JPH0623423B2 - Method for manufacturing Al-Cu-Mg alloy soft material - Google Patents

Description

The present invention relates to a method for producing an aluminum alloy wrought material, and more particularly to a method for producing an Al-Cu-Mg alloy soft material. It is a thing.

(Prior Art) Generally, since a high-strength aluminum alloy is inferior in formability, it is processed in the state of a soft material, and then solution treatment and quenching are performed. Al-Cu-Mg alloys, such as JIS A 2024, 2017, 2014, which are the subject of the present invention, are not examples.

As a method of manufacturing this soft material, annealing in a batch furnace has been conventionally performed, but in this case, the heating rate is slow (50 ° C / H
(less than r), the crystal grains of the soft material are coarsened and the formability is lowered. Further, when a slight amount of work is performed after the quenching process to correct the distortion due to the quenching process, roughening of the surface and minute cracks occur if the crystal grains are large. Processing rate of 10 especially for soft materials
The portion that has undergone a low processing of -30% becomes a remarkably coarse recrystallized grain structure in the subsequent solution heat treatment and quenching process, and roughening and microcracking occur during this strain correction, which is a serious problem in the appearance quality of the product.

(Problems to be solved by the invention) The present invention relates to the formability of the soft material of the Al-Cu-Mg alloy as described above, and the crystal grain coarsening at the time of solution treatment. The point is to solve the problem.

That is, in the soft material state, the crystal grains are fine, and the formability represented by elongation, Erichsen value, etc. is good, and even if cold working at any processing rate is performed in this state, it is re-processed by the solution treatment. Al-Cu-Mg where crystal grains do not become coarse
A method for manufacturing a base alloy material is provided.

Configuration of the Invention (Means for Solving the Problems) The method for producing the Al-Cu-Mg alloy soft material in the present invention is to use a so-called continuous annealing furnace, not a patch furnace, for the softening. In the long-cherished desire, 1. Cu1.0-6.0% (weight%, same below), Mg0.1-2.0
%, If necessary Mn0.01-1.2%, Si0.01-1.2
%, Cr 0.005-0.3%, Ti 0.005-0.15%, Zr 0.005-0.20
% Of 1% or 2% or more, and the alloy ingot composed of the balance unavoidable impurities and Al is plastically processed into a predetermined size by a conventional method, and the average temperature is 11 ° C at a temperature of 325 to 430 ° C.
/ Min (meaning the same below for minutes) at a faster heating rate to soften rapidly and then average 30 ℃ / Hr (meaning time,
The same applies hereinafter), a method for producing an Al-Cu-Mg alloy soft material having excellent formability, which comprises cooling at a cooling rate of less than.

2. Cu1.0-6.0%, Mg0.1-2.0%, further as needed
Mn0.01-1.2%, Si0.01-1.2%, Cr0.005-0.3%, Ti0.
A material containing one or more of 005 to 0.15% and Zr0.005 to 0.20%, and plastically working an alloy ingot made of the balance unavoidable impurities and Al into a predetermined size by an ordinary method,
Rapidly heats to a temperature of 325 to 430 ° C at a heating rate faster than 11 ° C / min to soften, then cools at an average cooling rate of 30 ° C / Hr or more, and further heats to 250 to 430 ° C within 24 hours. A method for producing an Al-Cu-Mg-based alloy soft material having excellent formability, which comprises holding and cooling at an average cooling rate of less than 30 ° C / Hr.

Is.

(Operation) The structure of the present invention will be described in detail below together with its operation.

The target alloys are θ phase (CuAl ₂ ) and s phase as hardening factors.
(CuMgAl ₂ ), which is an Al-Cu-Mg-based alloy containing JIS A 2
024,2117,2014 and the like are included, but are not limited to these.

If the composition range is specifically shown, as an essential component, Cu1.0 ~
6.0% (wt%, same below), Mg0.1-2.0%, Mn0.01-1.2%, Si0.01-1.2%, Cr0.005-
This alloy contains 0.3%, 0.005 to 0.15% of Ti, and 0.005 to 0.20% of Zr and contains one or more kinds, and the balance is unavoidable impurities and Al.

The reason for adding these alloy components will be described.

