JPS6188988A - Production of superplastic aluminum alloy having excellent corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain a superplastic Al alloy having excellent corrosion resistance by using a specifically composed Al-Cu alloy as a core material and cladding the same with specifically composed pure Al as a facing material then subjecting the clad material to cold rolling. CONSTITUTION:The Al-Cu alloy which contains Cu at specific %, contains further 1 or >=2 kinds selected from specific % Mg, Si, Mn, Cr, Zr, V and Ti and consists of the balance Al and impurities is used as the core material. The pure Al which contains 1 or >=2 kinds selected from specific % Cu, Zn, Mg, Mn, Cr, Zr and Ti and consists of the balance Al and impurities is used as the facing material. Such core material and facing material are subjected to hot cladding rolling to form the cladding material which is then subjected to one or two stages of heating and holding at a specific temp. The clad material is cooled at a specific cooling rate and is subjected to at least >=30% cold rolling or >=1 times of 20-60% cold rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method for producing a superplastic aluminum alloy having excellent corrosion resistance.

In the method for producing an aluminum alloy with excellent corrosion resistance according to the present invention, superplasticity means that under certain external conditions, the material undergoes a huge elongation of several tens per cent without necking. transformation superplasticity using isothermal transformation and fine-grained superplasticity (fM) observed in all fine-grained crystal materials.
The present invention is a method for producing the latter type of fine-grained superplastic material, and in order to induce this fine-grained superplasticity, generally the crystal grain size of the material is finely controlled. This is essential, and the present invention relates to a method for producing a flexible aluminum alloy with excellent corrosion resistance by imparting such @ fine grains to the material.

[Prior art] In general, high-strength Al-Cu-based aluminum alloys with excellent corrosion resistance are manufactured by homogenizing the core material (casting material) and then applying the skin material to both sides or one side during hot open rolling. Then, they are bonded together during rolling to form a laminated material (clad material), which is cold rolled and then subjected to solution treatment and aging treatment to form a predetermined product. In this case, 99.3 wt % or more of pure Al is used for the core material of the Al-Cu alloy.

However, in materials manufactured by such normal processes, the crystal grains are as large as 40 to 100 μm, and the desired superplastic elongation cannot be obtained even when deformed at high temperatures.

[Problem to be solved by the invention 1] The present invention solves the problem that the conventional method described above
Clad 7d material is made of T-alloy as the core material and pure Al as the skin material.
The present invention solves the problem of not being able to obtain superplastic elongation using conventional methods, and provides a method for producing a superplastic aluminum alloy having a fine grain structure with excellent corrosion resistance.

[Means for Solving the Problems 1] The method for producing a superplastic aluminum alloy with excellent corrosion resistance according to the present invention includes: (1) containing 2 to 7 wt% of Cu, and further containing 2.5 WL% or less per gram; Si2wt% or less, Mn
0005-2. 'Oa+t%, Cr 0.05-0.5
+nL%, Zr 0.05-0.5+Ilt%, V 0
．． 05~0.05~0.5wt%, Ti 0115ut
t\1-Cu containing one or more selected from % or less, with the remainder consisting of Al and impurities.
Cu O0IOw 1% or more, Zn O0lowt% or more
-1Mg 0.005~0.5wt% or less, Mn010
5-1.0wt%, Cr 0.05-0.25111j
%, Zr 0.05-0.20wt%, TiQ, 15w
Pure A containing one selected from t% or less or 2!9 or more, and the remaining 11tliA+ and impurities
1 is used as a skin material, and after hot rolling to form a cladding material on one or both sides, it is subjected to one or two stages at a temperature of 350 to 550°C.
31) Cool at a cooling rate of 31)'C/Hr or more and cold-roll at least 63()% or more, or cold-roll from 20 to 60% once. The Jj method for producing a superplastic aluminum alloy with excellent corrosion resistance characterized by carrying out the above is the first invention, and (2) contains Cu 2 to 7+oL%, and further contains M82.51111% or less and Si2+uL% or less. , Mn
0.05-2, kt%, Cr 0.05-0.51a
1%, "7.r 0.05~0.5++rt%,■
Al-Cu containing one or two selected from 0.05-0.5iot%, Ti 0.15u+L% or less, and the remainder consisting of Al and impurities.
based alloy as the core material, Cu 0110+at% or less, Zn 0. lou+t%
Hereinafter, N (go, 05 wt% or less, Mn 0.05 to 1
．． 0wt%, Cr 0.05-0.25wt%, Zr
0.05-0.20wt%, Ti 0. I05~0.5
Pure Al containing one or more selected from wt% or less, with the remainder being Al and impurities, is used as a skin material, and after hot bonding pressure f) Perform one or two stages of heating and holding at a temperature of 'C, cool at a cooling rate of 30°C/Hr, and then cold open rolling by at least 30%, or cold open rolling at a temperature of 20 to 6096 Rolling is performed one or more times, and then heated at a rate of 100° C./Hr or more,
1. Heat softening treatment at a temperature of 350 to 5S11'C. This invention consists of two inventions, the invention of @2 being a method for producing a superplastic aluminum alloy with excellent corrosion resistance and corrosion resistance.

