JPS62278255A - Manufacture of aluminum alloy excellent in formability - Google Patents

Abstract

PURPOSE:To develop an Al alloy excellent in formability, by subjecting an Al-Cu-Mg-Mn or Al-Cu-Mg-Mn-Si alloy having a specific composition to homogenizing treatment and then to rollings and solution heat treatment and further by applying cold working and softening treatment to the above. CONSTITUTION:An Al-alloy ingot containing, by weight, 1.4-5.5% Cu, 0.1-2.0% Mg, and 0.1-1.4% Mn or further containing <1.2% Si is heated to about 490 deg.C to undergo homogenizing treatment, which is hot-rolled at 460 deg.C to be formed into a plate and further cold-rolled to be worked into a 2mm sheet. After heated to 420-580 deg.C and held for about 1hr, the sheet is water-quenched at >=0.6 deg.C/min cooling rate and cooled down to room temp. to undergo solution heat treatment. Successively, the above sheet is cold-worked at 20-75% draft and then heated again up to 360-500 deg.C at >=40 deg.C/hr temp.-rise rate to undergo softening treatment. In this way, the Al alloy having fine grains and causing no rough surface at the time of subsequent forming can be obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a high-strength aluminum alloy for forming, and in particular Cu , Mg, Mn over Cu, Mg,
The present invention has developed a method for producing an aluminum alloy containing Mn and SL that does not cause surface roughening even when subjected to molding after softening treatment.

(Prior Art) In general, high-strength aluminum alloys for forming, such as 2014 and 2024, are used in large quantities as materials for aircraft or other structural materials, and 2036 alloy is used for various structural materials such as automobiles. widely used.

This aluminum alloy is usually made of a soft material that is pre-formed, then solution-treated and quenched. Immediately after quenching, the strength is low, but the final forming process is performed for a short period of time, and then aging treatment is applied to produce high-strength products. It depends on the process.

However, in the above manufacturing process, 1 to 10
% of the preforming process will form a significantly coarse recrystallized structure during the subsequent solution treatment and quenching process, resulting in rough skin or minute cracks during the final forming process, which may impair the performance of the product. This caused a decrease in

(Problems to be Solved by the Invention) As a result of intensive research in view of the current situation, the present invention has developed aluminum alloys for forming, such as 2014.2024°203.
Cu, Mg, Mn or C represented by 6 alloys
u, Mg.

In the manufacturing method of an aluminum alloy containing Mn and SI, the crystal grains are fine even in the soft material state, and rolling, drawing,
In swaging and cold forging, recrystallized grains do not become coarse even after solution treatment and quenching, and even after the final forming process, uniform and fine crystal grains are maintained, resulting in formability that does not cause surface roughness. The purpose of the present invention is to provide a method for manufacturing an aluminum alloy with excellent properties.

(A precautionary measure to solve the problem) The method of the present invention involves homogenizing and rolling an aluminum alloy containing Cu, Mg, Mn, and St, solid-dissolving the additive elements in the matrix through solution treatment, and then quenching. Then, in the state where the G, P phase or the G, P, B phase has precipitated, by applying appropriate strain, fine recrystallized grains can be formed in the softening process. The goal is to obtain a product that does not cause roughness even after being molded in this state, and then subjected to solution treatment and final molding.

That is, the method of the present invention uses Cu, Mg, Mnt, Cu
+ After homogenizing the aluminum alloy containing Mg r Mn rSI, it was rolled, and then it was rolled at 420 mm.
After heating and holding at a temperature of ℃ to 580℃, cooling to room temperature,
Then, after processing 20~75%, it was heated again at 360℃~5
A method for manufacturing an aluminum alloy with excellent formability characterized by softening at a temperature of 0.000C. After homogenizing an aluminum alloy ingot, hot rolling or further cold rolling is performed to form a plate material. First, the material is heated and maintained at a temperature of 420 DEG C. to 580 DEG C., and then cooled to room temperature, preferably at a cooling rate of 0.6 DEG C./min or more, more preferably by water quenching. This is a state in which the solute atoms are in a supersaturated solid solution.Importantly, the G-P phase or G-P-B phase will precipitate and form a nine-state state, but if the above heating temperature is less than 420°C, A sufficient solid solution cannot be obtained, and if the temperature exceeds 580°C, eutectic melting occurs, which is not preferable. Further, the heating and holding time may be approximately several minutes, but it is preferable to hold the heating for a sufficient time if possible. Also, the cooling rate after heating and holding is 0.6℃/m
If it is less than ln, a θ stable phase or an S stable phase will precipitate, and the effect of recrystallized grain refinement cannot be exhibited, which is not preferable. The reason for cooling to room temperature is to ensure that the solute atoms are sufficiently supersaturated in solid solution.

