JPH0734192A - Steel sheet suitable for application to thinned deep-drawn can and its production - Google Patents

Abstract

PURPOSE:To obtain a steel sheet for a thinned deep-drawn can excellent in workability, surface roughening properties and corrosion resistance by subjecting a steel sheet having a specified compsn. constituted of C, Si, Mn, P, S, Al, N and Fe to specified skinpass rolling and forming specified crystalline grains. CONSTITUTION:A steel slab contg. 0.01 td 0.15% C, <=0.05% Si, <=0.9% Mn, <=0.04% P, <=0.04% S, 0.015 to 0.10% Al and 0.0020 to 0.015% N and furthermore contg., at need, 0.001 to 0.020% Nb, and the balance Fe with inevitable impurities is subjected to hot rolling at about the Ar3 point or above. This hot rolled steel sheet is subjected to cold rolling at about >=75% draft. This cold rolled steel sheet is annealed by a heat cycle including averaging treatment. After that, the steel sheet is subjected to skinpass rolling at 0.5 to 2.0% elongation percentage or DR rolling at 20 to 50% draft. Thus, the average grain size is regulated to <=6.0mum. In this way, the steel sheet free from the generation of the breakage of the barrel at the time of continuous high speed can producing, furthermore excellent in workability and suitable for the application to a thinned deep-drawn can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container material for food cans, beverage cans, etc., and particularly to a steel sheet suitable for use in thin-walled deep-drawing cans, which has excellent deep-drawing workability, good skin roughness, and excellent corrosion resistance. It relates to the manufacturing method.

[0002]

2. Description of the Related Art Conventionally, side seamless (side seamless)
As a method of forming a can, a method of applying an organic coating to the inside and outside of the can after forming a surface-treated steel sheet and coating a resin film on the metal plate before forming in advance, and using the resin film as a kind of forming lubricant, the side wall of the can There is a so-called thinned squeeze can forming method in which the metal plate of the portion to be thinned is thinned. As an example of the latter,
The present inventors previously proposed a metal plate for a thinned squeezed can having excellent surface roughness resistance and corrosion resistance after can making by specifying the average crystal grain size and the average surface roughness of the metal plate ( See JP-A-4-314535).

[0003]

However, when a conventional thin metal can is formed using a metal plate coated with a resin film in advance, there is a problem that the side wall of the can after completion is extremely rough. That is, the clearance between the die and the punch is larger than the thickness of the side wall of the can, and the side wall of the can is not restricted by the punch and the die at the time of processing and is a so-called free surface.
There is a problem that the side wall of the can is liable to be rough compared to the molding method. When this rough skin condition occurs, the adhesive force between the original plate and the film is reduced, which also contributes to film peeling. In addition, rough skin is also triggered by an external impact such as contact between cans during transportation, which causes minute cracks on the film surface, and eventually leads to deterioration of corrosion resistance. In general, a thin-walled deep-drawing can is formed by punching a coated metal plate into a disc shape and then drawing this in two steps.
At the time of this second-stage drawing (redrawing), a high wrinkle holding force is applied to the flange portion to draw and project the side wall of the can to reduce the thickness of the side wall of the can. In the above-mentioned processing method, redrawing is an extremely severe forming method, so that there has been a problem that breakage easily occurs during continuous forming. When such crushing occurs, the productivity of high-speed can manufacturing is impaired, so crushing is less likely to occur,
Moreover, there was an urgent need to develop a steel sheet that has excellent workability and is suitable for thin-walled deep-drawing can applications. The present invention is intended to solve the above problems, and is suitable for use in thin-walled deep-drawing cans that have excellent skin roughness and corrosion resistance, do not break during continuous high-speed can manufacturing, and have excellent processability. An object is to provide a steel sheet and a manufacturing method thereof.

