JPH0681087A - Production of aluminum alloy sheet small in earing ratio - Google Patents

Abstract

PURPOSE:To obtain a low earing ratio high strength Al alloy sheet by subjecting an Al allay subjected to continuous casting and rolling to homogenizing treatment and intermediate treatment and final cold rolling under specified conditions. CONSTITUTION:The molten metal of an Al-Mn-Mg allay is continuously cast and rolled into a sheel material having 4 to 15mm thickness, and this sheet material is subjected to cold rolling at 10 to 50% reduction rate of the sheet thickness, is subjected to homogenizing treatment at 450 to 550 deg.C for 3 to 20hr, is subjected to cold rolling and intermediate heat treatment for recrystallization and is subjected to final cold rolling at 70 to 90% reduction rate of the sheet thickness. In this way, the Al-Mn-Kg allay sheet small in earing ratio and high in strength after subjected to baking can be obtd. The process is simple and the reduction of the cost can be attained, so that it is effective particularly as the method for producing a can material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy sheet having a small earring rate, more specifically, a sheet material suitable for a can body material by reducing the earring rate of a continuously cast rolled material of Al-Mn-Mg alloy. The present invention relates to a method for manufacturing an aluminum alloy plate for obtaining the same.

[0002]

2. Description of the Related Art As a body material for aluminum cans, M
Al-Mn-M such as JIS A 3004 containing n and Mg
g-based alloys are widely used, but in recent years, can materials have become thinner,
Due to demands such as cost reduction, more and more strict characteristics are required. The main requirements are that the ear ratio during deep drawing is 4% or less in order to maintain high formability, and that it can withstand the internal pressure from the contents after heat treatment (air baking) for baking coating 275N / to mm ² or more high strength is obtained, reducing the cost of the can material, a, to satisfy these required properties, in the conventional manufacturing method, adjusting the ingot making, homogenization of the alloy ingredients Various efforts have been made to combine the conditions in the manufacturing process such as treatment, chamfering, hot rolling, cold rolling, and intermediate annealing. However, in this method, although the above characteristics can be satisfied, the component adjustment and manufacturing conditions are complicated, and the cost of the material is increased.

On the other hand, from the viewpoint of cost reduction of materials, continuous casting and rolling technology has recently attracted attention and has begun to be applied to the production of aluminum alloy materials. Continuous casting and rolling is a method of manufacturing plate material directly from molten metal by passing molten metal between cold belts and rolls.Also known as direct casting, molten metal rolling, strip casting, chill roll casting, etc. The cost can be shortened and the cost can be reduced. Further, continuous casting and rolling has an advantage that the material strength is improved because the impurity element can be supersaturated as a solid solution because the molten metal is rapidly cooled.

For Al-Mn-Mg alloys for aluminum can materials, several manufacturing methods by continuous casting and rolling have been developed up to now (Japanese Patent Publication No. 62-42025 and Japanese Patent Laid-Open No. 5625/1987).
No. 62,952 and JP-A No. 57-169071), both methods can only obtain a plate material having an ear rate of 5% or more, and cannot satisfy the required characteristics. A method for producing an Al-Mn-Mg-based can material with less ears from continuous casting and rolling aluminum strip has also been proposed (Japanese Patent Laid-Open No. 59-64758). However, this method has a complicated manufacturing process and continuous casting and rolling. There is a difficulty in not taking advantage of the cost reduction, which is the greatest feature of the.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the conventional production of Al--Mn--Mg alloy plate by continuous casting and rolling, while utilizing the merit of cost reduction by continuous casting and rolling. It was made as a result of intensive research on a combination of manufacturing conditions for reducing the ear rate, and the purpose thereof is to stably obtain an ear rate of 4% or less in a shortened process, and a small ear rate of Al-Mn-Mg system. An object is to provide a method for manufacturing an alloy plate.

[0006]

In order to achieve the above-mentioned object, a method for producing an aluminum alloy plate having a small ear rate according to the present invention is a method of continuously casting and rolling a molten Al-Mn-Mg-based alloy to a thickness. 4 ~ 15 mm plate material, 10 ~ 50% of the plate material
After cold rolling at the sheet thickness reduction rate of 3 to 20 at 450 to 550 ° C.
The structural feature is that the homogenizing heat treatment is performed for a period of time, the cold rolling and the intermediate heat treatment for recrystallization are performed, and then the final cold rolling is performed at a strip thickness reduction rate of 70 to 90%.

In the present invention, as the Al-Mn-Mg-based alloy, in addition to the known JIS A 3004, for example, Mn0.5-
Fe containing 1.5%, Mg 0.5 to 1.5% and less than 1%,
0.5% or less Si, 0.25% or less Cu, 0.25% or less Z
An aluminum alloy containing n, 0.4% or less Cr, 0.1% or less Ti, 0.05% or less B, and the balance Al and unavoidable impurities is applied. First, this Al-Mn-
Melting Mg-based alloy, casting and rolling molten metal to a thickness of 4 to 15 mm
Plate material. If the thickness is less than 4 mm, it is difficult to manufacture a wide plate material having a width of 2 m, for example, and it is difficult to put it into industrial use. If the thickness exceeds 15 mm, the solid solution effect due to rapid cooling cannot be sufficiently obtained, and improvement in strength cannot be expected.

