JPH10330845A - Method for producing steel sheet for low earring container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a steel plate for a container, in which a bottom and a body part used in a beverage can are deep drawn and an earring of a two-piece can formed integrally by ironing is reduced. SOLUTION: In weight%, C ≦ 0.1, N ≦ 0.01,
Al = 0.005 to 1.0, and if necessary, B = 0.0
During hot rolling of a steel slab containing 002 to 11N / 14 + 0.001%, if necessary, after rough rolling, the leading end of the following material is joined to the rear end of the preceding material and subjected to finish rolling.
At the time of finish rolling, Ar ₃ transformation point to Ar ₃ transformation point +100
In the temperature range of ° C., the rolling with a total draft of 50% or more is lubricated and performed under the condition of μ ≦ 0.2, and the finishing temperature is Ar.
After performing finish rolling of ₃ transformation points or more, and then performing normal pickling, cold rolling, recrystallization annealing, and skin pass rolling are performed under the condition that the total draft of the cold rolling and skin pass rolling is 90 to 95%. A method for producing a steel plate for a low earring container, the method comprising:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a steel plate for a low-earring container, and more particularly to a two-piece can material which is often used for beverage cans and which is formed by integral drawing by deep drawing at the bottom and body. The present invention relates to a method for manufacturing a steel sheet for a container.

[0002]

2. Description of the Related Art Conventionally, two-piece cans are roughly classified into an aluminum plate and a steel plate. As the steel plate, an aluminum killed steel plate has been usually used. The outline of the method for producing such a steel sheet for containers is that the finishing temperature of hot rolling is set to the Ar ₃ transformation point or higher, winding is performed at a relatively low temperature of about 600 ° C., and thereafter, pickling, cold rolling, and annealing are performed. And skin pass rolling to produce a material for can making.

[0003] Container materials have a standard called a temper grade based on a hardness value, and in order to satisfy the standard, after annealing, hardening is performed by a high-pressure skin pass, and a grade is sometimes formed.

One of the characteristics desired as a material for a two-piece can is low earring properties. What is earrings?
It is a technical term indicating the unevenness of the height of the wall of the opening of the can where the bottom and the body are integrally formed by deep drawing and ironing, and the difference between the maximum value and the minimum value of the body height is the average. The earring rate obtained by multiplying the value obtained by dividing the value by the body height by 100 is used as the index. If the earring rate is increased, the lid cannot be mounted, so that trimming is required. This causes not only an increase in working cost but also a decrease in yield, and thus reducing the earring rate has been regarded as an important issue.

[0005]

In the recent development of container materials, thinner cans have been focused on in order to reduce the cost of the material. The thinning of the container material means an increase in the rolling reduction (hereinafter referred to as a cold rolling reduction) of the cold rolling, and one of the major problems caused thereby is an increase in the earring rate. The occurrence of earrings is caused by the in-plane anisotropy of deformation based on the texture of the material, and the texture is controlled by the optimal control of the integrated process of hot rolling-cold rolling-annealing-strong skin pass rolling, Low earrings need to be achieved.

Accordingly, the present invention has been made to advantageously solve the problem of earrings associated with thinner container materials, and the above-mentioned optimal texture control is achieved by controlling the texture during hot rolling. It is an object of the present invention to provide a method for producing a low-earring-container steel sheet, which can be realized by the above method and can improve the earring resistance of the container material.

[0007]

