling including rough rolling and finish rolling is performed. Further, the sheet bar obtained by rough rolling is subjected to descaling with ultra-high pressure water prior to finish rolling. First, rough rolling (Ar ₃ points +
The temperature range of (150 ℃) to (Ar ₃ points + 50 ℃) ends in the case where rough rolling is performed at a temperature lower than this range, finish rolling inevitably becomes the rolling in the α range, and the depth of the annealed sheet is increased. This is because it becomes a collective organization that is disadvantageous to the drawability. On the other hand, if rough rolling is finished at a high temperature exceeding this range, the effect of refining the steel strip surface by ultrahigh pressure water descaling, which is performed subsequent to rough rolling, will not be fully exerted, and the life of the rolling roll will be shortened. Connect Thus, rough rolling termination temperature range and (Ar ₃ point +150 ℃) ~ (Ar ₃ point + 50 ° C.).

After the rough rolling, ultrahigh pressure descaling and finish rolling are performed. In this case, in order to control the crystal grains of the surface layer and the inner layer of the annealed plate as described above, the surface of the sheet bar is strongly cooled, and a large temperature difference is created between the surface layer and the inside,
It is necessary to generate thermal strain in the surface layer. To do this,
The conditions for such ultra-high pressure descaling are: impact pressure on the surface of the sheet bar; 25 kgf / cm ² or more and liquid volume density of 0.002 liter / cm ² or more, and a temperature difference of 400 ℃ or more between the hot rolled steel strip surface and the center. In addition, it is necessary to set the time to start the finishing rolling after descaling within 5 seconds. Here, the liquid volume density represents the total liquid volume input per unit area of the plate surface in descaling. Further, the collision pressure p is generally obtained by the following equation from the ejection pressure P and the ejection amount Q of the nozzle and the distance H between the plate surface and the nozzle. (Refer to “Iron and Steel” 1991 vol.77 No.9 p11450) p = 5.64 PQ / H ² However, p: Impact pressure (MPa) on the surface of the sheet bar plate P: Discharge pressure (MPa) Q: Discharge amount ( L / sec) H: Distance between steel plate surface and nozzle (cm)

In the present invention, the mechanism by which the ultrahigh pressure descaling conditions and the time until the start of finish rolling after descaling affect the final grain size after cold rolling and annealing is not necessarily clear, but Collision pressure is 25
becomes a super high pressure of kgf / cm ² or more, smoothed surface irregularities disappeared locally without plate surface is cooled, the plate
And the uniform in a flat structure is obtained in the surface direction, water flow rate is 0.00
Beyond 2 liters / cm ² or more, the temperature difference between the surface and the center 40
Above 0 ℃, only the pole surface is effectively cooled, thermal strain occurs in the surface layer of the strip, and before the strain is released by heat transfer from inside the strip, that is, within 5 seconds after descaling. When finish-rolled, only the outermost layer of the hot-rolled sheet has uniform fine grains, and the inner layer has a coarse grain structure, and the grain size is sufficient to inherit this structure even after cold rolling and annealing. Conceivable. By the way, the collision pressure of the conventional high-pressure descaling is about 1.0 to 4.0 kgf / cm ² , so in the present invention,
It seems that the use of ultra-high pressure, which is 10 times as high, has produced a unique effect which was not expected under the conventional technology.

Next, finish rolling, which is performed subsequent to the high pressure descaling, must be carried out under the conditions of the rolling end temperature Ar ₃ transformation point or higher, cooled within 2 seconds, and wound up at 700 ° C. or lower. This is because when rolled below the Ar ₃ transformation point, the crystal grains of the hot rolled sheet have a coarse processed structure that extends in the rolling direction, and this structure is inherited even after cold rolling and annealing. Axial ratio of grains (long axis length / short axis length)
Is not an equiaxed grain of 1.5 or less and the deep drawability becomes poor. Further, after finishing rolling, in order to prevent the coarsening of the crystal grains, it is necessary to cool to a desired winding temperature at a cooling rate of 50 ° C./sec or more within 2 seconds. Here, when the winding temperature exceeds 700 ° C, scale growth after winding becomes remarkable and the pickling property deteriorates, and the crystal grains become abnormally coarse and the material deteriorates, and the skin resistance Will cause problems such as deterioration. Therefore, the coiling temperature is 700 ° C or lower, preferably 500 to 600 ° C.

Cold Rolling After the above hot rolling is finished, pickling is carried out by a conventional method to carry out cold rolling. In this cold rolling, if the rolling reduction is less than 80%, the crystal grains become abnormally coarse or mixed in the annealing process, the material deteriorates, and it becomes difficult to develop a texture effective for deep drawability. Therefore, it is desirable that the rolling reduction is 80% or more.