Cu: Cu is an element that imparts strength, and its content is 1.0%.
If it is less than 6.0%, the strength after T4 and T6 treatment will decrease, and if it exceeds 6.0%, the amount of crystallized substances will increase and the toughness and elongation after T4 and T6 treatment will decrease. Therefore, the Cu content is 1.0 to 6.0%.

Mg: Mg is an element that gives strength, and its content is 0.1%.
If the content is less than T4, the strength after T6 treatment will decrease, and if it exceeds 2.0%, the toughness and elongation after T4 and T6 treatment will decrease. Therefore, the Mg content is 0.1 to 2.0%.

The following are the components to be contained as necessary.

Mn: Mn is an element that stabilizes the structure and imparts strength. If the content is less than 0.01%, this effect does not occur, and if it exceeds 1.2%, the effect is saturated and large crystallized substances are formed. Therefore, the Mn content is 0.01-1.2%
And

Si: Si is an element that imparts strength, and its content is 0.01%.
If it is less than 1.2%, this effect does not occur, and if it exceeds 1.2%, the toughness after T4 / T6 treatment decreases. Therefore, the Si content is 0.01 to 1.2%.

However, when the strength is not required so much or when the strength level can be maintained by containing other elements, the Si content is not essential, and in this case, it is treated as an unavoidable impurity.

Cr: Cr is an element that stabilizes the structure and imparts strength. If the content is less than 0.005%, this effect does not occur, and if it exceeds 0.3%, large crystallized substances are produced. Therefore, the Cr content is 0.005 to 0.3%.

Ti: Ti is an element that refines the ingot structure, and its content is 0.
If it is less than 005%, this effect does not exist, and if it exceeds 0.15%, a large crystallized substance is formed. Therefore, the Ti content is 0.005
~ 0.15%

Zr: Zr is an element that refines the ingot structure and stabilizes the structure. If the content is less than 0.005%, this effect does not occur and 0.20%
If it is contained in excess of 100 g, a large crystallized substance is produced. Therefore, the Zr content is set to 0.005 to 0.20%.

Fe and Si as inevitable impurities are allowed up to 0.5%.

Next, the alloy ingot having the above composition is plastically worked into a predetermined size by an ordinary method.

That is, the ingot is subjected to hot working, or further cold working to obtain a predetermined size, but the ingot is heated for hot working, or before soaking. Often. This soaking is
The purpose is to form a solid solution of Cu, Mg and Si and to precipitate Mn, Cr, Zr and Ti. Ingot casting is heat treated at 400 to 520 ° C for 2 to 48 hours.
At temperatures below 400 ° C, the effect is not sufficient, and above 520 ° C, local melting occurs. Also, if the heating is less than 400 ° C, the hot workability is deteriorated, and if it exceeds 520 ° C, local melting occurs, so heat treatment is performed at 400-520 ° C.

Further, when cold working is performed, the effect of the present invention does not change even if intermediate annealing is performed at 350 to 500 ° C. before or during cold working.

In this way, the material plastically processed to the specified size is
The sample is rapidly heated to a temperature of ℃ at a heating rate faster than 11 ℃ / min to soften it.

If the heating temperature is less than 325 ° C., recrystallization does not end during rapid heating and a processed structure remains, resulting in deterioration of formability. At temperatures above 430 ° C, the amount of Mg, Cu, and Si dissolved in solid solution increases, and non-uniform precipitation occurs due to subsequent cooling, which reduces the formability of the soft material and further reduces the workability. The crystal grains become coarse during the solution treatment in the next step.

On the other hand, when the rate of temperature increase is less than 11 ° C./min on average, the crystal grains become coarse and the formability of the soft material deteriorates.

Next, in the first invention of the present application, cooling is performed at an average cooling rate of less than 30 ° C./Hr. When the cooling rate is less than 30 ° C / Hr on average, a completely soft material (0 material) is obtained, so the formability of the material is good, but if the cooling rate is higher than this, quenching and age hardening occur. Therefore, the moldability is lowered. In fact,
If the temperature is less than 250 ° C, migration hardening does not occur, so the cooling rate can be controlled up to this temperature.