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

First, in the method for manufacturing a superplastic aluminum alloy with excellent corrosion resistance according to the present invention (hereinafter simply referred to as the method according to the present invention), the components and component ratios of the core material and skin material used will be explained. .

(1) For the core Al C11 alloy, if the Cu content is less than 2 wt%, sufficient strength cannot be obtained;
If the content exceeds 7u+t%, the elongation decreases significantly. Therefore, the Cu content (2) is set to 2-7II11%.

If the content of 8f8 exceeds 2.5+u19, the elongation will decrease significantly in the i row.Therefore, the lV1g content is set to 2.5wt%.

If the Si content exceeds 2.7%, the elongation will be significantly reduced5.Therefore, the Si content should be 2.1% or less.

When the content of Mn, Cr, Zr, and V is 0.05-nj%, fine crystal grains cannot be obtained with wood leakage, and when the Mn content is 2.05-nj%.
0wt%, Cr, Zr, ＼゛ is 0.5+u+%t)yozoTi0. If each content exceeds I5-t%, it will not be sufficiently dissolved in solid solution during casting, and a giant metal open compound will be formed, making it impossible to obtain sufficient elongation. Therefore, Mn content f, l'j is 0.0
5-2.0IJL%, Cr content is 0.05-0.5v
L%, Zr content is 0.05-0.51%, ■ Contains H
f0. ,05~0.5u1%, T1 content is 0.1
5111L% or less.

(2) Regarding pure Al as a skin material.

In order to obtain fine crystal grains, Mn is 0.05 to 1. O
L%, Cr 0005~0.25u+t%, Z
r 0005~0.20uL%, Ti 0.15+a
5. If the lower limit of each of these elements is less than the lower limit, fine crystal grains cannot be obtained.5. If the content exceeds the upper limit, the number of crystallized substances increases and sufficient elongation cannot be obtained.

In addition, Cu, Zn, and Mg are contained as impurities and reduce corrosion resistance, so the Cu content is 0. IOu+t%, Zn-containing soybean powder is 0. IOu+j9 target Mg content is 0.05a+t% or less.

In addition, FC and Si contained as impurities in the core material
If the concentration exceeds 0.15a+L%, respectively, soluble crystallized substances will be formed in the casting a, and the superplastic elongation will be significant. 3.The Fe and Si content is 0.15w as it causes sweating.
It is necessary to regulate it to t% or less.

Next, heat treatment and processing in the method for manufacturing a superplastic aluminum alloy with excellent corrosion resistance according to the present invention will be explained.

In order to homogenize the main elements homogeneously distributed inside and improve hot rolling properties, an Al Cu-based aluminum alloy with a predetermined content and component ratio is ingot-formed using a normal DC casting method. A core material is obtained by homogenizing the material at a temperature of 1°C to 55°C for a sufficient period of time.

