KR20060096465A - Steel sheet for containers, and manufacturing method therefor - Google Patents

Abstract

Steel sheet and manufacturing method for manufacturing steel sheet for containers are provided. For example, the steel sheet (or at least a portion thereof) can include approximately, in terms of mass%, C: 0.0800% or less, N: 0.600% or less, Si: 2.0% or less, Mn: 2.0% or less, P: 0.10% or less, S: 0.05% or less, Al: 2.0% or less, and the remainder Fe. The sheet (or portion thereof) can be cold-rolled, and then the atmosphere, temperature, time, etc. of recrystallization annealing or subsequent heat treatment may be adjusted to control the change in N content in the steel, for example controlling the N content and hardness of the surface layer and mid-thickness layer to bring them within an appropriate range. The surface roughness can be 0.90 mum or less in terms of Ra, and PPI, which is the number of concavo-convex peaks per one inch of length, may be 250 or more.

Description

Steel plate for container and manufacturing method thereof {STEEL SHEET FOR CONTAINERS, AND MANUFACTURING METHOD THEREFOR}

The present invention relates to a steel sheet comprising a surface-treated steel sheet used in a metal container such as a beverage can and a method for producing the same.

This application is based on the priority of Japanese Patent Application No. 2003-409918, filed December 9, 2003, the contents of which are incorporated herein by reference.

Container steel sheets represented by beverage cans, food cans, and the like have used a material of 0.2 mm or less due to the ever-thinning thickness in order to reduce the manufacturing cost of various kinds of containers. Problems that occur when a container is manufactured using such an ultra-thin material include, for example, color tone, surface adhesiveness and weldability deterioration due to difficulty in controlling surface conditions.

As described in, for example, Japanese Patent Application Laid-Open Nos. Hei 11-197704, Hei 8-3781 and Hei 6-57448, it is well known that the surface conditions of steel sheets have a great influence on color tone, surface coating adhesion and weldability. to be. In addition, Japanese Patent Application Laid-open No. Hei 7-9005 describes a method for controlling surface roughness. In the above publication, there is a need to precisely control the manufacturing conditions in order to control the surface conditions, but the productivity decrease is obviously inevitable. In addition, the conventional control methods described in these publications do not always adequately improve the color tone, surface coating adhesion, and weldability of containers made using ultra-thin materials, which are one of the objects of the present invention.

One of the objects of the present invention is to solve the problems related to the color tone, surface coating adhesion and weldability of the container according to the surface state of the steel sheet in a container manufactured by using an ultra-thin sheet material by providing a special steel sheet and a method of manufacturing the same. It is another object of the present invention to control the surface state of the steel sheet and at the same time control any of both the surface layer and the mid-thickness layer of the material through the application of nitriding, which can prevent any special treatment that may reduce productivity. It is to provide an improvement by the state of.

Japanese Patent Application Nos. 2003-119381 and 2003-100720 describe a technique of nitriding steel sheets in a post annealing process and appropriately controlling nitriding conditions in the steel sheet thickness direction. Such a technique is provided for greatly improving the deformation resistance of the container without excessively reducing the ductility of the steel sheet, for example. While evaluating the weldability and the like of these materials, it was confirmed that there existed conditions in which the surface conditions of the steel sheet were satisfactory so that the color tone of the container, the surface coating adhesion, and the weldability could be greatly improved. These properties depend on the state of the surface of the steel sheet and, as previously practiced for this type of material, apply cathodic electrolysis, use surfactants, fine control of Cr oxides, special rolling with finely controlled precision rolls, etc. Even if this is not done, problems are brought about in containers made of ultra-thin steel sheet materials.

For example, when nitriding is performed after cold rolling to increase the nitrogen content in the steel, simply producing different surface hardness may not generally improve the color tone, surface coating adhesion or weldability of the can. However, exemplary embodiments of the present invention can improve color tone, surface coating adhesion, and weldability of cans made of ultra-thin materials by appropriately controlling the steel components, nitriding conditions, and post-nitriding steel sheet state. In addition, exemplary embodiments of the steel sheet according to the present invention and corresponding manufacturing methods show preferable conditions for achieving these exemplary advantages.

An exemplary embodiment of the steel sheet according to the present invention is a container steel sheet having a plate thickness of 0.400 mm or less, C: 0.0800% or less, N: 0.600% or less, Si: 2.0% or less, Mn: 2.0% or less based on mass% , P: 0.10% or less, S: 0.05% or less and Al: 2.0% or less, and (N content of 1/8 thick surface layer)-(N content of 1/4 thick mid-thick layer) is 10 ppm. (N content of the 1/8 thickness surface layer) is 20000 ppm or less, surface roughness is 0.90 μm or less based on Ra, and the number of uneven peaks per inch length is PPI of 250 or more.

Another exemplary embodiment of the steel sheet according to the present invention is a container steel sheet having a thickness of 0.400 mm or less, which is C: 0.0800% or less, N: 0.600% or less, Si: 2.0% or less, Mn: 2.0% based on mass% P: 0.10% or less, S: 0.05% or less, and Al: 2.0% or less, (steel sheet cross section average Vickers hardness of 1/8 thickness surface layer)-(steel sheet cross section of 1 / 4-thick intermediate-thickness layer) Average Vickers hardness)> 10 points or (average Vickers hardness of steel sheet cross section of 1/8 thick surface layer)-(average Vickers hardness of steel sheet cross section of 1/4 thick mid-thickness layer)> 20 and the surface roughness is 0.90 μm based on Ra PPI, which is less than and equal to the number of uneven peaks per inch, is characterized by being 250 or more.

Exemplary embodiments of the steel sheet according to the present invention may further contain one or two or more of Ti: 0.05% or less, Nb: 0.05% or less, and B: 0.015% or less on a mass% basis. In the average component of the 1 / 4-thick middle-thickness layer, the steel sheet is made of Ti: 4 × C + 1.5 × S + 3.4 × N or more, Nb: 7.8 × C + 6.6 × N or more and B: 0.8 × N or more It may contain one or more than two. In addition, the steel sheet may further contain one or two or more of Cr: 20% or less, Ni: 10% or less, and Cu: 5% or less. In addition, the steel sheet may further contain 0.1% or less of Sn, Sb, Mo, Ta, V, and W in total by mass.

An exemplary embodiment of the method for manufacturing a steel sheet for a container according to the present invention is a method for producing a steel sheet for a container having a thickness of 0.400 mm or less, which is C: 0.0800% or less, N: 0.0300% or less, Si: 2.0% based on mass%. Cold rolling of a steel plate containing Mn: 2.0% or less, P: 0.10% or less, S: 0.05% or less, Al: 2.0% or less, and residual Fe and unavoidable impurities, simultaneously with recrystallization annealing or after recrystallization annealing Nitriding is carried out such that the average content increase (mass%) of N is 6000 ppm or less throughout the thickness direction of the steel sheet, and [the N concentration increase of the 1/8 thickness surface layer] is 20000 ppm or less, and [1 / 8 increase in N content (mass%) of the surface layer] / [increase in N content (mass%) of the 1/4 thickness mid-thickness layer] is 2.0 or more and the surface roughness is 0.90 μm or less based on Ra. PPI, the number of uneven peaks per inch, And that is characterized.

