JPS6013064A - Manufacture of heat treated aluminum alloy with superior workability - Google Patents

Abstract

PURPOSE:To obtain a heat treated Al alloy with superior cold workability by homogenizing an Al alloy ingot to be heat treated, working the ingot, holding it at the soln. heat treatment temp., and cooling it under specified conditions. CONSTITUTION:An Al alloy ingot to be heat treated such as an ingot of an Al-Cu, Al-Mg-Si, Al-Zn-Mg or Al-Zn-Mg-Cu alloy is homogenized. The ingot is hot worked and cold worked, and it is heated and held at 400-550 deg.C soln. heat treatment temp. to form a fine recrystallized structure. The ingot is then cooled at >=30 deg.C/min cooling rate to make precipitated grains fine. When the resulting heat treated Al alloy material is subjected to finish cold working, a formed part free from surface roughness and working crack can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a heat-treatable aluminum alloy with excellent formability, and more specifically, to
-Mg-3i system, Al-ZnMg system, Al-7,n-M
The present invention relates to a method for producing an aluminum alloy with improved formability of a g-Cu-based heat-treatable aluminum alloy.

In general, heat-treated aluminum alloys have excellent mechanical properties and are used in a variety of ways, including land transportation vehicles and aircraft, as well as various structural strength components.

However, heat-treatable aluminum alloys have relatively poor formability despite their high strength, and for this reason, they are generally subjected to pre-processing (4i processing) in a soft state, followed by solution heat treatment and quenching treatment to age harden them. A molding process is used in which the material is subjected to two treatments in a short period of time, and then artificial aging treatment is performed at the end.

However, in this molding process, recrystallization occurs in the solution treatment after preliminary processing, especially at 20%
In areas that have undergone a certain degree of processing, a particularly coarse recrystallized structure develops, and subsequent finishing processing may cause surface roughness or minute cracks, making molding impossible or reducing product performance. was there.

As explained above, the present invention solves the problems of conventional heat treatment aluminum alloy processing, namely, the crystal grains are fine even in the state of soft material, and
After solution treatment and quenching after cold working at all cold working rates such as rolling, drawing, swaging, and cold forging applied to soft materials such as plates, tubes, and bars, recrystallized grains are The present invention provides a method for producing a heat-treated aluminum alloy that does not become coarse and has excellent formability.

The manufacturing method of the heat-treatable aluminum alloy with excellent formability according to the present invention is characterized by Al-Cu system, A
l-Mg-3i system, Al-Zn-Mg system, $3 yo 1/A
After homogenizing the t-Zn-Mg Cu-based heat-treated aluminum alloy ingot and subjecting it to hot working or further cold working, it was heated and maintained at a solution treatment temperature of 400 to 550°C, and then heated to 30°C/ The objective is to cool at a cooling rate higher than vlin.

That is, the method for producing a heat-treatable aluminum alloy with excellent formability according to the present invention is based on Al-Cu series, Al-Mg-8
Heat-treated aluminum alloy ingots of i-type, Al-ZnMg-type, and AlZn-Mg-Cu-type are heated to a temperature of 400 to 550°C for 4 to 24 hours or to a temperature of 300 to 450°C for 2 hours.
After heating for ~24Hr, 2- to a temperature of 400-550℃
Homogenization treatment is performed by heating at 248r, and Cu, Mg, Si, and Zn in the aluminum alloy are sufficiently diffused into solid solution to eliminate micro-segregation, and at the same time Mn is refined to refine the recrystallized grains.
, Cr, Zr, and l'i are finely and uniformly precipitated, and then hot working or further cold working is performed to form a predetermined shape and size. In this case, if the hot-worked grain is softened at a temperature of 350 to 500°C to create a recrystallized structure before cold working, the crystal grains will be fine in the soft material state, and the formability will be even better. become.

After this treatment, Cu, Mg,
After solid solution of 5iSZn, 30℃/m2! Cool to room temperature at a cooling rate of 11 or higher. In this case, Al-Cu
system, AI Z++-Mg system, AI Z++ Mg-Cu
400-500'C, Al
-450-550 for Mg-Si aluminum alloys
Although it is desirable to maintain the temperature within the temperature range of 0.degree. C., the optimal temperature is about 20 to 50.degree. C. lower than the general solution temperature.

