WO2000063453A1

WO2000063453A1 - Very thin 2-piece container steel sheet excellent in pucker resistance at neck diameter reduction and in earing and production method therefor

Info

Publication number: WO2000063453A1
Application number: PCT/JP2000/002426
Authority: WO
Inventors: Hidekuni Murakami; Masayoshi Suehiro; Seiichi Tanaka; Tetsurou Takeshita; Hirokazu Yokoya; Toru Chichiki
Original assignee: Nippon Steel Corporation
Priority date: 1999-04-20
Filing date: 2000-04-13
Publication date: 2000-10-26
Also published as: EP1088905A1; DE60043087D1; JP4213870B2; EP1088905B2; EP1088905B1; EP1088905A4

Abstract

A 2-piece-can steel sheet characterized in that (N present as AlN)/(N content) ⊃0.5, an average diameter of AlN is 0.01 to 0.10 νm with AlN in diameter of up to 0.01 νm accounting for up to 10% of that in diameter of at least 0.005 νm, and an average diameter of MnS is 0.03 to 0.40 νm with MnS in diameter of up to 0.03 νm accounting for up to 50% of that in diameter of at least 0.005 νm. Components, a slab heating temperature at hot rolling, a coiling temperature and a re-cold-rolling ratio are specified to fulfil the above requirements, thereby making it possible to produce a heat-buckle-free, high-efficiency 2-piece-can steel sheet which is high in steel sheet yield, excellent in a can formability and reduced in pucker occurrence ratio at neck diameter reducing after drawing, ironing and stretching, and can keep a satisfactory characteristics even when annealed at a low temperature. A 2-piece-can steel sheet with a sheet thickness of up to 0.19 mm can be provided which is free from coil break at annealing, from earing at cup forming and from pucker at opening diameter reducing in the can barrel.

Description

Technical Field Ultra-thin steel sheet for two-piece containers having excellent wrinkle resistance and shrinkage resistance when the diameter of the net is reduced, and a method for producing the same

The present invention relates to a steel sheet used as a material for cans manufactured by drawing, ironing and stretching, followed by reduction in diameter, as represented by the manufacture of two-piece cans, and a method for manufacturing the same. Particularly, it is an object of the present invention to provide a steel sheet for an ultra-thin container which has a small bearing, good neck wrinkle resistance and can be manufactured with high productivity in the field of can making, and a method for manufacturing the same. Background art

In the field of manufacturing beverage cans, food cans, and other products, the volume of containers called two-piece cans, which are integrally formed with a can and a body, is increasing. Usually, for 2-piece cans, after the drawing process, in order to obtain the required can height, a method of increasing the can wall height by ironing or stretching, as represented by DI cans and DTR cans, is adopted.

At the time of these formings, it is desired to suppress the occurrence of shearing that reduces the yield and ironing of the steel sheet or the drawability. In addition, in order to make the can lid smaller and reduce the material cost for the can lid, a process to reduce the diameter of the can opening (neck processing) is performed. However, in the case of a two-piece can, drawing, squeezing and stretching are performed. As a result, the material is hardened, and the occurrence of wrinkles becomes significant (deterioration of neck wrinkle resistance).

Techniques for improving these are disclosed in Japanese Patent Application Laid-Open Nos. Techniques disclosed in JP-A-1-184229, JP-A-2-141535 and the like have been proposed.

In general, it is effective to improve the wrinkle resistance by lowering the yield stress (0.2% resistance when no yield point is observed), but it is disclosed in the above-mentioned prior art. With the conventional technology, the softening after drawing and ironing is insufficient, so that ultra-thin material with a thickness of 0.2 mm or less is used as a material to further increase the diameter reduction rate, which is a trend in recent years. Also, in can molding, there is still a concern that the material may be hardened during processing or the neck wrinkle resistance may be degraded, and further improvement in properties is desired.

