JPS637336A - Production of extra-thin steel sheet for welded can having excellent flanging property - Google Patents

Abstract

PURPOSE:To produce an extra-thin steel sheet for welded cans having an excellent flanging property by subjecting a steel consisting of specifically composed C, Si, Mn, P, Al, N, and Fe to hot rolling, cold rolling, annealing, and secondary cold rolling under specific conditions. CONSTITUTION:A steel contg. 0.02-0.20% C, <=0.02% Si, 0.1-0.6% Mn, <=0.06% P, 0.005-0.1% Al, and <=0.1% N, and consisting of the balance Fe and unavoidable impurities is subjected to the hot rolling at the finishing temp. above the A3 transformation point and is coiled at <=680 deg.C coiling temp. After the hot rolled steel sheet is pickled, the steel sheet is subjected to rolling and annealing additionally as a pretreatment at need; thereafter, the sheet is subjected to the cold rolling at <=85% draft. The cold rolled sheet is then annealed at the temp. above the recrystallization temp. by continuous annealing or box annealing. The annealed steel sheet obtd. in such a manner is subjected to the secondary cold rolling at 10-40%, by which the stock for plating is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing an ultra-thin welded copper plate having excellent flanging properties.

[Conventional technology]

Conventionally, cans have been joined by soldering, resin adhesion, and welding. The welding cost for cans decreases in the order of seven: soldering, resin adhesion, and welding.In recent years, welding, which can reduce the joining cost for cans, has become mainstream, as the yield rate for steel plates is the same. Incidentally, in order to cover the joined can bodies, flange processing is performed to form a flange portion extending diametrically outward at the end of the can body. At that time, defects called cracks, bulges, and 7-lunge cracks may occur that cause the contents of the can to leak from the flange.

7. Causes of lunge cracking include poor welding, poor workability of the steel plate itself, inclusions in the steel plate, hardening of the weld, and softening of the weld heat affected zone. Among them, the part that leads to cracking during 7-lung processing is locally deformed, and 7. Lange cracking is often caused by the weld heat-affected zone due to the interaction of hardening of the weld and softening of the weld heat-affected zone. This is the biggest problem in lunge machining.

This problem is noticeable in the following steel plates.

In order to save resources, there is a trend toward thinner can materials, and this is being countered by increasing the hardness of steel sheets. Such a steel plate is produced by cold-rolling a hot-rolled steel plate, annealing it, and cold-rolling it again, which is the so-called two-time cold rolling process.

This twice cold-rolled material often suffers flange cracking during 7-lung processing after welding. The reason for this is thought to be that strain during flange processing concentrates on the weld heat-affected zone, which is softened by the welding and is sandwiched between the weld hardened by welding and the part of the original sheet that has been hardened by cold rolling twice, resulting in cracking.

On the other hand, regarding the manufacturing method of ultra-thin steel sheets for welded cans with excellent 7-lange workability, the conventional method is as described in Japanese Patent Application Laid-open No. 59-25934. Methods are being used to prevent this. However, it was insufficient to prevent 7-lunge cracking, and it was not possible to produce an ultra-thin steel plate for welded cans with excellent flange workability.

[Problem that the invention seeks to solve]

The present invention improves the above-mentioned drawbacks and provides a method for producing a 4-pole steel plate for welded cans with excellent 7-lung workability.

[Means for solving problems]

In the present invention, C: 0.02 to 0.20%, Si≦0, 02
%, Mn: 0.1-0.6%, P≦0.06
%, A1: 0.005 to 0.1%, N≦0.1%, and the balance is Fe and inevitable impurities.

Hot rolled at a finishing temperature above the transformation point and coiled at a temperature of 680°C.
After winding and pickling, cold rolling is performed at a cold rolling rate of 85 inches or less, followed by continuous annealing or box annealing at a temperature higher than the recrystallization temperature, and then secondary cold rolling of 10 to 40%. A method for manufacturing a pole 4 steel plate for welded cans with excellent 7-lunge workability, characterized in that the steel plate is subjected to a cold rolling process and used as a material for plating, and in the above method, the steel plate is additionally made to have a cold rolling rate of 85 inches or less. 7. A method for producing an ultra-thin steel plate for welded cans with excellent flange workability, characterized by rolling and annealing to reduce the thickness.
This makes it possible to economically advantageously produce ultra-thin steel plates for welded cans with excellent lunge workability.

The present invention will be explained in detail below.

The inventors of the present invention have conducted extensive studies on the manufacturing method of ultra-thin steel sheets for welded cans with excellent flanging properties, and have found that cold rolling is performed at a cold rolling rate of 85 inches or less to increase the r value in the rolling direction of the steel sheet. It was discovered that by improving the local deformability of the weld heat-affected zone and preventing flange cracking during 7-flange processing, an ultra-thin steel plate for welded cans with excellent flange workability could be obtained.

