JP7471499B1 - Aluminum alloy clad material - Google Patents

Abstract

[Problem] To provide an aluminum alloy clad material excellent in strength and formability with suppressed formation of giant intermetallic compounds. [Solution] The aluminum alloy clad material has a composition containing, by mass%, 0.7-1.7% Mn, 0.5-1.7% Si, 0.1-1.2% Cu, 0.2-0.8% Fe, 0.05-1.1% Zn, with the remainder being Al and unavoidable impurities, the component contents in the composition satisfying the relational expression [%Mn] + [%Fe] + |(1-[%Si])/[%Si]|≦2.6, and has a grain size of 100 nm to 50 The core material has a distribution density of 1.0 x 106 to 5.0 x 106 dispersed particles of 0 nm distributed per 1 mm2, and compounds of 200 μm or more distributed at 1 particle or less per 10 mm2, and is laminated with a skin material made of a brazing material or a sacrificial material. The tensile strength is 150 MPa to 250 MPa, and the average rave calculated from r values measured from directions of 0°, 45°, and 90° to the rolling direction is 0.6 or more. [Selected Figure] None

Description

This invention relates to an aluminum alloy clad material that has high strength and excellent formability.

It is known that aluminum alloy clad materials used in heat exchangers contain Mn, Si, Cu, and Fe in the core material in order to increase the strength.
For example, Patent Document 1 provides an aluminum alloy brazing sheet for heat exchangers that contains appropriate amounts of Si, Mn, and Fe, and is said to have high strength, excellent corrosion resistance, and bending fatigue properties.

JP 2006-152325 A

However, it is known that when the core material of an aluminum alloy clad material contains a large amount of Mn, Si, Cu, or Fe, a large amount of giant intermetallic compounds (e.g., 200 μm or more in diameter) is generated during casting. When a large amount of such compounds is generated, the distribution density of fine dispersed particles decreases, and the strengthening function of the material decreases. In addition, the presence of giant intermetallic compounds can reduce durability by acting as the starting point of destruction, and also deteriorate formability because cracks and fissures originating from the compounds are generated during forming.
For use as a wrought material, it is desirable to produce it in such a way that the formation of large intermetallic compounds is prevented from occurring from the viewpoints of the components and manufacturing process.
In addition, when a large amount of elements is added to increase the strength, the elongation generally decreases and the anisotropy of the sheet material increases, which reduces formability and makes it difficult to obtain products with the desired shape. For this reason, it is considered difficult to achieve both high strength and formability in a sheet material.
The present invention has been made in light of the above circumstances, and has an object to provide an aluminum alloy clad material in which the formation of large intermetallic compounds is suppressed, and which has high strength and excellent formability.

That is, the first embodiment of the aluminum alloy of the present invention is as follows:
On one or both sides of the core material made of an aluminum alloy,
Si: 2.0 to 13.0%; Fe: 0.8% or less;
Zn: 5.0% or less,
Cu: 1.0% or less,
Mn: 2.0% or less,
Cr: 0.50% or less,
Zr: 0.30% or less,
Ti: 0.30% or less,
Ni: 1.5% or less,
Mg: 2.0% or less,
Sr: 0.2% or less,
Na: 0.2% or less,
V: 0.2% or less,
Bi: 1.0% or less,
A brazing material containing one or more of Sb: 1.0% or less and Sn: 1.0% or less, with the remainder being Al and unavoidable impurities, or/and, in mass%,
Si: 1.5% or less,
Fe: 0.8% or less,
Zn: 0.4 to 10.0%
Cu: 1.0% or less,
Mn: 2.0% or less,
Cr: 0.50% or less,
Zr: 0.30% or less,
Ti: 0.30% or less,
Ni: 1.5% or less,
Mg: 3.0% or less,
Sr: 0.2% or less,
Na: 0.2% or less,
V: 0.2% or less,
Bi: 1.0% or less,
Sb: 1.0% or less, and Sn: 1.0% or less,
and the remainder being composed of Al and unavoidable impurities. One or more skin materials are laminated, the clad ratio of the core material being 60 to 97%, and the thickness of the clad material being 0.5 mm to 3.5 mm,
The core material comprises, in mass %,
Mn: 0.7 to 1.7%,
Si: 0.5 to 1.7%,
Cu: 0.1 to 1.2%,
Fe: 0.1 to 0.8%,
Zn: 0.05 to 1.1%,
The remainder is composed of Al and unavoidable impurities,
The component contents in the composition satisfy the relational expression [%Mn] + [%Fe] + | (1 - [%Si]) / [%Si] | ≦ 2.6,
The distribution density of dispersed particles of 100 nm to 500 nm is 1.0 x 10 ⁶ to 5.0 x 10 ⁶ per mm ² , and compounds of 200 μm or more are distributed at 1 particle or less per 10 mm ² ,
The aluminum alloy clad material has a tensile strength of 150 MPa to 250 MPa, and an average r _ave calculated from r values measured in the 0°, 45°, and 90° directions relative to the rolling direction of 0.6 or more.
Characterized by