Another exemplary embodiment of the method for manufacturing a steel sheet for a container according to the present invention is a method for producing a steel sheet for a container having a plate thickness of 0.400 mm or less, which is C: 0.0800% or less, N: 0.0300% or less, Si: 2.0 on a mass% basis. Cold rolling a steel sheet containing% or less, Mn: 2.0% or less, P: 0.10% or less, S: 0.05% or less, Al: 2.0% or less, and residual Fe and unavoidable impurities, simultaneously with recrystallization annealing or recrystallization annealing Nitriding is then performed such that an increase in N content across the thickness of the steel sheet is less than or equal to 6000 ppm, (steel plate cross section average Vickers hardness of 1/8 thick surface layer) − (1/4 thick mid-thickness layer). Steel plate cross section average Vickers hardness)> 10 points or (steel plate cross section average Vickers hardness of 1/8 thick surface layer)-(steel plate cross section average Vickers hardness of 1/4 thick mid-thickness layer)> 20 and make the surface roughness Ra 0.90 μm or less And a PPI of 250 or more, the number of uneven peaks per inch length.

Exemplary steel sheet components may further contain one or two or more of Ti: 0.05% or less, Nb: 0.05% or less and B: 0.015% or less on a mass% basis. One of Ti: 4 × C + 1.5 × S + 3.4 × N or more, Nb: 7.8 × C + 6.6 × N or more and B: 0.8 × N or more, based on the average component of the quarter-thick middle-thickness layer, or More than one may be included.

Other exemplary steel sheet components may further contain one or two or more of Cr: 20% or less, Ni: 10% or less and Cu: 5% or less on a mass% basis. In addition, the steel sheet component may further contain 0.1% or less of Sn, Sb, Mo, Ta, V, and W in total based on mass%. In order to perform nitriding at the same time as recrystallization annealing or after recrystallization annealing, the steel sheet is maintained at a temperature of 550 to 800 ° C. in an ammonia gas atmosphere of at least 0.02% for at least 360 seconds for at least 1 second, so that after the nitriding, the steel sheet is maintained in a high temperature range of at least 550 ° C. The product of temperature (° C) and time (seconds) in the thermal history can be made 48000 or less, or the average cooling rate can be made from 550 ° C to 300 ° C to 10 ° C / sec or more. The re-cold rolling reduction rate before or after recrystallization annealing and nitriding can be 20% or less.

The steel sheet for a container according to an exemplary embodiment of the present invention and a manufacturing method thereof can improve the color tone, surface coating adhesion and weldability of the container while preventing the complicated process after nitriding and the decrease in productivity due to such a complicated process. Thus, it is possible to maintain productivity as high as that of conventional steel sheets and methods that perform complex processing to produce steel sheets for ultra-thin containers and to provide industrially useful effects.

1 is an exemplary profile view of a quarter thickness surface layer and a 1/8 thickness surface layer of a container steel sheet according to an exemplary embodiment of the present invention.

Fig. 2 shows the layer of Fig. 1 in which the Vickers hardness measurement position is provided on a steel sheet.

Hereinafter, the steel sheet component used in the exemplary embodiment of the present invention will be described. Steel components will be indicated on a mass% basis.

The particular upper limit of the C content before annealing is preferably such as to prevent workability deterioration and C is set to 0.0800%. For example, an upper limit is 0.0600% or less, More preferably, it is 0.0400% or less.

A steel sheet according to an exemplary embodiment of the present invention in which the content of N having properties similar to C may be increased by nitriding after annealing may have a low C content, which is preferable in terms of ensuring strength and the like. Strength can be ensured at C: 0.0050% or less, and 0.0020% or less is likewise acceptable. At 0.0015% or less, it is possible to produce super ductile materials which, depending on the balance with the amount of nitride, deviate from the standard for common container materials.

As in C, the upper limit of the N content before annealing is preferably such as to prevent workability deterioration, and N is set to 0.0300%. N: 0.0200% or less may be preferable, N: 0.0150% or less may be more preferable, N: 0.0100% is even more preferable, N: 0.0050% or less may also be preferable, and N: 0.0030% is also preferable. As described below, N contained by nitriding after annealing provides a beneficial effect in terms of color tint, surface coating adhesion and weldability of the can, and has a different effect than N present before annealing.

Si may be added to adjust the strength of the vessel. Excess Si can reduce workability and coating properties, and therefore it is preferably at most 2.0%. In the steel according to the present invention, Si reacts with N penetrating into the steel by nitriding to form nitrides at grain boundaries, causing embrittlement cracking and inhibiting the effects of the present invention, thus limiting Si to 1.5% or less or 1.0% or less. It may be desirable to.

Mn may be added to adjust the strength. Excess Mn lowers workability and is therefore set to 2.0% or less.

P may be added to adjust the strength. Excess P not only lowers workability but also hinders nitriding of the steel sheet, and therefore P is preferably set to 0.10% or less.

S deteriorates high temperature ductility and hinders casting and hot rolling, so it is set to 0.05% or less.

Al is an element that can be added for deoxidation. Excess Al makes casting more difficult and causes damage such as an increase in surface defects, so Al can be set to 2.0% or less.

Hereinafter, the effect by the element other than the above-mentioned basic element considered in the steel plate for containers, and its control are demonstrated.

Ti increases the recrystallization temperature of the steel sheet and lowers the pass-through of the ultra-thin steel sheet, which is one of the objects of the present invention. Therefore, Ti can be 0.050% or less. In general use which does not require high r value, it is not necessary to add Ti, Preferably it is 0.03% or less, More preferably, it is 0.02% or less.

Nb has a similar effect to Ti, and increases the recrystallization temperature of the steel sheet and greatly reduces the annealing and passing property of the ultra-thin steel sheet, which is one of the objects of the present invention. Therefore, Nb becomes like this. Preferably it becomes 0.050% or less. In general use which does not require especially high r value, it is not necessary to add Nb so much, Preferably it is 0.03% or less, More preferably, it is 0.01% or less.

When B is added to a steel sheet according to an exemplary embodiment of the present invention containing about 0.01% or more of Ti and Nb, the recrystallization temperature of the steel sheet may be increased, and the annealing through-holes of the ultra-thin steel sheet, which is one of the objects of the present invention, are greatly increased. Degrades. On the other hand, when the content of Ti and Nb is low, there is almost no adverse effect associated with it, and the recrystallization temperature is substantially lowered to allow recrystallization annealing to be performed at low temperature. In addition, since B has an effect of improving annealing and passing through, B can be actively added. However, when excessively added, the crack of the slab (including bloom, billet and the like) becomes prominent during casting, so the upper limit thereof is preferably 0.015%. In order to lower the recrystallization temperature and improve the annealing pass-through, it is sufficient to make the relationship to N before nitriding to B / N = 0.6 to 1.5.

