JPH06306534A - Surface treated original sheet for di can good in pressure withstanding strength and necked-in property and its production - Google Patents

Abstract

PURPOSE:To provide a surface treated original sheet for a DI can good in pressure withstanding strength and necked-in properties and to provide its producing method. CONSTITUTION:This surface treated original sheet for a DI can good in pressure withstanding and necked-in properties is a one having a compsn. contg. 0.0050 to 0.0250% C, <=0.30% Si, 0.05 to 0.60% Mn, <=0.030% P, <=0.025% S, 0.002 to 0.100% sol.Al, <=0.0100% N and 0 to (0.0010+1.8XN%)% B, and the balance iron with inevitable impurities, and in which the content of solid solution C in the steel sheet is regulated to >=0.0040% and the difference between Y.P after heat treatment of 200 deg.CX10min after the application of strains by additional rolling at 3% elongation percentage and Y.P after BH heat treatment after the application of strains by additional rolling at 50% elongation percentage is regulated to <=24kgf/mm<2>. This original sheet is produced by controlling the cooling conditions by an ordinary continuous annealing method or controlling the cooling conditions by a compact continuous annealing method by rapid heating in a short time.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is a tin-plated DI.
The present invention relates to a surface-treated original plate for a DI can, which has good pressure resistance of the can and good necked-in property, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A tin-plated surface-treated original plate for a DI can has been manufactured in the past by a box annealing method as disclosed in JP-A-61-243124 and JP-A-53-48913. Equipped with equiaxed grain aluminum-killed (Al-K) steel and old stretched grain Al
-K steel is applied, and the degree of temper is 1-2 (hereinafter T-1,
The steel sheet was as soft as T-2) and non-aging.
After that, the thickness of the steel plate was reduced to reduce the weight of the DI can. In order to compensate for the lack of pressure resistance against the internal pressure of the bottom part of the DI can in performing this weight reduction, the conventionally manufactured Al-K steel is manufactured by continuous annealing T-4CA.
It has been applied by switching to a hard steel sheet having a BH property called ".

Recently, it has been desired to further reduce the weight of DI cans, while the diameter of the top part (necked-in part) of the DI cans is Al (aluminum) used for the can lid.
In order to reduce the cost of the plate, the diameter has been reduced and multi-step necked-in processing has been applied, and finally, 4-step necked-in processing has begun to be adopted. However, the current DI
With T-4CA, which is supplied as a material for cans, the weight of DI cans can be further reduced, and the 4-stage necked-in can be used.
All have problems and progress is stagnant. The reason is that from the viewpoint of pressure resistance strength of the bottom part, it is necessary to make the strength of the steel plate higher in order to achieve further weight reduction, but from the viewpoint of necked-in workability, the steel plate strength is as low as possible. There is a limit to the range of compatibility, and even in the current weight reduction of the 3-step necked-in processing and the adoption of the 4-step necked-in processing in the current weight reduction, the current T- It is presumed that this is because the range of compatibility is exceeded in 4CA.

It should be noted that, as a result of the study conducted by the present inventors, the trouble during necked-in working is that a steel sheet having a higher strength for further weight reduction has a higher deformation resistance of the steel sheet during necked-in working. , The problem of buckling and wrinkling that exceeds the buckling strength of the steel plate in the necked-in part (the buckling strength in this case is estimated to have a small contribution of the strength of the steel plate and is governed by the shape factor) I reached the idea that

As mentioned above, in order to make a DI can as a better metal container, D having sufficient characteristics is still available.
There is no surface-treated original plate for I cans. In order to solve this problem, it has been strongly desired to provide a surface-treated original plate for a DI can, which has good pressure resistance and good necked-in property, and a manufacturing method.

[0006]

The problem to be solved by the present invention in view of the above circumstances is to provide a surface-treated original plate for a DI can, which is excellent in pressure resistance and necked-in property, and a manufacturing method.

[0007]

In order to solve the above-mentioned problems, the inventors of the present invention have the characteristics of a steel plate capable of achieving both the pressure resistance and the necked-in property of a DI can, and what is the means for achieving the same? , Etc. were variously examined. As a result, for the first time, we have found a surface-treated original plate for DI cans which has both good pressure resistance and good necked-in property, and a manufacturing method thereof.

