JPS6086251A - Preparation of super-plastic aluminum alloy - Google Patents

Abstract

PURPOSE:To prepare a high strength super-plastic aluminum alloy having a fine grain structure, by applying heat treatment, hot processing and cold processing to an Al-Cu alloy ingot having a specific composition containing Mg, Si or the like in a combined form under a proper condition. CONSTITUTION:An Al-Cu alloy ingot, containing, on a wt. basis, 2-7% of Cu and further containing one or more of 2.5% or less Mg, 2% or less Si, 0.05- 0.5% Mn, 0.05-2.0% Cr, 0.05-0.5% Zr, 0.05-0.5% V and 0.15 or less Ti and comprising the remainder of Al and impurities, is subjected to homogenizing heat treatment at 400-550 deg.C and subsequently subjected to hot processing at 350-500 deg.C. In the next step, first heat holding is performed at 450-550 deg.C for 0.5-10hr and, subsequently, the hot processed one is cooled to a second heating temp. of 350-450 deg.C and held for 0.5-50hr. Thereafter, the processed one is cooled at a cooling speed of 30 deg.C/hr or more and subjected to cold processing under at least a draft of 30% or more to obtain a super-plastic aluminum alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a superplastic aluminum alloy, and more particularly to a method for producing a high strength superplastic aluminum alloy based on AI Cu.

Superplasticity refers to the phenomenon in which a material becomes constricted under certain external conditions.
It is a phenomenon that causes a huge elongation of several 100-100% without ki+18), and is broadly classified into transformation superplasticity using isothermal transformation and fine-grained superplasticity (structural superplasticity) observed in fine-grained crystalline materials. Ru. In order to cause this fine grain superplasticity, it is essential to finely control the crystal grain size of the material.

In general, high-strength aluminum alloys are made of 40% ingot after casting.
A homogenization treatment is carried out at a temperature of 0 to 550 °C, and then
Hot working and cold working are carried out at a temperature of 350 to 550'C, followed by solution treatment and aging treatment at a temperature of 4.50 to 550'C to obtain the desired material. In the normal process, the crystal grain size is 40~10'0μ.
``N becomes large, and superplastic elongation cannot be obtained even if deformation is performed at high temperatures.

As explained in section 11 of the present invention, AI
The present invention provides a method for producing a superplastic aluminum alloy that can obtain a fine grain structure that is difficult to obtain with Cu-based high-strength aluminum alloys.

The method for producing a superplastic aluminum alloy according to the present invention includes (
1) Cu2~7wt% is an essential component, -2,5+ut
%l; J, lower, 5i2u+1% or less, Mn O, 05~
2.0wt%, CrO, 05-2, Ou+1%, Zr
O,05-0,5wL%, ■0.05-0.5%,
400~5,'r
(Homogenization heat treatment was carried out at a temperature of 35 f'1 to 50 f'l'C, followed by a first heating and holding process. 450～
At a temperature of 550'C (), 5 ~] ('1llr, then cooled to the second heating temperature of 35 f-)~-
1,”) f'l 'C's ?1 grade (), 5~S f
') lLr is heated and held for the second time, and 3 ('l
'C/ l-(r い'ni no cold j', ll)! The first invention relates to a method for manufacturing a superplastic aluminum alloy, the key features of which are (1) cooling at a temperature of at least 3% or more (1) of reincarnation, and (2) a method for producing a superplastic aluminum alloy with at least 3(2%) of reincarnation. %% is an essential component, Njun2.5%l; J, lower, Si2+IIL
% or less, Mn O, 05~0.5u+t%, Cr 00
05-0.5+llt%, Zr O, 05-0,5u+
t%,\' 0.05~0.51%, Ti0.15ta1
A 'l' Cu-based alloy ingot containing one or more selected from the following, with the remainder A1 and impurities, is homogeneously heated at a temperature of 1.100 to 55 ('l'c). After chemical heat treatment and then hot working at a temperature of 35°C to 500'C, the first heating hold was carried out at 45°C.
0~5S 1) Perform 0.5-101-1r at a temperature of 'C, then cool at 4 degrees in the second heating chamber, and cool to 35 degrees)
At a temperature of ~450 °C (1, 5 ~ 501 - 1r second heating and holding, cooling rate of 3 f'l 'C / Hr or more), then 20 ~ 60 ° C A second invention provides a method for producing a superplastic aluminum alloy, characterized in that cold working is performed at a temperature of 30% (1'CI; J), followed by low temperature annealing and cold working at least once. (3)
2-7wt% of Cu is an essential component, and N is added.2. '5u
+t% or less, 5i2Illt% or less, Mn 0.05-
0.5+n1%, Cr 0005-0.5+ut%, Z
r0.05~0.51uL%, VO,05~0.51
%, Ti 0.15wt% 1 or 2 seizes selected from below, and the balance A) and impurities. 5
Homogenization heat treatment was carried out at a temperature of 50'C, followed by hot working at a temperature of 350~S O (1'C), followed by a first heating hold at a temperature of 4'5rl-55 (1'C). Rl, 5-1 r) Hr at a temperature of 350-4.5 + 1 °C, then a second heating temperature of 350-4.5 + 1 °C. After heating and holding for 3 times, cold working is performed at least 30% or more by cooling at a cooling rate of 3 (same C/Hr), or 20 to 60% cold working is performed. Do, followed by 3+
)r) One recovery of low temperature softening annealing and cold working below 'C'1
A third method for producing a superplastic aluminum alloy is characterized in that a softening treatment is carried out at a temperature of 350 to 550'C at a heating rate of 100°C/1-1r or higher.
This invention consists of three inventions.