In addition, in order to increase the effect by maintaining Ti in solid solution until nitriding and forming Ti nitride especially on the steel sheet surface due to N penetrating into the steel sheet from the surface during nitriding, the average component of the quarter-thick middle-thickness layer is referred to. Therefore, it is preferable to include at least one of Ti: 4 × C + 1.5 × S + 3.4 × N or more, Nb: 7.8 × C + 6.6 × N or more, and B: 0.8 × N or more. As such, the N content of the surface layer of the present invention varies greatly before and after nitriding and thus the above-described values change, so that the average component of the quarter-thick middle-thickness layer can be specified.

According to an exemplary embodiment of the present invention, it is possible to specify the value of the final steel sheet after nitriding by using the average component of the mid-thickness layer having a small change due to nitriding. In addition, in order to impart properties not specified by the exemplary embodiments of the present invention such as increased corrosion resistance, adding Cr: 20% or less, Ni: 10% or less and Cu: 5% or less is by no means Does not impair the effect In particular, Cr dissolved in steel before nitriding has the effect of forming fine Cr nitrides on the surface of steels, especially steel sheets, in combination with N, which has penetrated into the steel sheet due to nitriding, thereby using these nitrides to increase the effect of the present invention. Makes it possible. For this purpose, it is preferable to add 0.01% or more of Cr. However, Cr also increases the recrystallization temperature of the steel sheet and when the addition amount is excessive, it can greatly reduce the annealing through-holes of the ultra-thin steel sheet which is one of the objects of the present invention. In order to prevent the annealing sheet | seat fall off by the increase of recrystallization temperature, it is preferable to restrict the addition amount of Cr to 2.0% or less. At 0.6% or less, the increase in the recrystallization temperature can be suppressed to the extent that no substantial problem arises.

In addition, up to 0.1% of Sn, Sb, Mo, Ta, V, and W in total may be included to impart properties that are not explicitly specified in the exemplary embodiments of the present invention without any degrading effect of the present invention.

Among the above-mentioned elements, P, B, Sn and Sb can lower the efficiency of nitriding, which is an important condition of the present invention under certain conditions, and it is therefore desirable to consider limiting its maximum content in balance with nitriding conditions.

Hereinafter, with reference to Figure 1 will be described the division in the steel plate thickness direction that can be used to describe an exemplary embodiment of the present invention.

For example, " 1/8 thickness surface layer " represents the corresponding area in FIG. Further, " a quarter thickness mid-thickness layer " represents the corresponding area in FIG. Regions corresponding to “1/8 thickness surface layers” may be present on both sides of the steel sheet, and in accordance with exemplary embodiments of the present invention, at least one side of such surfaces may be applied to all materials within the scope of the present invention. The nitrogen distribution or hardness distribution between the top and the bottom can be altered not only by various types of treatment after nitriding but also by the nitriding method and the surface treatment before nitriding. Exemplary embodiments of the invention also apply to steel sheets having other top and bottom surface layers. This is because it is possible to achieve color tone, surface coating adhesion and weldability, for example, only on one surface, which is an object of the present invention.

The "N content in the 1/8 thickness surface layer" can be determined by analysis after polishing the steel sheet to leave only the target area. Likewise, in the case of "N content of the quarter-thick middle-thickness layer", the analysis value obtained by the analysis after polishing the steel sheet to leave only the target area is used.

For "steel plate cross section average Vickers hardness of 1/8 thick surface layer" and "steel plate cross section average Vickers hardness of 1/4 thick mid-thickness layer", small enough to allow proper evaluation of the hardness distribution in the thickness direction of the steel sheet cross section. Vickers hardness values measured at various locations in the thickness direction using loads leaving indentations can be used. The measurement positions in the thickness direction can be set to be obtained at at least two measurement positions within 1/8 thickness and are spaced at equal intervals in the thickness direction. Then, the average of the values measured in each area is judged as the respective cross-sectional average hardness. Although the distance between the indentations requires attention, in general, in Vickers hardness determination, a suitable distance from the nearest indentation may be provided depending on the size of the indentation point. To this end, as shown in Figure 2, by displacing at an appropriate distance along the direction of the steel sheet to maintain an appropriate distance between the indentation point. In addition, the influence of the steel plate surface in the region close to the steel plate surface may be a problem, in which case the measured value of the cross-sectional hardness obtained on the equally laminated and bound steel sheet will be used.

"Steel sheet cross section maximum Vickers hardness of 1/8 thick surface layer" and "Steel sheet cross section maximum Vickers hardness of 1/4 thick mid-thickness layer" described above "Steel sheet cross section average Vickers hardness of 1/8 thick surface layer" and "1 / 4 hardness represents the maximum hardness for each region in the hardness distribution obtained from "steel plate cross section average Vickers hardness of medium-thickness layer".

Analytical values and hardness distributions generally exhibit some degree of error and deviation due to local segregation and structural non-uniformity of the constituent elements, and can be determined by several attempts at an appropriate amount sufficient to exclude outliers.

Hereinafter, the state of nitriding, which is an important condition of the exemplary embodiment of the present invention, including the increase of N due to nitriding and the N content after annealing will be described.

An exemplary embodiment according to the invention presupposes that a difference in N content can be produced between the surface layer portion and the mid-thickness layer portion of the steel sheet. This difference is specified as (N content of 1/8 thickness surface layer) minus (N content of mid-thickness layer of 1/4 thickness). This value can be set to 100 ppm, preferably 200 ppm, more preferably 300 ppm, even more preferably 500 ppm, more preferably 1000 ppm, more preferably 2000 ppm, and still more Preferably 3000 ppm. If the difference is smaller than this, not only the color tone, surface coating adhesion and weldability, which are the objectives of the present invention, are achieved, but the quality of the material is substantially changed due to the difference in the nitriding content, so that the quality of the material in the coil and between the coils in actual manufacturing is changed. It can lead to significant deviations. In addition, the upper limit of (N content of the 1/8 thickness surface layer) may be set to 20000 ppm. The N content of the outermost layer becomes more than 20000 ppm under the normal conditions of the exemplary embodiment of the present invention, and on average 20000 ppm can be specified for the 1/8 thickness surface layer since it is easy to cause surface problems such as plating defects. Based on this situation, the upper limit of (N content of the 1/8 thickness surface layer) is preferably set to 6000 ppm and more preferably to 3000 ppm.

