JPH04187741A - Steel sheet for can, its manufacture and manufacture of three-piece can - Google Patents

Abstract

PURPOSE:To obtain a steel sheet for a can excellent in corrosion resistance and rusting resistance by rolling a continuously cast slab having a specified compsn., thereafter applying Ni plating thereto, subjecting it to continuous annealing to diffuse and infiltrate Ni into a matrix and thereafter executing skinpass rolling by using a rust preventing rolling oil. CONSTITUTION:A continuously cast slab constituted of, by weight, <=0.004% C, <=0.02% Sr, 0.05 to 0.30% Mn, <=0.020% P, <=0.020% S, <=0.0050% N, 0.02 to 0.2% Al, <=0.01% Nb and the balance Fe with inevitable impurities is subjected to hot rolling and cold rolling. This rolled stock is applied with Ni plating of 0.02 to 0.5g/m<2> and is subjected to continuous annealing in a reducing atmosphere to form an Fe-Ni alloy layer in which the weight ratio of Ni/(Fe+ Ni) is regulated to 0.02 to 0.5 and having 10 to 5000Angstrom thickness on the surface of the steel sheet. Next, skinpass rolling is executed by using a rust preventing rolling oil to form a rust preventing oil film having 1 to 100mg/m<2> dry weight. In the steel sheet for a can, rusting is not generated till coating for printing is executed. By using this steel sheet for a can, a three-piece can of high quality can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a steel plate for three-piece cans, a method for manufacturing the same, and a method for manufacturing three-piece cans.

<Prior art> Cans such as beverage cans, 18°C cans, and bale cans are divided into round and square cans in terms of shape, and are classified into two-piece cans and three-piece cans in terms of structure.

A two-piece can is a can made of two parts, which are a surface-treated steel sheet that has been subjected to treatments such as Sn plating, press processing, DI processing, etc., and a lid attached to it.A three-piece can is a can that is made of a surface-treated steel sheet that has been subjected to treatments such as Sn plating, and then has a lid attached to it. It is a can consisting of three parts: the can body is formed by bending and joining the ends together, and a top lid and bottom lid are attached to this can body.

Therefore, although 3-piece cans require more manufacturing steps and higher manufacturing costs than 2-piece cans, there are
Since strong processing such as I processing is not performed, there is an advantage that artistic printing is possible on the can body.

￥S2 Figure shows the manufacturing process for 3-piece cans.

That is, a continuously cast slab with a thickness of about 200 to 400 mm is hot rolled into a hot rolled steel plate with a thickness of 2 to 4 mm, and then coiled at a high temperature and self-annealed.

Next, the oxide scale on the surface is removed by pickling, and then cold rolled into a cold rolled steel sheet having a thickness of 0.1 to 0.6 mm.

Then, box annealing or continuous annealing is performed to recover the rolling set m<wb fibrous structure formed in the cold rolling process, proceed to recrystallization and grain growth, and obtain predetermined mechanical properties.

Thereafter, it is subjected to temper rolling to obtain a predetermined degree of temper (Tl to T6) to obtain a surface-treated original sheet.

This surface-treated original plate is plated with one or more of Sn, Cr, Ni, etc. (tin plated) and sheared into a predetermined length using a shear line.

Figure 3 shows this situation.

The polished steel plate 10 is cut so that the longitudinal direction (rolling direction) is in the bending direction of the can body to obtain the cut plate 1.

In the figure, 2 indicates the cutting line, and L indicates the cutting length.

Next, the cut plate 1 is painted and baked on the front and back surfaces in a painting line.

Note that the surface corresponding to the outer surface of the can is generally painted with white paint in consideration of printing in the next process.

Next, multicolor printing and baking are performed, but these coatings and
No printing is applied to the joints shown in FIG.

Next, the cut plate 1 is cut into a blank sheet 6 (FIG. 3 shows the case of two sheets, upper and lower) of the size per can by slit cutting, and this sheet 6 is bent into a cylindrical shape or a rectangular tube shape.

In the figure, 3 is a slit line, and 4 is a bending line for bending into a rectangular tube shape.

After the joints 5 at the longitudinal ends of the blank sheets 6 are overlapped and joined by welding or adhesive, the can 11 is completed by performing flanging, necking and beading as necessary, and attaching a top cover and a bottom cover. .

