JP2895510B2 - Manufacturing method of aluminum alloy material for forming - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing an aluminum alloy material for molding, and more particularly to a method for producing a metal can body and a cap for beverage cans, food cans and the like. The present invention relates to a method for producing a suitable aluminum alloy material for molding having high strength and excellent moldability.

(Prior art) In general, materials for beverage cans, food cans or PP caps manufactured by deep drawing are JIS3105 alloy, 3004
Hard and semi-hard materials such as alloys and 5052 alloys are used, but in order to further reduce the cost and weight of cans and caps, thinner aluminum alloy materials than before are strongly desired. There is a demand for an aluminum alloy material having higher strength than that conventionally used as this material.

(Problems to be Solved by the Invention) However, in order to increase the strength by simply increasing the cold rolling ratio or increasing the content of the main alloy-containing element, Mg, in conventional aluminum alloys, it is difficult to draw. In addition to an increase in ear ratio and a decrease in deep drawability at the time, a decrease in strength at the time of baking for painting is increased, and a problem arises in that strength required for thinning cannot be obtained.

Furthermore, as described above, if the cold rolling ratio and Mg content are simply increased in order to increase the strength of the conventional material, a shear band is generated during cold rolling and subsequent shrinkage flange processing during deep drawing. There was a problem that it became easier. The shear band appears as a linear pattern that intersects the plate surface at an inclination angle of about 30 to 40 ° when viewed from the plate thickness section parallel to the rolling direction of the rolled plate during cold rolling, and particularly has a high Mg content. In the case where the cold rolling rate is high or when the cold rolling rate is high, a shear band grows over the entire thickness of the sheet, so that it breaks from that portion during rolling or subsequent pressing, and further processing is not possible.

Also, at the time of deep drawing, about 30
The shear band or kagome pattern that appears as a group of curves intersecting at an inclination angle of ~ 40 ° impairs the appearance of the container, lowers the commercial value, and when the drawing ratio is high, cracks occur along the shear band However, the deep drawability is significantly deteriorated. Also, when drawing is performed after applying a coating film like a food can or a cap, the coating film may be peeled off and the corrosion resistance may be deteriorated.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a method for producing an aluminum alloy material for molding which is excellent in strength and formability and does not generate a kagome pattern during deep drawing.

(Means for Solving the Problems) In view of the above-mentioned state of the art, the present inventors have conducted intensive studies and as a result, have found that the conventional Al-Mn-Mg and other 3000-series and Al-
Instead of 5000-based non-heat-treated aluminum alloys such as Mg-based, heat-treated aluminum alloys, especially Al-Mg-Si-based alloys that cause the precipitation effect of Mg-Si-based intermetallic compounds by aging or baking, By using, sufficient strength and good formability can be obtained as an aluminum alloy plate for cans or caps, and the shear band is 3000 series, 5000 series, etc. Atoms and mobile dislocations introduced by cold rolling etc. are caused by dynamic strain aging, and this develops in the thickness direction during cold rolling or subsequent pressing, leading to fracture, Even in heat-treated alloys such as 6000 series alloys, fine and matrix-coherent or semi-coherent precipitates that occur in the early stages of aging are crossed by mobile dislocations introduced by cold rolling etc. Breaking occurs, however, by performing a precipitation treatment before cold rolling, and by coarsening the precipitate to some extent, the formation of a shear band can be prevented, and it has been found that the formability of the final sheet is improved, The present invention has been accomplished based on the findings.

That is, the present invention relates to (1) Mg 0.5 to 3.5% by weight (hereinafter, referred to as
% Of the metal composition indicates% by weight), 0.1% or more and less than 0.4% of Si, 0.05 to 1.5% of Mn, and 0.05 to 0.2% of Cu.
A homogenization treatment and hot rolling are performed on an aluminum alloy ingot containing at least one selected from Fe 0.1 to 0.6% and Cr 0.05 to 0.3% and having Al and unavoidable impurities as a balance. The solution obtained is subjected to solution treatment at a temperature of 450 to 580 ° C, and subsequently at a temperature of 130 ° C or more and less than 250 ° C.
(1) A method for producing an aluminum alloy material for forming, characterized by performing cold rolling at a rolling reduction of 30% or more without performing intermediate annealing after performing precipitation treatment for 0.1 minutes or more (referred to as a first invention). The present invention provides a method (hereinafter referred to as a second invention) for producing a forming aluminum alloy material according to the above (1), wherein finish annealing is performed at a temperature of 100 to 250 ° C. after cold rolling.

The action of each component and the reason for limiting the content of the aluminum alloy material according to the present invention will be described below.

