JPS58181851A - Preparation of al-zn-mg-cu base alloy material having uniform moldability - Google Patents

Abstract

PURPOSE:To prepare an Al-Zn-Mg-Cu base alloy material having uniform moldability, by carrying out proper heat treatment with respect to an Al alloy cast ingot cntaining Zn, Mg and Cu as essential components and having Mn, Cr, Zr, Ti or V further added thereto. CONSTITUTION:An Al alloy cast ingot containing 3-8% Zn, 1-3% Mg and 0.5-3% Cu as essential components and one kind or more 0.05-0.8% Mn, 0.05- 0.3% Cr, 0.05-0.3% Zr, 0.01-0.15% Ri or 0.01-0.15% V and comprising the remainder Al and impurities is subjected to homogenizing treatment and hot processing or further cold processing successively and, after the resulting cast ingot is heated to 350-500 deg.C to be held at that temp., the heated cast ingot is cooled at a cooling speed of 10 deg.C/min or more. In the next step, the treated cast ingot is subjected to precipitation treatment by heating and holding the same to 200-400 deg.C within 24hr to obtain an Al-Zn-Mg-Cu base alloy material having uniform moldability of which the recrystallized particle after solution heat- treatment and hardening treatment succeeding cold molding processing does not become coarse.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides kl-Zn-Mg-C having uniform formability.
Regarding the manufacturing method of U-based alloy materials, we would like to further discuss the manufacturing of an improved aluminum alloy that has uniform formability even if the forming rate of 7075-based alloy material, which is a typical high-strength aluminum alloy, is different. Regarding the law.

In general, 7000 series high-strength aluminum alloys have poor formability, so preliminary processing is performed using a soft material, followed by solution treatment and quenching, and the strength immediately after quenching is low. After performing the main processing, aging treatment is performed (T6
Processing) manufacturing method is adopted.

However, in this manufacturing method, the part of the soft material that has been subjected to preliminary processing with a processing rate of 10 to 20 becomes extremely coarse recrystallized structure during the subsequent solution treatment and quenching treatment, and the surface becomes rough or microscopic during the main processing. This poses a serious problem in that large cracks occur, making molding impossible or completely reducing the performance of the product.

The present invention was made in view of the above-mentioned problems in the conventional manufacturing method of 7000 series high-strength aluminum alloy, namely, the crystal grains are fine even in the case of soft materials, and plate materials, pipe materials, and Rolling applied to soft materials such as bars,
Drawing, swaging.

An At-Zn-Mg-Cu alloy material with uniform formability that prevents recrystallized grains from becoming coarse after subsequent solution treatment and quenching in all parts of cold-processed cars such as cold forging. It provides a manufacturing method.

At-Zn-Mf- having uniform formability according to the present invention
The manufacturing method of Cu-based alloy material is characterized by Zn5~
8 capsules, Mg 1-3%, Cu[L5-5% k as essential components tlL, Mna05-α8 list Cr (105
~0.3%, Zrα05~0.3%, TiCLol
~CL15%, V CLDl ~CL15% O1
After homogenizing an aluminum alloy ingot containing Aj or two or more and consisting of the remainder Aj and impurities, the aluminum alloy ingot is subjected to heat treatment or cold working to 550' to 500°C.
The method is to heat and maintain at a temperature of 200 DEG to 400 DEG C. for less than 24 hours, cool at a cooling rate of 10 DEG C./min or more, and then heat and maintain at 200 DEG C. to 400 DEG C. for less than 24 hours to carry out a precipitation treatment.

At-Zn-M having uniform formability according to the present invention
In the manufacturing method of g-Cu alloy, as mentioned above, Cu, Mg, and Znf are essential components in a certain proportion, and Mn,
Cr, Zr.