The final hardness difference between the surface layer and the mid-thickness layer of the steel is another prominent feature of the exemplary embodiment of the present invention. This difference can be specified as the steel sheet cross section maximum Vickers hardness of the 1/8 thickness surface layer minus the steel sheet cross section maximum Vickers hardness of the 1/4 thickness mid-thickness layer, the value being at least 10 points, preferably at least 30 points, More preferably, it is 90 points or more. If the difference is smaller than this value, color tone, surface coating adhesion and weldability which are some objects of the present invention cannot be obtained. Further, the hardness difference between the surface layer of the steel material and the mid-thickness layer can be specified as (steel plate cross section maximum Vickers hardness of the 1/8 thickness surface layer)-(steel plate cross section maximum Vickers hardness of the 1/4 thickness medium-thickness layer). In this case, this value is 20 points or more, Preferably it is 60 points or more, More preferably, it can be 120 points or more.

As described above, in order to control the N content and the hardness of the surface layer as compared to the values of the mid-thickness layer, the state before nitriding must also be appropriate. For example, the N content of the steel sheet before nitriding is preferably 0.0300% as described above. If a large amount of N is previously contained before nitriding, it may be difficult to produce the effects of the present invention. In addition, in order to increase the N content by nitriding while preventing workability deterioration, the upper limit of the N content after nitriding needs to be set to N: 0.600% or less. The N content is preferably N: 0.300% or less, more preferably N: 0.150% or less, even more preferably N: 0.100% or less, still more preferably N: 0.050% or less, still more preferred. N: 0.030% or less. However, a high N content is desirable not only to further cure the region cured by nitriding but also to stably obtain the effect of nitriding.

In addition, according to an exemplary embodiment of the present invention, the N increase does not need to extend over the entire steel sheet thickness. For example, it is preferable to efficiently increase the N content of the surface layer portion so that the absolute value of (increase N of the 1/8 thickness surface layer) / (increase N of the 1/4 thickness mid-thickness layer) becomes 2.0 or more. The reason for specifying the absolute value here is that the analytical value of the N content of the intermediate-thickness layer, whose components hardly change, may in some cases be smaller than the value for the overall steel thickness due to various types of errors and variations in the measurements. Because. This coefficient becomes like this. Preferably it becomes 3.0, More preferably, it becomes 5.0 or more, More preferably, it becomes 10 or more.

Hereinafter, the control of the surface state which is the greatest effect of this invention is demonstrated. Although there are various possibilities to describe the surface state, exemplary embodiments of the present invention are described based on surface roughness Ra and PPI, the number of uneven peaks per inch length. There is no particular limitation on the determination method, and conventional methods such as a tracker and a laser method, two-dimensional and three-dimensional measurement, and the like can be used.

Exemplary embodiments of the invention can be distinguished in that Ra is 0.90 μm or less and PPI is 250 or more. If Ra is too high or PPI is too low, the characteristics such as color tone, surface coating adhesion, weldability, etc., which are the object of the present invention, will be deteriorated due to the surface irregularities. Ra is preferably 0.80 µm or less, more preferably 0.70 µm or less, even more preferably 0.60 µm or less, and still more preferably 0.50 µm or less. In addition, the PPI is preferably at least 300, still preferably at least 350, even more preferably at least 400, even more preferably at least 450, still more preferably at least 500. Qualitatively, it is preferable that unevenness | corrugation of uniform height exists in high density. There is no special lower limit value specified for Ra, which can be controlled to a value suitable for the purpose based on nitriding conditions, temper rolling conditions and the like. However, the lower limit of Ra preferably does not include 0 and may be substantially 0.02 μm or more. The upper limit of the PPI is also not specified, and may be controlled based on nitriding conditions, temper rolling conditions and the like depending on the purpose. Basically, the more N is segregated so that the N concentration is closer to the surface, the more Ra will be and the higher the PPI will be. One exemplary method of segregating N towards the surface is to perform nitriding for a relatively short time in an ammonia atmosphere. Surface conditions can be influenced by already existing steel components and grain diameters, annealing temperatures and cold rolling conditions, as well as rolling reduction during temper rolling, number of passes and roughness of rolls, plating conditions when performing plating, and the like. Thus, although it is difficult to limit the surface state to a specific range, basic control is the same as that performed conventionally and can be achieved without problems by those skilled in the art after several tests.

Conventionally, in order to control the roughness in this manner, since the roughness largely depends on the adhesion state of the plating to the surface of the steel sheet, etc., the roughness of the roll is transferred or the morphological control of the film is precisely performed during temper rolling after annealing. It is also possible to perform morphological control based on surface coatings such as special electrolytic treatment or plating of metals or other materials. However, exemplary embodiments of the present invention may be advantageous for manufacturing operations by being hardly affected by such conditions. For example, in connection with the unevenness of the roll, conventionally, since the unevenness of the roll is worn out by rolling, the roll repair needs to be frequently performed by repositioning or uneven processing of the roll in order to keep the unevenness of the steel sheet surface within the desired range. Excessive burden on productivity and labor, such as production interruption. On the other hand, according to the present invention, the surface state of the steel sheet is hardly affected by the method of temper rolling, and it is not necessary to manage the uneven wear of the roll, so that mass production can be performed. In addition, with regard to the form of metal plating, it becomes possible to uniformly disperse a very fine plated film of a uniform form without particularly controlling the plating conditions and the like. It is not clear why the roughness of the steel sheet surface is hardly affected in this way by the technique and conditions for producing the roughness, but it is believed that the cause of the roughness is due to the steel sheet itself. The mechanism of this technique will now be described.

For example, a large difference in N concentration and a final hardness difference can be formed between the surface of the steel and the mid-thickness layer according to an exemplary embodiment of the present invention. In particular, the N concentration of the outermost surface layer of the steel sheet is considered to contain a high N concentration which is generally not obtained in steel materials obtained by conventional decomposition action. On the other hand, the middle-thickness layer of the steel sheet is as soft as a conventional steel sheet. When such a sheet is rolled, many fine cracks are formed in the surface layer, resulting in poor ductility, which directly and indirectly affects the unevenness of the steel sheet surface specified by another exemplary embodiment of the present invention and which is essential for a container steel sheet. It is thought to exert. In this case, the performance of the steel sheet of the present invention to form the unevenness generated by the light treatment inherent in the steel sheet itself, not the treatment condition, is due to the ductility difference between the surface layer portion and the middle-thickness layer portion of the steel sheet and indirectly due to the hardness difference. It is possible to assume that it is due. Therefore, it may be desirable to appropriately control the hardness of the steel sheet in the thickness direction in the steel sheet according to an exemplary embodiment of the present invention.

The thickness of the cured layer in the surface layer, the quality of the material, in particular the ductility of the surface layer portion, the ratio between the surface layer and the mid-thickness layer portion, etc., can affect the unevenness of the surface layer which is desirable according to the present invention. Thus, when there are no excessive conditions deviating from the present invention such as uniform nitriding over the entire sheet thickness, excessive increase in the surface layer nitride concentration or formation of excessive Ti nitride due to the Ti content of the steel sheet, and the steel sheet is manufactured under the conditions according to the present invention. The roughness of the surface of the steel sheet may be in a preferred range.

