JPS6058299B2 - Method for producing Al-Zn-Mg-Cu alloy material with excellent formability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an Al-Zn-Mg-Cu alloy material with excellent formability. Al-Zn-Mg-C with excellent uniform formability even though different
This invention relates to a method for manufacturing a U-based alloy material.

In general, 7000 series back aluminum alloys have poor formability, so preliminary processing is performed using a soft material, followed by solution treatment and quenching treatment, and the strength immediately after quenching is low. After the main processing, aging treatment is performed (T
6) manufacturing process is adopted. Although I am calm,
In such a manufacturing process, the part of the soft material that has undergone preliminary processing at a processing rate of 10 to 20% becomes a significantly coarse recrystallized structure during the subsequent solution treatment and scraping process, and during the main processing, the surface becomes rough and rough.
Alternatively, there was a major problem in that minute cracks occurred, making molding impossible or degrading the performance of the product.

The present invention was made in view of the problems of the manufacturing method of 7000 series backside aluminum alloy as explained above, namely, the crystal grains are fine even in the state of soft material, and the In cold processing areas such as rolling, drawing, swaging, and cold forging applied to soft materials such as bars, recrystallized grains do not become coarse after subsequent solution treatment and quenching, and the forming processing rate is reduced. Al-Zn- has excellent uniform formability even though it is different.
The present invention provides a method for manufacturing a Mg-Cu alloy material.

Al-Zn-Mg-C with excellent moldability in the present invention
The manufacturing method of U-based alloy material is characterized by Zn3-8
%, Mg1-3%, Cu0.5-3%, 'Mn
0.05% to 0.80%, Cr0.05 to 0.30%,
Zr0.05~0.30%, T10.01~0.15%
, one type selected from V0.01-0.15%, or
After homogenizing an aluminum alloy ingot containing two or more types and consisting of the remainder Al and impurities, hot working or further cold working is performed, and then the aluminum alloy ingot is heated to 350°C at a heating rate of 10°C/ml or less. Heating and holding at ~5000C, cooling rate 10
Cool at ℃/Min or higher, then 200-400℃
The purpose is to heat and hold the mixture for less than 2 hours to perform a precipitation treatment.

As explained in the above-mentioned claims, the method for manufacturing the N-Zn-Mg-Cu alloy material with excellent formability according to the present invention includes a certain proportion of Zn, Mg, and Cu as essential components. An aluminum alloy ingot containing one or more selected from Mn, Cr, Zr, Tl,
4 to 24 hours at ℃ temperature or 2 to 24 hours at 300 to 450 degrees Celsius, then 2 to 24 hours at 450 to 500 degrees Celsius.
Perform homogenization treatment by heating to sufficiently diffuse and dissolve Zn, Mg, and Cu to eliminate microscopic segregation, and at the same time precipitate finely and uniformly Mn, Cr, Zr, Ti, and V, which are effective in stabilizing the structure. . Then, hot working is performed, or
Further, cold working is performed to obtain the required dimensions. Before performing this cold working, it is best to soften the hot-worked material at 350 to 500°C to form a recrystallized structure, and then heat the material to 350 to 500°C at a heating rate of 10 C/Min or less.
After heating to a temperature of Precipitation treatment is carried out by heating and holding for a certain period of time to uniformly precipitate Mg and Zn compounds. In this precipitation treatment, the heating rate is 150'C/Hr or less, and the cooling rate is 15
It is preferable to carry out the treatment at 0°C/Hr or less. As described above, Al-Zn-Mg-Cu with excellent formability according to the present invention
When the aluminum alloy material obtained by the manufacturing method of the alloy material is cold-worked, it becomes matrices. Zn uniformly deposited on the rice cake
, Dislocations introduced during cold working are distributed as a fine and uniform cell structure by the Mg compound particles, and the subsequent solution treatment and quenching treatment create a fine and uniformly distributed cell structure. Fine recrystallization occurs because recrystallization occurs as nuclei 6
A crystal structure can be obtained. Therefore, even if pre-processed materials have been subjected to forming processes with different processing rates, uniform forming process is possible without cracking or roughening during the main forming process after solution treatment and quenching treatment. Desired characteristics can be ensured by aging and aging treatment after processing.

A method for manufacturing an N-Zn-Mg-Cu alloy material with excellent moldability according to the present invention will be explained in detail.

First, the components and proportions of the aluminum alloy used will be explained.

If the Zn content is less than 3%, the strength of the T6-treated molded material will decrease, and if it is contained in excess, insoluble compounds will increase and the toughness will deteriorate, and stress corrosion cracking may occur, so the Zn content is 8%. Must not exceed.

Therefore, the Zn content is set to 3 to 8%. Mg is included in a content exceeding 1% to improve the strength of T6-treated molded materials in the same way as Zn, but excessive content impairs cold workability and deteriorates toughness. The content must not exceed 3%. Therefore, the Mg content is 1~
3%. If the Cu content is less than 0.5%, the strength of the T6-treated molded material will decrease, and if the content exceeds 3%, the amount of insoluble compounds will increase and the toughness will deteriorate.

Therefore, the Cu content is set to 0.5 to 3%. Mn, Cr
, Zr, Ti, ■ are elements that stabilize the structure, and Mn
O. O less than 4%, CrO. O less than 5%, ZrO. O5%
Less than TlO. If MnO.O.O. 8%, CrO. 3%, ZrO.
3%, TlO. l5%, VO. If the content exceeds 15%, the effect will be saturated and giant crystallized substances will be crystallized.

Therefore, the Mn content is 0.05 to 0.8%, the Cr content is 0.05 to 0.3%, and the Zr content is 0.05 to 0.3%.
, T1 content is 0.01 to 0.15%. others,
As impurities, FeO. 5% or less, SlO. A content of 4% or less is permissible.