Another aspect of the invention of the aluminum alloy is the above-mentioned aspect of the invention,
The composition of the core material further comprises:
In mass percent,
Cr: 0.01 to 0.30%,
Zr: 0.01 to 0.30%,
Ti: 0.01-0.30%, and Mg: 0.1-1.2%,
Contains one or more of the following.

In another embodiment of the aluminum alloy, in the above-described embodiment, only the brazing material is laminated as the skin material, and the brazing material/core material is laminated in that order on one or both sides of the core material.

In another form of the aluminum alloy invention, in the above-mentioned form of the invention, the brazing material and the sacrificial material are laminated as the skin material, and the brazing material/core material/sacrificial material are laminated in this order on both sides of the core material.

The reasons for specifying the compositional components and other items specified in this invention are explained below.

(Heart Composition)
The formation of giant intermetallic compounds is suppressed by optimizing the balance of each element added. The following contents are all shown in mass%.

Mn: 0.7 to 1.7%
The inclusion of Mn improves the strength of the material through solid solution strengthening and precipitation as intermetallic compounds such as Al-Mn, Al-Mn-Si, Al-Mn-Fe, and Al-Mn-Fe-Si. If the Mn content is too low, the desired strength improvement effect cannot be obtained. On the other hand, if the content is excessive, giant intermetallic compounds are generated during casting, reducing manufacturability. For this reason, the lower limit of the Mn content is set to 0.7% and the upper limit to 1.7%.
For the same reason, it is preferable to set the upper limit at 1.5% and the lower limit at 0.8%.

Si: 0.5 to 1.7%
The inclusion of Si improves the material strength through solid solution strengthening and dispersion strengthening in which Si precipitates as intermetallic compounds such as Al--Mn--Si and Al--Mn--Fe--Si.
If the Si content is too low, the desired strength improvement effect cannot be obtained. On the other hand, if the content is too high, large intermetallic compounds are generated during casting, which reduces manufacturability. For this reason, the lower limit of the Si content is set to 0.5% and the upper limit is set to 1.7%.
For the same reason, it is preferable to set the upper limit at 1.6% and the lower limit at 0.6%.

Cu: 0.1 to 1.2%
The inclusion of Cu improves the strength of the material through solid solution strengthening. In addition, by adding Cu together with Zn, it contributes to improving elongation and formability. If the Cu content is too low, the desired strength improvement effect cannot be obtained. On the other hand, if the content is excessive, cracks are likely to occur during casting. For this reason, the lower limit of the Cu content is set to 0.1% and the upper limit to 1.2%.
For the same reason, it is preferable to set the upper limit at 0.9% and the lower limit at 0.15%.

Fe: 0.1 to 0.8%
The inclusion of Fe causes the alloy to precipitate as intermetallic compounds, mainly Al-Fe, Al-Fe-Si, Al-Mn-Fe, and Al-Mn-Fe-Si compounds, thereby improving the strength of the alloy.
Since Fe exists as an impurity in the raw material, if it is contained below the lower limit, it will be costly. In addition, the desired strength improvement effect will not be obtained. On the other hand, if it is contained in excess, giant intermetallic compounds will be generated during casting, reducing manufacturability. For this reason, the lower limit of the Fe content is set to 0.1% and the upper limit to 0.8%.
For the same reasons, the upper limit is preferably set at 0.65% and the lower limit at 0.20%, and more preferably the lower limit is set at 0.25%.