That is, the gist of the present invention is as follows. (1) C: 0.0050 to 0.0250% by weight, S
i: ≦ 0.30%, Mn: 0.05 to 0.60%,
P: ≤0.030%, S: ≤0.025%,
sol.Al: 0.002 to 0.100%, N: ≤
0.0100%, B: 0- (0.0010 + 1.8 × N
%)%, The balance being unavoidable impurities and iron, and the solid solution C content of the steel sheet is 0.0040%. P (3% BH) and Y. D with good pressure resistance and necked-in properties characterized by a difference of less than 24 kgf / mm ^{2 from} P (50% BH)
Surface-treated original plate for I can. (2) C: 0.0050 to 0.0250% by weight, S
i: ≦ 0.30%, Mn: 0.05 to 0.60%,
P: ≤0.030%, S: ≤0.025%,
sol.Al: 0.002 to 0.100%, N: ≤
0.0100%, B: 0- (0.0010 + 1.8 × N
%)%, The balance unavoidable impurities and iron slabs are formed into hot-rolled steel strips by a continuous hot rolling mill, cold rolled at a cold rolling rate of 87 to 94%, and recrystallized by a continuous annealing method. Temperature ~ 850
Recrystallization annealing at ℃, after that, upon cooling to room temperature, the temperature range of 500 to 450 ℃ is cooled in 5 seconds or less, so that the solid solution C content of the steel sheet is contained at 0.0040% or more, and then temper rolling. And the Y. P (3% BH) and Y. P (5
0% BH) is less than or equal to 24 kgf / mm ² and a method for producing a surface-treated original plate for DI can having good pressure resistance and necked-in properties. (3) In the method described in (2) above, at the time of continuous annealing, a temperature range of at least 500 ° C or higher is 100 to 2500 ° C / s.
A method for producing a surface-treated original plate for a DI can having good pressure resistance and necked-in properties, which is characterized by comprising: heating at 0 ° C., holding at a recrystallization temperature of 900 ° C. for 0 to 5 seconds, and performing recrystallization annealing.

The present invention will be described in detail below. The inventors of the present invention firstly required a higher strength on the one hand, and a softer steel on the other hand. We examined whether there might be characteristics and found that there was a possibility.

It is true that the steel plate properties that can achieve both the pressure resistance and the necked-in property of this DI can are required to have higher strength on the one hand and softer on the other hand, but it is true that the present invention Are seeking the possibility,
It was examined whether the pressure resistance strength of the DI can and the strength of the necked-in part are exactly the same. As a result, the present inventors have reached the conclusion that the strengths of the both are not the same, and that there may be compatible steel sheet properties. Below, the idea which can be made compatible is explained.

The pressure resistance of the DI can is B after DI processing.
Deformation resistance of the bottom steel plate of a DI can that has been baked and coated corresponding to H heat treatment. The deformation resistance is the deformation resistance of the part where the dome processing of the bottom part has been performed and BH heat treatment has been performed for several% after processing. Is. On the other hand, the strength of the necked-in part is
It is the deformation resistance of a portion that has been subjected to BH heat treatment after plastic working as much as about 40% in plate thickness strain (corresponding to about 67% in elongation) after ironing after drawing.

The conventional idea is that the pressure resistance strength of the DI can and the strength of the necked-in part are proportional to the strength of the original plate.
The higher the original plate strength, the higher it becomes. Therefore, it has been considered that the weight reduction due to the strength increase of the steel sheet and the improvement of the necked-in property due to the softening of the steel sheet are not compatible with each other. As a result of various studies on the properties of steel, the present inventors found that the strengths of both of these were
We have reached the idea that the characteristic values are not necessarily the same, and that their characteristic values are factors that may be independently changed. That is, the inventors of the present invention think that these strengths are the same in terms of the deformation resistance after the pre-deformation BH heat treatment, but have a large difference that the pre-deformation strain amounts are significantly different. Yes, with different characteristic values. Therefore, there is a possibility that they can be changed independently. Specifically, it is only necessary that the steel has a higher deformation resistance after BH heat treatment after working of several% and a lower deformation resistance after BH heat treatment after working of about 40% in plate thickness strain. It is an idea.