The method for producing a superplastic aluminum alloy according to the present invention will be described in detail below.

First, the components and component ratios of the aluminum alloy will be explained.

If the Cu content is less than 2U+1%, sufficient strength cannot be obtained, and if the Cu content exceeds 7+I11%, the elongation decreases significantly. Therefore, the Cu content is set to 2-7u+L%.

When the Mg content exceeds 2.5+ut%, the elongation decreases significantly. Therefore, the Ma content is set to 2.5 uut% or less.

When Mn, Cr, and Zr5V are less than 1%, fine crystal grains cannot be obtained as described later, and
If Mn, Cr, Zr, and ■ are contained in amounts exceeding 0.5 + u1% and T10, ]5 + ut%, respectively, they will not be solidly dissolved sufficiently during casting, and large intermetallic compounds will occur, making it difficult to obtain sufficient elongation. do not have. Therefore, the Mn content is between 0.05 and 0.
．． 5+++t%, Cr content is 0.05-0.5u+L
%, Zr 0005~0.5+IIL%, VO,05
~0.5u+L%, Ti 0.15wt% or less.

Note that Fc, which may be contained as an impurity, is
If 5 exceeds 1% of O, 15w, insoluble products will be generated and the elongation will be significantly reduced. Therefore, the content of Fe is 0
．． 15.1% or less.

Next, the heat treatment method will be explained.

In order to homogenize the main elements that are heterogeneously distributed inside the ingot obtained by casting an aluminum alloy having the above-mentioned contents and proportions, and to improve hot workability, 1.1. Homogenization heat treatment is carried out for a sufficient time at a temperature of 350-50°C (Of) to 550°C, followed by
Hot working is carried out at a temperature of 1'C to process the plate to a predetermined plate p7, and the structure becomes hot fiber silk and at the same time, precipitates such as Zn, N18, CLI, etc. and Mn, Some of the transition elements of Cr, Zr, \゛, and Ti caps will be analyzed. Furthermore, after hot working, perform cold working to a temperature of 30% or more.
I or A: 1- will also increase the super Wj elongation.

This hot-heated material is subjected to a first heating and holding period of 0.5-H)l(r) at a temperature of 4.50-55rl'C, followed by a second heating and holding temperature. 350-4
．． A second heating hold of 0.5-500 r is carried out at a temperature of 5 f'1°C, and cooling is performed at a cooling rate of 3 (')' C/Hr or less. The higher the temperature for this heating and holding, the shorter the time.

During the two heating and holding cycles, most of the solute elements precipitated by the first heating and holding process are dissolved into solid solution, and during the second heating and holding process, the transferred elements Mn, Cr, Zr, etc. and A1
Intermetallic compound M n A 13, Cr2Mg3At
,,, ZrAl3 etc. are precipitated, and fine nets 4 are generated in the material by heating in the Mi plastic temperature range after the next cold opening process.
The silk weave is retained and superplasticity is obtained.