Next, cold working is carried out by 20 to 75%, preferably at room temperature.
Machining of less than 75% results in a small amount of dislocations, while machining of more than 75% results in a large amount of dislocations, both of which are undesirable because recrystallized grains become large. Further, it is not preferable that the processing temperature at this time be a high temperature (approximately 250° C. or higher) at which precipitation of the θ stable phase or S stable phase or disappearance of dislocations occurs. Therefore, cold working at room temperature is preferred.

Then, by rapid heating (about 40'C/hr or more)
The softening treatment is carried out at a temperature of 60°C to 500°C. This is to distribute the dislocations introduced during processing into a fine, uniform cell structure through rapid heating, and recrystallize using the dislocations as nuclei to form a fine recrystallized structure. If the heating rate is long in this process, non-uniform precipitation will occur during heating to the softening temperature, and dislocations will either disappear completely or a coarse cell structure of non-uniform size will remain, resulting in coarse crystal grains. It is not desirable because

Further, if the heating temperature is less than 360° C., it will not be softened sufficiently, and if it exceeds 500° C., crystal grains will grow significantly or eutectic melting will occur, which is not preferable.

The heating and holding time is the time necessary for recrystallization, and at high temperatures it may be several minutes to several hours, and at low temperatures a longer holding time is required, but a holding time of up to about 6 hours is sufficient. Note that cooling after softening is preferably slow cooling.

As the aluminum alloy to which the method of the present invention is applied, Cu
1.4-5.5 wt%, Mg 0.1-2. Ow
t%, Mn011~l, 4 wt%, or this alloy containing 1.2 wt4 or less St
It is an alloy containing

(Example) kl-Cu-Mg-Mn of 6 scales A to F shown in Table 1
Cu, Mg, M
An aluminum alloy containing n and Si was used. Note that B, C, and E in the table contain Si to an impurity level.

These six types of aluminum alloys were homogenized at 490°C for 24 hours, then hot rolled at 460°C to a thickness of 5.
A plate material having a thickness of 2 wm was obtained by cold rolling.

This plate material was subjected to solution treatment, processing and softening treatment under the conditions shown in Table 2 to produce an aluminum alloy according to the method of the present invention, an aluminum alloy according to the comparative example method, and an aluminum alloy according to the conventional method.

In both methods, the solution treatment was followed by cooling to room temperature.

The softening treatment was carried out under the conditions shown in Table 2 by heating at 80°C/hr and then slowly cooling to 250°C at a cooling rate of 25°C/hr.

In order to test the performance of the nine aluminum alloys of the present invention, comparative aluminum alloys, and conventional aluminum alloys, preforming was performed as shown in Table 3, followed by solution treatment and quenching at 518°C x/hr. (Water quenching) Immediately, the final molding process (2 to 10% L direction, tension) was performed, and the presence or absence of surface roughness after the final molding process and the crystal grain size were measured. The results are shown in Table 3.

Table 2 (1) Table 2 (2) Table 2 (3) Table 3 (4) Crystal grain size (μm) A: ≦20.8: >20 to ≦30
゜r・＼す＾− どのえ n−＼A＾−／２８ 口・へ C
As is clear from Table 8-3, according to the method of the present invention, even if the preform processing rate after the softening treatment increased, no roughening of the surface occurred after the final forming process, and the crystal grain size was fine.

In addition, in the case of the comparative example method, it was observed that after the final molding process, primary cracking occurred and the crystal grain size became coarse.

(Effects) As detailed above, according to the method of the present invention, the part that has undergone preforming with the softened material has a fine and uniform recrystallized structure even after solution treatment and quenching, and after the final forming process, It is extremely useful industrially because it can produce aluminum alloys that do not cause roughness, that is, excellent high-strength aluminum alloys after forming.

Claims (1)

[Claims] 1) After homogenizing an aluminum alloy containing Cu, Mg, and Mn, it is rolled, then heated and maintained at 420°C to 580°C, cooled to room temperature, and then processed by 20 to 75%. A method for producing an aluminum alloy with excellent formability, which comprises softening the aluminum alloy again at 360°C to 500°C. 2) After homogenizing an aluminum alloy containing Cu, Mg, Mn, and Si, it is rolled and then heated at 420°C to 58°C.
After heating and holding at 0°C, cool to room temperature, then 20-75%
A method for producing an aluminum alloy with excellent formability, which comprises softening the aluminum alloy again at 360°C to 500°C.