Continuous annealing The continuous annealing requires a temperature higher than the recrystallization temperature.
If the annealing temperature is too high, the crystal grains will become abnormally coarse and the surface roughness after processing will increase, and in thin materials such as steel plates for cans, the risk of fracture in the furnace and buckling will increase.
It is desirable to set the upper limit to 750 ° C.

Temper rolling The reduction ratio of temper rolling is determined by the temper ratio of the steel sheet at any time, but in order to prevent the occurrence of stretcher strain, it is necessary to roll at a rolling ratio of 0.5% or more. . on the other hand,
If rolled at a rolling reduction of more than 10%, the steel sheet excessively hardens and the workability deteriorates, so the upper limit is made 10%.

Structure of Steel Sheet Crystal grains of the steel sheet produced by the above method are AST in the surface area from the surface of the steel sheet to 1/10 of the sheet thickness.
Equiaxed crystal grains with M grain size No. 10 or more (crystal grain axis ratio 1.5 or less)
As a structure, the inner layer of the steel plate excluding this surface layer, ASTM grain size N
Coarse equiaxed crystal grains of o.9 or less (crystal grain axis ratio of 1.5 or less) can be formed. Here, the axial ratio refers to the length in the major axis direction / the length in the minor axis direction. Grain axis ratio is Δr
In order to reduce the thickness and improve the non-earring property, the total thickness from the surface of the steel sheet to the central portion must be 1.5 or less. In addition, the surface layer has a grain size of No. 10 or more to improve the resistance to roughening after processing, and only the extreme surface layer (from the surface to 1/10 of the plate thickness) is fine to ensure processability, The inner layer needs to be coarse grains having a grain size of No. 9 or less, preferably No. 8.5 or less. The crystal grain size (grain size No.) and axial ratio in each of the above regions shall be expressed as the average value in each region.

[0029]

EXAMPLE A slab obtained by continuous casting of molten steel consisting of components compatible with the present invention shown in Table 1 and components having a C content outside the range of the present invention was subjected to hot rolling and cold rolling under the conditions shown in Table 2. Then, the product was annealed, temper-rolled, and then plated with tin in the 25th order to obtain a product, which was then subjected to various characteristic tests. The thickness of the sheet bar after rough rolling was 40 mm, and the temperature difference in the thickness direction after performing ultrahigh pressure descaling on this was determined by heat transfer calculation based on data such as the heat transfer coefficient of steel. . The validity of the values used for calculation such as heat transfer coefficient and the calculated temperature values were confirmed by comparison with the values measured off-line.
The thickness of the cold rolled sheet was 0.1 to 0.3 mm.

[0030]

[Table 1]

[0031]

[Table 2]

The test method is shown below. (A) Metallographic structure After polishing and etching the product cross section, by optical microscope observation, the ASTM grain size No. and crystal grain axial ratio are divided into the region from the outermost surface to the 1/10 position of the plate thickness and other regions. It measured and calculated | required each average value in each area | region. (B) Mechanical Properties A tensile test of the product was carried out using a JIS No. 5 test piece.
The r-value and the anisotropy of the r-value were calculated as the average r-value and Δr by the following equations, respectively. Average r value = (r ₀ + r ₉₀ + 2r ₄₅ ) / 4 Δr = (r ₀ + r ₉₀ −2r ₄₅ ) / 2 where r _{0 is} the r value in the rolling direction r ₉₀ is the direction forming a 90 ° inclination with the rolling direction R value r ₄₅ : r value in the direction that forms an inclination of 45 degrees with the rolling direction (C) Surface roughness Roughness is measured by applying 20% tensile strain to the JIS No. 5 test piece. did. In addition, all the product surface roughness Ra before the tension was 0.21 μm. Further, it has been confirmed by the experiments by the present inventors that if the surface roughness Ra after the 20% tensile test is 0.65 μm or less, the problem due to the rough surface after pressing does not occur. (D) Cylindrical processing test A cylindrical processing test was conducted in order to investigate the workability during deep drawing, surface roughness, and earring properties. A circular blank with a diameter of 100 mm is formed into a cup shape with a drawing ratio of 2.2, and the cracking state, skin roughening state and earring generation state during processing are indicated by ○: no or minute, △: mild to moderate, ×: not practical It was evaluated in three stages.

Table 3 shows the above test results. From Table 3,
It can be seen that the steel sheet according to the present invention is excellent in elongation and satisfies all of press workability, surface roughening resistance and non-earring property, while the comparative example is inferior to any of the properties.