Figure 1 shows C: 0.05%, Si: 0.012%, Mn
: 0.32%, P: 0.01%, AZ: 0.0
35%, N: 0. A steel containing OO43 was melted and hot-rolled according to a conventional method at a finishing temperature of 870°C and a winding temperature of 630°C, resulting in a hot-rolled steel plate with a plate thickness of 1.4, zl, and 2.8 m. After that, the plate thickness 2.8wg material was cold rolled at a cold rolling rate of 75.70.
After performing cold rolling at 61 mm and box annealing at 680°C for 2 hours to obtain a plate thickness of 0.71 to 18 mx, cold rolling was performed at a cold rolling rate of 70 to 92% according to a conventional method. Finished, board thickness 0.
After forming a 213 m steel plate, it was subjected to continuous annealing at 680°C for 20 seconds and box annealing at 640°C for 2 hours, and then cold rolling with a cold rolling rate of 20 inches, so-called secondary cold rolling, to obtain a plate with a thickness of 0.
It is a figure which investigated the relationship between the cold rolling rate, the r value in the rolling direction, and the flange-up ratio when a 17 mm ultra-thin steel plate for welded cans was made. Here, the r value in the rolling direction is determined by measuring the Young's modulus in the rolling direction, the direction perpendicular to the rolling direction, and the Young's modulus in the 45 degree direction from the rolling direction.
It was determined from the correspondence equation between Young's modulus and r value. In addition, the flange up rate is calculated based on the range without 7-lunge cracking.
It was determined by (diameter of can body) x 100 (ch). The hardness of the steel plate must be 70 or higher at Hr30T, and the hardness is DR8, D, which is the general standard for ultra-thin steel plates for welding cans, which indicates the strength of the steel plate.
R9, within the DRIQ range. From the figure, it can be seen that when the cold rolling ratio is 85% or less, the r value in the rolling direction is not high, the flange up ratio is high, and the 7-lung workability is improved. In contrast, it can be seen that when the cold rolling rate exceeds 85 inches, the r value in the rolling direction is low, the 7-range up ratio is low, and the 7-range workability is poor. This is because the processing direction during 7-lange processing is the same as the rolling direction, so the r value in the rolling direction increases and the local elongation improves, so the local elongation of the weld heat affected zone increases. Since the properties are also improved, a steel plate that does not cause 7-lunge cracking and has good 7-lunge workability can be obtained. Moreover, in order to lower the cold rolling rate, it is necessary to reduce the thickness of the hot rolled steel sheet, but there is a limit to reducing the thickness during hot rolling due to the manufacturing process. It can be said that cold rolling and annealing processes for reducing the plate thickness as pretreatment are also effective.

Incidentally, steels having the composition range specified in the present invention show substantially similar results.

In the present invention, the reasons for limiting the components as described above are as follows.

The lower limit of the C content is set to 0.02% because if it is less than that, the strength as an ultra-thin steel plate cannot be obtained. Further, the reason why the upper limit of the amount of C is set to 0.2° is that if it exceeds this value, the material becomes hard and the 7-lunge workability deteriorates.

The reason why the amount of 81 is set to be 0.02- or less is because if it exceeds this amount, the 7 lunge workability deteriorates. Furthermore, if the amount of Si increases, the adhesion of the first plating will deteriorate when plating with Sn, Cr, Nt, AII, etc. is applied to produce a plated steel sheet, so it is necessary to reduce the amount of Si. Furthermore, it is desirable to reduce the amount of Si, which is effective from the viewpoint of corrosion resistance of one can.

The reason why Mn1i is limited to 0.1 to 0.6 is because if it is less than 0.1, the strength as an ultra-thin steel plate cannot be obtained.
Moreover, if it exceeds 0.6%, it will become hard, resulting in poor lunge workability and high manufacturing cost, which is economically disadvantageous.

The reason why the amount of P is limited to 0.06% or less is because it is effective as a solid solution strengthening element, but if it is more than necessary, it will worsen flange workability, and if it is too much, it is not preferable from the viewpoint of corrosion resistance. be.

The AII amount is limited to 0.005 to 0.1, and the lower limit is 0,
The reason why we set the OQ to 5chi is because if it is less than that, deoxidation will not be sufficient, resulting in a steel with many inclusions, and flange cracking will easily occur.Also, we set the upper limit to 041chi because if the content is higher than that, the steel will have many inclusions. Then, the crystal grains become fine and hard due to solid solution M,
7. This is because it deteriorates the lunge workability.

Limiting the amount of N to 0.1 or less is effective as a solid solution strengthening element, but if it is increased more than necessary, it may become hard. A! This is because N is precipitated and hardened, which deteriorates the 7-lunge workability.