Here, the above-mentioned flange processing is performed, for example, on the canopy 13 and the bottom lid 1.
This is done in order to attach 4 by seaming, and the process is shown in Fig. 4.

In the figure, 12 is a can body, 17 is a flange, and 18 is a seaming part.

Further, the necking process and beading process are performed to increase the strength of the can.

<Tita that the invention seeks to solve> As mentioned above, the manufacturing process for 3-piece cans is complex and uses expensive plated steel sheets, which increases costs. Na 3
There are increasing demands on the manufacturing method for peace cans.

In order to meet this demand, there are several issues to be solved as shown below.

(1) There are box annealing methods and continuous annealing methods for annealing after cold rolling.
It is used to obtain hard materials of T4 to T6, but recently, improvements in heat patterns have made it possible to manufacture T2.5 and T3 class hard materials by continuous annealing.

Therefore, if continuous annealing is further promoted and T1 class can be continuously annealed, it will lead to cost reduction.

(2) As mentioned above, when painting and baking are performed on cut boards, it is necessary to pass each cut board through the painting line twice, and twice on the front and back sides (2 coats, 2 bakes, 2 coats, 2 bakes).

Therefore, instead of painting and baking the cut plate, a method can be considered in which the strip is painted and baked, and then it is made into a cut plate.

In this method, it is possible to sequentially apply coating to the surface corresponding to the inner surface of the can and to the surface corresponding to the outer surface of the can, and then perform the subsequent baking simultaneously on the front and back sides (two coats and one hake).

By performing painting and baking after cutting on the same painting line, the process can be simplified and made more continuous.

However, as shown in FIG.
(usually both joint widths are about 6 mm), it is very difficult to control the coating, and even if painting is possible, the strip is moving at high speed at the middle (3 mm) of the joint 5. It is difficult to cut.

In this way, poor control accuracy of the painting range and cutting position can lead to the following problems.

For example, if paint is present at the joint, if the welding is repeated as it is, the paint will burn, causing an explosion phenomenon, and not only will the nucket not be formed properly, but it may also form a hole.

Furthermore, in the case of bonding with adhesive, sufficient adhesive strength cannot be obtained.

On the other hand, if the area that should be painted is not painted,
There is no problem with joining, but there are problems with rust resistance, corrosion resistance, etc.

(3) There are tin-free steel sheets, thin Sn-plated steel sheets, and Ni-plated steel sheets as low-cost alternative materials for cans, but all of them require plating treatment after temper rolling, and further cost reductions are impossible. I can't hope.

As an even lower-cost material for cans, JP-A-59-145
Publication No. 076 proposes a steel plate for cans that uses tempered rolling oil that has excellent rust prevention properties and direct paintability.

This steel sheet for cans is manufactured by FDA as a component of temper rolling oil.
(Food and Drug Administrator
Since it uses a substance approved by Japan, it can be used as a material for cans for food and beverages.

However, when used as a welded can, since the contact resistance of the iron oxide film on the surface is high, a method is used in which welding is performed while removing the oxide film. Moreover, although it can be used as an art can among food and drink cans, its corrosion resistance when used as a beverage can containing liquid is insufficient, and its use as a steel sheet for cans has been limited.

An object of the present invention is to solve the problems of the prior art described above, and to provide an inexpensive and high-quality steel plate for cans, a method for manufacturing the same, and a method for manufacturing three-piece cans.

According to a first aspect of the present invention, in order to achieve the above object, Co: 0.004% by weight or less, Si: 0.0% by weight or less
2% by weight or less, Mn: 0305-0.30% by weight, p:
o, 0.020% by weight or less, S・0.020% by weight or less, N
・0.0050% by weight or less, Afl: 0.02-0.2
% by weight, Nb: 0.01% by weight or less, the balance being Fe and unavoidable impurities, and the surface layer has a Ni/(Fe+Nt) weight ratio of 0.02 to 0.
5 and has a Fe-Ni alloy layer with a thickness of 10 to 5000 people, and a rust preventive oil film on the Fe-Ni alloy layer with a dry weight of 1 to 5,000 people.
100 l11g/m''