Mg is 0.5-3.5%. Mg forms a solid solution in the matrix and has the effect of increasing the strength of the base plate and precipitating and strengthening the Mg-Si compound. If the content of Mg is less than 0.5%, M
It is insufficient in quantity to precipitate and strengthen the g-Si compound, and if it exceeds 3.5%, toughness is deteriorated and formability is impaired.

Si is set to 0.1% or more and less than 0.4%. Si is Mg-Si with Mg
It has the effect of precipitating and strengthening the system compound. If the content of Si is less than 0.1%, Al-Mg
-Insufficient quantity to precipitate and strengthen Si-based compounds. If the content is more than 0.4% and more than 0.6%, quenching sensitivity increases and coarse Mg in the cooling process after solution treatment is performed.
-Si-based alloys precipitate at grain boundaries, toughness is deteriorated, and formability is reduced. Further, the amount of Al-Mg-Si-based compound deposited during aging treatment or baking is insufficient, and sufficient strength cannot be obtained.

Mn is set to 0.05 to 1.5%. Mn has the effect of improving the formability by refining the crystal grains and improving the strength.
If the content is less than 0.05%, the above effect is small, and if it exceeds 1.5%, a coarse intermetallic compound is formed to deteriorate draw formability.

Cu is 0.05-0.2%. Cu has the effect of forming fine precipitates during baking and improving the strength. If the content is less than 0.05%, the above effect is small, and if it exceeds 0.2%, on the other hand, the crystal grains are coarsened, roughening occurs at the time of deep drawing, and the corrosion resistance is deteriorated.

Fe 0.1 to 0.6% and Cr 0.05 to 0.3% contain at least one or more selected from the above within the above range. Fe, Cr
Has the effect of improving the formability by refining the crystal grains, stabilizing the texture, reducing the cup ear ratio, and further improving the strength. If the content is less than 0.1% and 0.05%, respectively, the above effect is small, and if the content exceeds 0.6% and 0.3%, respectively, a coarse intermetallic compound is formed and the drawability is deteriorated.

Further, Ti which is usually added as a refiner of the ingot structure,
B is preferably added in the range of 0.1% or less and 0.02% or less, respectively.

There is no particular problem if other impurities are 0.1% or less.

 Next, a method for producing the alloy material of the present invention will be described.

First, an aluminum alloy melt containing the above-described components is cast according to a conventional method. As this casting method, a semi-continuous casting method is generally used. However, continuous casting of a thin plate may be performed in order to save energy and improve mechanical properties. The obtained ingot is subjected to soaking (homogenization). It is preferable that the soaking conditions include a soaking temperature of 450 to 600 ° C. and a soaking time of 48 hours or less in order to refine crystal grains in the solution treatment.

After soaking, hot rolling is performed, but there is no particular need to strictly control this hot rolling, and 400
The hot rolling may be performed at ~ 500 ° C.

Next, solution treatment is performed, but cold rolling may be performed before that. By performing cold rolling, crystal grains in the solution treatment can be further refined.

In the solution treatment, the heating temperature is set in the range of 450 to 580 ° C. to promote solid solution of Mg and Si in the alloy. That is, if the solution temperature is lower than 450 ° C., the solid solution of Mg and Si is not sufficiently performed.
Temperatures exceeding 80 ° C. are not preferred because local melting of Mg occurs due to burning. The solution treatment method may be rapid cooling after ordinary batch annealing or rapid annealing or continuous annealing with rapid cooling. However, continuous annealing method controls ear ratio, improves formability by refining crystal grains, and improves productivity. It is desirable from the point of view. Further, the cooling temperature is desirably 5 ° C./sec or more from the viewpoint of preventing the formation of precipitates in the cooling process after the solution heating and securing the strength of the final plate.

Next, a precipitation treatment is performed.
Performing at a temperature lower than ℃ is intended to improve the strength of the final sheet by precipitation hardening, to coarsen the precipitation phase, to suppress the generation and growth of shear bands during cold rolling and subsequent pressing. When the treatment temperature is lower than 130 ° C, a large number of fine precipitate phases are generated and the strength is improved, but the shear band is easily generated, which is not preferable.At a temperature of 250 ° C or higher, the shear band is not formed, but the strength is reduced. Is not preferred. The reason why the aging holding time is set to 0.1 minute or more is that if the holding time is less than 0.1 minute, the above effect is insufficient.

Next, cold rolling is performed. The reason why cold rolling is performed at a rolling reduction of 30% or more is to improve the strength of the raw material by work hardening, and if the rolling reduction is less than 30%, it corresponds to thinning of the raw material. This is not preferable because sufficient strength cannot be obtained.