Next, the manufacturing process of the present invention will be described.

The finishing temperature of the hot rolling process was limited to A, the transformation point or higher, because if it was lower than that, rolling distortion would remain and the structure could not be made uniform, which could lead to 7-lunge cracking in hard parts.

The reason why the coiling temperature in the hot rolling process is limited to 680℃ or less is because if the coiling temperature is higher than 680℃, the material quality of the steel sheet will be uneven in the longitudinal and width directions, and the material for welded cans will be This is because uniformity is required over the entire surface.

After pickling, cold rolling is performed, but the main focus of the present invention is to limit the cold rolling rate to 85 inches or less, and to increase the r value in the rolling direction and improve local deformability. 7. This is to improve lunge workability. When the cold rolling rate exceeds 85 inches, the r value in the rolling direction becomes low and the flange workability deteriorates.

In addition, if the thickness of the hot rolled steel sheet cannot be reduced and the cold rolling rate exceeds 85%, cold rolling and annealing may not be performed as pretreatment before cold rolling so that the cold rolling rate can be lowered. It is valid. The conditions are not limited, but the cold rolling rate is 40 to 8.
5. Annealing is performed at a temperature higher than the temperature at which recrystallization occurs in box annealing or continuous annealing. The standard annealing temperature for box annealing is 620-700℃ for 2-5 hours, and the annealing temperature for continuous annealing is 620-700℃.
The standard time is 20 to 60 seconds.

Annealing after cold rolling is performed at a temperature higher than the temperature at which recrystallization occurs in box annealing or continuous annealing. The annealing temperature for box annealing is 620-700℃.
~5 hours is standard, and the annealing temperature of continuous annealing is 620 ~ 7
The standard temperature is 20 to 60 seconds at 00°C. Furthermore, in continuous annealing, in order to reduce solid solution carbon, it is desirable to perform overaging treatment, and the conditions are as follows:
, the time is 1 to 3 minutes.

Cold rolling after annealing The cold rolling rate of so-called secondary cold rolling is 10 to 4.
The reason why it is limited to 0% is because if the cold rolling ratio is less than 10%, the strength of the ultra-thin steel sheet as a material for welded cans cannot be obtained. This is because when a steel plate containing carbon ages, only the parts where Lüders bands are generated deform, a phenomenon that leads to breakage and deteriorates the flanging process.Furthermore, when the cold rolling rate exceeds 40%, the steel plate becomes hard. This is because too much 7. lunge workability deteriorates.

The steel plate obtained in this way is used as a raw material and its surface is plated to produce a plated steel plate.This steel plate can be plated with Sn, thin Sn plating, multi-layer plating of Sn and other metals, etc. Ni plating and multilayer plating of N1 and other metals, C
It exhibits equally good effects on various plating layers such as R plating and multilayer plating of Cr and other metals.

As described above, according to the present invention, it is possible to economically produce an ultra-thin steel plate for welded cans with excellent 7-lung workability.

do.

'-1+-;, - Rolling, pickling, cold rolling, annealing, secondary cold rolling, including those subjected to cold rolling and annealing as pre-treatment before annealing, secondary cold rolling The flange-up ratio of the steel plate obtained later was investigated.

From Table 1, it can be seen that the desired 7-range up ratio, etc. cannot be obtained with the comparative methods other than the method of the present invention, whereas the desired flange amplifier ratio, etc. can be obtained with the method of the present invention. .

〔Effect of the invention〕

As explained above, according to the present invention, there are effects such as excellent 7-lunge workability and the ability to reduce the thickness of the steel plate, which greatly contributes to resource and energy conservation. Therefore, it is possible to economically advantageously produce an ultra-thin steel plate for welded cans with excellent 7-lung workability.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the cold rolling rate, the r value in the rolling direction, and the flange up ratio. Figure 1 5 δ065
)

Claims (2)

[Claims] (1) C: 0.02-0.20% Si≦0.02% Mn: 0.1-0.6% P≦0.06% M: 0.005-0.1% N≦0.1 %, with the balance consisting of Fe and unavoidable impurities, is hot rolled at a finishing temperature of A_3 transformation point or higher, and then rolled at a coiling temperature of 6.
After winding at 80℃ or less and pickling, cold rolling at a cold rolling rate of 85% or less, continuous annealing or box annealing at a temperature higher than the recrystallization temperature, and then secondary cold rolling at 10 to 40%. A method for producing an ultra-thin steel plate for welded cans with excellent flange workability, characterized by rolling it and using it as a plating material. (2) A patent claim characterized in that the hot rolled steel sheet is additionally subjected to rolling and annealing as a pretreatment before cold rolling after pickling, and then cold rolling is performed at a cold rolling rate of 85% or less. Method for producing ultra-thin steel plates for welded cans with excellent flange workability as set forth in item 1