According to the second aspect of the present invention, the weight ratio of C:0.
0041i amount% or less, Si: 0.02% by weight or less, Mn
: 0.05-0.30% by weight, P: 0.020% by weight or less, S: 0.020% by weight or less, N: 0050% by weight or less, Aj2: 0.02-0.2ji% by weight, Nb
: 0.01% by weight or less, the balance being Fe and unavoidable impurities. 02~0. 5g/m" Ni plating is applied, followed by continuous annealing in a reducing atmosphere to diffuse and penetrate Ni into the base steel sheet, resulting in Ni/(Fe+Ni) on the surface layer of the steel sheet.
A Fe-Ni alloy layer with a weight ratio of OO2N2.5 and a thickness of 10 to 5,000 is formed, and then temper rolling is performed using antirust rolling oil to form an Fe-Ni alloy layer with a dry weight of 1 to 100 on the surface of the steel plate. A method for manufacturing a steel sheet for cans is provided, which is characterized by forming a rust-preventing oil film of mg/m2.

According to the third aspect of the present invention, the front and back surfaces of a steel plate for cans are coated and baked except for a predetermined width at both ends in the width direction, cut into a predetermined length, and then blanked. A method for manufacturing a three-piece can, characterized in that a ranking sheet is used, the blanking sheet is bent in a direction perpendicular to the rolling direction, the non-painted parts are overlapped and joined, and then a top cover and a bottom cover are attached and finished by flanging. provided.

The present invention will be explained in more detail below.

First, the circumstances leading to the present invention will be described.

As a result of research, the present inventors came up with the idea that the above-mentioned joint problem in strip coating can be solved by changing the bending direction during can manufacturing from the conventional rolling direction to a direction perpendicular to the rolling direction.

This is shown in FIG. 1, in which the same parts as in FIG.

In the figure, reference numeral 2 indicates a cutting line, which is provided in the width direction of the plate and is cut to a predetermined length.

Blank sheet 6 slit-cut along slit line 3
is bent into a cylindrical shape or into a rectangular tube shape along bending line 4.

As a result, the coating is applied to the joints 5 located at both ends of the strip plate 10.
All you have to do is remove it and apply it continuously in the longitudinal direction of the strip 1.
Painting problems can be easily resolved.

However, when the blank sheet 6 manufactured in this manner was subjected to bending, seam welding, and flange processing, the frequency of cracking in the heat affected zone (HAZ) increased significantly.

Therefore, in order to eliminate this HAZ cracking, we conducted experiments with various welding conditions (heating temperature, electrode ring pressure, overlapping margin, etc.), and found that the greater the total thickness of the overlapping part, the higher the frequency of HAZ cracking. Furthermore, it is difficult to eliminate HAZ cracks by reducing the total thickness by optimizing welding conditions.Furthermore, even if the body is bent in the conventional rolling direction and overlapped welded, HAZ cracks do not occur, and welding at right angles to the rolling direction does not occur. The reason why HAZ cracking occurs in the direction is thought to be due to the anisotropy of the strip.

As a result of studying this anisotropy, the following was found.

In other words, anisotropy appears due to the effect of skin pass rolling after annealing, but if the grain size after annealing is large, almost no anisotropy appears, and conversely, if the grain size is small, the anisotropy becomes large. appear.

Furthermore, it was found that even if the rolling reduction during temper rolling is increased, anisotropy does not appear if the grain size after annealing is large.

In order to increase the grain size after annealing, considering productivity, corrosion resistance, etc., the amount of C should be reduced as much as possible, and the Mn
It was concluded that the method of continuous annealing using ultra-low carbon steel with reduced S, N, etc. as a material is optimal and led to the present invention.

The components and reasons for limitation of the can steel sheet (ultra-low carbon steel) of the present invention are as follows.

First, the amount of C is the most important factor in this invention, and needs to be 0.004% by weight or less in order to uniformly coarsen the crystal grains.

It is generally known that in regions where the amount of C is small, the grain size is uniquely determined by the amount of C in the steel, but even if the amount of C is the same, small grains exist next to large grains, a so-called mixed grain structure. In this case, anisotropy appears due to small-diameter crystal grains.

If the amount of C is 0.004% by weight or less, generation of a mixed grain structure can be prevented.

Since Si deteriorates corrosion resistance, etc., it is set to 0.02% by weight or less.

Mn is 0.05% by weight to prevent hot rolling embrittlement.
If the content exceeds 0.30% by weight, cold rolling properties will deteriorate and the amount of precipitates will increase, so the content was set at 0.30% by weight or less. In particular, a large amount of precipitates is undesirable because it inhibits coarsening of crystal grains.