In general, since temper rolling is generally carried out to a large extent after annealing, the desired surface condition can be obtained in a steel sheet according to an exemplary embodiment of the present invention without performing special control, but through conventional continuous annealing lines Temper rolling is not considered essential because bending of the hearth roll when passing through the steel sheet causes fine cracks in the steel sheet surface.

When the steel sheet itself has the ability to form fine uniform unevenness on the surface in this manner, the coating can be fine and uniformly adhered and according to the unevenness of the steel sheet even if fine control such as coating conditions is not performed in the coating process The preferred form and distribution are shown.

Hereinafter, the nitriding conditions will be described in detail. In terms of productivity, the nitriding treatment according to an exemplary embodiment of the present invention may be advantageously performed at the same time as recrystallization annealing after cold rolling or continuously after recrystallization annealing after recrystallization annealing, but is not limited now. With regard to the annealing method, both batch and continuous annealing can be used. However, continuous annealing is advantageous in view of the productivity of the nitriding treatment and the uniformity of the material quality in the coil of the nitrided material. It may also be disadvantageous that the nitriding time and subsequent thermal history become too long, in order to obtain great benefits by controlling the material quality of the steel plate surface and the mid-thickness layer as specified by the exemplary embodiment of the present invention, In this connection it is likewise preferred that at least the nitriding treatment can be carried out with a continuous annealing plant. Unless otherwise specified, continuous annealed steel sheets are considered to be used. Performing continuous annealing by controlling the in-furnace atmosphere of the zone to perform recrystallization in the first place and nitriding in the second place has particular advantages such as productivity, uniformity of material quality and ease of nitriding state control.

In addition, when nitriding treatment is performed before recrystallization is completed, recrystallization is suppressed, so that a steel sheet which is not recrystallized may be left, which may significantly degrade workability, so attention is required. This boundary is complicatedly determined by the steel component, nitriding conditions, recrystallization annealing conditions, etc., but it is easy for those skilled in the art to find a condition in which an unrecrystallized material is not left through appropriate tests. Nitriding treatment should be determined by considering not only the increase in N content of the steel sheet due to nitriding, but also the steel sheet components and recrystallization annealing conditions, as well as the N diffusion from the steel sheet surface to the inner region and the hardness change along the cross section of the sheet. Hue, surface coating adhesion and weldability, which are the objectives of the present invention, cannot be obtained when the user uses only the material quality determined by Rockwell hardness as an indicator. In practical application, such conditions need to be determined with reference to the appropriate number of tests, but the basic concept is as follows and thus exemplary embodiments of the present invention can be specified.

For example, nitriding should be carried out at a board temperature of 550-800 ° C. This can be achieved by setting the nitriding atmosphere to such a temperature as in conventional annealing and passing the steel sheet through this atmosphere so as to keep the temperature of the steel sheet in this range and simultaneously performing nitriding. Alternatively, the nitriding atmosphere can be set to a low temperature and nitriding can be performed by inserting a steel sheet heated to this temperature range into this atmosphere. When the nitriding crisis is raised to this temperature, the steel sheet nitriding efficiency is reduced in some cases due to the change and deterioration of the atmosphere not related to the nitriding of the steel sheet, and thus can be specified at 550 to 750 ° C. Preferably it is 600-700 degreeC, More preferably, it is 630-680 degreeC.

The nitriding atmosphere may contain 10% or more, preferably 20% or more, more preferably 40% or more, even more preferably 60% or more nitrogen gas in a volume ratio, essentially 90% or less, preferably 80% or less, more preferably 60% or less, even more preferably 20% or less of hydrogen gas may be contained, and 0.02% or more of ammonia gas may be essentially included. The remainder can be oxygen gas, hydrogen gas, carbon dioxide gas, hydrocarbon gas and various inert gases. In particular, ammonia gas is very efficient at increasing nitriding efficiency and enables to obtain a certain amount of nitriding within a short period of time, thereby preventing N diffusion into the steel plate mid-thickness and providing a desirable effect in the exemplary embodiment of the present invention. . In order to achieve such an effect, 0.02% or less is also appropriate, but preferably 0.1% or more, more preferably 0.2% or more, even more preferably 1.0% or more, still more preferably 5% or more. At 10% or more, an appropriate effect can be obtained by nitriding shorter than 5 seconds. In addition, with respect to gas ratios other than ammonia, in particular, when nitrogen gas and hydrogen gas are the main gas components, it is preferable in terms of nitriding efficiency to make the volume ratio of (nitrogen gas) / (hydrogen gas) to 1 or more. Making the volume ratio above 2 also allows for more efficient nitriding. In addition, conventional annealing is carried out under conditions such that nitriding generally does not occur in an atmosphere consisting mainly of nitrogen gas and hydrogen gas, but those skilled in the art will be aware of the dew point as well as by incorporation of ammonia gas as described above. Changes, incorporation of trace gases, changes in gas proportions, etc., may also be changed to an atmosphere where nitriding occurs through appropriate testing. Exemplary embodiments of the present invention encompass an atmosphere that can be detected based on the current analytical capability of nitriding to occur due to at least annealing, including annealing.

The retention time in the nitriding atmosphere is generally not limited, but due to the nitriding by the diffusion of N in the steel sheet while considering the steel sheet thickness of up to 0.400 mm in relation to the high temperature condition of 550 ° C. or higher of the present invention and the N being maintained in the nitriding atmosphere The upper limit is set to 360 seconds in consideration of the fact that when N penetrating from the steel plate surface reaches the steel plate mid-thickness layer at the same time, it is not possible to obtain N distribution or hardness distribution which is the object of the present invention. In addition, even when the nitriding efficiency is improved, one second is required to obtain the amount of nitriding required by the present invention and nitrogen and hardness distribution in the steel plate thickness direction. The retention time is preferably 2 to 120 seconds, more preferably 3 to 60 seconds, even more preferably 4 to 30 seconds, still more preferably 5 to 15 seconds. Nitriding efficiency should be increased by increasing the ammonia concentration or the like when controlling for a short period of time.

The thermal history of the steel sheet after nitriding is also important for controlling the nitrogen distribution in the steel sheet thickness direction. Considering the thickness of the steel sheet as a target and the nitrogen diffusion in the steel, a long retention time at a high temperature will not be desirable.

However, it is also possible to make the effect of the exemplary embodiment of the present invention more pronounced by making the nitrogen distribution appropriately through heat treatment. For this purpose, the hysteresis in the temperature range of 550 ° C. or higher is important, and the product of temperature (° C.) and time (seconds) in this temperature range is preferably 48000 or less. This corresponds to 80 seconds at 600 ° C. or 60 seconds at 800 ° C., but if the temperature changes continuously, the effect is to record the change in temperature in the time division of approximately 5 seconds and the temperature (° C.) in each time division. It can be appropriately evaluated by finding the sum of the products of time (seconds). Preferably it is 24000 or less and more preferably 12000 or less, and generally, nitriding conditions are preferably set such that the nitrogen distribution in the steel is substantially determined after nitriding is completed.