In the steel plates for containers developed so far, the occurrence of wrinkles when the diameter of the material is reduced after ironing during the formation of the can body of ordinary two-piece cans and the material after extensive processing such as stretching has been suppressed. No effective means has been found to date. Further, in such a thin material having a thickness of 0.2 mm or less, a steel sheet called a heat buckle is broken at the time of annealing, and the production efficiency is reduced.

As a countermeasure against heat backlash, a method has been put into practical use in which a steel sheet thicker than the target thickness is passed during annealing and then re-rolled (2CR) to obtain the target thickness. This method is a convenient manufacturing method to secure the strength of the can by work hardening to compensate for the decrease in strength by using work-hardening even when an ultra-low carbon IF steel, which is originally soft, is applied. In addition, drawing, ironing and elongation are also overlapped, so that the neck wrinkle resistance is significantly degraded. Disclosure of the invention

The present invention has high drawability, and

1) Productivity decrease due to breakage in the annealing process,

2) Wrinkling when reducing the diameter of the opening of the can body, 3) The development of carrying in ultra-thin materials with a thickness of 0.2 mm or less, produced at a high cold rolling rate,

The present invention is to provide a steel plate which is manufactured through drawing and ironing or elongation processing, which is used for a two-piece container, and a method for manufacturing the same.

The present inventors have developed a method based on a low carbon steel of about 0.03% C, which has a low recrystallization temperature and good deep drawability. While examining the suppression of wrinkles, we found that there was a correlation between the amount and size of precipitates such as A1N and MnS and the occurrence of wrinkles. Although this mechanism is not clear, the combination of the crystal grain size after annealing, texture formation, etc., mainly affects the work hardening behavior of the material, improving neck wrinkle resistance. it is conceivable that.

In particular, in cold rolling, drawing, ironing, elongating, and reducing diameters after annealing, since the processing direction differs in each process, so-called Bausinger effective elements are also affected. Conceivable. The coarser the grain size, the higher the {100} plane strength for the texture and the lower the {111} plane strength for the texture, and the

The coarser and the lower the density, the better the wrinkle resistance. In addition,

— The present invention was completed in consideration of workability as a two-piece can annealed in a relatively low temperature range in order to suppress the buckle.

Based on the knowledge that wrinkle resistance is affected by the amount and size of A1N and MnS, a more detailed study was conducted to determine the ratio of N present as A1 nitride to the contained N, or the size distribution of A1N and MnS. The result was that the wrinkle resistance could be determined with the above restriction. That is,

AIN, MnS are the following conditions,

1) (N existing as A1N) / (Contained N)> 0.5,

2) A1N with a diameter of 0.015 m or less among A1Ns with a diameter of 0.005 m or more Is less than 10% (RA),

3) The average diameter of A1N with a diameter of 0.005 m or more is 0.01 ~ 0.10 ^ m (DA),

4) Of MnS with a diameter of 0.005 m or more, the ratio of the number of MnS with a diameter of 0.03 m or less is 50% or less (RM),

5) The average diameter of MnS with a diameter of 0.3 m or more is 0.03 to 0.40 m (DM

),

By satisfying the above conditions, the present invention makes it possible to produce a two-piece container steel sheet having a thickness of 0.19 mm or less, which is excellent in neck wrinkle resistance and earing property. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the relationship between the average diameter of MnS, hot rolling conditions (slab heating temperature, winding temperature), and the critical diameter reduction rate. 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. Coarse cementite, when exposed to the surface, may degrade the plating properties of the steel sheet. Coarse cementite may also be a starting point for cracking during ironing, stretching and flange forming in the container manufacturing process. From these points, it is desirable to set the upper limit of C to 0.08%. In particular, when a material having good ductility is required for ironing, stretching, and flange forming, the characteristics can be significantly improved by setting the content to 0.06% or less. However, an incomplete reduction in the region of less than 0.008% is not desirable for control of aging with residual solid solution C. Insufficient can strength However, this is not desirable from the viewpoint of rising decarburization costs. From these facts, it is desirable that C be 0.008% or more. Further, in order to obtain high quality and high ductility characteristics which are preferable as a two-piece can at low cost without using vacuum degassing, 0.02 to 0.04% is more desirable.