Plate thickness reduction rate after casting and rolling 10 to 50%
The cold rolling in combination with the subsequent homogenizing heat treatment promotes the effect of reducing the earing of the final plate. If the thickness reduction rate is less than 10%, the effect is small, and if it exceeds 50%, the ear generation direction changes and the ear rate exceeds 4%, which is not preferable.
Homogenization heat treatment has the effect of reducing the ear rate of the final plate,
It is preferably carried out at a temperature of 450 to 550 ° C. for 3 to 20 hours. When the heat treatment temperature is out of this range and the heat treatment time is 3
If it is less than the time, the ear rate tends to be large. If the heat treatment is performed for more than 20 hours, the ear reduction effect will be saturated,
It also increases costs. Therefore, 20 hours is a practical upper limit.

The homogenizing heat treatment is followed by one or more cold rolling and intermediate heat treatments for recrystallization. The cold rolling and the intermediate heat treatment are for adjusting the strength and the ear ratio of the final plate, and the treatment conditions are appropriately determined. For example, cold rolling is performed at a sheet thickness reduction rate of 30 to 80%, and intermediate heat treatment is performed at 350 to 450 ° C. Plate thickness reduction rate after intermediate heat treatment
Final cold rolling 70-90%. Final cold rolling is 4%
It has the following low ear rate and a high yield strength of 275 N / mm ² or more after heat treatment (air baking) for baking coating. If the thickness reduction rate is less than 70%, the strength of the final plate is sufficient. However, if it exceeds 90%, the ear rate increases.

[0010]

The present invention is based on the material characteristics based on continuous casting and rolling,
Ear ratio of 4 based on the structural properties obtained from the specified combination of intermediate cold rolling, homogenizing heat treatment and final cold rolling.
% Or less, a high-strength Al-Mn-Mg-based alloy plate is stably manufactured.

[0011]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Example 1 Mn1.53% (mass%, the same applies hereinafter), Mg1.47%, Si
0.18%, Fe0.36%, Cu0.13%, Zn0.03%, Ti0.
A molten aluminum alloy consisting of 04%, balance Al and unavoidable impurities was continuously cast and rolled using a roll caster manufactured by US Hunter Co. to obtain a plate material having a thickness of 6 mm. This plate material was processed under the conditions shown in Table 1 to obtain a plate material having a final thickness of 0.32 mm.

[0012]

[Table 1]

For the plate materials in Table 1, the ear ratio and 205 ° C
The mechanical properties were measured after air-baking in an oil bath for 10 minutes. Ear diameter is measured by blank diameter 55mm, punch diameter 33mm (
Squeeze into a cup with a flat head punch, {(mountain height)-(valley height)} / [{(mountain height) + (valley height)} / 2] ×
It was calculated by the formula of 100. The mechanical properties of each plate are JI
S5 test pieces were molded and stretched in the rolling direction, and 0.2% proof stress, tensile strength and elongation at break were measured. Table 2 shows the measurement results
Shown in. As can be seen from Table 2, all the plate materials manufactured according to the conditions of the present invention have excellent properties such as a selvedge ratio of 4% or less and a yield strength after air baking of 275 N / mm ² or more.

[0014]

[Table 2]

Comparative Example 1 A molten metal of Al--Mn--Mg alloy having the same composition as in Example 1 was continuously cast and rolled in the same manner as in Example 1 to obtain a thickness.
After manufacturing 6mm plate material, the process shown in Table 3 for this plate material,
A plate material having a thickness of 0.32 mm was processed under the conditions. Items outside the scope of the present invention are underlined.

[0016]

[Table 3]

For the plate materials in Table 3, the ear ratio and the plate materials are
The mechanical properties after air-baking in an oil bath at 205 ° C. for 10 minutes were measured by the same method as in Example 1. The measurement results are shown in Table 4. As shown in Table 4, sample Nos. 1 to 3 in which the thickness reduction rate of the cold rolling for the continuously cast rolled sheet is less than 10%
And sample No. 4 with a homogenization heat treatment temperature of less than 3 hours and the homogenization heat treatment temperature is out of the limited range.
No. 7 also has an ear rate of over 4%. Sample No. 8, which had a reduction rate of plate thickness in the final cold rolling of less than 70%, had a small selvedge ratio of 2%, but had poor yield strength after air-baking. Sample No. 9 with a plate thickness reduction rate of more than 90% had sufficient strength, but had an ear rate of more than 4%.

[0018]

[Table 4]

[0019]

As described above, according to the present invention, the conventional A
The ear ratio, which was a problem of the continuously cast and rolled material of the 1-Mn-Mg-based alloy, can be reduced, and the strength after air baking is high,
Since the manufacturing process is also simple, the cost can be reduced as compared with the conventional manufacturing method by ingot casting, and it is industrially very useful especially in the manufacturing of can body materials.

Claims (1)

[Claims] 1. Al-Mn-containing Mn and Mg
The Mg-based aluminum alloy melt is continuously cast and rolled into a plate material having a thickness of 4 to 15 mm, and the plate material is cold rolled at a plate thickness reduction rate of 10 to 50%, and then at 3 to 20 at 450 to 550 ° C. Aluminum with a small ear rate, characterized by performing a homogenizing heat treatment for an hour, an intermediate heat treatment for cold rolling and recrystallization, and then performing a final cold rolling at a sheet thickness reduction rate of 70 to 90%. Method for manufacturing alloy plate.