If too much P is included, it will deteriorate corrosion resistance, etc., so 0.0
The content was 20% by weight or less.

Similarly, S not only deteriorates corrosion resistance, etc., but also worsens hot rolling brittleness and increases the amount of precipitates, so S is set at 0.020% by weight or less.

If a large amount of N is contained, the ductility deteriorates and the number of precipitates increases, so the content is set to 0.0050% by weight or less.

AJ2 is added at the steel manufacturing stage to obtain An quilted steel, but it is uneconomical if too much expensive A1 is added, and on the other hand, if too little is added, sufficient deoxidation is not achieved. .

Although Nb has the effect of lowering the recrystallization temperature during continuous annealing, it forms carbides and nitrides, so the content was set to 0.01% by weight or less.

In summary, if ultra-low carbon steel with a C content of 0.004% by weight or less is used as the starting material, continuous annealing becomes possible, the crystal grains become coarser, and the anisotropy caused by temper rolling can be eliminated. Therefore, it is possible to perform strip coating instead of the conventional cut plate coating, and the manufacturing process for three-piece cans can be made significantly more continuous.

Now, tin is the mainstream material for cans, and tin-free steel sheets, thin Sn
Although there are galvanized steel sheets and Ni-plated steel sheets, it is difficult to further reduce costs.

In order to make it the cheapest, in the extreme it would be possible to use a bare steel plate without plating, but in reality, rust will occur before the bare steel plate is painted and baked, and if painted as is, the paint adhesion will be poor. .

Furthermore, even if painting and baking are performed before rust occurs, filiform rust (filiform corrode) may occur from the edge of the board.
sion) cannot be prevented.

Materials for three-piece cans are required to have rust resistance, paint adhesion, post-paint corrosion resistance, weldability, and the like.

As a material for three-piece cans that satisfies these requirements and achieves cost reduction, it is thought that a material that is located between conventionally plated steel sheets and bare steel sheets is optimal, and the present inventors have developed Ni We focused on plating diffusion treated steel sheets.

After Ni plating, this steel plate is annealed and Ni
By diffusing Ni and Fe, Ni and Fe can be completely alloyed to form a Fe--Ni alloy layer with excellent corrosion resistance.

This Fe-Ni alloy layer itself has excellent corrosion resistance, and since the potential is closer to Fe than Ni, even if there is a scratch that reaches the base iron, Fe will not be leached out. Excellent.

However, Ni-plated diffusion-treated steel sheets have the disadvantage that welding is difficult.

As a result of various experiments, it was found that this steel plate can be welded without paint baking, but welding becomes difficult if paint baking is performed.

That is, it is considered that Fe oxide is sometimes formed during paint baking, which deteriorates weldability.

Therefore, as a method to prevent the formation of Fe oxides after baking the paint, it is possible to perform further plating, but not only is it impossible to manufacture at a low cost, but further dissimilar plating is difficult because of the amount of plating. If there is less,
A battery is formed between this new plating metal and the Fe-Ni alloy, which causes a decrease in corrosion resistance.

Therefore, the present inventors have found that the formation of Fe oxides can be reduced by applying a wet skin bath using rolling oil with excellent rust prevention properties to a steel plate that has been subjected to Ni diffusion treatment by annealing after Ni plating. I found it.

This is considered to be due to the following reasons.

In other words, during temper rolling, a large amount of strain occurs on the surface of the steel sheet, but
Fe oxides are likely to be formed in this strained portion, and therefore, if temper rolling is performed while supplying temper rolling oil having rust prevention properties during skin pass rolling, the formation of oxides can be suppressed. Also,
For the same reason, filamentous rust can also be prevented.

Although it is common to apply anti-corrosion oil after temper rolling, this method did not provide sufficient weldability.

Fe-N formed on the surface layer of the three-piece can steel sheet of the present invention
The weight ratio of Ni/(Fe+N1)(7) in the i alloy layer is 0.02 to 0.5, preferably 0.05 to 0.20.

The weight ratio of Ni/(Fe+Ni) in the Ni diffusion layer is 0.
．． If it is less than 02, the corrosion resistance of the Fe-Ni alloy layer itself will be insufficient, and if it exceeds 0 or 5, if defects such as abrasions that reach the base steel plate occur, the base steel plate will melt from this defect. becomes significant.