[0004]

A steel sheet suitable for use in a thin-walled deep-drawn can of the present invention is C: 0.01 to 0.15%, Si ≦.
0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦
0.04%, Al: 0.015 to 0.10%, N: 0.
Hot rolled steel sheet consisting of 0020 to 0.015%, balance Fe and unavoidable impurities is annealed in a heat cycle including cold rolling and overaging treatment, and temper rolling at an elongation of 0.5 to 2.0%. It is desirable that the average grain size of the steel sheet after temper rolling be 6.0 μm or less. Also, C:
0.01 to 0.15%, Si ≦ 0.05%, Mn ≦ 0.
9%, P ≦ 0.04%, S ≦ 0.04%, Al: 0.0
15 to 0.10%, N: 0.0020 to 0.015%,
A hot-rolled steel sheet consisting of the balance Fe and unavoidable impurities is sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and DR rolling at a reduction rate of 20 to 50%, and the average of the steel sheets after DR rolling. It is also preferable that the crystal grain size is 6.0 μm or less. Furthermore, C: 0.01 to 0.15%, Si ≦
0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦
0.04%, Al: 0.015 to 0.10%, N: 0.
0020 to 0.015%, Nb: 0.001 to 0.02
Hot-rolled steel sheet consisting of 0%, balance Fe and unavoidable impurities is sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and temper rolling at an elongation rate of 0.5 to 2.0%. The average grain size of the steel sheet after temper rolling may be 6.0 μm or less. Further, C: 0.01 to 0.15%, S
i ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S
≦ 0.04%, Al: 0.015 to 0.10%, N:
0.0020 to 0.015%, Nb: 0.001 to 0.
A hot-rolled steel sheet consisting of 020%, the balance Fe and unavoidable impurities is sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and DR rolling at a reduction rate of 20 to 50%, and after DR rolling. It is also desirable that the average crystal grain size of the steel sheet is 6.0 μm or less. Next, the manufacturing method of the steel sheet suitable for use in the thin-walled deep drawing can of the present invention is C: 0.01 to 0.1.
5%, Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.0
4%, S ≦ 0.04%, Al: 0.015 to 0.10.
%, N: 0.0020 to 0.015%, the balance of Fe and unavoidable impurities in a hot rolled steel sheet, cold rolling, annealing in a heat cycle including overaging treatment, elongation 0.5 to.
It is desirable to perform temper rolling at 2.0% sequentially. Further, C: 0.01 to 0.15%, Si ≦ 0.05%, M
n ≦ 0.9%, P ≦ 0.04%, S ≦ 0.04%, A
1: 0.015-0.10%, N: 0.0020-0.
It is also preferable to sequentially perform cold rolling, annealing in a heat cycle including overaging treatment, and DR rolling at a reduction rate of 20 to 50% on a hot-rolled steel sheet containing 015%, balance Fe and unavoidable impurities. Furthermore, C: 0.01 to 0.15%,
Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%,
S ≦ 0.04%, Al: 0.015 to 0.10%, N:
0.0020 to 0.015%, Nb: 0.001 to 0.
A hot-rolled steel sheet consisting of 020% and the balance Fe and unavoidable impurities is sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and temper rolling at an elongation of 0.5 to 2.0%. May be. Further, C: 0.01 to 0.15%, Si
≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦
0.04%, Al: 0.015 to 0.10%, N: 0.
0020 to 0.015%, Nb: 0.001 to 0.02
It is also preferable to sequentially perform cold rolling, annealing in a heat cycle including overaging treatment, and DR rolling with a reduction rate of 20 to 50% on a hot-rolled steel sheet containing 0%, the balance Fe and unavoidable impurities.

[0005]

The steel sheet of the present invention is coated with a resin film such as polyester and punched into a disk shape, and even if it is subjected to continuous high-speed can-making processing by two-step drawing, no crushing occurs and the workability is improved. Can form excellent thin-walled deep-drawn cans.

[0006]