N is an important element that controls the formation of nitrides. If contained in a large amount, a large amount of nitride is generated, and it is difficult to achieve the object of the present invention. Therefore, it is desirable to set the upper limit to 0.0040%. It is more desirable to reduce the content to 0.0020% or less by performing sufficient vacuum degassing, because the amount of nitride formed is reduced and the target characteristics are improved.

If Si is contained in a large amount, the material becomes hard and workability deteriorates. Therefore, 0.05% or less is desirable. Even more preferably less than 0.029% o

If Mn is contained in a large amount, the material becomes hard and the workability deteriorates, and excessive reduction leads to high cost. Therefore, 0.04 to 0.4% is desirable. Further, it is more preferably 0.15 to 0.25%.

If P is contained in a large amount, the material becomes hard and the workability is deteriorated. Furthermore, it is more preferably 0.010% or less.o

If S is contained in a large amount, MnS precipitates are formed in a large amount, the material becomes hard, and the workability is deteriorated. Therefore, 0.04% or less is desirable. Furthermore, it is more preferably at most 0.020%.

A1, like N, is an important element for controlling nitride, which is an important requirement of the present invention. From this point, 0.02 to 0.10% or less is desirable. Further, it is more desirably 0.050 to 0.080%.

An important condition in the present invention is control of the amount of nitride. The present invention mainly uses A1 nitride as a precipitate, and does not mainly use compounds such as B, Ti, and V. Therefore, B, Ti, V, etc. Not graphically added.

Since nitride is mainly A1N,

(N existing as A1N) Z (contained N)〉 0.5

And Here, N (Nas A1N), which is present as ADI, refers to the analysis of the amount of A1 in the residue when a steel sheet is dissolved in a hydrogen alcohol solution, and the total amount of A1N to be the N amount. It is a converted value.

The size distribution of A1 and MnS is also an important factor for improving the resistance to net wrinkling. In the present invention, the ratio of the number of A1N having a diameter of 0.10 / m or less among those having a diameter of 0.005 / zm or less is 10% or less, the average diameter is 0.01 to 0.10 m, and the diameter of MnS is 0%. Limit the number of those with a diameter of 0.03 or less out of 005 m or more to 50% or less, and the average diameter from 0.03 to 0.40 m.

This is a value obtained by observing an extracted replica obtained from a steel sheet by the SPEED method using an electron microscope, and measuring the diameter and number of precipitates in a field of view that is not biased.

By controlling the precipitates in this way, as described above, the crystal structure, the texture, and the like can be controlled, and the net wrinkle resistance of a thin material having a thickness of 0.19 dragon or less can be improved.

The size distribution can also be obtained by taking a picture of the field of view and performing image analysis and the like. As mentioned above, in order to improve neck wrinkle resistance, it is necessary to consider the work hardening behavior of the material, including the Binger singer 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 techniques. Easy to cause errors. Therefore, in the present invention, the claims are specified in relation to coarse precipitates that can be expected to reduce measurement errors.

In addition, especially in the case of MnS, there are cases where the shape is elongated. If the shape is not isotropic, the average of the major axis and minor axis is taken as the diameter of the deposit.

To control nitrides and sulfides in this way, the thermal history of the entire manufacturing process is important. As the heat history, the slab heating temperature and the winding temperature during hot rolling are greatly affected, and it is necessary to control the reheating temperature of the billet within a predetermined range.

The slab reheating temperature (SRT) is determined in combination with the coiling temperature (CT: Coiling Temperature). If the reheating temperature of the slab is 1150-: L250 ° C, the winding temperature must be limited to 690-750 ° C. The reason is not clear, but in particular, by maintaining the temperature in this temperature range and changing the A1N precipitate size distribution in the steel sheet, the work hardening behavior of the material after cold rolling recrystallization is affected. It seems to be. In general, the reduction of fine precipitates directly affects the work hardening behavior, and in addition to improving the crystal grain growth during cold rolling recrystallization and increasing the crystal grain size, It is considered that work hardening is suppressed even through the change in orientation (texture).