Based on this idea, the present inventors
Pressure resistance strength of DI can, necked-in property and conventional T-4CA
In addition, using various trial-produced steels, studies were conducted to clarify the concrete material index of the steel targeted by the present invention. As a result of various studies, the pressure resistance strength of the DI can and the strength of the necked-in portion are determined by the Y. P (3% BH) and Y. P (5
0% BH), and a target of the present invention is a surface-treated raw steel sheet for DI cans having good pressure resistance and good necked-in property. And the Y.P (50% BH) difference is 24 kgf / mm ² or less ”.

The strength of the necked-in portion of the DI can is preferably evaluated by the original evaluation of the deformation resistance after giving a very high strain of about 40% in plate thickness strain (67% in elongation).
As a result of investigating various steel sheets, it is possible to sufficiently substitute the measured value of the deformation resistance of the plate thickness strain of 40% by the deformation resistance at the elongation rate of 50%, and the strain of the plate thickness strain as high as 40%. The measurement of the deformation resistance (yield stress due to JIS- # 5 test piece) after the addition of is likely to be affected by the processing accuracy of the tensile test piece and the like, and the measured value varies. Therefore, the strength of the necked-in part is Y. The index value was defined as P (50% BH).

As a result of research on conventional steels for DI cans, T for SDI which has been used for weight reduction until now.
-4CA is Y. P (3% BH) and Y. P (50
% BH) (hereinafter, ΔY.P (50% BH-3% B
H)) is 26 to 35 kgf / mm ² , and the difference is 35-45 kgf / mm for the box annealed Al-K steel used before.
² is extremely high, and both are 24 kgf /
There was nothing less than mm ² . The steels of the present invention are all 2
It is 4kgf / mm ² or less, which is significantly lower than that of conventional steel, and has excellent pressure resistance and necked-in properties, and is a surface-treated raw steel sheet for DI cans.

Next, "ΔY.P of steel plate (50% BH-3
% BH) is set to 24 kgf / mm ² or less. ”The metallurgy means will be described. The present inventors examined the metallurgical means to be achieved, and finally, "C: 0.005" of the present invention.
0 to 0.0250%, preferably 0.0060 to 0.0
Using 150% of Al-K steel, the solid solution C content of the steel sheet is 0.
By adding 0040% or more, preferably 0.0050% or more. " He found that P could be achieved. The idea of the method of the present invention is that it is mistaken that the so-called bake hardening amount (BH amount) of a steel plate is always constant regardless of the pre-deformation amount if the amount of solid solution C in the steel plate is the same. , Y., Y. P
(3% BH) is the solid solution C in the steel plate, similar to the so-called BH amount.
In proportion to the amount of Y. This is because P (50% BH) has a large number of mobile dislocations and therefore hardly increases even when the solid solution C increases.

In order to examine the validity of this viewpoint, solid solution C
With respect to the steel with the increased amount, additional rolling with an elongation rate of 3% and 50% is performed, BH heat treatment is performed, and Y.
The P difference was investigated. As a result, when the additional rolling amount was 3%, the Y. The P difference increases in proportion to the amount of dissolved C, but the elongation rate is 5
At the time of 0% additional rolling, Y. A very interesting result was obtained in which the P difference did not increase at all and was almost zero. That is, by increasing the amount of solute C, the ΔY. It was found that P (50% BH-3% BH) can be significantly reduced. FIG. 1 shows Al-K with various C contents.
After making a hot-rolled steel strip into a cold-rolled steel sheet at a cold rolling rate of 91%, the solid solution C content of the surface-treated original sheet obtained by temper rolling an annealed sheet in which the solid solution C content was changed by continuous annealing ΔY. P (50
% BH-3% BH). That is, ΔY. P (50% BH-3% BH) can be set to 24 kgf / mm ² or less by setting the solid solution C amount to 0.0040% or more, and the target characteristic value of the steel sheet of the present invention is obtained. You can see that