Zn: 0.05 to 1.1%
The inclusion of Zn improves strength and formability by refining crystal grains. In addition, adding Zn together with Cu improves elongation and contributes to improving formability. If the content is less than the lower limit, the desired effect cannot be obtained. On the other hand, if the content is excessive, the effect on formability is small, but the self-corrosion rate increases, thereby decreasing corrosion resistance. For this reason, it is preferable to set the lower limit of the Zn content to 0.05% and the upper limit to 1.1%.
For the same reason, it is preferable to set the upper limit at 1.0% and the lower limit at 0.35%.

Ti, Zr, Cr: 0.01 to 0.30%
These components improve the strength of the material by solid solution strengthening and dispersion strengthening due to precipitation as intermetallic compounds, so one or more of them may be contained as desired.
If the content of these elements is too small, the desired strength improvement effect cannot be obtained. On the other hand, if the content is excessive, large intermetallic compounds are generated during casting, and manufacturability is reduced. Therefore, the lower limit of the content of these elements is set to 0.01% and the upper limit is set to 0.30%.
For the same reason, it is preferable to set the upper limit of the Ti and Zr contents at 0.1% and the lower limit at 0.05%.
The upper limit of the Cr content is preferably 0.08% and the lower limit is preferably 0.05%. Even if these elements are not added, any of the elements may be contained as an inevitable impurity, and in that case, each of them is preferably less than 0.01%.

Mg: 0.1 to 1.2%
The inclusion of Mg improves the strength of the material by providing solid solution strengthening and aging precipitation ability as an Mg--Si based intermetallic compound, and therefore Mg is added as desired.
If the Mg content is too low, the desired strength improvement effect cannot be obtained. On the other hand, if the Mg content is excessive, cracks are likely to occur during hot rolling, and manufacturability is reduced. Therefore, when Mg is contained, the lower limit is set to 0.1% and the upper limit is set to 1.2%.
For the same reason, it is preferable to set the upper limit at 1.0% and the lower limit at 0.4%.
Even if Mg is not added, Mg may be contained as an inevitable impurity, and in that case, the Mg content is preferably 0.05% or less.

Component content [%Mn] + [%Fe] + |(1-[%Si])/[%Si]|≦2.6
By satisfying these relations, the formation of giant intermetallic compounds is suppressed. If these relations are not satisfied, it becomes difficult to suppress the formation of giant intermetallic compounds, regardless of the conditions of the production method and the like.
The above-mentioned relational expression is a relationship between the component content and the number of compounds having a diameter of 200 μm or more per unit area, which is determined by a regression analysis of the correspondence between the number of compounds having a diameter of 200 μm or more present in the manufactured alloy and the amounts of Mn, Fe, and Si added, and by satisfying the above-mentioned relational expression, the number of compounds having a diameter of 200 μm or more can be reduced to 1 or less per 10 mm ^2. If the above-mentioned relational expression is not satisfied, it becomes difficult to reduce the number of the giant compounds to 1 or less per 10 mm ² .

(Heartwood characteristics)
The distribution density of the dispersed particles of 100 nm to 500 nm is 1.0 x 10 ⁶ to 5.0 x 10 ⁶ per mm ^2. In order to obtain the desired tensile strength after annealing, it is necessary to adjust the distribution state of the intermetallic compounds. If the particle size of the intermetallic compounds is less than 100 nm or more than 500 nm, the desired strength cannot be obtained, so we focused on dispersed particles of 100 nm to 500 nm. If the dispersion density of these dispersed particles is less than 1.0 x 10 ⁶ or more than 5.0 x 10 ⁶ , the desired strength cannot be obtained.

Compounds with a size of 200 μm or more are one or less per ¹⁰ mm2. If these compounds are present, they may cause surface peeling or breakage during rolling, resulting in a decrease in rollability. In addition, these large compounds may act as starting points to promote destruction during part molding or product specification.