Since the temperature rising rate has to be faster than the average of 11 ° C./min for the above reason, a continuous annealing furnace is often used,
Setting the cooling rate to an average of less than 30 ° C / Hr is almost impossible for efficient production in a normal continuous annealing furnace.
When the average cooling rate is 30 ° C./Hr or more, the method of the second invention of the present application may be used.

That is, after softening, it is cooled at an average cooling rate of 30 ° C./Hr or higher, reheated to 250 to 430 ° C., held for 24 hours, and cooled at an average cooling rate of less than 30 ° C./Hr. In the case of this reheating, you can use a batch furnace that does not need to control the heating rate,
Therefore, the cooling rate can be set to less than 30 ° C./Hr on average.

Thus, even if the cooling rate after the first stage softening is fast, by reheating and slowing the subsequent cooling rate,
As a result, it is possible to obtain an Al-Cu-Mg alloy soft material having good formability.

The reheating temperature is preferably lower than the rapid heating temperature in the first step for better moldability.

(Example) After semi-continuously casting three kinds of alloys of A, B, and C shown in Table 1, and subjecting the ingots to a soaking treatment at 490 ° C. × 10 Hr,
It was heated at 460 ° C. × 3 Hr, hot-rolled to a plate thickness of 4 mm, subjected to intermediate annealing at 370 ° C. × 3 Hr in a batch furnace, and cold-rolled to a plate material having a thickness of 0.8 mm.

This material is subjected to heat treatment within the scope of the present invention or other heat treatment to make it a soft material and measure its mechanical properties (tensile strength σB, proof stress σ0.2, elongation δ, Erichsen value, rough skin). did. In addition, after subjecting this soft material to cold rolling by 15%, it is subjected to solution treatment by placing it in a furnace whose temperature has risen (A alloy, B alloy, 493 ° C x 40 min, C alloy
Immediately after water quenching, the degree of skin roughness due to 180 ° bending was observed.

The heat treatment conditions, the mechanical properties of the soft material, and the bendability of the soft material after cold bending and solution heat treatment and water quenching are shown in Tables 2 and 3.
The results are shown in Table 4 and Table 4.

In the table, the first-stage heat treatment refers to rapid heating / softening and subsequent cooling common to the first and second inventions of the present application, and the second-stage heat treatment refers to after the first-stage heat treatment of the second invention of the present application. Reheat and cool.

(Effects of the invention) As is clear from Tables 2, 3, and 4, the material obtained by the production method of the present invention has improved elongation / Erichsen value of the soft material, and the crystal grains are finely processed. At times, it does not cause skin roughening, and since crystal grains do not coarsen even after solution treatment after low working, it has many advantages such as a good product appearance at the time of strain correction after quenching.

Claims (2)

[Claims] 1. Cu1.0 to 6.0% (weight%, the same applies hereinafter), Mg0.
1-2.0%, Mn0.01-1.2%, Si0.01 if necessary
~ 1.2%, Cr0.005-0.3%, Ti0.005-0.15%, Zr0.005
~ 0.20% of 1 or 2 or more of them, and the material with the predetermined dimensions obtained by plastically working the alloy ingot consisting of the balance unavoidable impurities and Al in accordance with the usual method, to the average temperature of 325 ~ 430 ℃ Characterized by rapidly heating and softening at a temperature rising rate faster than 11 ° C / min (the same meaning in minutes) and then cooling at an average cooling rate of less than 30 ° C / Hr (meaning time, the same below). A method for producing an Al-Cu-Mg alloy soft material having excellent formability. 2. Cu1.0 to 6.0% (weight%, the same applies hereinafter), Mg0.
1-2.0%, Mn0.01-1.2%, Si0.01 if necessary
~ 1.2%, Cr0.005-0.3%, Ti0.005-0.15%, Zr0.005
~ 0.20% of 1 or 2 or more of them, and the material with the predetermined dimensions obtained by plastically working the alloy ingot consisting of the balance unavoidable impurities and Al in accordance with the usual method, to the average temperature of 325 ~ 430 ℃ Rapidly heats and softens at a heating rate faster than 11 ° C / min, then cools at an average cooling rate of 30 ° C / Hr or higher, then heats to 250-430 ° C and holds for 24 hours and averages 30 ° C / Hr.
A method for producing an Al-Cu-Mg alloy soft material having excellent formability, which comprises cooling at a cooling rate of less than 1.