The structural conditions of the steel sheet will be described in detail below. C is an extremely important element for increasing the amount of solid solution C described above as compared with the conventional steel, and if it is less than 0.0050%, the target solid solution C amount of 40 ppm or more cannot be obtained.
The lower limit was 0050%. On the other hand, if it exceeds 0.0250%, the solid solution C precipitates as cementite during cooling even if the cooling rate is increased within the range where the plate shape can be secured as the cooling condition of the continuous annealing, and the target solid solution is obtained. 40pp of C amount
Since m or more cannot be obtained, 0.0250% was made the upper limit. In order to obtain better pressure resistance and necked-in properties, the solid solution C content of the steel sheet should be 0.0050 to 0.0140%.
It is desirable that the C content be 0.
It is preferably set to 0060 to 0.0150%. Also,
When the C content is 0.0150% ≦, the amount of cementite is reduced and the flange formability is also improved.

Each of Si, Mn, P and S is an element that has a great influence on the corrosion resistance of the steel sheet. From the viewpoint of corrosion resistance,
≤0.30%, ≤0.60%, ≤0.30, respectively
%, ≤0.25%. In addition, since Mn needs to be contained at least 0.05% or more from the viewpoint of ear roughness during hot rolling, the lower limit was made 0.05%. The other Si, P, and S did not hinder at least, so the lower limit value was not regulated. sol.Al is used as a deoxidizer, and 0.002% remains, so the lower limit is 0.00.
It was set to 2%. On the other hand, if it exceeds 0.100%, the air oxidation of the molten steel is likely to occur during casting, the amount of inclusions increases, and the workability and plating quality also deteriorate.
% Was the upper limit.

If the content of N exceeds 0.0100%, the grain size of the crystal grains becomes remarkable and the press workability deteriorates, so the upper limit value was made 0.0100%. It should be noted that N does not need to be restricted because it does not adversely affect the material. B may be appropriately added when N is fixed as BN and it is desired to soften the steel sheet. B content is 0.00
If it exceeds 10 + 1.8 × N%, the solidification of B will cause remarkable hardening, so the upper limit is 0.0010 + 1.8 ×
It was set to N%.

The amount of solute C is one of the important points of the present invention.
Then, as shown in FIG. P (50% BH-3% B
In order to reduce H) to 24 kgf / mm ² or less, it is necessary to set it to 0.0040% or more. Since there is no inconvenience even if the amount of solute C is large, the upper limit is not particularly limited.

Steel plate Y. P (3% BH) and Y. P (50
% BH), that is, ΔY. P (50% BH-3% B
H) is the most important point of the present invention and is 24 kgf / mm ²
Compared with the conventional T-4CA, it will not be possible to obtain better pressure resistance and necked-in properties, so the upper limit is 24 kg.
It was f / mm ² . In addition, ΔY. P (50% BH-3% BH)
The lower limit did not regulate the lower limit because lower pressures give better pressure resistance and necked-in properties.

Manufacturing conditions other than the constituent conditions of the steel sheet will be described in detail below. <Production conditions for claim (2)>
Any method may be used as long as the steel composition of (1) can be obtained, and there is no particular restriction. The hot rolling conditions also do not need to be particularly regulated, and may be ordinary hot rolling conditions.Also, the hot strip produced by continuous casting for energy saving may be directly hot-rolled. A method of hot rolling after inserting may be used. Further, the winding temperature does not need to be particularly limited, but when obtaining a soft material, it is preferable to adopt medium-high temperature winding.

The cold rolling rate has a great influence on the earrings of DI cans, so it is necessary to set it to 87 to 94%. still,
In order to obtain an earring rate close to zero, it is preferable to make fine adjustments in consideration of steel composition, hot rolling conditions, and annealing conditions.