Moreover, the thickness of this Fe-Ni alloy layer is 10 to 5000, preferably 200 to 5000.

If the thickness of the Fe-Ni alloy layer is less than 10, the corrosion resistance will be insufficient, and if it exceeds 5,000, the Fe-N
Since the i-alloy is hard and brittle, when a welded can is manufactured using the obtained steel plate, defects are likely to occur during forming processes such as flanging of the can body, and corrosion resistance may also be reduced.

The rust preventive oil used in the rust preventive oil film formed on the Fe--Nf alloy layer is not particularly limited, and may be any directly coatable rust preventive oil that is commonly used in the temper rolling process of steel plates.

In particular, as a rust preventive oil, (a) FDA (Food and Drug)
(Abbreviation for Administration) 10% petroleum wax and/or synthetic wax and/or lanolin specified in Baragraph No. 178-3910.
~60% by weight, (b) 5-40% by weight of fatty acids as specified in FDA Paragraph No. 178-3910, (c) 5-30% by weight of triethanolamine as specified in FDA Paragraph No. 17B-3910. (d) 10 to 40% by weight of mineral oil as specified in FDA Paragraph No. 178-3910; (e) nonionic active agent polyethylene glycol monostearate and/or FDA Paragraph No. 1;
1 to 2 nonionic active agents specified in 78-3400
If a composition oil in which 0% by weight is dispersed and emulsified in an aqueous solvent, specifically, a composition oil described in JP-A-59-145076, it is very hygienic and suitable for can stock for food and drink. A three-piece can steel plate can be obtained.

This anti-rust oil film dries on the Fe-Ni alloy layer! ! i
1 to 100 mg/m2. Preferably 1-23mg
/l112 is formed.

By forming a rust-preventing oil film in the range of 1 to 100 mg/m2, it is possible to obtain a steel plate for three-piece cans with excellent rust prevention, weldability, and direct paintability.

In addition, when using the above composition as a rust preventive oil to make a three-piece steel plate for food and drink cans, there is a limit to the amount of the coating applied to the food and drink can stock, so the dry weight 1~
A range of 23 mg/m2 is preferred.

In manufacturing the three-piece steel plate for cans according to the present invention, first, a continuously cast slab having the above-mentioned composition is subjected to hot rolling and cold rolling by a conventional method.

Next, the surface of the steel plate is plated with 0.02 to 0.5 g/m2 of Ni, followed by continuous annealing in a reducing atmosphere to diffuse and infiltrate the Ni into the base steel plate, coating the surface layer of the steel plate with Ni/(
Weight ratio of Fe+Ni) is 0.02 to 0.5 and thickness is 10 to
After forming the 5,000-layer Fe-Ni alloy layer, it was continuously subjected to temper rolling using rust-preventing rolling oil to form a rust-preventing oil film with a dry weight of 1 to 100 mg/m2 on the surface of the steel plate. Bye.

Note that if the amount of Ni plating is less than 0.02 g/m2, the corrosion resistance will decrease, and if it exceeds 0.5 g/m', no further improvement in corrosion resistance will be obtained, which will be disadvantageous in terms of cost.

Further, the reducing atmosphere is not particularly limited, and includes, for example, a mixed atmosphere of N2 and H2, and continuous annealing is usually performed at 650 to 750°C for 30 seconds to 10 minutes.

The temper rolling treatment can be carried out according to a conventional method and is not particularly limited.

By performing rolling using the anti-corrosion oil in this temper rolling process, there is no need to degrease before can manufacturing, and there is no need to provide an oiling process, which is not only economical, but also
A three-piece can steel plate with excellent weldability can be obtained.

Furthermore, in order to carry out the present invention most effectively, it is preferable to provide Ni plating equipment before the continuous annealing line and provide temper rolling equipment on the outlet side of the annealing line.

By connecting plating, annealing, and temper rolling as one line and completing the process all at once, it is possible to significantly reduce costs by making it continuous.

In addition, since each piece of equipment is connected, the plating, annealing, and temper rolling processes can be performed continuously without any time delay, preventing the formation of Fe oxides, etc., and improving weldability. , the effect of improving corrosion resistance becomes even greater.

