JPH10280095A - A steel plate for a two-piece container having excellent wrinkle resistance when neck diameter is reduced, and a method for producing the same. - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To be manufactured through drawing, ironing or elongating, which can avoid a decrease in productivity due to hip breakage in an annealing step and a generation of wrinkles when reducing the diameter of an opening of a can body. 2
Provided are a steel sheet used for a piece container and a method for manufacturing the same. SOLUTION: In weight%, C: 0.01-0.05%,
N: not more than 0.004%, (N existing as AlN) / (contained N)> 0.5, or B / N: 0.6 to
1.4, (N existing as BN) / (N existing as AIN) ≧ 0.5, and the proportion of MnS having a diameter of 0.25 μm or more among MnS having a diameter of 0.1 μm or more is 5.0%
A steel sheet characterized by the following: a steel sheet is manufactured at a slab heating temperature of 1100 ° C. or less in hot rolling.

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 sheet used as a material for cans produced by drawing, ironing and elongating processes represented by the production of two-piece cans, followed by reduction forming. . Steel plate manufacturing field,
An object of the present invention is to provide an ultra-thin container material having good neck wrinkle resistance and high productivity in the field of can making.

[0002]

2. Description of the Related Art In the field of manufacturing beverage cans, food cans, and the like, the production of containers called a two-piece can, in which a bottom and a body are integrally formed, is increasing. Usually, in the case of a two-piece can, after the drawing step, in order to obtain the required can height, a method of increasing the can wall height by ironing or stretching, as represented by a DI can or DTR can, is employed.

[0003] In these two-piece cans, since the material is hardened due to drawing, ironing and stretching, the diameter of the can opening is reduced in order to tighten the can lid on the opening of the manufactured can body. In (neck processing), there is a problem that wrinkles are significantly generated (deterioration of neck wrinkle resistance).

Generally, it is effective to lower the yield stress (0.2% proof stress when no yield point is observed) in order to improve the wrinkle resistance. Therefore, the C content is reduced. The use of ultra-low carbon steel is being considered. JP-A-5-287
In No. 443, hardening at the time of paint baking is suppressed by IF formation by adding Ti, and deterioration of neck wrinkle resistance is avoided by keeping the neck processed portion soft.

However, when an IF steel containing Ti or Nb is applied to a container material, fine carbonitrides and solid-solution Ti and Nb formed by adding Ti and Nb increase the recrystallization temperature of the steel sheet. The recrystallization annealing temperature after cold rolling must be higher than that of general aluminum killed steel. For thin materials with a thickness of 0.3 mm or less used for containers,
At the time of annealing, a steel plate called a heat buckle breaks and the production efficiency is reduced. For this reason, a steel sheet in which an increase in the recrystallization temperature is suppressed by applying an aluminum-killed steel containing no Ti or Nb is disclosed in JP-A-61-291922 and JP-A-61-26.
724 and so on. However, in these steel plates, no consideration is given to neck wrinkle resistance, which is a problem in thin container materials.

As a countermeasure against heat buckle, at the time of annealing, a steel sheet thicker than the target thickness is passed, and then re-rolled (2C
R) has been put to practical use to obtain the target plate thickness. This method is a convenient manufacturing method for compensating for the strength reduction due to the application of ultra-low carbon IF steel, which is originally soft, from the viewpoint of securing the strength of the can by work hardening. However, in addition to drawing, ironing and stretching, 2CR Processing also overlaps,
The neck wrinkle resistance is significantly deteriorated.

Further, in the steel developed so far, work hardening behavior of the material by strong working such as ironing and elongation when forming the can body of a normal 2P can, and deterioration of neck wrinkle resistance due to work hardening are taken into consideration. No effective means has been found to suppress the occurrence of wrinkles during diameter reduction in the material after being subjected to deep drawing and ironing or stretching, which is a two-piece container, and has not been done so far. .

[0008]

SUMMARY OF THE INVENTION The present invention has high drawability, and (1) lowers productivity due to breakage in the annealing step. (2) reduces wrinkles when the opening of the can body is reduced in diameter. An object of the present invention is to provide a steel plate used for a two-piece container which is manufactured through drawing, ironing or stretching, and a method for manufacturing the same.

[0009]

Means for Solving the Problems The present inventor examines the suppression of wrinkling during neck reduction after 2CR, drawing, ironing and stretching based on Ti-added ultra-low carbon steel having good deep drawing properties. Among them, it was found that the amount and size of nitrides such as AlN and BN and MnS are correlated with the generation of wrinkles. Although the mechanism is not clear, it is thought that it is related to neck wrinkle resistance mainly by affecting the work hardening behavior of the material by combining the crystal grain size after annealing and the formation of texture. Can be Cold rolling, especially after annealing,
In a series of processing in drawing, ironing, stretching, and reducing the diameter, the processing direction is different in each step, and it is considered that a so-called Bauschinger effect element is also affecting. The larger the crystal grain size, the higher the {100} plane strength and the lower the {111} plane strength of the texture, and the coarser and the lower the density of the precipitate, the better the wrinkle resistance.