The remainder A contains one or more of V and Ti
An aluminum alloy consisting of T and impurities is ingot manufactured by a normal melting process at a temperature of 450° to 500°C.
24 hours or 2 to 24 hours at a temperature of 300° to 450°C
After heating for 1 hour, homogenization treatment is performed by heating at a temperature of 450° to 500°C for 2 to 24 hours, and Cu, Mg, and Zn are sufficiently diffused in the same bath to eliminate microsegregation and at the same time are effective in stabilizing the structure. Mn, Cr, Zr, Ti′t
- Precipitate finely and uniformly, then perform hot working or rough cold IV1 processing to obtain the required shape and size.
It takes 70 hours. Before performing this cold working, hot working material 1
A softening treatment is performed at 550' to 500'C to form a recrystallized structure. After that, Mg
, Znt-10°C after holding for a sufficient time to form a solid solution.
Cool to room temperature at a cooling rate of >/min, followed by 200°
The precipitation treatment is carried out by heating and holding at a temperature of ~400°C for up to 24 hours to uniformly precipitate the Mg and Zn compounds. In this precipitation treatment, the heating rate was 150°.
It is preferable to carry out the treatment at a temperature of C/hr or less and a cooling rate of 150° C./hr or less.

In this way, the AL- containing uniform formability according to the present invention
When an aluminum alloy material obtained by the manufacturing method of Zn-MIK-Cu alloy material is cold-formed, the dislocations introduced during cold-working are finely and uniformly formed by particles of Mg and Zn compounds precipitated uniformly in the matrix. A fine recrystallized structure is obtained because recrystallization occurs using the fine and uniformly distributed cell structure as a nucleus by the subsequent solution heat treatment.

For this reason, even if pre-processed materials have been subjected to forming processes with different processing rates, in the main forming process after solution treatment and quenching,
Uniform molding is possible without cracking or roughening, and required properties can be maintained through aging treatment after processing.

AL-Zn-Mg- having uniform formability according to the present invention
A method for manufacturing a Cu-based alloy material will be explained in detail.

First, the ingredients of the aluminum alloy used.

The component ratio will be explained.

Zn14 is an element that imparts strength, and if the content is less than 3 capsules, the strength of the T6-treated molded material will decrease, and ssf
: If the content exceeds the amount, the amount of insoluble compounds increases, resulting in deterioration of toughness and the risk of stress corrosion cracking. Therefore, the Zn content is set to 5 to 8.

Similar to Zn, the structure is an element that imparts strength. If the content is less than 1%, the strength of the T6 treated molded material will decrease, and if it is contained in excess of 6eIIK, the cold steel workability will be poor.・Deterioration of toughness. Therefore, the number of pigeon coops should be 1 to 6 pigeons.

Cu is an element that imparts total strength, and when the content is 0.5%, the strength of the T6-treated molded material decreases, and when the content is 0.5%
If the content exceeds the amount, the amount of insoluble compounds increases and the toughness deteriorates. Therefore, the Cu content is set to CL5-5-.

Mn, Cr, Zr, Ti, and V are elements that stabilize the structure, and Mn is less than 0.05%, Cr105
Less than 1, Zrα less than 05, Tiα less than 01%, Vα
If it is less than 0.01%, there is no effect on structure stabilization, and Mn
l18qb, Crα5%, Zrα61, Ti115
%, the effect of stabilizing the structure with VCL of 15% is saturated, and giant crystallized substances are further crystallized. Therefore, Mn content Q, 05~o, slG, Cr
Content 15-5%, Zrα 05-13%, Tiα 01-
α151G, VCLO1 to α15chi. One or more of these components may be contained.

As impurities, inclusions of F@CL5 or less and 81α4 or less are allowed.

Next, heat treatment will be explained.

The homogenization treatment of the ingot causes the solid solution of Cu, Mg, and Zn, and the precipitation of Mn, Cr, Zn, and Ti, but this effect is not sufficient if the homogenization treatment temperature is less than 400 @ C. Furthermore, if the temperature exceeds 500°C, local dissolution will occur, and the homogenization process will require more than 4 hours.
Even after 24 hours, the effect is saturated and it is uneconomical. In this case, the heating rate is 100° C./hr or less. When conducting in two stages, limiting the heating rate is useful; in the first stage, M
The purpose of the second heating is to promote the formation of precipitation nuclei of n, Cr, Zn, Ti, and V, and to prevent local melting, and the optimum temperature range is 500° to 450°C. In any case, the holding time is preferably 2 to 24 hours; if it is shorter than 2 hours, the effect will be small, and if it is longer than 24 hours, the effect will be saturated and it will be uneconomical.