In addition, compared to the case where heating and holding is performed only once, these two heating and holding processes result in finer precipitation of transition elements and the formation of some high-temperature aging precipitates of Cu, Mg, etc. and A1. In order to ensure that
Cold opening]: The density of dislocations generated during cold opening is higher, finer grains are generated, and the superplastic elongation is larger. A: I get 1. By this heating and holding, the dislocation underlying structure forming the hot fiber button weave is recovered and recrystallized, reducing the strain energy, making it easier for dislocations to be introduced in the subsequent cold working.

The cooling rate after this heating and holding is 3 (', l'C/H
The end of r? ! /i, superplastic elongation makes it difficult to rub.

After cooling, a cold working process of at least 30% or more is performed, or if the working rate is less than 30%, sufficiently fine crystal grains cannot be removed.

In addition, 20-60% cold working and subsequent 3Q (1
It is also possible to carry out low temperature annealing at a temperature below C and cold working once, and by carrying out this low temperature annealing, the crystal grains are further refined.

In the material cold-worked in this manner, a substructure of dislocations with high strain energy of 1:1 is formed at high density. When this material is heated normally (1,5 Tmi Tan is the melting point (absolute temperature) of the material l l' J, above the superplastic temperature range (for aluminum alloys, it is more than 4 o f'l 'C'2), a high density of dislocations occurs. New crystal grains are formed starting from the structure,
Therefore, the higher the density of the dislocation structure, the more a-fine grain structure is obtained and the greater the superplastic elongation. Once recrystallization is completed, dislocations move to reduce the energy at grain boundaries, and the grains tend to become coarser, and these coarsened grains inhibit superplastic deformation. .

Therefore, in the method for producing a superplastic aluminum alloy according to the present invention, the M formed during heating and holding after hot rolling is
n A l 6, Cr2Mg5A11B, ZrAl3
By controlling the size and distribution of such precipitates, the movement of dislocations is inhibited and the fine-grained weave is maintained. That is, if the size of the precipitates is too small or the grain spacing is too large, the dislocation movement stopping effect cannot be achieved.

In addition, in the method for producing a superplastic aluminum alloy according to the present invention, it is possible to superplastically work the material as it is cold worked, or at a heating rate of less than f'l'C/llr. It is also possible to perform heating and softening treatment at a temperature of 350 to 55 f)'C and then conduct the superplastic temperature range.

The fine-grained superplastic material produced by the method for producing a superplastic aluminum alloy according to the present invention has a 5 f'lO % or more of superplastic elongation can be obtained.

An example of the method for manufacturing a superplastic aluminum alloy according to the present invention will be described.

Example I Cu 4.5w1%, Mg 1,5u+1%, Mn
O; 6u+I%, FeO,IO+u1% remainder＼1
(Alloy 1) and CL16.3 1%, Mn O, 3
u+t%, Zr O, ]5wL%, \' 0. IO+u
An ingot (thickness 34.Ofi +11m) consisting of 1% Ti0106 and A bulk gold2) was cast by the normal DC casting method, and after homogenization heat treatment for 12 hours at a temperature of 1,190°C, it was heated to 120°C. Hot rolling at a temperature of 6,3
mm thick plate and waist 3Hr and 45 at a temperature of 520°C
Heated and held at a temperature of 12)-1r at a temperature of 0 °C, cooled at a cooling rate of approximately] strain rate IX ] ('
, 1-'/SeC.

As is clear from Table 1, the superplastic elongation of the material produced by the method for producing a superplastic aluminum alloy according to the present invention is more than twice that of the comparative material.

Table 1 Example 2 The alloy 2 of Example 1 (thickness 4 (l Omm)) was cast by the usual l)C casting method at a temperature of 490°C.
(After homogenization heat treatment at 42 f') It was processed into a plate with a thickness of 12.5 + nm by hot rolling at 520'C.
31-f r at a temperature of 31-fr and i 5 (at a temperature of 1° C.).
1) A material with a thickness of 2.5 va was prepared by cooling at a cooling rate of 1r, cold rolling and low-temperature softening annealing shown in Table 2, and after heating to 1.475°C, a strain rate of 1 x 10- 3/se
It was transformed by c. It can be seen that the superplastic elongation of the material manufactured by the method for manufacturing a superplastic aluminum alloy according to the present invention is significantly superior to that of a material that is not subjected to low-temperature softening annealing.

