JPS60251260A - Manufacture of super plastic aluminum alloy - Google Patents

Abstract

PURPOSE:To obtain an Al alloy whose super plasticity is further improved, by applying homogenizing heat treatment in two steps to an Al alloy ingot, then hot and cold rolling said ingot by cross rolling. CONSTITUTION:The Al alloy ingot of systems of Al-Cu, Al-Mg, Al-Mg-Si, Al- Zn-Mg is homogenizing heat treated at 400-550 deg.C, then subjected to said treatment at 300-550 deg.C. Said ingot is hot rolled at 300-550 deg.C, then heating held in 1-2 steps at said temp., and precipitation treated. Next, cooled by >=30 deg.C/hr rate, cold rolled by >=30% or 20-60%, then annealed for low temp. softening and cold rolled at >=300 deg.C. Thereat, during hot rolling, rolled by 10-40% reduction quantity, then cross rolled against the remaining reduction quantity. During cold rolling, cross rolling by 10-40% reduction quantity is added. By this method, the movement of dislocated precipitates is obstructed, the fine particle structure is maintained and the Al alloy whose super plastic elongation is improved is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application J The present invention relates to a method for producing a superplastic aluminum alloy, and more particularly to a method for producing a superplastic aluminum alloy with excellent superplastic elongation.

[Jumeishijutsu 1 Superplasticity means that under certain external conditions (・Al is constricted (n
This is a phenomenon in which a huge elongation of several hundred to several thousand percent occurs without eckinFi), and is broadly classified into transformation superplasticity using isothermal transformation and fine-grained superplasticity. In order to induce fine-grain superplasticity, it is essential to finely control the crystal grain size of the material. This can be achieved by optimizing the alloy composition and manufacturing conditions such as processing and heat treatment.

Example Eva, AI-Zn-MPIM alloy Teha, Zn3-8a
rt%, MHO, 5-3+nt%, essential components, Cu
3+ut% or less, MnO, 05-2,0wt%, C
-r O,05-0,,5+uL%, Zr0.05~0
．． 5u+t%,\! 0.05-0.511 It%, T
Al containing one or more selected from i0.15u+t% or less, with the remainder consisting of AI and impurities.
-The Zn-Mg alloy ingot was subjected to homogenization heat treatment at a temperature of 40 () to 550 °C.
'After hot working at a temperature of 1 to 500°C, the first heating holding is performed at a temperature of 450 to 550°C for 0.5 to 1.
(1 Hr, then cool to the second heating temperature, perform a second heating hold at a temperature of 350 to 450'C for 0.5 to 50 Hr, and cool to 30°C/Hr or more. Either the material is cooled at a speed of at least 3()% or cold working is performed at a rate of 20% to 60%, followed by low temperature softening annealing and cold working at a temperature below 300°C. A material with an elongation of 500% or more can be manufactured by performing heat softening annealing at a temperature of 350-55 ('l'C) at a rate of 100℃/Hr or more. can do.

Broadly speaking, this elongation is limited by (1) cessation of superplasticity due to coarsening of crystal grains during deformation, and (2) rupture of the material due to generation of voids due to stress concentration around crystallized compounds. receive. For the former, intermetallic compounds of transition elements MIIAI6, Cr2Mg5A11e
, ZrAl, etc. can be finely dispersed to suppress coarsening of crystal grains, and the latter can be improved by first controlling the content of Fe, Si, etc. and further, reducing the amount of
The relationship between the crystallized material size and the stress concentration factor is: K-f(a) PI-...(1) a ; Outer diameter of the crystallized material f(a) : Crystallized material size According to equation (1), by reducing the size of the crystallized material and dispersing it uniformly, it is possible to reduce the stress concentration around the crystallized material, thereby increasing the superplastic elongation. It is hoped that this will lead to improvements in material properties when used as structural materials.