The heat-treatable aluminum alloy obtained by the method of producing a heat-treatable aluminum alloy with excellent formability according to the present invention has finely uniformly precipitated Mn, Cr, and Z" when cold working is performed during forming. , Ti precipitated particles disperse the dislocations introduced by cold working into a fine and uniform cell structure, and recrystallization occurs with the fine and uniformly distributed cell structure as nuclei during the subsequent solution treatment and quenching treatment. A fine recrystallized structure is obtained.For this reason, materials produced using conventional manufacturing methods have a coarse recrystallized structure.
% cold-worked portion also becomes fine recrystallized 1 fibers in the material produced by the manufacturing method of the present invention.

Therefore, in the method of manufacturing a heat-treated aluminum alloy with excellent formability according to the present invention, the material subjected to cold working at any working rate becomes finely recrystallized during the subsequent solution and quenching treatment, resulting in a fine finish. This enables uniform molding without causing cracks or rough skin during molding.

In the method for producing a heat-treated aluminum alloy with excellent formability according to the present invention, a heat-treated aluminum alloy ingot is homogenized and hot-worked or further cold-worked, and then heated at 4()0 to 550°C. The reason why cooling is performed at a cooling rate of 30° C./'lfl j 11 or more after heating and holding at the solution treatment temperature will be explained.

That is, an aluminum alloy ingot is homogenized to finely and uniformly precipitate compounds of Mu, Cr, Zr, and 1'i, which have the effect of refining crystal grains. The heating conditions in this case are 4-24 hours at a temperature of 400-550°C or 2-24 hours at a temperature of 300-450°C, followed by 400
If heated for 2-24 hours at a temperature of -550°C, a precipitation state with a large refinement effect can be observed.

After this homogenization treatment, after hot working or further cold working, heating and holding at a solution temperature of 400 to 550°C, cooling is performed at a cooling rate of 30°C/min or more, Therefore, the precipitated particles of Mu, Cr, Zr, and Ti that are precipitated by the homogenization treatment of aluminum alloy ingots have an effect on refining, relatively small particles have no effect, and coarse particles have no effect on refining. Has a negative effect. Therefore, the purpose of this heat treatment is to dissolve coarse precipitated particles that have a negative effect on refinement into a solid solution and eliminate this effect, but if the heating temperature is less than 400°C, sufficient solid solution cannot be achieved. AI
For Cu-based and Al-Zn-Mg-Cu-based alloys, temperatures exceeding about 500°C, and for Al-Zn-Mg-based alloys,
In Al-Mg-Si alloys, partial melting occurs at temperatures exceeding about 550'C, making it impossible to obtain a sound material. Therefore, the heating temperature is in the range of 400 to 550°C. Further, the time to maintain this heating temperature may be about several minutes if the heating temperature is high, but several hours are required if the heating temperature is low.

If the cooling rate after this heating is less than 30°C/+++in,
Coarse precipitates of Cu, Mg, Si, and Zn are generated, making it impossible to refine them.

An aluminum alloy that is symmetrical in the method for producing a heat-treatable aluminum alloy with excellent formability according to the present invention will be described.

Al-Cu alloy: A heat-treated aluminum alloy equivalent to JTSA2000 units, Cu2~7wL
%, Mg 0.2~2w1% as main component, MnO, 05-0,8u+L%, Cr 0105-0 as necessary
．． 3wL%, Zr O, 05=0, ht%, Ti 00
01-0.15WL%, V 00Of-0,15wL%
Contains one or more selected from the following.

AlMg-Si alloy: A heat-treated aluminum alloy equivalent to JIS A6000, M2O,3
-1.5wt%, Si0.2-1.5111t% as main components, other Mn 0.05-1,0iut%, Cr
O,05-0,4wL%, Cu O,05-0,4+
ut%, ZrO,05-0,hL%, TiO,01-
0.15wt%, VO,01-0.15u+t% Contains one or more selected Nauchikara.

AlZn-Mg alloy: JIS 7N01.70
It is a heat-treated aluminum alloy equivalent to or similar to 03, Zn 3.0-8.0+ut%, M2O, 5
-3, OwL% as the main component, and other Cu 0003-
0.5ulL%, M no, 05-0.4u+L%, C
rO,05-0,4wt%, ZrO,05-0,2
5wt%, l'i 0.005-0.20u+t%, V
0001~0.151%, BO,0005~0.0
Contains one or more selected from among 5wL%.