【Example】

Components of hot-rolled steel sheet C: 0.01 to 0.15%, Si ≤ 0.05
%, Mn ≦ 0.9%, P ≦ 0.04%, S = 0.04
%, Al: 0.015 to 0.10%, N: 0.0020
˜0.015%, balance Fe and unavoidable impurities. Moreover, what added 0.001 to 0.02% of Nb to the said component is also used suitably. The reasons for controlling the steel composition are described below. When C is less than 0.01%, the crystal grains are coarsened, and the lower limit is made 0.01%. On the other hand, 0.15
%, The drawability deteriorates, so the range was made 0.08 to 0.15%. Si is an element harmful to corrosion resistance as a can material, but is an element inevitably contained in Al-killed steel, and the upper limit was set to 0.05%. Mn is a component necessary to prevent red hot embrittlement due to impurities S during hot rolling. On the other hand, if it exceeds 0.9%, drawability deteriorates, so the upper limit was made 0.9%. P is an effective component for refining crystal grains, and it is added in a fixed ratio because it increases the strength of the original plate, but it impairs corrosion resistance. The steel sheet for cans used in the present invention is P
If it exceeds 0.04%, the corrosion resistance, especially the hole-proofing property, remarkably decreases, so the upper limit was made 0.04%. S is an impurity component that causes red hot embrittlement during hot rolling, and it is desirable that the content is as small as possible, but it is an element that is inevitably contained and the upper limit was made 0.04%. Al is added as a deoxidizing agent in the steel bath during steelmaking and is removed as slag. However, if the addition amount is too small, a stable deoxidizing effect cannot be obtained.
Need more than%. Also, Al reacts with the solid bath N to form AlN
And contributes to the refinement of crystal grains. On the other hand, 0.
The addition of more than 10% has little technical effect and is economically unfavorable, so the upper limit was made 0.10%. N forms a nitride with Al and Nb and is an effective component for refining fine grains, but if it is less than 0.002%, precipitation with nitride is small, and the effect of refining is lost. On the other hand, if it exceeds 0.015%, cracks are likely to occur on the slab surface and structural defects occur, so the range was made 0.002 to 0.015%. Nb has an effect of making crystal grains fine and contributes to the reduction of solid solution C and N. If it is less than 0.001%, there is no effect of grain refining, while if it exceeds 0.020%, the amount of solute Nb increases and conversely the drawability deteriorates, so the upper limit was made 0.020%.

The slab heating temperature and hot rolling conditions are not specified in the present invention, but the slab heating temperature is 1100 ° C. from the viewpoint of positive decomposition of N and solid solution and stable hot rolling temperature. It is desirable to set it as above. When the hot rolling finish temperature is set to Ar3 point or lower, the crystal structure of the hot rolled sheet is mixed and coarsened. Therefore, the hot rolling finish temperature was set to Ar3 point or higher. The coiling temperature has a lower limit of 450 ° C in consideration of the quality stability in the coil width direction and the longitudinal direction during hot rolling, and if it exceeds 650 ° C, the crystal grains become coarse,
Since the skin becomes rough, the winding temperature is preferably in the range of 450 to 650 ° C.

Cold rolling process If the rolling reduction is less than 75%, the grain size of the steel sheet is coarsened or mixed in the annealing process, and the grain size cannot be sufficiently reduced. It is desirable that the lower limit be 75%.

Annealing Step In the present invention, it has been found that by adopting annealing in a heat cycle including overaging treatment, it is effective in breaking a cylinder. It is considered that this is because the solid solution C and N were reduced. The annealing may be performed either by continuous annealing and then by over-aging treatment by continuous annealing as it is, or by temporarily cooling and performing box annealing treatment again. The treatment temperature of the continuous annealing in the previous stage may be the recrystallization temperature or higher,
If the temperature exceeds 0 ° C., coarsening of crystal grains occurs, which is not preferable. The term "over-aging treatment" as used herein means a heat treatment at a low temperature for a long time as compared with a general annealing treatment. When the over-aging treatment is performed after continuous annealing, soaking is performed at 400 to 550 ° C. for 1 to 3 minutes. If it is less than 400 ° C, the solid solution C and N cannot be reduced, and if it exceeds 550 ° C, the crystal grains become coarse. If it is less than 1 minute, the solid solution C and N cannot be sufficiently reduced, and if it exceeds 3 minutes, the furnace length becomes long, so
It should be in the range of minutes. The overaging treatment may be box annealing. When using box annealing, lower the temperature once to 400-5
The temperature is raised to 50 ° C. and soaking is performed for 2 to 10 hours. 400 ° C
When the amount is less than the above, the quality as overaging treatment is not stable and the characteristics vary. If it exceeds 550 ° C, the crystal grains become coarser as in continuous annealing. If it is less than 2 hours, the quality as overaging treatment is not stable and the characteristics vary. On the other hand, the treatment of more than 10 hours is not economically advantageous.