(Clad material characteristics)
Tensile strength: 150MPa to 250MPa
After annealing, the tensile strength is preferably in the above range. If the strength is less than 150 MPa, the structural strength after forming cannot be maintained. On the other hand, if the tensile strength is more than 250 MPa, cracks may occur during forming.

The average value r _ave calculated from the r values (Lankford value) measured from the 0°, 45°, and 90° directions relative to the rolling direction is 0.6 or more. The r value is preferably 0.6 or more. r _ave is measured at room temperature and calculated by the following formula based on the r values (r0°, r45°, r90°) measured at 0°, 45°, and 90° at a strain amount of minus 0.5% from the strain amount (uniform elongation) at which tensile strength is obtained.
r _ave = (r0° + r90° + 2 * r45°) / 4
If r _ave is less than 0.6, the anisotropy becomes high, the press formability decreases, and cracks and the like tend to occur.

(Layer structure of clad material)
The clad material has one or more skin materials, which are skin materials or sacrificial materials, laminated on one or both sides of the core material.
Although there are no particular limitations on the cladding ratio of each layer of the cladding material, it is desirable for the cladding ratio of the core material to be in the range of 60 to 97%.
The skin material is selected from a brazing material and a sacrificial material. The lamination structure is not particularly limited, but examples thereof include an aluminum alloy clad material laminated in the order of brazing material/core material, an aluminum alloy clad material laminated in the order of brazing material/core material/brazing material, an aluminum alloy clad material laminated in the order of brazing material/core material/sacrificial material, an aluminum alloy clad material laminated in the order of brazing material/core material/sacrificial material/brazing material, an aluminum alloy clad material laminated in the order of brazing material/sacrificial material/core material/sacrificial material/brazing material, an aluminum alloy clad material laminated in the order of sacrificial material/core material, an aluminum alloy clad material laminated in the order of sacrificial material/core material, and an aluminum alloy clad material laminated in the order of sacrificial material/core material.

Brazing filler metal type: The core material can be bonded with Al-Si alloys, which are common brazing filler metals used as skin materials, as well as brazing filler metals containing various elements. The contribution of the brazing filler metal to the overall strength of the clad material is small, but if the brazing filler metal contains an element that has a particularly large effect on improving strength, the strength of the entire clad material can be adjusted by taking into account its influence.

The strength of the entire clad material can be calculated by dividing the strength of each layer by the clad ratio as shown in the formula below.
Overall strength of clad material = (strength of skin material alone x skin clad ratio) + (strength of core material alone x core clad ratio)

Furthermore, among the elements optionally contained in the brazing filler metal, Mg, Mn, Cu, and Fe can be cited as elements that easily contribute to the strength of the brazing filler metal alone. The effect of each of these on the strength of the brazing filler metal alone is as follows:
[Tensile strength]
Contains Mg: 5 MPa/0.1%, Mn: 2 MPa/0.1%, Cu: 5 MPa/0.1%, Fe: 2 MPa/0.1%.

On the other hand, the formability of the entire clad material is such that the formability of the skin material is greater than that of the core material, so it is basically determined by the formability of the core material, i.e., its chemical composition and metal structure.

(Brazing composition)
The components contained in the brazing material are not limited to specific ones, but the following are typical examples of the components.

Si: 2.0 to 13.0%
It lowers the melting point and produces a liquid phase at the brazing temperature, making brazing possible.
Below the lower limit, the amount of liquid phase generated is small, resulting in poor brazing, whereas above the upper limit, erosion occurs due to excess Si.

Fe: 0.8% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are generated, making production difficult.

Zn: 5.0% or less May be contained (may be 0%). Contains when it is desired for the brazing material to function as a corrosion protection layer for the core material. When contained, the potential becomes less noble and acts as a sacrificial anode for the core material. If the upper limit is exceeded, the corrosion rate becomes too fast.

Cu: 1.0% or less May be contained (may be 0%). If the content exceeds the upper limit, the material becomes hard and manufacturing becomes difficult.

Mn: 2.0% or less May be contained (may be 0%). If the content exceeds the upper limit, huge compounds are formed, making production difficult.