Further, the present invention has been achieved in consideration of workability as a 2P can when annealing is performed in a relatively low temperature range in order to suppress heat buckle during annealing. Since the wrinkle resistance is affected by the amounts and sizes of nitrides such as AlN and BN and MnS, a more detailed study was conducted.
1 With the restriction of the ratio of N present and N present as nitride and N present as B nitride or the size distribution of MnS,
The result that wrinkle resistance can be determined was obtained. The gist of the present invention is that in a low-carbon aluminum-killed steel, N present as Al nitride and N present as B nitride
Even in annealing at a relatively low temperature range by limiting the ratio of the content N and the size distribution of MnS, 2CR, drawing,
An object of the present invention is to obtain a steel sheet capable of suppressing wrinkling during neck diameter reduction after ironing and stretching.

The specific means of the present invention are as follows. C: 0.01-0.05% by weight%, N: 0.00
(1) (N present as AlN) / (N contained) ≧ 0.
5 (2) B / N: 0.6 to 1.4, (N existing as BN) / (N existing as AlN) ≧ 0.5 (3) MnS having a diameter of 0.1 μm or more has a diameter of 0 .2
The ratio of those having a size of 5 μm or more is 5.0% or less. (4) As a most suitable manufacturing method, the slab heating temperature in hot rolling is set to 1100 ° C. or less to obtain a two-piece container steel sheet excellent in neck wrinkle resistance. be able to.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

First, the components will be described. All components are% by weight.

C forms cementite in steel when its content is high. When coarse cementite is exposed on the surface, the plating property of the steel sheet may be deteriorated. In addition, coarse cementite may be a starting point of cracking at the time of ironing, stretching, and flange forming in the manufacturing process of the container. Therefore, the upper limit of C is set to 0.05%. In particular, when a material having good ductility is required at the time of ironing, stretching, and flange forming, if the material is reduced to 0.03% or less, the characteristics can be significantly improved. However, a halfway reduction in the region of less than 0.01% not only raises the recrystallization temperature and makes it difficult to control aging due to the remaining solid solution C, but also causes the steel sheet to become soft and insufficient can strength. Therefore, the lower limit is set to 0.01%.

N is an important element in controlling the formation of nitride, which is an important requirement in the present invention. If it is contained in a large amount, a large amount of nitride is generated and the object of the present invention cannot be achieved, so the upper limit is made 0.004%. If the content is reduced to 0.002% or less by performing sufficient vacuum degassing,
The amount of nitride formed is reduced, and the target characteristics are improved.

B affects the nitride morphology and improves the neck formability. However, excessive addition degrades neck wrinkle resistance and raises the recrystallization temperature, necessitating an increase in the annealing temperature, and easily causing heat buckles. Since the main point is the ratio to N, the B / N is set to 0.6 to 1.4. B / N is preferably 0.8 or more.

An important condition in the present invention is the control of the type and amount of the chamber. In the case where B is not added, since the nitride is mainly AlN (N existing as AlN) / (content N) ≧
0.5. When B is added, it is necessary that (N existing as BN) / (N existing as AlN) ≧ 0.5. Here, N that is present as AlN means that the residue obtained when a steel sheet is dissolved in an iodine alcohol solution is dissolved in an aqueous sodium hydroxide solution, and A in the solution is dissolved.
This is a value obtained by analyzing the amount of 1 and converting this to the amount of N as the total amount of AlN. Also, N present as BN refers to a residue obtained when a steel sheet is dissolved in a bromine alcohol solution, phosphoric acid, nitric acid,
This is a value obtained by analyzing the amount of B in a mixed solution of perchloric acid, sulfuric acid, and the like, and converting this to the amount of N as the total amount of BN.

The size distribution of MnS is also an important factor for improving neck wrinkle resistance. In the present invention, the diameter is 0.
The ratio of MnS having a diameter of 0.25 μm or more to MnS of 1 μm or more is limited to 5.0% or less. This is a value obtained by observing the extracted replica obtained from the steel sheet by the SPEED method with an electron microscope, and measuring the diameter and number of precipitates in a visual field of a degree that there is no deviation. The size distribution can also be obtained by photographing the visual field and performing image analysis and the like. As described above, in order to improve neck wrinkle resistance, it is necessary to consider the work hardening behavior of the material including the Bauschinger effect. It is generally thought that fine precipitates have a large effect on the work hardening behavior of materials.However, the quantitative and qualitative analysis of fine precipitates cannot be said to be complete even with the latest measurement technology, and large errors may occur. Easy to occur. Therefore, in the present invention, the claims are specified in relation to the size distribution of coarse precipitates that can be expected to reduce the measurement error.