Further, if the billet is set to a predetermined range lower than the above temperature range of 1000 to 150 L, the steel sheet of the present invention can be obtained without specifying the winding temperature. Although the reason is not clear, the precipitation of MnS during slab heating progresses by lowering the heating temperature during slab to 1150 ° C or less, and the amount of fine MnS that precipitates as the temperature decreases during hot rolling is reduced. Therefore, it seems that the same effect as in the case of A1N described above is exhibited. At this time, precipitation of A1N is also promoted during slab heating, so it is considered unnecessary to specify the winding temperature.

The cold rolling reduction (CR) is 82-94%. This is because of the productivity in producing thin materials and the suppression of in-plane anisotropy in terms of material. If the cold rolling rate is low, reduce the thickness of the hot rolled sheet Therefore, the in-plane anisotropy increases as the hot-rolling productivity decreases, and when the cold-rolling rate is high, the load on the cold-rolling process increases, and the in-plane anisotropy also increases. Increase.

The annealing temperature (AT: Annealing Temperature) is ~ 720. The same. The reason is that recrystallization is necessary to obtain good ductility, and that the productivity of annealing may decrease at a high temperature exceeding 720 ° C. More preferably, it is 650-670 ° C.

It is desirable to perform the re-cold rolling reduction ratio (RCR) after annealing at 1 to 10%. This is because the effect of re-cold rolling can be obtained at a cold rolling rate of 1% or more, and if the re-cold rolling rate is too high, the material becomes hard and the workability deteriorates. More preferably, it is 1-2%.

Note that the effect of the present invention is not lost even if a large amount of reinforcing elements such as Si, Mn, and P are added instead of employing 2CR to increase the steel sheet strength.

Further, although the steel sheet of the present invention is used as an original sheet of a surface-treated steel sheet, the effect of the present invention is not impaired at all by the surface treatment.

As the surface-treated steel sheet for cans, tin, chrome (tin free), etc. are usually applied. Furthermore, even a base plate for a laminated steel sheet to which an organic film, which has been used in recent years, is pasted, can be used without impairing the effects of the present invention.

Example

A steel sheet of each component shown in Table 1 was manufactured under the manufacturing conditions shown in Table 2 to produce a 0.180 mm steel sheet, and the present invention was evaluated based on the steel sheet. With respect to the earring property, a drawn cup was formed under certain conditions, and the maximum and minimum values of the cup rim height were evaluated at the earring rate calculated from the following equation (1).

Carrying ratio = (maximum value-minimum value) Z minimum value (1) Regarding the net wrinkle resistance, for cans with a constant drawing ratio and ironing rate and a thickness of 125 m for the net forming section, multiple steps of diameter reduction are performed in the same way as with normal cans. The critical diameter reduction rate was determined by the following equation (2) as the limit at which wrinkles occurred. The higher the critical diameter reduction ratio, the greater the margin of the material in actual operation, so that the generation of wrinkles can be suppressed.

Critical diameter reduction == (initial diameter-wrinkling diameter) / (initial diameter) ... (2) For heat buckle, heat buckle when passing through continuous annealing line at recrystallization temperature + 40 ° C Judgment was made based on the presence or absence.

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

Figure 1 shows the relationship between the MnS size distribution and neck wrinkle resistance for a steel composition with a steel composition of 0.03% C by mass. Those having a MnS size distribution within the range of the present invention have good neck wrinkle resistance. In Fig. 1, the effect of the MnS size distribution is stratified by the slab heating temperature.However, even if the MnS size distribution is similar, when the slab heating temperature is 1250 ° C or less and the winding temperature is 690 ° C or more, In the graph, the net diameter reduction is improved.