[Problems to be Solved by the Invention] As explained in Section 1, the present invention provides a method for producing a superplastic aluminum alloy that can further improve the superplasticity of conventional superplastic aluminum alloys. It provides:

[Means for Solving the Problems 1] The superplastic aluminum alloy according to the present invention is characterized by: Al-Cu system, AI-h sheath thread, AI-th-8i system, A
l-Zn-Mg based aluminum alloy ingot from 400~
Homogenization heat treatment is carried out at a temperature of 550 °C, then 30
Homogenization heat treatment is performed at a temperature of 0 to 550°C, and then
After hot rolling at a temperature of 30()~550℃, 350~
Perform one or two stages of heating and holding at a temperature of 550°C, cool at a cooling rate of 30°CHr or more, and then perform cold open rolling of at least 30% or 20°C.
In the case where low-temperature softening annealing at 300°C or less and cold rolling are performed at least once after cold rolling of ~60%, the plate material is Cross rolling is carried out in directions perpendicular to each other, and after this cross rolling is rolled with a constant reduction of 10 to 4 (1%) during hot rolling, the remaining reduction is carried out in the direction perpendicular to this rolling direction. During cold-open rolling, a predetermined reduction amount of 10~
The purpose is to add a step of rolling in a direction perpendicular to the rolling direction with a reduction of 40%.

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

First, heat treatment and processing in the method for producing a superplastic aluminum alloy according to the present invention will be explained.

Al-Cu series, Al-Mg series, Al-Mg-8i series, A
An ingot obtained by casting an l-Zn-Mg-based aluminum alloy with a predetermined content and ratio of ingredients by a conventional method is homogenized and hot worked to homogenize the main elements that are heterogeneously distributed inside. In order to improve the properties, homogenization heat treatment is carried out at a temperature of 400 to 550°C for a sufficient period of time, followed by hot rolling at a temperature of 300 to 550°C to reach a predetermined thickness, and the coarse cast structure is removed. At the same time as the thermally opened fiber structure is formed, precipitates such as Zn, Mg, CLI, etc. and some transition elements such as C, Zr, \I, and Ti are partially separated out in the weave. 1 of the predetermined reduction amount
If rolling is performed from 0 to 40%, then the slab is rotated and the remaining reduction is cross-rolled, Fe and Si
Insoluble crystallized substances mainly composed of Mn, Cr, Zr,
By subjecting the insoluble crystallized substances mainly composed of V and the like to vertical and horizontal cross rolling, they are broken much more finely than when cross rolling is not carried out, and their distribution becomes uniform. Perhaps because of this, the stress concentration around the crystallized substances, which had been largely inhibiting superplastic elongation, is significantly relaxed, and the material exhibits a large elongation. During this cross rolling, the rolling of the previous stage is 10%
If it is lower than
Moreover, if the rolling rate exceeds 40%, the effect of dispersing crystallized substances by rolling in the next rolling direction will be reduced. Therefore, the amount of reduction in the first stage of cross rolling is set to 10 to 40%.

Further, after this hot rolling, by preferably performing cold opening of 30% or more, a material with even finer grains can be obtained and the superplastic elongation can also be increased. Next, after this hot rolling, 3
Heating is maintained at a temperature of 50 to 550° C. for 0.5 to 20 hours, and cooling is performed at a cooling rate of 100° C./hour or higher to force solid solution of the solid solution elements.

In addition, this heat treatment is performed in a continuous annealing furnace capable of rapid cooling and rapid heating at a temperature of 400 to 550°C for 1.0 seconds to
]0m1n, and by this heating and holding, Zn
, H, Cu, etc. are dissolved in solid solution, while the transition elements Mn,
Or, Zr, etc. are AI and intermetallic compounds MnAL, Cr2
Mg3Al+a, ZrAl3, etc. are precipitated.

The cooling rate after this one-stage heating and holding is 1 (l O℃/I
If it is less than -1r, superplasticity will not be obtained and elongation will be difficult to achieve.

In addition, when heating and holding is performed in two stages, first, 450-5
The first heating and holding time was carried out at a temperature of 50°C for 0.5-10Hr, followed by cooling to the second heating and holding temperature, and
0.5-50 HrI7) 2nd at a temperature of 50-450°C
The sample is heated and held twice, and then cooled at a cooling rate of 30°C/Hr or more. The higher the temperature for this heating and holding, the shorter the time may be.