Next, in the second invention, finish annealing is performed after cold rolling. This is for recovering the work structure and improving the formability (drawing and stretching workability). If the annealing temperature is lower than 100 ° C., the desired formability cannot be secured, while the temperature exceeds 250 ° C. , The recovery proceeds too much, so that sufficient strength cannot be obtained, which is not preferable.

The alloy material of the present invention obtained in this manner is subjected to paint baking (baking) at a temperature of about 200 ° C. for several minutes before being subjected to a degreasing treatment or the like before drawing, or even if the paint bake is performed, This is suitable as an aluminum alloy material for forming cans, caps and the like, since the decrease in the amount is smaller or the strength is improved more than before baking.

(Examples) Next, the present invention will be described in more detail based on examples.

The Al alloy having the composition shown in Table 1 was melted by a usual method,
After agglomeration and surface grinding, this was homogenized and then rolled into a 3 mm thick plate by hot rolling. Next, the hot-rolled plate is subjected to cold rolling, and after rolling to a plate having a thickness of 0.4 to 1.5 mm, solution treatment, precipitation treatment, final cold rolling and finish annealing are also performed under the conditions shown in Table 1. The methods 1 and 2 of the present invention and the comparative methods 4 to 14 were carried out by performing the respective methods, thereby producing Al alloy plates 1 and 2 by the method of the present invention and comparative Al alloy plates 4 to 14 by the comparative method. These Al alloy plates (final thickness
25mm) after baking at 200 ℃ for 10 minutes,
A draw cup was made by deep drawing using a die with a diameter of 33 mm and a shoulder radius of curvature of 4.5 mm, and the limit drawing ratio (LD
R.) and the presence or absence of a kagome pattern on the side wall of the cup. The 0.2% proof stress of the plate before and after baking was measured by a tensile test. Table 2 shows the results.

As is evident from the results in Table 2, the Al alloy plates 1 and 2 of the present invention produced by the methods 1 to 3 of the present invention were all conventional JIS 5052 (No. 15), JIS 3004 (No. 16) and JIS 3105.
(No.17) Higher strength and better formability than alloy plate
No kagome pattern was observed.

Comparative Al alloy plate manufactured by the comparison method (No. 4 to 14)
Nos. 4 to 14 are inferior in at least one of these properties.

That is, an alloy plate having an Mg content less than the lower limit (No. 4), Cu
The alloy plate (No. 8) whose content is less than the lower limit has good formability but lacks strength. In addition, the alloy plate (No. 5) having an Mg content equal to or higher than the upper limit and the alloy plate (No. 7) having a Si content exceeding the upper limit have a large decrease in strength due to baking heating, resulting in insufficient strength. In addition, the formability of the alloy plate (No. 8) in which the Mn content is equal to or more than the upper limit is deteriorated. Furthermore, the alloy sheet (No. 10) with a solution heat temperature lower than the lower limit has insufficient strength and a kagome pattern is likely to occur, and the alloy sheet (No. 11) with a cold rolling reduction below the lower limit has insufficient strength. I do.

Further, alloy sheets Nos. 12 and 13 in which the precipitation treatment temperature or time is less than the lower limit have sufficient strength, but a kagome pattern occurs frequently and the formability is deteriorated. Further, the alloy plate (No. 14) in which the precipitation treatment time exceeds the upper limit has insufficient strength and deteriorates formability.

(Effect of the Invention) As described above, according to the method of the present invention, an aluminum alloy material for molding which is excellent in strength and formability and does not generate a kagome pattern during deep drawing can be obtained. It can be suitably used for packaging containers.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22F 1/00 685 C22F 1/00 685Z 686 686B 691 691B 691C 694 694A

Claims (2)

(57) [Claims] (1) Mg 0.5-3.5%, Si 0.1% or more and less than 0.4%, Mn
0.05 to 1.5% and Cu 0.05 to 0.2%
-0.6%, Cr-0.05-0.3% (more than% indicates% by weight), and a homogeneous aluminum alloy ingot containing Al and unavoidable impurities as the balance Alloy material obtained by subjecting to hot rolling and hot rolling
Solution treatment at a temperature of 450 to 580 ° C, followed by 130 ° C
A method for producing an aluminum alloy material for forming, comprising: performing a precipitation treatment at a temperature of at least 250 ° C. for at least 0.1 minute, and then performing cold rolling at a rolling reduction of 30% or more without performing intermediate annealing. 2. The method according to claim 1, wherein the finish annealing is performed at a temperature of 100 to 250 ° C. after the cold rolling.