The gist of the present invention is as follows. (1) By weight ratio, C ≦ 0.1%, N ≦ 0.01%, Al
In the finish rolling in the hot rolling of steel slabs containing 0.005 to 1.0%, the total reduction is 50% or more in the temperature range of Ar ₃ transformation point to Ar ₃ transformation point + 100 ° C. While performing the lubrication under the condition that the coefficient of friction is 0.2 or less, the finish temperature is subjected to finish rolling of the Ar ₃ transformation point or more,
Thereafter, after normal pickling, cold rolling, recrystallization annealing, and skin pass rolling are performed under the condition that the total draft of the cold rolling and the skin pass rolling is 90 to 95%, for a low earring container. Steel plate manufacturing method. (2) The steel has a weight ratio of B = 0.0002
The method for producing a steel sheet for a low-earring container according to the above (1), wherein the steel sheet contains 0.1 to 11 N / 14 + 0.001%. (3) The method according to the above (1) or (2), wherein in the hot rolling, after rough rolling, a leading end of a succeeding material is joined to a rear end of the preceding material and subjected to finish rolling. Manufacturing method of steel plate for low earring container.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
First, the reasons for limiting the components in steel will be described. The reason for setting the C content to 0.1% or less is that the addition of C exceeding this amount causes deterioration of workability. The amount of N is set to 0.01% or less because the addition of N exceeding this amount causes deterioration of workability. The reason for setting the lower limit of the Al content to 0.005% is to sufficiently perform deoxidation. The upper limit is limited to 1.0% or less from the viewpoint of workability.

B contributes to the improvement of the secondary workability, so that its effect is clearly exhibited depending on the application.
% Or more is required. B has the effect of reducing solid solution N from steel in the form of BN and improving workability.
In this case, the effect increases as the amount of B increases, but the effect saturates at 11N / 14. And an excessive addition deteriorates the workability, so the upper limit is 11N / 14 + 0.001.
% Or less.

The other components are not particularly limited, but Mn ≦ M in a range that enhances strength and does not significantly deteriorate workability.
The addition of 0.5%, Si ≦ 0.5%, and P ≦ 0.1% does not impair the purpose of the present invention.

Next, the reasons for limiting the process conditions will be described. The present inventors have studied in detail the influence of the texture of the hot-rolled steel sheet on the formability of the cold-rolled steel sheet, and found that the texture formed in the surface layer portion of the hot-rolled steel sheet is a steel sheet for containers during high-pressure cold rolling. Was found to have an adverse effect on the earring resistance. That is, in hot rolling, since the friction coefficient between the roll and the rolled piece is large, the shear strain that does not exist at the center of the sheet thickness is large near the surface of the sheet thickness, so that the crystal rotation is significantly different from the center of the sheet thickness. A heterogeneous texture is formed. This difference in texture exists even though the quality changes after the transformation.

Therefore, the present inventor has made intensive research on texture control in hot rolling in the γ-region, and it has been found that the formation of the texture in the surface layer can be made closer to that in the central portion, so that the formation of the container during cold rolling under high pressure can be performed. It has been found that this is a measure to improve the earring resistance of the steel sheet.

The hot rolling conditions for realizing this are the limiting conditions for hot rolling. The limiting conditions are the Ar ₃ transformation point to Ar
Rolling with a total draft of 50% or more in a temperature range of ( ₃ transformation point + 100 ° C) is lubricated and the friction coefficient is 0.2 or less. By applying lubrication at the time of rolling, when the friction coefficient between the roll and the rolled plate becomes 0.2 or less, the shear strain on the surface can be reduced. However, if the total rolling reduction in lubricating rolling is small, the formation of a texture that reduces in-plane anisotropy becomes insufficient, so it is necessary to apply at least 50% or more rolling in one pass or multiple passes. At this time, if the rolling temperature is too high, recrystallization and grain growth occur remarkably, and sharpening of the texture is prevented. Therefore, the upper limit was the Ar ₃ transformation point + 100 ° C. If the rolling is performed at a temperature lower than the Ar ₃ transformation point, the earring resistance of the steel sheet for containers is significantly deteriorated during high-pressure cold rolling. Therefore, the lower limit of the lubricating rolling temperature range is Ar _3.
It was a transformation point.

When the finishing temperature is lower than the Ar ₃ transformation point, the earring resistance of the steel sheet for containers is significantly deteriorated during high-pressure cold rolling. Therefore, the lower limit is set to the Ar ₃ transformation point.

[0015] In lubricating rolling, when rolling into a roll bite, if the rolling is performed in a lubricated state, there is a high possibility that poor biting or slippage will occur. It is common practice to not lubricate until it is taken. However, in this case, the properties of the non-lubricated part and the lubricated part differ in the longitudinal direction, which may hinder quality control. It is preferable to provide for rolling and continuously perform hot rolling. This measure ensures quality stability.