7- In two heating and holding operations, most of the solute elements precipitated by the first heating and holding process are dissolved by force 1, and then by the second heating and holding process, the transition elements Mn, Cr, Zr, etc. and A1 are dissolved.
Intermetallic compounds with, MnA16, Cr2Mg, , AI+
a, Z r A l 3, etc. are precipitated.

In addition, compared to the case where heating and holding is performed only once, these two heating and holding operations result in finer precipitated forms of transition elements and some high-temperature aging precipitates of Zn, Mg, Cu, etc. and A1. In order to form, the cooling rate after heating and holding is also 30℃/
Hr may be slower, manufacturing is easier, and the density of dislocations generated during cold opening is higher,
Furthermore, finer crystal grains are generated and a product with large superplastic elongation can be obtained.

If the cooling rate after this two-stage heating and holding is less than 30° C./Hr, it becomes difficult to obtain superplastic elongation.

Through these heating and holding operations, the dislocation substructure that had formed the hot fiber structure recovers and recrystallization reduces strain energy, making it easier for dislocations to be introduced during subsequent cold working.
In addition, due to the small particles of Mn, Cr, and Zr, the fine grain structure generated in the material is maintained by heating in the superplastic temperature range after the next cold opening process, and superplasticity is obtained. .

After cooling, cold opening rolling is performed at least by 30% or more, but if the working rate is less than 30%, sufficiently fine grains cannot be obtained.

Further, 20-60% cold rolling followed by low-temperature softening annealing at 300°C or less can be performed one or more times, and by introducing this low-temperature annealing, the crystal grains are further refined. During the cold opening rolling in this case, 10 of the predetermined cold rolling amount
The reason for performing ~40% cold cross rolling is to improve superplastic elongation due to the destructive effect of crystallized substances, and the reason for setting this cold cross rolling amount to 10~40% is to improve the superplastic elongation due to the destructive effect of crystallized substances. The reason is the same as in the case.

In this manner, a dislocation substructure having high strain energy is formed in the cold-worked material at a high density.

If this material is subsequently heated to the superplastic temperature range (400°C or higher for aluminum alloys) above normal (1,5TmfTm is the absolute temperature of the material), new crystals start from the high-density dislocation structure. Grains are formed, and therefore, the higher the density of the dislocation structure, the finer the grain structure, the more superplastic it becomes, and the greater the elongation. Once recrystallization is completed, the energy at the grain boundaries decreases, dislocations move and the grains become coarser, and this coarsened structure inhibits superplastic deformation.

Therefore, in the heat treatment in the method for producing a superplastic aluminum alloy according to the present invention, the intermetallic compounds formed by heating and holding after hot rolling, M11A16, CrJ4
g++A11s, ZrA1. By controlling the size and distribution of such precipitates, the movement of dislocations is blocked and the fine grain structure is maintained. That is, if the size of the precipitates is too small or the distance between the precipitated particles is too large, the effect of inhibiting dislocation movement cannot be obtained.

In addition, although the material produced by the method for producing a superplastic aluminum alloy according to the present invention may be subjected to superplastic processing in the same state as it has been cold worked, after cold working,
Heating at a heating rate of 350 to 550 °C/Hr or more
It may be softened at a temperature of 'C and subjected to superplastic working.

Next, an aluminum alloy to be used in the method for producing a superplastic aluminum alloy according to the present invention will be explained.

Al-Cu based aluminum alloy has Cu2~7u+t%
Contains Mg2.5 as an essential component, 1% or less, 5i
2u+t% or less, Mn 0.05-2. Ou+t%, C
r O, 05-0, 5u+t%, Zr O, 05-0,
5u+1%, V 0105-0,5u+t%, Ti
It is an aluminum alloy containing one or more selected from O, 15+++t% or more, and the balance consisting of AI and impurities.

Al-Mg aluminum alloy has 1% of Mg2
Contains as an essential component, Mn0.05-1.5u+t
%, CrO,05~0.5u+t%,VO,05-
It is an aluminum alloy containing one or more selected from 0.5u+t%, TiO, 15u+t% or less, and the balance A and impurities.