The recrystallization annealing conditions for continuous annealing are as follows: recrystallization annealing is performed at a recrystallization temperature of up to 850 ° C. by a normal continuous annealing method, and then, when cooled to room temperature, the temperature range of 500 to 450 ° C. is 5 seconds or less. , Preferably cooled in 1 second or less, and the solid solution C content of the steel sheet is 0.0040% or more, preferably 0.005
It is necessary to contain 0% or more. If the annealing temperature is lower than the recrystallization temperature, the workability deteriorates, and if it exceeds 850 ° C, the crystal grain size becomes abnormally large and the DI can becomes rough, so the recrystallization temperature is limited to 850 ° C. Upon cooling to room temperature after recrystallization annealing, if the residence time in the temperature range of 500 to 450 ° C. exceeds 5 seconds, precipitation of cementite occurs, and the solid solution C content of the steel sheet may be 0.0040% or more. Since it becomes difficult, at least it is necessary to regulate the residence time in this temperature range to 5 seconds or less. In order to contain a higher amount of solute C, the residence time in this temperature range is preferably set to 1 second or less. Temper rolling may be performed as needed, and there is no particular need to regulate it.

<Production conditions for claim (3)> Claim (3) is
Compared with the method of manufacturing using a continuous annealing equipment that is normally used as shown in claim (2), the total annealing time is extremely short and the staying time at the high temperature part is short. The present invention relates to manufacturing conditions for annealing in an ultra-rapid heating short-time continuous annealing facility, which is characterized by easy annealing. Except for the recrystallization annealing condition of continuous annealing, the same as claim (2). Recrystallization annealing of continuous annealing is at least 500
It is necessary to heat the temperature range of 100 ° C. or higher at 100 to 2500 ° C./s, hold at a recrystallization temperature of 900 ° C. for 0 to 5 seconds, and perform recrystallization annealing. The heating rate is such that halfway rapid heating such as less than 100 ° C./s not only makes it difficult to anneal the ultrathin material due to the long residence time in the high temperature part, but also raises the recrystallization temperature and extremely Since it is difficult to make it soft enough by holding for a short time such as 5 seconds, the lower limit value is 100 ° C.
/ S. The recrystallization annealing temperature is below the recrystallization temperature,
The workability deteriorates, and if the temperature exceeds 900 ° C, the crystal grain size becomes abnormally large and the DI can becomes rough, so the recrystallization temperature is regulated to 900 ° C. If the soaking time exceeds 5 seconds, the staying time in the high temperature portion becomes long and it becomes difficult to anneal the ultrathin material. Therefore, the upper limit was set to 5 seconds. In the method of the present invention, a sufficiently soft steel plate can be obtained even if the holding time is 0 seconds, so the lower limit value was set to 0 seconds.

[0027]

EXAMPLES The effects of the present invention will be described below with reference to examples. 0.245 mm surface-treated original plate was manufactured under the conditions shown in Table 1 and Table 2, continuous hot rolling, cold rolling, continuous annealing, temper rolling. Solid solution C content of manufactured surface-treated original plate, HR3
0T, ΔY. P (50% BH-3% BH) was measured, and DI performance was investigated after Sn plating, and the results are shown in Table 2.
Also described in.

[0028]

[Table 1]

[0029]

[Table 2]

In Table 1, Steel A has a C content of 0.002.
The production conditions are in the range of components of the comparative example, which is as low as 5%. Steel B is a conventional T with a C content of 0.0510%.
-4CA under the manufacturing conditions in the component range. Steel C,
D, E, and F are manufacturing conditions within the range of the method of the present invention, steels C, D, and E are examples of components in which C is changed, and steel F is within the range of the method of the present invention. And B is 0.0018
% Of the added components.

In Table 2, sample 1 is a comparative example, and the amount of solid solution C is as low as 13 ppm and ΔY. P (50% BH-3% BH) is 3
Targeted amount of solid solution C as high as 5 kgf / mm ² , ΔY. P (50
% BH-3% BH) is not obtained. In addition, the DI performance is insufficient in pressure resistance and cannot be used for DI cans. Sample 2 has a low solute C content of 25 ppm in the conventional example and ΔY.
P (50% BH-3% BH) is as high as 29 kgf / mm ² and the target amount of solid solution C, ΔY. P (50% BH-3% BH) is not obtained. In addition, the DI performance is insufficient in pressure resistance and necked-in property, and cannot be used in applications for DI cans with more severe processing.