Effect of overaging treatment Generally, an increase in solid solution C and N causes a decrease in total elongation and a deterioration in uniform elongation. This is the constriction that occurs when stretching,
It is considered that solid solution C and N act on the void connection mechanism. Overaging treatment reduces solid solution C and N in steel,
Effective in softening steel. It is considered that the overaging treatment reduces the solid solution C and N in the steel, suppresses the occurrence of necking and the connection of voids, and consequently reduces the susceptibility to fracture and shattering.

Conditioned rolling Conditioned rolling (SR, Single Reduce Roll)
(abbreviation of "ring") is suitable in the range where the elongation is in the range of 0.5 to 2.0% because the occurrence of stretcher strain is prevented.

DR rolling DR rolling is necessary to give can strength after forming, but the rolling reduction is 20 to 50%. If it is less than 20%, sufficient can strength cannot be obtained, and if it exceeds 50%, the steel sheet becomes high in strength, which causes difficulty in can forming. Here, the DR rolling is an abbreviation for Double Reduce Rolling, and is a rolling method that more positively reduces the sheet thickness and increases the sheet strength than the temper rolling. In the present invention, the secondary cold rolling includes the temper rolling and the DR rolling.

Next, examples of the steel sheet used in the present invention include sheet-shaped and coil-shaped steel sheets, steel foils, and those obtained by subjecting these steel sheets to surface treatment. In particular,
Electrolytic chromic acid-treated steel sheet or ultra-thin tin-plated steel sheet, nickel-plated steel sheet, zinc-plated steel sheet having a two-layer structure in which the lower layer is metallic chromium and the upper layer is chromium hydrated oxide, and chromium hydrated oxide or upper layer on these plated steel sheets Is a hydrated chrome oxide, and the one having a two-layer structure consisting of a metal chrome layer as the lower layer is excellent in contact with the polyester resin.

Average Crystal Grain Size Identification of the crystal grain size will be described with reference to FIGS. 1 and 2. FIG. 1 shows the relationship between the average crystal grain size and the surface roughness of the can side wall after the can manufacturing process. It can be seen from FIG. 1 that when the average crystal grain size becomes large, the surface roughness of the surface after the can manufacturing process deteriorates. When the average crystal grain size exceeds 6 μm, the surface roughness is deteriorated, and the appearance and properties of the can are impaired. Therefore, the average crystal grain size should not exceed 6 μm. Further, FIG. 2 shows the relationship between the average crystal grain size and the corrosion resistance. It can be seen from FIG. 2 that the corrosion resistance is good in the range where the average crystal grain size does not exceed 6 μm. The corrosion resistance was evaluated as follows. After the can-making process, the can was heat-treated at 130 ° C. for 20 minutes, filled with water, and visually evaluated for the degree of corrosion (blackening) of the inner surface of the can after 37 ° C. and 2 weeks.

[0015]

[Table 1]

[0016]

[Table 2]

Evaluation Example No. 1 of the present invention. 1 to 6 are within the range of the components of the present invention,
It is overaged and has excellent workability. Comparative Example No. No. 7 has a small amount of C and is inferior in corrosion resistance. Comparative Example N
o. Nos. 8 to 10 were not overaged and were inferior in workability. The evaluation methods are as follows ,. The surface roughness is evaluated by measuring the surface roughness of the can side wall on the inner surface of the can after forming the thin-walled deep-drawing can. Ra of 1 μm or less is ◎ (best), 1 to 1.5 μm is ○ (good), 1.
5 to 2 μm was evaluated as Δ (slightly defective), and 2 μm or more was evaluated as × (defective). The corrosion resistance was evaluated by visualizing the degree of corrosion (blackening) of the inner surface of the can after heat treatment at 130 ° C. for 20 minutes, filling with water after forming for 2 weeks at 37 ° C. after forming the thinned drawn can. ◎ If the surface is not blackened at all
(Best), the degree of blackening is minute (good), the degree of blackening is small (diameter 5 mm or less) is Δ (somewhat bad), and large (diameter 5 mm or more) is x ( It was evaluated as (defective). The workability was evaluated by increasing the wrinkle holding pressure during the forming of the thin-walled deep-drawing can and evaluating the size of the wrinkle holding pressure before breaking. A crushed product with a wrinkle holding pressure of 5 tons or less was rated as Δ (somewhat poor), a crushed product with 5 to 7 tons was rated as ◯ (good), and a product crushed with 7 tons or more was rated as ◎ (best). did.