0 ΐ

2200 • 0 L90 • 0 ΟΤΟ • 0 900 · 0 ST · 0 20 · 0 S80 • 0

8Τ00 • 0 £ 90 • 0 010 • 0 910 · 0 ST Ό 20 · 0 200 • 0

LZ0 • 0 890 • 0 010 • 0 ΟΤΟ · 02,0 20 · 0 ^ 90 • 0 Ρ

5800 • 0 ιο • 0 600 • 0 9Τ0 · 0 Z · 0 εο · ο 580 • 0 0

9100 Ό 690 • 0 600 • 0 800 • 0 LO '0 10' 0 • 0 q

8200 • 0 990 • 0 600 • 0 00 "0 Ζ · 0 20. · 0 τζο • 0

(% 畺蔞:

Ialla

Hi ZO / 0 (Wf / IDd eSW9 / 00 OAV Table 2 Steel SRT CT CR AT RCR RA DA RM DM Carry down

NasAlN / N size

(° C) (° C) (%) (° C) (%) (%) (%) m) (%) (μ τη) (! ¾) Buckle ratio (! ¾) a 1250 .550 93 680 5.0 40 15 0.02 55 0.08 5.6 X 16 Comparison a 1250 690 93 650 5.0 60 5 0.02 35 0.06 2.6 〇 22 Invention a 1250 730 93 640 5.0 100 1 0.05 40 0.25 1.3 〇 26 Invention a 1100 550 93 650 5.0 85 3 0.04 15 0.15 2.5 〇 26 Invention a 1 100 700 93 630 5.0 100 1 0.07 5 0.35 1.1 〇 28 Invention b 1200 550 92 670 1.5 40 20 0.03 40 0.20 4.4 X 12 Compare

1050 550 92 650 1.5 40 5 0.04 10 0.15 1.5 2D invention ac 1200 680 90 650 15.0 40 10 0.02 40 0.25 1.5 〇22 invention d 1200 690 90 650 5.0 40 1 0.04 35 0.10 2.7 〇22 invention e 1200 600 93 700 5.0 50 15 0.04 70 0.02 3.2 X 16 Hikoko e 1200 680 93 670 5.0 90 1 0.06 60 0.05 2.0 X16 Comparison f 1100 650 92 650 5.0 80 15 0.02 20 0.10 5.8 〇 12 Hikoko

[Note] Heat buckle 〇: No occurrence. x: Occurs.

Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, the wrinkle generation rate at the time of a network diameter reduction can be reduced. Furthermore, since the steel of the present invention exhibits good properties even at an annealing temperature lower than that of the conventional material, generation of a heat buckle can be avoided, and highly efficient production of an ultra-thin container material becomes possible.

Claims

The scope of the claims

1.A1N with a diameter of 0.005 m or more has an average diameter of 0.01 to 0.10 ^ m, and the ratio of the number of A1Ns with a diameter of 0.01 m or less among A1Ns with a diameter of 0.005 m or more is 10% or less,

The average diameter of MnS with a diameter of 0.005 m or more is 0.03 to 0.40 m, and the ratio of the number of MnS with a diameter of 0.03 m or less among MnS with a diameter of 0.005 / m or less is 50% or less,

(N existing as A1N) / (Contained N)> 0.5,

Board thickness 0.19mm or less

A two-piece container steel sheet having excellent neck wrinkle resistance and carrying properties, characterized in that:

2. In mass%,

C: 0.08% or less,

Si: 0.05% or less,

n: 0.04-0.4%,

P: 0.04% or less,

S: 0.04% or less,

A1: 0.02-0.10%,

N: 40 ppm or less

Containing

The average diameter of A1N with a diameter of 0.005 jum or more is 0.01 to 0.10 m, and the proportion of A1N with a diameter of 0.01 m or less among A1N with a diameter of 0.005 / m or more is 10% or less,

The average diameter of MnS with a diameter of 0.005 m or more is 0.03 to 0.40 m, and the proportion of MnS with a diameter of 0.03 m or less among the MnS with a diameter of 0.005 m or more is 50% or less, (N existing as A1N) / (Contained N)> 0.5,

Board thickness 0.19mm or less

A two-piece container steel sheet with excellent neck wrinkle resistance and sealing properties.