Of course, in the present invention, since the material is manufactured using ultra-low carbon steel using a continuous annealing method, compared to the box annealing method using low carbon steel as the material, there is no concentration of impurities on the surface and it is advantageous in terms of rust resistance. Become.

<Example> The present invention will be specifically explained below based on examples.

(Example 1) Continuously cast slabs manufactured under the manufacturing conditions shown in Table 1 were turned into hot-rolled steel strips with a thickness of 3 mm using a hot rolling mill, and then into 0.323 mm thick sheets using a cold rolling mill.

Cold-rolled steel strips with plate thicknesses of 0.34 mm and 0.38 mm were used.

Subsequently, Ni plating diffusion treatment was performed by continuous annealing,
The above 0.3
For the 8mm and 0.34mm ones, use antirust oil A and B.
After temper rolling to a thickness of 32mm or 01323mm without using any anti-rust oil, the sheet is sheared into a cut plate so that it is bent perpendicular to the rolling direction, then painted, printed and baked. After heat-rolling and temper rolling, the strips are continuously bent in a direction perpendicular to the rolling direction, painted, printed and baked, then sheared into cut plates, and copper wire is attached to the intermediate electrode. The body of the 181 can was formed by welding using a wire seam welding machine using a wire seam welding machine, followed by flange processing using a die flancher and evaluation of flange cracking.

In addition, the raw steel sheets were evaluated for rust prevention, and the painted steel sheets were evaluated for corrosion resistance, filamentous rust, and paint density. Weldability was also evaluated. The results are shown in Table 1. From these results, it is clear that the steel plate of the present invention is an excellent steel plate that does not cause HAZ cracking even when bent in a direction perpendicular to the rolling direction, and can be painted as a strip, compared to comparative steel plates. Furthermore, it is clear that the bare steel plate has excellent rust resistance and paint adhesion.

The Ni polishing bath and annealing conditions used are as follows.

Ni plating bath composition: Nickel sulfate 250 g / 11 Nickel chloride 45 g/f Boric acid 30 g/j2 Bath temperature 60 Current density 5 A/dm2 Annealing conditions Atmosphere: NHX gas atmosphere (10% H2 + 90% N2
) Annealing temperature: 750 Rust-preventing rolling oil having the following composition was used.

The Ni plating amount of this sample, Ni / (
Ni + Fe) ratio, as well as rust prevention and corrosion resistance,
Paint adhesion by T-beer test and high-speed weldability were measured or evaluated according to the following methods. For comparison, similar measurements and evaluations were also carried out on tinplate (Comparative Example 6), TFS (Comparative Example 7), and thin Sn-plated steel sheet (Comparative Example 8).

Ni plating amount It was measured using fluorescent X-rays.

Nf (Ni+Fe ratio The weight ratio was investigated in the depth direction using GDS.

Temperature: 25°C, relative humidity: 50% using a "L" dry-wet cycle tester
dry state and wet state at temperature 50°C and relative humidity 98°C.
The sample was exposed under conditions of scrubbing every 0 minutes, and after one week, the number of rust occurrences on the sample surface was measured, and the rust prevention property was evaluated according to the following criteria.

After coating the surface of the base 1 JL sample with epoxy phenol paint to a thickness of 5 μm, make an X scratch on the diagonal, and test it in a dry state at a temperature of 25°C and a relative humidity of 50% using a dry-wet cycle tester. ℃ and a humid state of 98% relative humidity.
The samples were exposed to conditions that were repeated every 0 minutes, and the occurrence of filamentous rust was observed every two months, and the degree of rust was evaluated according to the following five grades.

◎: No thread-like corrosion Q: Slight thread-like corrosion Δ: Moderate thread-like corrosion 70ml of tomato juice at 90℃
Hotbacked A.

After this hot bag was kept at 55° C. for 10 days, it was taken out, the corrosion state was observed, and the corrosion resistance was evaluated according to the following criteria.

Using a copper wire with a wire diameter of about 1.5 mmφ as a welding electrode, the two samples were superimposed under constant pressure, and electric resistance welding was performed at a welding speed of 20 m/min while moving the welding electrode.

At this time, weldability was evaluated based on the size of the appropriate range of welding current and pressurizing force determined under the conditions that the welded part has sufficient strength and no splash occurs.