Table 2 Example 3 Alloy 2 of Example 1 (
Thickness 4. Of) mll+), i 9 f')'
After a homogenization treatment of 12T-1r at a temperature of C, hot rolling was carried out at a temperature of 420°C to form a plate with a thickness of 6.3 man. After heating and holding at 108 r, approximately 1 f'l
After cooling at a cooling rate of f', l'C/I-1r, it was processed into a plate with a thickness of 2.5 man by cold rolling, and then heated and softened at a temperature of 175°C at the heating rate shown in Table 3. The sample was deformed at a temperature of 475°C and a strain rate of +X1n-'.

Table 3: Method for producing superplastic aluminum alloy according to the present invention
In Alloy 3, where the heating rate is 100°C/Hr or less, the superplastic elongation is about 1/2 or less.

As explained above, since the method for producing a superplastic aluminum alloy according to the present invention has the above configuration, it can produce excellent superplasticity without local elongation of necking at an appropriate temperature. This has the effect that a material with elongation can be obtained.

Claims (3)

[Claims] (1) 1% of CL12-7 is an essential component, Mg2.
5u+1% or less, Si2+ut% or less, Mn O, 05
-0, Fouj%, Cr O, 05-2, Ou+t%,
Zr 0.05-0.5u+t%, VO, 05-0,
Contains one or more selected from 5+ut%, TiO, 15u+1% or less, and the remainder is A.
An Al-Cu alloy ingot consisting of 1 and impurities was heated to 40
Homogenization heat treatment at a temperature of 0 to 55 f'l''C, followed by hot working at a temperature of 350 to 5no'C, followed by a first heating hold at a temperature of 450 to 550C. , 5-101-[r, followed by 12 heatings and cooling to a temperature of 350~, i 5 +)'C, followed by a second heating and holding of (1,5-501-1r), After cooling at a cooling rate of 30°C/Hr or higher,
1. A method for producing a superplastic aluminum alloy, characterized by performing cold working of at least 3()% or more. (2) Cu2~7u+t% is an essential component, Mg2,
5u+t% or less, 5i2u+t% or less, Mn 0.05
-0.5iut%, CrO,05-0.5u+t%,
Zr 0.05-0.5u+t%, \IO, 05-0
, 5u+t%, Ti O, 15u+t% or less, and the remainder is A.
An AI-CLI alloy ingot consisting of 1 and impurities, 4
．． Homogenization heat treatment at a temperature of OO~550'C, followed by hot working at a temperature of 350~500°C, followed by 11 heating holds at 4,50~550°C.
0.5-108r at a temperature of 350-450°C, then cooled at a second heating temperature of
Perform a second heating hold at 0 Hr, cool at a cooling rate of 30°C/Hr or higher, then perform 20-60% cold working, followed by low-temperature annealing and cold working at 300°C or lower. A method for producing a superplastic aluminum alloy, characterized in that the process is carried out at least once or twice. (3) Cu 2-7u+t% is an essential component, Mg2.
51% or less, 5i2u+t% or less, Mn 0105-0
．． 5+ut%, CrO, 05-2, Ou+1%, Zr
0.05-0.5ujj%, V 0605-0.5u
+t%, TiO, 1 type or 2 types selected from below 15u+L%1? The At Cu-based alloy Q ingot containing Gekiji and afterglow)<A+ and impurities was subjected to homogenization heat treatment at a temperature of 40C) to 55(')''C, and then at a temperature of 350 to 500C. After hot working at ~150-S
5f',) 'C at a temperature of 0.5-1 (11-1r row), then cooled to the second heating temperature, 350~
．． Perform a second heating and holding of Q, 5-5ol-Ir at a temperature of 15 f'l'C, cool at a cooling rate of 30"C/H", and then at least 30%] Alternatively, 20~60% cold working is performed, followed by low temperature softening annealing and cold working at 30°C (1'C or less) once a month, and then 100% cold working. °C/1
-1 A method for producing a superplastic aluminum alloy, characterized in that a softening treatment is performed at a temperature of 350 to 550°C at a heating rate of less than or equal to 1 r.