3. In mass%,

C: 0.02 ~ 0.4%,

Si: 0.029% or less,

Mn: 0.15-0.25%,

P: 0.010% or less,

S: 0.020% or less,

A1: 0.050-0.080%,

N: 40 ppm or less

Containing

The average diameter of A1N with a diameter of 0.005 ^ m or more is 0.01 to 0.10 m, and the ratio of A1N with a diameter of 0.01 m or less among A1N with a diameter of 0.005 / m or more is 10% or less,

The average diameter of MnS with a diameter of 0.005 m or more is 0.03 to 0.40 m, and the ratio of the number of MnS with a diameter of 0.03 m or less among MnS with a diameter of 0.005 m or more is 50% or less,

(N existing as A1N) / (Contained N)> 0.5,

Board thickness 0.19mm or less

A two-piece steel sheet with excellent neck wrinkle resistance and carrying properties, characterized in that:

4. In mass%,

C: 0.08% or less,

Si: 0.05% or less,

Mn: 0.04-0.4%, P: 0.04% or less,

S: 0.04% or less,

Al: 0.02 ~ 0.10%,

Ν: 40ppm or less

Containing

Hot rolling at 1150-1250 ° C, hot rolling coiling temperature 690-750 ° C, cold rolling at a cold rolling rate of 82-94%, annealing at recrystallization temperature ~ 720 ° C And re-rolling at a rolling reduction of 1 to 10%,

The average diameter of A1N with a diameter of 0.005 m or more is 0.01 to 0.10 m, and the proportion of A1N with a diameter of 0.01 μm or less in A1N with a diameter of 0.005 m or more is 10% or less,

(N existing as A1N) / (Contained N)> 0.5,

Board thickness 0.19mm or less

A method for producing a steel sheet for a two-piece container, which is excellent in net wrinkle resistance and carrying properties.

5. In mass%,

C: 0.08% or less,

Si: 0.05% or less,

Mn: 0.04-0.4%,

P: 0.04% or less,

S: 0.04% or less,

A1: 0.02-0.10%,

N: 40 ppm or less

Containing Cold rolling at a reheating temperature of 1000-1150 ° C and a cold rolling rate of 82-94%, annealing at a recrystallization temperature of ~ 720 ° C, and re-rolling at a rolling reduction of 1-10% Natsute

The average diameter of A1N with a diameter of 0.005 / m or more is 0.01 to 0.10 μm, and the proportion of A1N with a diameter of 0.01 μm or less among A1N with a diameter of 0.005 m or more is 10% or less,

The average diameter of MnS with a diameter of 0.m or more is 0.03-0.40 / m, and the ratio of the number of MnS with a diameter of 0.03 m or less among MnS with a diameter of 0.005 / 2 m or more is 50% or less,

(N existing as A1N) / (Contained N)〉 0.5,

Board thickness 0.19mm or less

A method for producing a two-piece steel sheet having excellent wrinkle resistance and carrying properties, characterized in that:

6. In mass%,

C: 0.02-0.04%,

Si: 0.029% or less,

Mn: 0.15-0.25%,

P: 0.010% or less,

S: 0.020% or less,

A1: 0.050-0.080%,

N: 40PPD1 or less

Containing

Hot rolling at 1150-1250 ° C, hot rolling coiling temperature 690-750 ° C, cold rolling at a cold rolling rate of 82-94%, recrystallization temperature 650-670 ° C And re-rolled at a rolling reduction of 1-2%.

A1N with a diameter of 0.005 m or more has an average diameter of 0.01 to 0.10 ^ m, and A1N with a diameter of 0.005 // m or more and a diameter of 0.01 // m or less Number percentage is 10% or less,

The average diameter of MnS with a diameter of 0.005 i m or more is 0.03 to 0.40 m, and the ratio of the number of MnS with a diameter of 0.03 m or less among the MnS with a diameter of 0.005 / m or less is 50% or less,

(N existing as A1N) / (Contained N)> 0.5,

Board thickness 0.19mm or less

A method for producing a two-piece container steel sheet having excellent neck wrinkle resistance and carrying properties.