JPH05295476A - Aluminum alloy sheet for deep draw forming - Google Patents

Abstract

PURPOSE:To obtain an Al alloy sheet for deep draw forming excellent in mechanical properties and deep draw formability by incorporating specified amounts of Mg, Mn, Cr, Ti and B therein and specifying the accumulation degree of the texture of the sheet surface and the crystalline grain size. CONSTITUTION:The objective Al alloy sheet for deep draw formability contains, by weight, 2 to 6% Mg, 0.03 to 0.20% Mn, 0.01 to 0.10% Cr, 0.005 to 0.10% Ti and 0.001 to 0.02% B and in which the accumulation degree in the (110) orientation in the sheet surface is regulated to >=10% as well as the ratio of the accumulation degree in the (110) orientation to that in the (112) orientation is regulated to >=1.5 and, moreover, the crystalline grain size is regulated to 35 to 80mum. In this Al alloy sheet, the generation of stretcher strain marks is prevented. The manufacture of the Al alloy sheet is executed, preferably, in such a manner that an ingot subjected to DC casting is subjected to homogenizing treatment at 400 to 550 deg.C for about <=24hr, after that, its hot rolling is completed at about >=370 deg.C, and it is subjected to cold rolling at about 70 to 85% draft, is subsequently subjected to process annealing, is furthermore subjected to cold rolling and batch type or continuous annealing and is cooled at about >=10 deg.C/sec rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy sheet for deep drawing, and more particularly to an aluminum alloy sheet which is suitable for materials such as automobile panels and electric machine parts and has excellent deep drawing formability.

[0002]

2. Description of the Related Art Al-Mg-based 5052 alloy materials and 5182 alloy materials have been conventionally used as aluminum alloy plates for forming. However, recently, the necessity of reducing the weight of automobiles and the like has been strongly socially demanded from the viewpoint of global environmental protection, and therefore, aluminum alloy plates are often used instead of steel plates. Therefore, the above conventional Al
As for the -Mg alloy plate, the same strength as the steel plate was obtained, but the formability, especially the deep drawing formability, was inferior to that of the steel plate.

[0003]

As described above, the aluminum alloy sheet is inferior in formability, in particular, deep drawing formability as compared with the steel sheet. Therefore, even if the aluminum alloy sheet has the same strength as the steel sheet, the deep drawing formability is obtained. In view of the above, its use is limited, and the lightness and other characteristics of the bent aluminum alloy plate cannot be fully utilized.

[0004]

Means for Solving the Problems The present invention has been studied repeatedly for solving the problems in the prior art as described above, and has elucidated various characteristics of Al-Mg alloys, and at the same time, control of texture and crystal of annealed sheet. The inventors have found that deep drawing formability can be improved by optimizing the particle size, and have reached the present invention.

That is, the inventors of the present invention have made earnest studies on the factors affecting the deep drawing formability of the Al-Mg alloy plate, and as a result, the (110) orientation integration of the final annealed plate is 10% or more,
It has been found that the deep drawing formability is improved when the ratio of the integration degree of the 10) orientation to the (112) orientation is 1.5 or more and the crystal grain size is in the range of 35 to 80 μm. Also,
35 ~ 80μm to prevent the occurrence of stretcher strain marks that occur when the product is lightly processed
It has been found that it is effective to set the crystal grain size within the range as follows.

% By weight, Mg: 2-6%, Mn: 0.03-0.2
0%, Cr: 0.01 to 0.10%, Ti: 0.005 to 0.10
%, B: 0.001 to 0.02%, the degree of integration in the (110) orientation on the plane of the plate is 10% or more, and (11
An aluminum alloy sheet for deep drawing, characterized in that the ratio of the degree of integration of (0) orientation to (112) orientation is 1.5 or more, and the grain size is 35 to 80 μm.

The above-mentioned orientation integration degree is (110), (112) with respect to the integrated intensity of the random orientation sample obtained from the inverse Schlutz pole figure measured from X-ray diffraction.
The ratio of the relative integrated intensity of the azimuth and the like to the entire azimuth is shown as a percentage.