Al-Mg-3i series aluminum alloy has Mg0.5~
Contains 2.0 t%, Si 0.3-5.0+ut% as essential components, Cu 1ust% or less, Mn 0.5-1,
5u+t%, CrO, 05-0,5iut%, Zr
O,05-0,5u+t%, ■0.05-0.5u+t
%, TiO, and one or more selected from 15 wt% or less, and the balance is A1 and impurities.

AlZn-Mg aluminum alloy contains 3 to 81% Zn.
, Mg O, 5 to 3111 t% as essential components, Cu 3u+t% or less, Mn O, 05-2, Ou+
t%, CrO, 05-0.5u+t%, Zr 0.05
-0,5u+t%, VO,05-0,5...t%, Ti
It is an aluminum alloy containing one or more selected from O, 15u+t%, and the balance A1 and impurities.

Note that if the content of Fe and Si contained as impurities exceeds 0.15u+t%, insoluble crystallized substances will be formed and the elongation will be significantly reduced, so the content of Fe and Si should be set to 0.
．． It is regulated to 15wt% or less.

[Example 1] An actual paper example will be explained regarding the method for manufacturing a superplastic aluminum alloy according to the present invention.

Example 112= Typical Al-C shown in Table 1 by normal DC casting method
u system, Al-Mg system, AI Mg Si system,
A1-Zn-Mg-based aluminum alloy ingot (thickness: 400 mm) was produced, and then during the steps shown in Table 2,
Cross rolling was carried out during hot rolling and cold rolling to produce materials with a final thickness of 1.5 or 2.5 nm, and the materials were deformed under the conditions shown in Table 2.

As shown in Table 2, the elongation due to superplastic deformation is as follows:
It can be seen that the superplastic elongation is improved by 80 to 15% or more compared to the material that is not cross-rolled.

[Effects of the Invention] As explained in detail above, since the method for producing a superplastic aluminum alloy according to the present invention has the above configuration, a material with significantly superior superplastic elongation can be produced. It has this effect.

Patent Applicant Kobe Steel Co., Ltd. Agent Yoshihisa Maruki, Patent Attorney Procedural Amendment (Voluntary) June 1980, Busy 5th, Commissioner of the Patent Office 1, Indication of Case, 1989 Patent Application No. 107195 2, Title of the invention: Process for producing superplastic aluminum alloy 3, relationship to the amended case Patent applicant address: 1-3-18 Wakihama-cho, Chuo-ku, Kobe Name (1)
19) Kobe Steel, Ltd. Representative: Fuyuhiko Maki 4, Agent address: 901 Fujiwa Toyocho Co-op, 2-2-15 Minamisuna, Koto-ku, Tokyo Address: 136 Telephone (646) 6194 Name: Patent attorney (6937) Ryo Maruki Ku-17-
6. Subject of amendment (1) Detailed description of the invention column 7 of the specification, Contents of amendment (1) rTi O, 15a+t on page 12, line 10 of the specification
% or more" is corrected to "T i 0.15111t% or less."

(2) On page 12, line 16 of the specification, [from 0.15 iut% or less] is changed to “0.15+ut% or less, Zr O,05
-0, 5u+t%”.

Claims (1)

[Claims] Al-Cu series, Al-Mg series, Al-Mg-8i series, A
l-Zn-Mg based aluminum alloy ingot from 400~
homogenization heat treatment at a temperature of 550 °C, then 3
After homogenization heat treatment at a temperature of 00 to 550 °C, and then hot rolling at a temperature of 300 to 550 °C,
Perform one or two stages of heating and holding at a temperature of 550°C, cool at a cooling rate of 30°C/Hr or more, and then perform cold open rolling of at least 30%, or
In the case where low-temperature softening annealing at 300°C or less and cold rolling are performed once or more after cold rolling of 0 to 60%, the plate material is Cross rolling is carried out in directions perpendicular to each other, and when this cross rolling is hot rolled, it is rolled with a reduction amount of 10 to 40% of the predetermined reduction amount, and then rolled with the remaining reduction amount in a direction perpendicular to this rolling direction. , a superplastic aluminum alloy characterized in that during cold rolling, a step of rolling in a direction perpendicular to the rolling direction with a reduction amount of 1 ( ) to 40% of a predetermined reduction amount is added during the cold rolling process. manufacturing method.