In addition to the thermal history described above, the cooling rate after nitriding can greatly affect the effects of the present invention. For example, when the nitrogen distribution is hardly changed, the cross-sectional hardness distribution difference can be observed since the formation state of the nitride changes significantly during the cooling process even at low temperatures and short periods of time. When the average cooling rate at 550 ° C. to 300 ° C. or more is 10 ° C./sec or more, nitrogen is more dissolved and the surface layer portion is harder than the intermediate layer, and color tone, surface coating adhesion, and weldability are improved. Preferably it is 20 degree-C / sec or more, More preferably, it will be 50 degree-C / sec or more. However, it is desirable to control with regard to excessively remaining solid nitrogen, since this may cause aging problems depending on the application.

In the production of the steel plate for thin containers, re-cold rolling may be performed after recrystallization annealing for hardness control and steel sheet thickness control. The range of the reduction ratio used at this time is from 1% close to the reduction ratio in the skin pass performed for shape control to 50% or more such as the reduction ratio in cold rolling. According to an exemplary embodiment of the present invention, the same type of re-cold rolling as in conventional steel sheets can be used. If shape correction or the like is not required, it is also possible not to perform re-cold rolling at all, but for the purpose of shape correction or the like, re-cold rolling is performed in the range of about 0.5% to 2.5%. The steel sheet of the present invention is generally also subjected to rolling in this range. When a high re-cold reduction rate of more than 2.5% is used to achieve high strength and thin thickness, special operations or controls must be applied to the steel sheet of the present invention. For example, when re-cold rolling is applied to the steel of the present invention having a hard surface layer and a soft medium-thick layer, only the soft medium-thick layer preferentially undergoes work hardening and is provided in the present invention to increase the deformation resistance. The preferential curing of the surface layer alone may be lost, but the opposite is true. That is, in the steel sheet according to the exemplary embodiment of the present invention, when the re-cold reduction ratio is in the general range, the re-cold rolling is the surface and intermediate formed on the steel sheet of the present invention by preferentially hardening the hard surface layer portion with a high N content. Make the hardness difference between the thickness layers more pronounced. This is because the surface layer is more susceptible to work hardening due to the large amount of dissolved N content and nitride, while the mid-thickness layer is suppressed by the surface layer and therefore cannot be preferentially deformed and does not selectively harden significantly beyond the hardening of the surface layer. to be. However, when the re-cold reduction rate is significantly increased, the steel sheet itself is sufficiently hardened so that an appropriate can strength can be obtained without controlling the material quality distribution in the thickness direction of the steel sheet, unlike in the prior art of the present invention, but at the same time the surface roughness The control of 를 reduces the effect of improved surface properties and weldability, and therefore has little meaning to increase the re-cold reduction rate beyond the normally applied range. In addition, since the workability decreases as the re-cold reduction rate is high, improper application of the high pressure reduction rate should be prevented. On the basis of this, when re-cold rolling is performed on the steel of the present invention, the reduction ratio is preferably increased to about 70%.

In order to produce a hard material, when re-cold rolling is carried out, a higher re-cold reduction rate is preferred, preferably at least 6%, more preferably at least 10%, even more preferably at least 20%, further Preferably it is 30% or more, and still more preferably 40% or more. On the other hand, the low rolling reduction of re-cold rolling is preferred from the viewpoint of ductility, preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, even more preferably 20% And still more preferably 10% or less, and still more preferably 5% or less. In particular, considering the effect of re-cold rolling from the initial stage to the intermediate stage where the surface layer preferentially hardens and greatly increases the deformation resistance, the reduction ratio is preferably 0.8 to 45%, more preferably 4 to 35%, Even more preferably 6 to 30%, still more preferably 8 to 25%. In terms of productivity, the recrystallization annealing and nitriding may be performed after nitriding in a process in which recrystallization annealing and nitriding are performed continuously. However, when recrystallization annealing and nitriding are performed separately, re-cold rolling may be performed before nitriding.

In addition, considering the welding area, in the conventional material, the material may be softened locally due to the heat of welding and the work deformation may be concentrated during flange forming or the like, thereby degrading the formability, but containing a large amount of N in the surface layer portion. In the steel sheet of the present invention, the softening due to the heat of welding is suppressed, so that the benefits related to the moldability of the weld zone can be obtained.

In the process where recrystallization annealing and nitriding can be carried out continuously as preferable in terms of productivity, the timing of re-cold rolling may be after nitriding, but if recrystallization annealing and nitriding is performed separately, re-cold rolling may be performed before nitriding. .

An exemplary embodiment of the present invention can be applied to a steel sheet having a plate thickness of 0.400 mm or less. This is because deformation of the molded member is not easy to be a problem in the case of a steel sheet thicker. In addition, the larger the plate thickness, the smaller the thickness of the surface layer hardening due to nitriding, so that the effects of the present invention may not be readily exhibited. Preferably a steel sheet of 0.300 mm or less, more preferably 0.240 mm or less is used, and a very pronounced effect can be obtained with a steel sheet of 0.200 mm or less.

One of the effects of an exemplary embodiment of the present invention does not depend on the thermal history or manufacturing history after component control and before annealing. The slab, bloom or billet in the case where hot rolling is performed is not limited to any manufacturing method such as ingot or continuous casting method, and the effect of the present invention is that the slab reheating method, hot rolling is performed directly without reheating the casting slab It can be obtained by thin slab casting in which CC-DR method or rough rolling is omitted, since the effect of the present invention does not depend on the thermal history before annealing. The effect of an exemplary embodiment of the present invention does not need to depend on the hot rolling conditions and is by means of continuous hot rolling, rolling in two-phase zone rolling at α + γ two-phase zone finishing temperature or by connecting a rough bar. Can be obtained.

In addition, when the steel sheet of the exemplary embodiment of the present invention is used as a material for a container having a welded area, softening of the heat-affected area is suppressed and in particular, the surface layer area having a high N concentration is rapidly cooled and cured, thereby improving the weld strength. Has the effect of increasing. This is made more pronounced by the addition of elements such as B and Nb which are conventionally used to control the softening of the heat affected zone.

The steel sheet of an exemplary embodiment of the present invention includes the case where any kind of surface treatment is performed. That is, in the steel sheet used by the consumer after the surface treatment, the color tone and weldability are essential for the steel sheet after the surface treatment, and the good state of the steel sheet surface essential for these properties is not damaged by the surface treatment for the steel sheet manufactured as described above. . Of course, the absolute value of PPI or Ra may vary greatly due to the surface treatment, but the ability to provide a good surface state of the steel sheet, i.e., a state where numerous low unevennesses are formed by controlling the hardness of the steel sheet in the thickness direction, remains on the steel sheet even after the surface treatment. Can be detected as appropriate. This effect provides good color tone and weldability to the surface treated steel sheet.