The aluminum alloy sheet of the present invention as described above is produced by the usual method of producing an alloy having the above-mentioned composition in the usual steps of DC casting, homogenizing treatment, hot rolling, cold rolling and annealing. can get. At this time, the hot rolling finish temperature was set to 370 ° C. or higher and the rolling ratio before intermediate annealing was 70 to 85%.
Is desirable. Or hot rolling finish temperature 370
When the temperature is lower than 0 ° C, it is desirable to perform annealing at a temperature of 370 ° C or higher and then perform cold rolling.

[0009]

The reasons for limiting the chemical components of the present invention are as follows. Mg: 2 to 6% Mg is an element that imparts strength and moldability. Two
If it is less than 6%, the strength equivalent to a steel sheet cannot be obtained, while if it exceeds 6%, the formability is not greatly improved, and the oxidation of Mg during melting is likely to occur, and casting cracks are likely to occur during DC casting. The Mg content was set to the range of 2 to 6%, because defects such as edge cracking during hot rolling tend to occur and stress corrosion cracking becomes more sensitive. A preferable range is 2.5 to 6%.

Mn: 0.03 to 0.20% Mn is an element which brings the texture and crystal grain size of the annealed plate into an appropriate range and improves the formability. If it is less than 0.03%, large recrystallized grains with a crystal grain size of the annealed plate exceeding 80 μm tend to be generated, and a desired texture cannot be obtained. On the other hand, if it exceeds 0.20%, the crystal grain size of the annealed plate tends to be less than 35 μm, so the Mn content was made 0.03 to 0.20%.

Cr: 0.01 to 0.10% Cr is an element that improves the formability by setting the texture and crystal grain size of the annealed plate in an appropriate range, like Mn.
If it is less than 0.01%, large recrystallized grains with a crystal grain size of the annealed plate exceeding 80 μm tend to be generated, and a desired texture cannot be obtained. On the other hand, if it exceeds 0.10%, the crystal grain size of the annealed plate tends to be less than 35 μm, so the Cr content is 0.01 to 0.1.
The range is 10%.

Ti: 0.005 to 0.10% Ti is an element which, together with B, makes the grain size of the ingot finer and is effective in preventing casting cracks. If it is less than 0.005%, the effect is not sufficient, and if it exceeds 0.10%, the effect is not only saturated, but also coarse particles of Al ₃ Ti are formed and the moldability is deteriorated. Is 0.005% to 0.10%
The range is.

B: 0.001 to 0.02% B is an element which, together with the above Ti, makes the grain size of the ingot finer and is effective in preventing casting cracks. If it is less than 0.001%, the effect is not sufficient, and if it exceeds 0.02%, the effect is saturated and coarse particles such as AlB ₂ and TiB ₂ are formed to deteriorate the moldability. Is 0.001% to 0.
The range was set to 02%.

The content of other elements is not specified, but
Cu is an element effective in improving strength and preventing stress corrosion cracking, and if it is contained in an amount of 0.5% or less, the effect of the present invention is not impaired, so its inclusion is allowed. Since Zn is an element effective in preventing stress corrosion cracking, if it is contained in an amount of 0.5% or less, it is allowed without impairing the effect of the present invention. Zr,
Elements such as V and Ni are elements that are effective in adjusting the crystal grain size. When the content of each is 0.05% or less, the effect of the present invention is not impaired, so that the content is allowed. Fe and Si are elements that exist as impurities in aluminum ingots.
If the content exceeds 2%, the moldability deteriorates, so
0.2% or less, preferably 0.1% or less.

The alloy sheet of the present invention is manufactured by ordinary DC casting,
Homogenization, hot rolling, cold rolling, intermediate annealing, cold rolling, and final annealing are performed as described above, but the effect of the present invention is when the following manufacturing conditions are adopted. In particular,

As a method for producing the ingot, a usual DC casting method (semi-continuous casting method) may be applied. In addition, the homogenization treatment of the ingot is a process necessary for improving the strength and the formability due to the homogenous distribution of elements such as Mg generated during casting.
It is desirable to perform heating for 24 hours or less in the temperature range of 00 to 550 ° C.

After the homogenizing treatment, hot rolling is carried out by an ordinary method, but it is desirable that the hot rolling be completed at 370 ° C. or higher. This is because recrystallization occurs at 370 ° C. or higher, a uniform crystal grain size is obtained in the state of the hot rolled plate, and it is effective in controlling the formability of the final annealed plate, particularly the texture. 370
When hot rolling cannot be completed at a temperature of 370C or higher, it is desirable to anneal the hot rolled plate at a temperature of 370 ° C or higher.