Next, heat treatment will be explained.

The soaking treatment of the ingot produces a solid solution of Cu, Mg, and Zn, and
The purpose is to precipitate n, Cr, Zr, Tl,
If the homogenization temperature is less than 450°C, the effect will not be sufficient;
Local dissolution occurs when the temperature exceeds 500°C.

The heating time requires 4 hours or more, but heating for 2S or more has no effect. In this case, the heating rate is 100°C/Hr.
The following shall apply. When heating in two stages, there is no particular restriction on the heating rate; the purpose of the first stage is to promote the formation of precipitation nuclei of Mn, Cr, Zr, Tl, and ■, and to prevent local melting in the second stage. So, the optimal temperature range is 300-45
It is 0°C.

The holding time is 2 to 24 hr in any case, and when it is shorter than the lower limit, the effect is small, and when it is longer than the upper limit, the effect is saturated. If softening treatment is performed after hot working, 35
If the temperature is less than 0'C, the softening will not be sufficient and cracks may occur during cold working in the subsequent process, and if it exceeds 500C, local melting may occur. The holding time may be several minutes at a high temperature of about 500°C, but several hours is required at a low temperature of about 400°C. Next, hot processing after this soaking treatment, or
Furthermore, two-stage heat treatment after cold working will be explained.

The first heat treatment is a softening treatment and solid solution of Zn and Mg, but sufficient softening is not achieved at temperatures lower than 350°C, and local dissolution occurs at temperatures exceeding 500°C.

The heating and holding time may be several minutes at high temperatures near 500'C, but several hours are required at low temperatures below 400°C. If the heating rate is faster than 10° C./Min, a fine structure will be formed, but the recrystallized grains after forming will become coarse grains. In addition, the cooling rate should not exceed 10°C/Min.
g cannot be sufficiently dissolved in solid solution. Next, in the second stage of heat treatment, if the temperature is less than 200°C, the strength will increase and the moldability will deteriorate, and if it exceeds 400°C, Mg, Zn
The micronization effect is lost because the particles are dissolved, and the heating holding time may be several minutes at high temperatures near 400°C, but it takes a long time at low temperatures near 200'C due to the precipitation of Mg and Zn compounds. Although a holding time is required, holding it for up to 2@ is sufficient.

Examples of the method for producing an N-Zn-Mg-Cu alloy material with excellent formability according to the present invention will be described together with comparative examples.

Example An ingot having the ingredients and proportions equivalent to 70758 gold shown in Table 1 was cast by a normal melting method, and the ingot was heated at 450°C.
Soaking treatment was carried out for 2Sf, hot rolling was carried out between 450°C and 300°C to produce a plate of 8TmInt, and then,
After softening between the two rails at 460℃, it is cold rolled to a thickness of 3Tn1! &t plate material.

This plate material was subjected to the heat treatment shown in Table 2. In Table 2, No. Nos. 1 to 6 are produced by the method of manufacturing an N-Zn-Mg-Cu alloy with excellent formability according to the present invention; 7~NO. 14 is a comparative example, and NO. 15 is a conventional one (O material). Each of these test materials was further divided into 3
0% (plate thickness 2.1wn), 20% (plate thickness 2.4Tfn)
cold rolled, and solution quenched (480°C
Immediately performed 900 bending (L direction 4Tf0nR 900 bend), and further aging treatment (120°C x 2411r)
I did this.

The mechanical properties of each test material under the heat treatment conditions shown in Table 2, the recrystallized grain size, 900 bending workability, and the aging-treated T
Table 3 shows the mechanical properties of the 6-treated specimens.

As is clear from Table 3, according to the method for producing a cold-rolled material having excellent formability according to the present invention, the processing rate is reduced in the subsequent cold-forming process. No roughness or cracks will occur during bending even if the surface is different.

The recrystallized grain size of the specimen cold-rolled and solution-quenched at a working rate of up to 30% is 20μ or less, and 1 at a working rate of 30%.
It becomes 0 μ or less, and becomes finer as the processing rate is increased.

From this point of view, sample material No. The same thing can be said about 9, l2, and l3, but cracks occurred during bending. This is because the rapid heating, low-temperature heating, and cooling rate were increased in the second heat treatment, resulting in increased strength and deteriorated workability. Other sample material plate NO. 7,8,lO,l
In samples 1 and 14, the recrystallized grain size became 30μ or more depending on the processing rate, and roughness and cracking occurred during bending.

As explained above, N-
The manufacturing method for the Zn-Mg-Cu alloy material has the above-mentioned structure.Furthermore, the method for manufacturing the Zn-Mg-Cu alloy material is performed by subjecting the cold-formed material of the A1-Zn-Mg-Cu alloy material to two-step heat treatment. In inter-forming processing, there is an excellent manufacturing method that allows uniform forming processing even if the processing rate is different.

Claims (1)

[Claims] 1 Contains 3~8% Zn, 1~3% Mg, 0.5~3% Cu, 0.05%~0.80% Mn, 0.05~Cr
0.30%, Zr0.05-0.30%, Ti0.01
~0.15%, V0.01~0.15%, or two or more selected from the group consisting of aluminum and impurities with the remainder being homogenized and then hot worked. ,
Alternatively, after further cold working, the temperature is maintained at 350 to 500°C at a temperature increase rate of 10°C/min or less, cooled at a cooling rate of 10°C/min or more, and then heated to 200 to 400°C.
1. A method for producing an Al-Zn-Mg-Cu alloy material having uniform formability even at different forming rates, the method comprising performing precipitation treatment by heating and holding at 0°C for within 24 hours.