With regard to the adhesion of surface coatings such as metal plating, painting or organic films (laminates), the condition of the steel sheet surface prior to surface treatment can be important. Even in this characteristic, forming a good steel sheet surface state by controlling the hardness of the steel sheet in the thickness direction as disclosed in accordance with an exemplary embodiment of the present invention, for example, forming a state in which a large number of low irregularities are formed may provide good adhesion. Can be. In the surface treatment, tin, (tin) chromium, nickel, zinc, aluminum and the like conventionally used in the case of metal plating are applied. Not only the adhesion of these coatings but also the color tone and weldability after coating are improved. Adhesion can be improved by the effect of the present invention even in the case of a base material for laminated steel sheets coated with an organic film, which has been recently used, and even when steel sheets are coated directly or after metal plating.

In terms of use, exemplary embodiments of the present invention may be used in containers, generally two- or three-piece cans, and may be used for any application where the problem to be solved is similar to that described above. .

[Yes]

As an exemplary embodiment of the present invention, evaluation of color tone, surface coating adhesion and weldability was performed using Sn-plated steel sheet, which is one of the types most commonly used as a container steel sheet.

Regarding the adhesion, two sheets coated on both sides with an epoxy phenolic coating of 25 mg / m 2 were fired and pressed together using a nylon adhesive to prepare test pieces, which were wetted with tap water, and then peeled off. T-type peeling test was done to determine the strength. Unsurprisingly, high peel strength was considered to be good adhesion in the specimen grade. Since the peel strength also depends on the steel components and the conditions other than the manufacturing conditions for obtaining the present invention and the required level varies depending on the application or the like, determining the acceptability based only on an absolute value is in some way always consistent with the actual use. It may not. Nevertheless, 1.5 kg / 5 mm was judged to be "improvement", 1.5 to 2.5 kg / 5 mm was considered "available" and 2.5 to 3.5 kg / 5 mm was considered "good" and 3.5 kg / 5 Mm was judged to be “very good”.

Regarding the color tone, the L value obtained using a spectrophotometer after applying and drying a 10 μm transparent polyester resin was used as an index. Higher L values indicate better hue, and these values were used to grade the specimens. Since the L value also depends on the steel components and the conditions other than the manufacturing conditions for obtaining the present invention and the required level varies depending on the application or the like, determining the suitability based only on an absolute value may not always coincide with the actual use in some respects. Can be. Nevertheless, values smaller than 60 were judged to be "needs to be improved", 60 to 75 were judged to be "available", 75 to 90 were judged to be "good", and 90 and above were judged to be "very good".

In terms of weldability, for seam welding commonly used in three-piece cans, welding was performed with varying welding currents, and the weldable current ranges were splash (generated spatter), peeling test (hein) welding strength based on (heing test), weld surface damage due to arc current between the steel plate surface and the electrode ring during welding, and the determination was made based on the width and the lower limit of the area. The decision was made by judging a wide range as desirable in terms of high manufacturing stability and judging a low lower limit to less plating peeling due to changes in material quality and increased temperature in the weld zone. In an exemplary embodiment, with respect to the welding current range, the evaluation was made by finding the ratio to the median of the welding current and judging when the ratio is high. Since this ratio also depends on conditions other than steel components and manufacturing conditions for obtaining exemplary embodiments of the present invention and the required level depends on the application and the like, it is only in some respects to determine the acceptability based on absolute values. May not always match. Nevertheless, values less than 1% were judged to be "improved", 1 to 3% were judged "available", 3 to 6% were judged "good" and 6% or more judged "very good" It became.

Productivity was evaluated based on productivity during temper rolling. "Productivity" here does not only mean production volume per unit time, but also includes the ease of manpower and facility management to maintain expected line work. The reason for focusing on temper rolling is that surface control, which is a salient feature of the steel of the present invention, is carried out mainly in the state of the art through the management of rolling roughness and rolling conditions during temper rolling. In the category, studies based on management and the number of rolling passes mainly related to roll roughness have been conducted, and basically, when rolling at low roughness is possible, it is preferable that the roll roughness management tolerance is wide and the number of rolling passes is small. In practice, however, it can also be made in consideration of lubricating conditions, rolling speed management, and tension management to ensure the shape and thickness accuracy of the plate after rolling and the ease of plate temperature management. The management tolerances for these parameters also depend on conditions other than the steel components and manufacturing conditions for obtaining the present invention and the required levels vary depending on the application, etc., so that it is difficult to explain only the absolute value formula of tolerance.

Regarding the components of the mid-thickness layer, since the steel sheet before nitriding is produced by a conventional method, the elemental change in the thickness direction before nitriding is extremely small to be negligible in the effect of the exemplary embodiment of the present invention. That is, the N content of the 1/8 thick surface layer and the N content of the 1/4 thick mid-thickness layer were assumed to be the same in the steel sheet before nitriding.

Hot rolling, cold rolling and recrystallization annealing were carried out to prepare the steel sheet from the steel materials of the components shown in Tables 1-4. In Tables 1 to 4, the N content is the average N content in the steel sheet thickness direction before nitriding. Some materials were nitrided by passing steel sheets under the conditions shown in Tables 1-4 while controlling the temperature, atmosphere, etc. in the nitriding furnace followed by a high temperature holding furnace for recrystallization annealing. All nitriding treatments were performed starting from the intermediate stage of annealing under conditions where recrystallization could be considered complete before nitriding occurred.

In addition, temper rolling was performed to produce the steel sheet. 5 to 8 show rolling conditions, final steel sheet thickness, nitrogen component analysis results, and characteristic evaluation results of these steels. It was confirmed that good color tone, surface coating adhesion and weldability could be obtained by controlling the state in the steel plate thickness direction to be within the scope of the present invention by the production method of the present invention. In some cases, attempts have been made to control surface roughness by special temper rolling conditions for non-nitrided materials, but efficient production has been hampered by roll wear, number of passes, and the like. It is also possible for this kind of special rolling to yield a material having an evaluation of steel sheet roughness substantially equivalent to the material using the steel of the present invention, but its properties were not as good as the properties of the steel of the present invention. The reason is not clear, but it is contemplated that there may be some difference in the surface state which cannot be detected by the roughness measurement of this exemplary embodiment.

The steel sheet for a container according to an exemplary embodiment of the present invention and its manufacturing method can improve the color tone, surface coating adhesion and weldability of the container while preventing the complicated treatment after nitriding and the productivity obstacle due to such a complicated treatment. Therefore, the productivity of the ultra-thin container steel sheet can be improved, thereby providing a remarkably industrially useful effect.