After casting, the skin material with the specified ingredients and composition ratio is subjected to homogenization heat treatment at a temperature of 400 to 600°C, and then hot rolled at 71J degrees at 30() to 50+1'C to form a specified plate. Processed thickly.

Next, layer the skin material on one or both sides of the core material and
It is reheated to a temperature of 550°C, hot rolled at a temperature of 300 to 550°C, and processed to a predetermined thickness.
At the same time, the core material and skin material are made into a hot 7-fiber structure.
Precipitates such as u, Mg, Zn, Si and Zr, Cr
, Mn, Ti, and other transition elements are partially released into the structure6.Furthermore, after this hot working, preferably 30% or more cold opening is performed to further improve the core material and skin material. A fine-grained material is obtained and the superplastic elongation is increased.

Next, after this hot working, a temperature of 350 to 550°C is applied.
Maintain heating for 5 to 20 hours, at least 30℃
/Hr or higher, particularly at a cooling rate of 100° C./Hr or higher to force solid solution of the solid solution elements.

In addition, this heat treatment was performed at a temperature of 400 to 55 tl'C using a continuous annealing furnace capable of continuous heating, 2, and rapid cooling.
It may be opened for 0 sec to 10 ml, and Cu, Mg, Zn, Si, etc. in the core material are dissolved in solid solution by this heating and holding.
On the other hand, the transition elements Zr, Cr, )iln, etc. are intermetallic compounds with Al, Z r A l h, CrJig+ALa
etc. are precipitated. In addition, ZrAl=, MnAl=, MnAl in the skin material
- etc. are precipitated. The heating rate after this first stage heating is 100℃
If it is less than /Hr, V&fine grains cannot be obtained and elongation becomes difficult.

When heating and holding is performed in two stages, first, 450 to s s
Perform the first heating and holding at a temperature of 0°C to 1OHr, then cool to the second heating and holding temperature,
A second heating and holding period is performed for 0.5 to 50 hours at a temperature of 350 to 450°C, and cooling is performed 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.

In such two heating and holding operations, most of the solute elements precipitated by the first heating and holding process are dissolved in solid solution, and the transition elements Zr and Cr are dissolved by the second heating and holding process.
, an intermetallic compound of Mn etc. and ＼I, ZrA l=, C
r2MR: +AL@ etc. are precipitated.

This two-stage heating and holding process is different from the case where the heating and holding process is performed once, because the precipitation form of transition elements is finer and some high temperature aging precipitates of Cu%tVIg, Zn, Si, etc. and A; Because of the formation of , a material with large superplastic elongation due to the formation of fine grains can be obtained.

The cooling rate after this two-stage heating and holding is 3+)'C/Hr
If it is less than that, it becomes difficult to obtain fine grains.

By such heating and holding, the dislocation substructure that had formed the hot fiber structure is recovered, the strain energy is reduced by recrystallization, and dislocations are easily introduced in the subsequent cold working, and Zr, Cr, Due to precipitated particles such as λ1n,
By heating in the superplastic temperature range after the next cold opening process,
Is it generated in the material? ! ! After cooling, at least 30% or more cold working is performed to maintain the 111tb structure and obtain superplasticity, but sufficiently fine grains cannot be obtained at a working rate of less than 30%.

Also, 20-60% cold working followed by 3()0℃
The following low-temperature softening annealing can be performed one or more times, and by introducing this low-temperature softening annealing, the crystal grains are further refined.

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

When this material is subsequently heated to a diffusion bonding temperature I&(400'C or higher for aluminum alloys) which is normally 0°5Ta+ (Tm is the melting point (absolute temperature) of the material) or higher (400'C or higher for aluminum alloys), the high-density dislocation structure in the material is new crystal grains are formed as The higher the dislocation density is, the finer the grain structure is obtained, and when anti-old crystallization is completed, dislocations move to reduce the energy of the grain boundaries, and the grains become coarser.
This coarsened structure inhibits superplastic deformation.