After hot rolling, ordinary cold rolling is performed.
It is desirable that the cold reduction ratio before the intermediate annealing be in the range of 70 to 85 to sufficiently develop the cold rolling texture. 70
If it is less than%, the cold rolling texture is not sufficiently developed, while if it exceeds 85%, the (112) component of the cold rolling texture increases, which is not desirable.

The intermediate annealing can be carried out in a usual batch type furnace or continuous annealing apparatus. In the case of a batch type furnace, it may be annealed in a temperature range of 300 to 400 ° C. for 24 hours or less. On the other hand, in the case of a continuous annealing device, for example, 350-
The holding may be performed for 1 minute or less within a temperature range of 520 ° C.

After the intermediate annealing, the sheet is cold-rolled to a desired sheet and finally annealed. The final annealing may be performed in a usual batch type furnace or continuous annealing device. 300-4 in batch type
Annealing is performed at 00 ° C. for 24 hours or less. On the other hand, in the continuous annealing device, annealing is performed at 350 to 520 ° C. for 1 minute or less. The continuous annealing temperature range is 480 to 520 ° C., and the annealing is followed by cooling at a cooling rate of 10 ° C./sec or more to make the crystal grain size 35 to 80 μm, as well as forming with a mild degree of processing. Effective in preventing stretcher strain marks, which often occur.

[0021]

EXAMPLES To explain specific examples of the present invention, the present inventors have found that a 70 mm-thick DC ingot made of an aluminum alloy having the chemical composition shown in the following Table 1 was chamfered on one side by 10 mm and then 440 After homogenizing treatment at 8 ° C. for 8 hours and then at 520 ° C. for 4 hours, hot rolling was performed to a thickness of 6 mm.

[0022]

[Table 1]

The hot rolling finish temperature as described above is 385 ° C.
Met. Next, cold rolling with a cold rolling reduction of 78% was applied to a thickness of 1.3 mm, but cracks at the edges became noticeable. At that stage, intermediate annealing was performed at 340 ° C. for 1 hour, and then, It was cold-rolled to a thickness of 1 mm, finally rapidly heated to 500 ° C., kept at that temperature for 2 seconds, and finally annealed by cooling at a cooling rate of 40 ° C./second to obtain a test material.

The mechanical properties, deep drawability, crystal grain size, and (220) orientation integration degree (224) orientation integration degree obtained from the inverse Schlutz pole figure obtained from X-ray diffraction were obtained for each of the obtained test materials. I asked. The (220) orientation is the (110) orientation,
The (224) orientation is equivalent to the (112) orientation. The results are shown in Table 2 below. In the comprehensive evaluation, the tensile strength was 200 N / mm ² or more, the limiting drawing ratio LDR was 2.15 or more, and no stretcher strain mark was generated. And the thing which does not satisfy either of them was set as improper (x).

[0025]

[Table 2]

According to the results of Table 2 as described above,
The aluminum alloy sheet of the present invention has a (220) orientation integration degree of 1.
0% or more and the ratio of the degree of integration of the (220) orientation to the (224) orientation is 1.5 or more, the crystal grain size is in the range of 30 to 80 μm, and the tensile strength is 200 N / mm ² or more, Moreover, it is clear that it exhibits good deep drawing formability with a limiting drawing ratio of 2.15 or more.

[0027]

According to the present invention as described above, it is possible to provide an aluminum alloy sheet having excellent tensile strength and other mechanical properties and preferable formability, that is, it is lightweight and has high strength. In addition, since it has a high degree of moldability, it can provide an advantageous product as an automobile or other vehicle or a part for electromechanical devices, and is an invention having a great industrial effect.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Tsuchida 1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Nipparu Giken Co., Ltd. No. 1 Nichiru Giken Co., Ltd.

Claims (1)

[Claims] 1. Wt%, Mg: 2-6%, Mn: 0.03-0.
20%, Cr: 0.01 to 0.10%, Ti: 0.005 to 0.10
%, B: 0.001 to 0.02%, the degree of integration in the (110) orientation on the plane of the plate is 10% or more, and (11
An aluminum alloy sheet for deep drawing, characterized in that the ratio of the degree of integration of (0) orientation to (112) orientation is 1.5 or more, and the grain size is 35 to 80 μm.