The foregoing merely illustrates the principles of the invention. Various changes and modifications to the above-described embodiments will be apparent to those skilled in the art by reference to the contents described herein. Accordingly, those skilled in the art will recognize that although not explicitly shown herein, numerous modifications may be made to the steel plates and methods for manufacturing the same that embody the principles of the invention and are within the spirit and scope of the invention. Although various publications have been cited in the present specification, the contents are incorporated by reference in their entirety.

The steel sheet for a container according to an exemplary embodiment of the present invention and its manufacturing method can improve the color tone, surface coating adhesion and weldability of the container while preventing the complicated treatment after nitriding and the productivity obstacle due to such a complicated treatment. Thus, it becomes possible to maintain a high degree of productivity and to provide an industrially useful effect as the conventional method of performing a complicated process for the production of the conventional steel sheet and the steel sheet for ultra-thin container.

Claims (14)

At least one container steel plate, At least a portion having a sheet thickness of 0.400 mm or less, approximately on a mass% basis, C: 0.0800% or less, N: 0.600% or less, Si: 2.0% or less, Mn: 2.0% or less, P: 0.10% or less, S: 0.05% or less, and Al: contains 2.0% or less, The at least one portion comprises a 1/8 thick surface layer and a 1/4 thick surface layer and the first N content of the 1/8 thick surface layer minus the second N content of the 1/4 thick mid-thick layer is at least approximately 10 ppm, The first N content is about 20000 ppm or less and the surface roughness of the at least part is about 0.90 μm or less based on Ra, Wherein the number of uneven peaks (" PPI ") per inch length of the at least one portion is at least approximately 250. At least one container steel plate, At least a portion having a sheet thickness of 0.400 mm or less, approximately by mass% C: 0.0800% or less, N: 0.600% or less, Si: 2.0% or less, Mn: 2.0% or less, P: 0.10% or less, S: 0.05% or less, and Al: contains 2.0% or less, Said at least one portion comprising a 1/8 thick surface layer and a 1/4 thick mid-thick surface layer, One of the values obtained by subtracting the first steel plate cross section average Vickers hardness of the 1/8 thick surface layer minus the second steel plate cross section average Vickers hardness of the 1/4 thick mid-thickness layer is one of greater than 10 and greater than 20; Partial surface roughness is approximately 0.90 μm or less based on Ra, Wherein the number of uneven peaks (" PPI ") per inch length of the at least one portion is at least approximately 250. The steel sheet for a container according to claim 1 or 2, wherein the at least one portion further comprises at least one of Ti: 0.05% or less, Nb: 0.05% or less, and B: 0.015% or less on a mass% basis. The mean component of the quarter-plate thickness mid-thickness layer according to claim 2, wherein the average component of the quarter-plate thick-thickness layer is Ti: 4 × C + 1.5 × S + 3.4 × N or more, Nb: 7.8 × C + 6.6 × N or more and B: 0.8 × N Steel plate for containers composed of at least one of the above. The steel sheet for a container according to claim 1 or 2, wherein the at least one portion further comprises at least one of Cr: 20% or less, Ni: 10% or less, and Cu: 5% or less on a mass% basis. The steel sheet for a container according to claim 1 or 2, wherein the at least one portion further comprises 0.1% or less of Sn, Sb, Mo, Ta, V, and W on a mass% basis. A method for producing at least one steel sheet for at least one container, The at least one steel sheet includes at least one portion having a sheet thickness of 0.400 mm or less, and the at least one portion is approximately C: 0.0800% or less, N: 0.0300% or less, Si: 2.0% or less, Mn: 2.0% based on mass% P: 0.10% or less, S: 0.05% or less, Al: 2.0% or less and the remaining amount of Fe and unavoidable impurities, The method, a) cold rolling the steel sheet, b) recrystallization annealing the steel sheet; c) nitriding the steel sheet during step (b) or after step (b), The average increase in N content in the plate thickness average of the at least one portion is about 6000 ppm or less and the first N concentration increase in the at least one portion of the 1/8 thickness surface layer is about 20000 ppm or less and 1/4 thickness mid-thickness. The absolute value of the N concentration increase of the 1/8 thickness surface layer divided by the second N concentration increase of the layer is approximately 2.0 or less, Wherein the surface roughness is approximately 0.90 μm or less based on Ra and the number of uneven peaks per inch length (“PPI”) of the at least part is at least approximately 250. A method for producing at least one steel sheet for at least one container, The at least one steel sheet includes at least one portion having a sheet thickness of 0.400 mm or less, wherein the at least one portion is approximately C: 0.0800% or less, N: 0.0300% or less, Si: 2.0% or less, Mn: 2.0 based on mass% % Or less, P: 0.10% or less, S: 0.05% or less, Al: 2.0% or less and the remaining amount of Fe and unavoidable impurities, The method, a) cold rolling the steel sheet, b) recrystallization annealing the steel sheet; c) nitriding the steel sheet during step (b) or after step (b), The increase in N content is approximately 6000 ppm or less in the thickness average of the at least one portion, The first steel plate cross section average Vickers hardness of the 1/8 thick surface layer minus the second steel plate cross section average Vickers hardness of the 1/4 thick mid-thickness layer is approximately greater than either 10 points or 20 points, The surface roughness of the at least one portion is about 0.90 μm or less based on Ra, The number of uneven peaks per 1 inch length of the at least one portion is at least 250. The method according to claim 7 or 8, wherein the at least one portion further comprises at least one of Ti: 0.05% or less, Nb: 0.05% or less, and B: 0.015% or less. The method of claim 8, wherein the at least one portion comprises Ti: 4 × C + 1.5 × S + 3.4 × N or more, Nb: 7.8 × C + 6.6 × N based on the average component of the quarter-plate thickness mid-thickness layer. And B: steel sheet manufacturing method containing at least one of 0.8 x N or more. The steel sheet manufacturing method according to claim 7 or 8, wherein the at least one portion further comprises at least one of Cr: 20% or less, Ni: 10% or less, and Cu: 5% or less. The method for manufacturing a steel sheet according to claim 7 or 8, wherein the at least one portion contains not more than 0.1% of Sn, Sb, Mo, Ta, V, and W, based on mass%, as a steel component. The steel according to claim 7 or 8, in order to carry out step (c) concurrently with or after step (b), A steel sheet of 550 to 800 ° C. in an atmosphere containing at least 0.02% ammonia gas for at least 360 seconds for at least 1 second to produce a product of temperature (° C.) and time (seconds) at 48000 or less in the thermal history in the high temperature range of 550 ° C. or higher after nitriding. Maintained at temperature, The steel sheet manufacturing method which is at least one of setting an average cooling rate at 550 degreeC-300 degreeC to 10 degreeC / sec or more. The method for manufacturing a steel sheet according to claim 7 or 8, wherein the re-cold reduction ratio after performing step (b) and before and after step (c) is 20% or less.

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