Therefore, the corrosion resistant f according to the present invention has a superior superφIJ1/
In the heat treatment in the J method of manufacturing aluminum alloys, Z r A l +, Cr:Mg)Al1 formed by one or two stages of heating and holding after hot working.
By controlling the size and distribution of precipitates such as n, MnAl1, etc., movement of dislocations is prevented and a 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 wide, the effect of inhibiting dislocation movement cannot be obtained. The material may be subjected to superplastic processing in the cold-worked state, but after cold-opening, the material may be heated at a heating rate of 00'C/Hr or more,
It may be softened at a temperature of 350-550'C to undergo superplastic deformation.

[Example 1] Examples of the Mlvii aluminum alloy method with excellent corrosion resistance according to the present invention will be explained.Example 1 Representative Al-Cu alloy core materials shown in Table 1 and pure,
＼11- for a while with the 1-series leather material, small F-shi in the second part! ! Due to the double-striped nature of the final board 1!72, 5m11I ÷
((11 sides hollowed out/total ratio 3%) was manufactured.

The superplastic properties are shown in 3&.

In addition, as a comparative material, a test was conducted using a material produced by a normal process.

Example 2 Using the sample material B of Example 1 (plate 1! 72.5 mm 1) and a plate material (cladding ratio 0%) of 2.5 vn of the No. I alloy of the first nozzle by a normal process, A corrosion resistance test was conducted.

The results are shown in Table 4.

This Example 1 (more clearly from Example 2) shows that the elongation of the aluminum alloy produced by the method for producing a highly malleable aluminum alloy according to the present invention is This is approximately three times as high as that of the comparative example, and it is also found to have excellent stress corrosion resistance, f!l! cracking resistance, intergranular corrosion resistance, and exfoliation corrosion resistance, indicating extremely excellent corrosion resistance.

[Effect of the invention 1 As explained above, the M plastic aluminum alloy with excellent corrosion resistance according to the present invention! Since the method has the above-mentioned structure, it has the effect of being able to produce an aluminum alloy with very high elongation and excellent corrosion resistance.

Claims (2)

[Claims] (1) Contains Cu2-7wt%, and further contains Mg2.5wt% or less, Si2.0wt% or less, Mn0
．． 05-2.0wt%, Cr0.05-0.5wt%,
Zr0.05~0.5wt%, V0.05~0.5wt
%, Ti or less than 0.15 wt%, and the balance is Al and impurities. M
g0.05wt% or less, Mn0.05-1.0wt%,
Cr0.05~0.25wt%, Zr0.05~0.2
Pure Al- containing one or more selected from 0wt%Ti0.15wt% or less, the balance being Al and impurities, is used as a skin material, and after hot rolling to form a cladding material on one or both sides. , perform one or two stages of heating and holding at a temperature of 350 to 550°C, cool at a cooling rate of 30°C/Hr or more, and then cold-roll at least 30% or 20 to 60%. 1. A method for producing a superplastic aluminum alloy with excellent corrosion resistance, which comprises performing cold rolling one or more times. (2) Contains 2 to 7 wt% of Cu, and further contains 2.5 wt% or less of Mg, 2 wt% or less of Si, and 0.0 Mn.
5-2.0wt%, Cr0.05-0.5wt%, Zr
0.05-0.5wt%, V0.05-0.5wt%,
The core material is an Al-Cu alloy containing one or more selected from Ti0.15wt% or less, the balance being Al and impurities, Cu0.10wt% or less, Zn0.2wt% or less, Mg
0.05wt% or less, Mn0.05-1.0wt%, C
r0.05~0.25wt%, Zr0.05~0.20
wt%, Ti containing one or more selected from 0.15wt% or less, with the remainder being Al and impurities as a skin material, and after hot rolling to form a cladding material on one or both sides. , carry out one or two stages of heating and holding at a temperature of 350 to 550°C, cool at a cooling rate of 30°C/Hr, and then cold-roll at least 30% or 20 to 60%. Cold rolling is performed one or more times, and then heated at a rate of 100°C/Hr or higher to a temperature of 350 to 5
A method for producing a superplastic aluminum alloy with excellent corrosion resistance, characterized by carrying out a heat softening treatment at a temperature of 50°C.