AI-Zn-MS-Cu alloy: J I 57075
It is a heat-treatable aluminum alloy equivalent to and similar to this, and contains 3-8wt% Zn, 1-3wL% Mg, Cu
The main component is O, 5-3 wL%, Sono and other Mn 0.0
5-0.80 wL%, CrO, 05-0,30 wt%
, ZrO,05-0,30WL%, TiO,01-
0,15wL%, VO,01-0,1! Contains one or more selected from out%.

. Examples of the method for manufacturing a heat-treated aluminum alloy with excellent formability according to the present invention will be described below.

EXAMPLE Ingots having the components and proportions equivalent to the 2025 alloy, 7075 alloy, 7050 alloy, and 6061 alloy shown in Table 1 were cast by normal melting, and were used as representative examples of heat-treatable aluminum alloys.

Each ingot was soaked for 24 hours. Prisoner, 202
4 alloy is 470℃, 7075 alloy is 450℃, 7050
The temperature is 475°C for the alloy and 500°C for the 6061 alloy. After this soaking treatment, hot rolling was carried out at a temperature ranging from 450°C to 300°C to produce a plate with a thickness of 8 mm.
(After being softened for 4 hours at 1'C, cold rolling was performed to produce a 1v3IIIO plate.

These plate materials were subjected to the manufacturing method of a heat-treatable aluminum alloy with excellent formability according to the present invention, heat treatment conditions that differ from the manufacturing method according to the present invention (comparative conditions), and annealing treatment performed conventionally (O material). The heat treatment conditions (conventional conditions) are shown in Table 2.

In order to investigate the moldability of the heat-treated plate materials produced in this way, each plate material was subjected to the following molding process and heat treatment.

1) Preliminary cold open forming cold rolling a) No rolling (rolling rate 0% plate thickness 3+am) Rolling (rolling rate 20% plate thickness 2.4 wheels + o) c) Rolling (
Rolling rate: 30%, plate thickness: 2.1 m) 2) Solution treatment/quenching treatment conditions 2024: 495°C x 30 minutes WQ707
5: 480°C x 30 minutes WQ 7050: 475°C x 30 minutes WQ 6061: 535°c x 30 minutes WQ 3) Cold open forming bending I5 direction 4++++++R90° bending plate thickness 2
．． 4m (20% rolled material) Immediately after cooling 4) Aging treatment (
T6 treatment) Treatment conditions 2024: 190℃X8Hr7075
: 120℃×24Hr 7050 : 120℃×24Hr-+150℃×12
Hr 6061: 170℃X8Hr Table 3 shows the recrystallized grain size (LT-3T surface 1/4
Section E), bending workability (rough skin, cracks), and mechanical properties when made into a T6 material as a final product.

As is clear from Table 3, the formed plate materials (Nos. 1 to 8) manufactured by the method for producing heat-treated aluminum alloys with excellent formability according to the present invention are cold-rolled by 0 to 30%. The recrystallized grains during post-solution treatment and sizing are fine, and roughness and cracking will not occur even when bending is performed. Furthermore, when the final product T6 material is subjected to aging treatment, it exhibits the desired excellent mechanical properties.

On the other hand, the materials manufactured under comparative conditions and conventional conditions (Nos. 9 to 20) had coarse recrystallized grains when subjected to solution treatment and quenching after 0 to 30% cold rolling, and Cracks occur during processing.

As explained in detail above, the method for producing a heat-treatable aluminum alloy with excellent formability according to the present invention has the above-mentioned structure, but the produced heat-treatable aluminum alloy material is finished by cooling. Even when subjected to open molding, a molded product without rough skin or processing cracks can be obtained.

Claims (1)

[Claims] Al-Cu system, AlMg-8i system, AI-Zo-M) (
After homogenizing heat-treated aluminum alloys and AI Zn-Mg-Cu-based aluminum composites, hot working or further cold working, they were heated and held at a solution treatment temperature of 400 to 550'C. After that, 30℃/Ill in''
A method for producing a heat-treatable aluminum alloy with excellent formability, characterized by cooling at a cooling force j rate of -.