Paint adhesion After coating the surfaces of two samples with epoxyphenol paint to a thickness of 5 μm, the coated surfaces were separated to a thickness of 40 μm.
A μm nylon I2 film is sandwiched and bonded under pressure.
A tensile test piece was prepared. This test piece was subjected to a T-beer test using a tensile tester to measure adhesive strength, which was used as an index of paint adhesion.

<Effects of the Invention> Since the present invention is constructed as described above, the steel sheet for cans of the present invention does not rust before being coated and printed as an original sheet after temper rolling, After rolling, it is also possible to directly paint or print the strip.

Further, even when performing high-speed welding using such a coated plate, since the appropriate welding current range is wide, stable high-speed welding work can be performed without prior grinding.

In addition, even if the can body is bent and welded in a direction perpendicular to the rolling direction and flanged, it will not crack in the heat-affected zone, and this makes it possible to paint the can body in a band-like manner. It is possible to shorten the time and reduce costs.

In addition, by Ni plating diffusion treatment before annealing and anti-corrosion oil temper rolling, corrosion resistance, rust resistance, paint density, etc. are significantly improved, and they are equivalent to conventional electroplating after temper rolling. There is a lot of trouble. Therefore, it is possible to shorten the manufacturing process and reduce costs.

In addition, by continuously applying coating and printing after temper rolling, quality can be further stabilized.

It should be noted that there was no problem when plating was performed using the original plate of the present invention in the conventional manner, and on the contrary, there was a tendency for plating to occur more easily than in the conventional method.

[Brief explanation of drawings]

FIG. 1 is a plan view for explaining the coating and cutting positions of the steel plate for cans of the present invention. FIG. 2 is an explanatory diagram of the manufacturing process of a three-piece can. Figure 'fS3 is an explanatory diagram of the painting and cutting positions of a conventional three-piece can steel plate. FIG. 4 is an explanatory diagram of flange processing of a can. Explanation of symbols 1... Cutting plate, 2... Cutting line, 3... Slit line, 4... Bending line, 5... Joint part, 6... Blank sheet, 10... Plating Steel plate (band plate), 11... Can, 12... Can body, 13... Canopy, 14... Bottom cover, 17... Flange part, 18... Sealing part FIG, 1 F I G, 2 F I G, 4

Claims (3)

[Claims] (1) Weight ratio: C: 0.004% by weight or less, Si: 0
．． 02% by weight or less, Mn: 0.05 to 0.30% by weight,
P: 0.020% by weight or less, S: 0.020% by weight or less, N: 0.0050% by weight or less, Al: 0.02-0.
2% by weight, Nb: 0.01% by weight or less, the balance being Fe and unavoidable impurities, and the surface layer has a Ni/(Fe+Ni) weight ratio of 0.02 to 0.5 and a thickness of 10 to 10% by weight. 5000 Å Fe-N
1. A steel sheet for cans, comprising an i-alloy layer, and a rust preventive oil film formed on the Fe--Ni alloy layer at a dry weight of 1 to 100 mg/m^2. (2) C: 0.004% by weight or less, Si: 0.
02% by weight or less, Mn: 0.05-0.30% by weight, P
: 0.020% by weight or less, S: 0.020% by weight or less,
N: 0.0050% by weight or less, Al: 0.02-0.2
A continuous cast slab consisting of Nb: 0.01 wt% or less, the balance being Fe and unavoidable impurities, is subjected to hot rolling and cold rolling. Ni plating is applied, followed by continuous annealing in a reducing atmosphere to diffuse and penetrate Ni into the base steel sheet, resulting in Ni/(
Weight ratio of Fe+Ni) is 0.02 to 0.5 and thickness is 10
A Fe-Ni alloy layer of ~5000 Å is formed, and then temper rolling is performed using anti-rust rolling oil to form an anti-rust oil film of 1 to 100 mg/m^2 in dry weight on the surface of the steel plate. Characteristic manufacturing method for steel sheets for cans. (3) The front and back surfaces of the steel plate for cans according to claim 1 are coated and baked except for a predetermined width at both ends in the width direction, cut into a predetermined length, and further blanked to form a blanking sheet; A method for manufacturing a three-piece can, characterized in that a blanking sheet is bent in a direction perpendicular to the rolling direction, the unpainted parts are overlapped and joined, and then a top cover and a bottom cover are attached and finished by flanging.