[0034]

[Table 3]

[0035]

As described above, according to the present invention,
It becomes possible to manufacture a steel sheet for cans which is excellent in press workability, resistance to surface roughening, and non-earring resistance, and the steel sheet according to the present invention can be suitably used as a material for food cans and beverage cans to which deep drawing is particularly applied. In addition, the steel sheet according to the present invention is expected to be utilized in a wide range of various metal cans, as well as internal cans for dry batteries, various home appliances / electric parts, automobile parts, and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between grain size No. and elongation.

FIG. 2 is a diagram showing the relationship between the crystal grain axial ratio and Δr.

FIG. 3 is a diagram showing a relationship between grain size No. and skin roughness.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Furukun 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Co., Ltd. Kawasaki Steel Corporation Chiba Works

Claims (5)

[Claims] 1. C: 0.0010 to 0.0150 wt%, Si: 0.10 wt% or less, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less, S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.02 wt% or less, the balance consisting of Fe and unavoidable impurities, and the crystal grains in the surface layer region from the surface of the steel plate to 1/10 of the plate thickness are ASTM grain size No. 10 or more and crystal grain axial ratio. It is characterized by having a fine equiaxed grain structure of 1.5 or less, and the inner layer of the steel sheet excluding this surface layer is composed of a coarse equiaxed grain structure of ASTM grain size No. 9 or less and a grain axis ratio of 1.5 or less. A steel plate for cans that has excellent workability, non-earring properties, and resistance to rough skin. 2. C: 0.0010 to 0.0150 wt%, Si: 0.10 wt% or less, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less, S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.02 wt% or less, Nb: 0.020 wt% or less, Ti: 0.020 wt% or less, and the balance is
Crystal grains consisting of Fe and inevitable impurities in the surface layer area from the surface of the steel plate to 1/10 of the plate thickness are ASTM grain size.
It consists of a fine equiaxed grain structure with a grain axis ratio of No.10 or more and a grain axis ratio of 1.5 or less.
A steel sheet for cans having excellent workability, non-earring property, and resistance to surface roughening, which is characterized by having a coarse equiaxed grain structure with an M grain size of 9 or less and a grain axis ratio of 1.5 or less. 3. C: 0.0010 to 0.0150 wt%, Si: 0.10 wt% or less, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less, S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.02 wt% or less, B: 0.0020 wt% or less, the balance Fe and unavoidable impurities, and the crystal grains in the surface region from the surface of the steel plate to 1/10 of the plate thickness are ASTM It consists of a fine equiaxed grain structure with grain size No.10 or more and grain axis ratio of 1.5 or less. The inner layer of the steel sheet excluding this surface layer is coarse grained with ASTM grain size No.9 or less and grain grain axis ratio of 1.5 or less. A steel sheet for cans, which is excellent in workability, non-earring property, and resistance to roughening, which is characterized by having an axial grain structure. 4. C: 0.0010 to 0.0150 wt%, Si: 0.10 wt% or less, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less, S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: 0.02 wt% or less, Nb: 0.020 wt% or less, Ti: 0.020 wt% or less, and 1 or 2 selected, and B: 0.0020 wt% or less, and the balance is The crystal grains consisting of Fe and unavoidable impurities in the surface layer area from the surface of the steel sheet to 1/10 of the sheet thickness have a fine equiaxed crystal grain structure with ASTM grain size No. 10 or more and grain axis ratio 1.5 or less. The inner layer of the steel sheet, excluding this surface layer, is characterized by a coarse equiaxed grain structure with ASTM grain size No. 9 or less and grain axis ratio of 1.5 or less. Excellent steel sheet for cans. 5. C: 0.0010 to 0.0150 wt%, Si: 0.10 wt% or less, Mn: 0.1 to 0.6 wt%, P: 0.02 wt% or less, S: 0.02 wt% or less, Al: 0.015 to 0.15 wt%, N: a steel slab containing less 0.02 wt%, the average temperature is heated so that the above _three points Ac, ends the rough rolling in the temperature range of (Ar ₃ point +150 ℃) ~ (Ar ₃ point + 50 ° C.) The resulting sheet bar had an impact pressure of 25 kgf / cm ² or more and a liquid volume density of 0.002 liter / c.
subjected to ultra-high pressure descaling conditions satisfying m ² or more, the temperature difference between the surface and the thickness direction center of the sheet bar and 400 ° C. or higher, subsequently, finishing starts rolling within 5 seconds, Ar ₃
It finishes above the point, and 50 ℃ / se within 2 seconds after finishing rolling.
Characterized by cooling above c, winding at 700 ℃ or below, pickling by the conventional method, cold rolling, continuous annealing above the recrystallization temperature, and temper rolling at a rolling reduction of 0.5 to 10%. The method for manufacturing a steel sheet for cans according to any one of claims 1 to 4.