Next, we will explain that after homogenization treatment, hot working or further cold working is performed to obtain the desired shape and size, and then two-stage heat treatment is performed. Temperatures lower than 650°C may not soften sufficiently and cracks may occur during cold working. At temperatures exceeding this, local melting occurs. The heating time may be several minutes at high temperatures near 500°C, but several hours at low temperatures around 400°C. The heating rate is not affected, but the cooling rate is 1
If the speed is not faster than 0°C/min, Mg and Zni cannot be sufficiently solid-dissolved, and the heat escape field in the next second stage is 200° to 400°C.
Precipitation treatment is carried out by heating and holding at a temperature of 24 hours or less, but temperatures below 200°C deteriorate the formability that increases strength, and temperatures above 400°C deteriorate
Since n is dissolved, the refinement effect is lost, and the heating holding time may be several minutes at high temperatures near 400°C;
On the low temperature side near 0°C, a long holding time is required due to the precipitation of Mg and Zn compounds, but holding for up to about 24 hours is sufficient.

kl-Zn-Mg- having uniform formability according to the present invention
An example of a method for manufacturing a Cu-based alloy material will be described together with a ratio example.

Example 1 An ingot with the ingredients and proportions equivalent to the 7075 alloy shown in Table 1 was cast by conventional melting, and the ingot was homogenized at a temperature of 450°C for 24 hours, and the ingot was heated from 450°C. 500
℃ to make 8wt plate, followed by 460wt.
After softening for 4 hours at a temperature of 5°C, cold rolling
It was made into an mtO plate.

This board was used to undergo the heat treatment shown in Table 2. In this @2 table, sample plates A1 to jf66Fi are produced by the manufacturing method of the At-Zn-ME-Cu alloy material having uniform formability according to the present invention, and A7 to A12 are produced by the heat treatment method for comparison. The material 15 is obtained by heat treatment using the conventional method (O material).

Table 2 These sample plates were further processed at a processing rate of 30 mm (plate thickness 2.1 nm).
+), cold rolled at 20% (plate thickness 2.4 m), and solution hardening treatment (480°C x
Add water for 50 minutes), then immediately bend 90 degrees (L direction).

4jIllLR 90° bending), and then an aging treatment (120°C x 24 hr).

@Table 3 shows the mechanical properties of the valley sample plate heat-treated under the conditions shown in Table 2, as well as the paleograin size and 90' bending of the cold-rolled, solution-hardened sample plate. It shows the caroe properties and the mechanical properties of aged T6 treated wood.

As is clear from this 'Ig5 table, the cold-rolled material was processed into At-Zn-Mg-C having uniform formability according to the present invention.
According to the manufacturing method of U-based alloys, even if the processing rate is low in the subsequent cold forming process, the surface may become rough during the bending process.

No cracking occurs. In addition, the recrystallized grain size of the sample plate cold-rolled with a processing rate of up to 50%, solution-treated and quenched is 2.
It becomes 0μ or less, 10μ or less at a processing rate of 50 or more, and becomes finer as the processing rate is increased.

Judging from this point w4, the same thing can be said about sample plates 9 and 112, but cracks have occurred during bending. This indicates that, as shown in Table 5, because the low temperature heating and cooling rate were increased in the second heat treatment, the strength increased and the workability deteriorated, as shown in Table 5. Other sample plates I67, M8.410,
411. In case of No. 15, the recrystallized grain size was 50μ or more depending on the processing rate, and roughness and cracking occurred during bending.

As explained above, M-Zn corresponding to 7075 alloy
- Since the forming method for Mg-Cu alloy material has the above-mentioned configuration, the cold-formed material of kA-Zn-Mg-Cu alloy material is cold-formed in a two-stage heat treatment plant. In the interforming process, even if the 7JO processing rate is different, the effect is achieved as long as the forming process is uniform.

Claims (1)

[Claims] Zn5-8%, Mg 1-3%, Cu[L5-5-
Contains Mn[L05~(L8(Cr
(LO5~0.5%, ZrCLO5~CL3'Ik,
After homogenizing an aluminum alloy ingot containing one or more of Ti101~(L15S, Vlol~α15s, and the remainder being At and impurities), hot working,
Or after further cold working, 550″~500″
℃, cooled at a cooling rate of 10℃/min or more, and then heated and maintained at 200℃ to 400℃ for less than 24 hours to perform precipitation treatment.Characteristics: Uniform even if the molding rate is different. kt-Zn-Mg-Cu with excellent formability
Manufacturing method for alloy materials.