As described above, in order to control nitrides and sulfides, the heat history over the entire production process is important. The thermal history is greatly affected by the slab heating temperature during hot rolling. By limiting this temperature to 1100 ° C. or less, neck wrinkle resistance can be further improved. Although the cause is not clear, it is considered that fine nitrides or sulfides decrease and affect the work hardening behavior in the working steps after annealing.

As described above, in the manufacture of containers, a steel plate hardened by work hardening after 2CR rolling after annealing is sometimes used in order to impart strength to the container. According to this, the effect of improving deep drawability and neck wrinkle resistance can be obtained. In addition, the effect of the present invention is lost even if a reinforcing element such as Si, Mn, or P is added instead of 2CR to increase the strength of the steel sheet, and if an element is added to improve various properties such as corrosion resistance. Not something.

Usually, the steel sheet of the present invention is used as an original sheet for a surface-treated steel sheet, but the effect of the present invention is not impaired by the surface treatment. As the surface treatment for cans, tin, chromium (tin-free) or the like is usually applied. In addition, it can be used as a base plate for a laminated steel sheet to which an organic film, which has been used in recent years, is attached without impairing the effects of the invention.

[0022]

EXAMPLES The evaluation of the present invention was carried out on steel sheets having the respective components shown in Table 1 and subjected to ordinary hot rolling, cold rolling, annealing, and 5% 2CR for adjusting the hardness thereafter.

[0023]

[Table 1] For neck wrinkle resistance, draw ratio, ironing rate-
For the fixed cans, diameter reduction was performed by the same method as that used for ordinary cans, and the diameter reduction limit ratio according to the formula 1 was determined as the maximum diameter reduction amount at which wrinkling occurs. The higher the diameter reduction limit ratio, the greater the margin of the material in actual operation, so that the occurrence of wrinkles can be suppressed.

Diameter limit ratio = (initial diameter−wrinkle generation diameter) / (initial diameter) Equation 1 For the heat buckle, the heat buckle when a continuous annealing line is passed at a recrystallization temperature + 40 ° C. Judgment was made by the presence or absence of occurrence.

As is clear from Table 2, those manufactured within the scope of the present invention have good properties in all of neck wrinkle resistance and heat buckle resistance.

[0026]

[Table 2] FIG. 1 shows that the steel component is expressed by weight% C: 0.01-0.05%,
It shows the relationship between MnS size distribution and neck wrinkle resistance for steel sheets of N: 0.004% or less. Those having a MnS size distribution within the range of the present invention have good neck wrinkle resistance.

In FIG. 1, the influence of the MnS size distribution is stratified by the slab heating temperature. Even if the MnS size distribution is of the same level, the neck diameter reduction can be improved when the slab heating temperature is 1100 ° C. or less. Can be seen.

[0028]

As described above, according to the present invention, the rate of occurrence of wrinkles at the time of neck diameter reduction can be reduced. Further, since the steel of the present invention exhibits good characteristics even at an annealing temperature lower than that of the conventional material, generation of heat buckle can be avoided, and highly efficient production of ultra-thin container material becomes possible.

[Brief description of the drawings]

FIG. 1 is a view showing the relationship between MnS size distribution and neck wrinkle resistance of a steel sheet.

Claims (4)

[Claims] C .: 0.01 to 0.05% by weight,
N: not more than 0.004%, and (N present as AlN) / (contained N) ≧ 0.5, a two-piece container steel sheet excellent in neck wrinkle resistance. 2. C: 0.01 to 0.05% by weight,
N: 0.004% or less, B / N: 0.6-1.
4. A two-piece container steel sheet having excellent neck wrinkle resistance, wherein (N present as BN) / (N present as AlN) ≧ 0.5. 3. C: 0.01 to 0.05% by weight,
N: M containing 0.004% or less and having a diameter of 0.1 μm or more
A steel sheet for a two-piece container excellent in neck wrinkle resistance, characterized in that the proportion of nS having a diameter of 0.25 μm or more is 5.0% or less. 4. C: 0.01 to 0.05% by weight,
The slab containing N: 0.004% or less is cast, and the slab heating temperature in hot rolling is set to 1100 ° C or less, wherein the neck wrinkle resistance 2 according to claim 1, 2 or 3 is excellent. Manufacturing method of steel sheet for piece container.