The present inventor has studied the effects of the cold rolling ratio and the skin pass rolling reduction on the earring ratio, and found that the earring ratio can be arranged by the total rolling reduction of the cold rolling and the skin pass rolling. According to the index, within the scope of the present invention, the earring rate is high when the total rolling reduction of the cold rolling and skin pass rolling is less than 90%, and conversely, even if it exceeds 95%, the deterioration of the earring resistance becomes apparent. I understood. on the other hand,
According to the conventional method, it was found that not only the optimum cold rolling reduction shifted to the low draft reduction side, but also the achievable earring rate was higher than that of the steel of the present invention.

[0017]

EXAMPLES Examples of the present invention will be described together with comparative examples.
In the examples, steels having the component compositions shown in Table 1 were used.
Hot rolling conditions (total rolling reduction of lubricating rolling performed under the condition of friction coefficient μ = 0.2 in the temperature range from Ar ₃ transformation point to Ar ₃ + 100 ° C.), total rolling reduction of cold rolling + skin pass rolling, and Table 2 shows the earring ratio when a two-piece can was manufactured. Other manufacturing conditions include a slab heating temperature of 12
The recrystallization treatment after cold rolling at around 00 ° C, winding temperature around 630 ° C, and continuous annealing of steel types A, B, and E at 680 ° C for 30 seconds and steel types C, D, and F at 750 ° C for 30 seconds. went.

Experiment Nos. 1, 2, and 2 satisfying the scope of the present invention.
Materials 3,5,7,9-14,16-18,20,21 show low earring rates. On the other hand, the materials of Experiment Nos. 22, 25 to 27 manufactured by the conventional method show a higher earring rate than the steel of the present invention. In the conventional method, as shown in the result of Experiment No. 27, the earring rate is reduced when the total rolling reduction of the cold rolling and the skin pass rolling is small, but in order to meet the market needs for thinner final sheet thickness, In order to secure the total draft of the cold rolling and the skin pass rolling, the thickness of the hot-rolled steel sheet must be reduced, and there is a disadvantage that productivity is reduced.

In the material of Experiment No. 4 rolled under the condition of friction coefficient μ ≦ 0.2 in the temperature range of Ar ₃ transformation point to Ar ₃ transformation point + 100 ° C. and the total rolling reduction is as low as 40%, the low earring rate is as follows. I could not achieve it. Experiment Nos. 6, 8, and 1 in which the total rolling reduction of the cold rolling and the skin pass rolling were out of the range of the present invention.
The 5,19 materials also showed high earring rates. With the materials of Experiment Nos. 23 and 24 in which the finishing temperature was lower than the Ar ₃ transformation point, a low earring rate could not be obtained.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

As described above in detail, according to the present invention, it is possible to supply a low-earring material while ensuring high productivity in response to the current and future market needs for thinner container steel plates. Therefore, it can be said that the present invention is an industrially valuable invention.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C22C 38/06 C22C 38/06

Claims (3)

[Claims] In the finish rolling in hot rolling of a slab of steel containing C ≦ 0.1%, N ≦ 0.01%, and Al = 0.005 to 1.0% by weight, In the temperature range from the Ar ₃ transformation point to the Ar ₃ transformation point + 100 ° C., rolling with a total draft of 50% or more is performed under lubrication and at a friction coefficient of 0.2 or less, and the finishing temperature is Ar _3.
After finish rolling at a temperature equal to or higher than the transformation point, and then performing normal pickling, cold rolling, recrystallization annealing, and skin pass rolling are performed under the condition that the total draft of the cold rolling and skin pass rolling is 90 to 95%. A method for producing a steel plate for a low earring container, comprising: 2. The method for producing a steel sheet for a low earring container according to claim 1, wherein the steel further contains B = 0.002-11N / 14 + 0.001% by weight. 3. The hot rolling process according to claim 1, wherein after the rough rolling, the leading end of the succeeding material is joined to the trailing end of the preceding material and subjected to finish rolling. Of producing a steel plate for a low earring container.