[0018]

According to the present invention, there is provided a steel sheet which is excellent in surface roughening and corrosion resistance, does not break even during continuous high-speed can manufacturing, and is excellent in workability and suitable for use in thin-walled deep-drawing cans. You can The steel sheet provided by the present invention can be used alone as a steel sheet as a can application.
The steel sheet can be surface-treated and used as tinplate, TFS, nickel-plated steel sheet, or the like. Further, the surface-treated steel sheet may be coated with a resin film such as polyester. Also, a steel sheet coated with a paint such as epoxy can be applied to a thin-walled deep drawing can application.

[Brief description of drawings]

FIG. 1 is a graph showing the effect of average crystal grain size on skin roughness.

FIG. 2 is a graph showing the effect of average crystal grain size on corrosion resistance.

Claims (8)

[Claims] 1. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
Hot-rolled steel sheet consisting of 0 to 0.015%, balance Fe and unavoidable impurities is annealed by heat rolling including cold rolling and overaging treatment, and temper rolling at an elongation of 0.5 to 2.0%. The steel sheet suitable for use in thin-walled deep-drawing cans, in which the average grain size of the steel sheet after temper rolling is 6.0 μm or less. 2. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
0 to 0.015%, the hot rolled steel sheet consisting of the balance Fe and unavoidable impurities are sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and DR rolling at a reduction rate of 20 to 50%, The average grain size of the steel sheet after DR rolling is 6.0μ
A steel plate with a thickness of m or less, which is suitable for thin-walled deep drawing can applications. 3. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
0 to 0.015%, Nb: 0.001 to 0.020%,
A hot-rolled steel sheet consisting of the balance Fe and unavoidable impurities is subjected to cold rolling, annealing in a heat cycle including overaging treatment, and temper rolling at an elongation rate of 0.5 to 2.0%, in order. A steel sheet suitable for thin-walled deep-drawing can applications, in which the average grain size of the rolled steel sheet is 6.0 μm or less. 4. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
0 to 0.015%, Nb: 0.001 to 0.020%,
A hot-rolled steel sheet consisting of the balance Fe and unavoidable impurities is sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and DR rolling at a reduction rate of 20 to 50%, and the average of the steel sheets after DR rolling. A steel sheet with a crystal grain size of 6.0 μm or less, which is suitable for thin-walled deep-drawing can applications. 5. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
Hot-rolled steel sheet consisting of 0 to 0.015%, balance Fe and unavoidable impurities is continuously annealed in a heat cycle including cold rolling and overaging treatment, and tempered at an elongation rate of 0.5 to 2.0%. A method for manufacturing steel sheets suitable for thin-walled deep-drawing can applications, in which rolling is performed sequentially. 6. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
A thin-walled steel sheet in which 0 to 0.015% and the balance Fe and unavoidable impurities are sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and DR rolling at a reduction rate of 20 to 50%. Steel plate manufacturing method suitable for deep drawing deep can applications. 7. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
0 to 0.015%, Nb: 0.001 to 0.020%,
A hot-rolled steel sheet consisting of the balance Fe and unavoidable impurities is sequentially subjected to cold rolling, annealing in a heat cycle including overaging treatment, and temper rolling at an elongation rate of 0.5 to 2.0%. Steel plate manufacturing method suitable for squeezing cans. 8. C: 0.01 to 0.15%, Si ≦ 0.
05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.0
4%, Al: 0.015 to 0.10%, N: 0.002
0 to 0.015%, Nb: 0.001 to 0.020%,
Suitable for thin-walled deep-drawing can applications in which a hot-rolled steel sheet consisting of the balance Fe and unavoidable impurities is sequentially cold-rolled, annealed in a heat cycle including overaging treatment, and DR-rolled at a reduction rate of 20 to 50%. Steel plate manufacturing method.