Samples 3, 4, 5, 6, and 7 are examples of the method of the present invention according to claim (2).
ΔY. P (50% BH-3% BH) is obtained. In addition, the DI performance is compatible with both pressure resistance and necked-in property, and can be used for applications for DI cans with more severe processing. Sample 8 is an embodiment of the method of the present invention according to claim (3),
Even in the extremely compact continuous annealing method, in which the total annealing time is only a few seconds, the target solid solution C amount, ΔY. P (50% BH
-3% BH) is obtained. In addition, the DI performance is compatible with both pressure resistance and necked-in property, and can be used for applications for more severely processed DI cans.

As is clear from the results of the above examples,
The steel sheet of the present invention has good pressure resistance and necked-in property, and it is well understood whether it is excellent as a more severe surface-treated original sheet for DI cans. Also, claim (2) for normal continuous annealing equipment and claim (3) for extremely compact continuous annealing method
It can be seen that by the method of 1, the pressure-resistant strength and necked-in property of the present invention are good, and a stricter surface-treated original plate for DI can can be manufactured.

[0034]

The present invention has been described in detail above. However, the steel sheet of the present invention has good pressure resistance and necked-in properties, can be applied to more severely molded DI cans, and can exhibit excellent effects. The method in the annealing equipment (claim (2)), and the method in the extremely compact continuous annealing method (claim (3)), it becomes possible to produce the steel sheet of the present invention,
Its industrial value is great.

[Brief description of drawings]

FIG. 1 shows the amount of solid solution C and ΔY. P (50% BH-3% BH)
It is a figure which shows the relationship with.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akihiko Inoue 1 Fuji-machi, Hirohata-ku, Himeji-shi, Hyogo Nippon Steel Co., Ltd. Hirohata Works (72) Inventor Kazuya Eren 1 Fuji-cho, Hirohata-ku, Himeji-shi, Hyogo Address: Nippon Steel Co., Ltd., Hirohata Works (72) Inventor, Ryoichi Yoshihara, 1 Fuji-machi, Hirohata-ku, Himeji City, Hyogo Prefecture, Nippon Steel Works, Hirohata Works

Claims (3)

[Claims] 1. By weight%, C: 0.0050 to 0.0250%, Si: ≤ 0.30%, Mn: 0.05 to 0.60%, P: ≤ 0.030%, S: ≤ 0.025%, sol.Al: 0.002 to 0.100%, N: ≦ 0.0100%, B: 0 to (0.0010 + 1.8 × N%)%, balance unavoidable impurities and iron The steel plate contains 0.0040% or more of solute C and has an elongation of 3% and is preheated by additional rolling.
Y) after heat treatment). P (hereinafter, this Y.P is referred to as Y.P.
(Denoted as 3% BH)), and Y.I. P (hereinafter, this Y.P.
P (50% BH)) is 24 kgf / mm ² or less, which is a surface-treated original plate for DI can with good pressure resistance and necked-in property. 2. By weight%, C: 0.0050 to 0.0250%, Si: ≤ 0.30%, Mn: 0.05 to 0.60%, P: ≤ 0.030%, S: ≤ 0.025%, sol.Al: 0.002 to 0.100%, N: ≦ 0.0100%, B: 0 to (0.0010 + 1.8 × N%)%, balance unavoidable impurities and iron The slab is formed into a hot rolled steel strip by a continuous hot rolling mill, cold rolled at a cold rolling rate of 87 to 94%, and recrystallized at a recrystallization temperature of 850 ° C. by a continuous annealing method, and then, , Cooling to room temperature, 50
The temperature range of 0 to 450 ° C. is cooled in 5 seconds or less, the solid solution C content of the steel sheet is contained at 0.0040% or more, and then temper rolling is performed, and the Y. P (3% BH) and Y. P (50% B
The method for producing a surface-treated original plate for a DI can having a good pressure resistance and a good necked-in property, characterized in that the difference from H) is 24 kgf / mm ² or less. 3. The method according to claim 2, wherein at the time of continuous annealing, the temperature range of at least 500 ° C. or higher is 100 to 25.
A method for producing a surface-treated original plate for a DI can having good pressure resistance and necked-in properties, which comprises heating at 00 ° C./s, holding at a recrystallization temperature of 900 ° C. for 0 to 5 seconds, and performing recrystallization annealing.