Cr: 0.50% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are formed, making production difficult.

Zr: 0.30% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are formed, making production difficult.

Ti: 0.30% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are formed, making production difficult.

Ni: 1.5% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are formed, making production difficult.

Mg: 2.0% or less May be contained (may be 0%). Contains when used for vacuum brazing, etc. If the content exceeds the upper limit, the material becomes hard and manufacturing becomes difficult.

Sr: 0.2% or less May be contained (may be 0%).

Na: 0.2% or less May be contained (may be 0%).

V: 0.2% or less May be contained (may be 0%).

Bi: 1.0% or less May be contained (may be 0%).

Sb: 1.0% or less May be contained (may be 0%).

Sn: 1.0% or less May be contained (may be 0%).

(Sacrificial material composition)
The core material may be clad with a sacrificial material having a lower electrical potential than the core material as a skin material.
In addition to the common sacrificial material Al-Zn alloy, sacrificial materials containing various elements can be bonded to the clad material. Although the contribution of the sacrificial material to the overall strength of the clad material is small, when the sacrificial material contains an element that has a particularly large effect of improving strength, the strength of the entire clad material can be adjusted by taking into account the effect of the element.

The strength of the entire clad material can be calculated by dividing the strength of each layer by the clad ratio as shown in the formula below.
Overall strength of clad material = (strength of skin material alone x skin clad ratio) + (strength of core material alone x core clad ratio)

Furthermore, among the elements optionally contained in the sacrificial material, Mg, Mn, Si, Cu, and Fe can be cited as elements that easily contribute to the strength of the sacrificial material alone. The effect of each of these on the strength of the sacrificial material alone is as follows:
[Tensile strength]
Contains Mg: 5 MPa/0.1%, Mn: 2 MPa/0.1%, Si: 5 MPa/0.1%, Cu: 5 MPa/0.1%, Fe: 2 MPa/0.1%.

The formability of the entire clad material, like that of brazing filler metal, is determined by the formability of the skin material > that of the core material, and is therefore essentially determined by the formability of the core material, i.e., its chemical composition and metal structure.

(Sacrificial material composition)
The components contained in the sacrificial material are not limited to any particular ones, but the following are representative examples of the components.

Si: 1.5% or less May be contained (may be 0%). If the content exceeds the upper limit, the melting point decreases and local melting occurs.

Fe: 0.8% or less May be contained (may be 0%).

Zn: 0.4 to 10.0%
It may be contained (it may be 0%). It is contained to obtain a sacrificial anode effect on the core material by making the potential baser. Below the lower limit, the effect is small, while above the upper limit, the corrosion rate becomes too fast and the sacrificial material is consumed early, so the sacrificial anode effect cannot be exerted for a long period of time.

Cu: 1.0% or less May be contained (may be 0%). If the content exceeds the upper limit, the material becomes hard and manufacturing becomes difficult.

Mn: 2.0% or less May be contained (may be 0%). If the content exceeds the upper limit, huge compounds are formed, making production difficult.

Cr: 0.50% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are generated, making production difficult.

Zr: 0.30% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are formed, making production difficult.

Ti: 0.30% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are formed, making production difficult.

Ni: 1.5% or less May be contained (may be 0%). If the content exceeds the upper limit, giant compounds are formed, making production difficult.

Mg: 3.0% or less May be contained (may be 0%). Contains when used for vacuum brazing, etc. If the content exceeds the upper limit, the material becomes hard and manufacturing becomes difficult.

Sr: 0.2% or less May be contained (may be 0%).

Na: 0.2% or less May be contained (may be 0%).

V: 0.2% or less May be contained (may be 0%).

Bi: 1.0% or less May be contained (may be 0%).

Sb: 1.0% or less May be contained (may be 0%).

Sn: 1.0% or less May be contained (may be 0%).

The present invention makes it possible to obtain clad materials with high strength and excellent formability.

[Creating core material]
[Core composition]
The aluminum alloy for the core material is prepared to contain, by mass%, 0.7-1.7% Mn, 0.5-1.7% Si, 0.1-1.2% Cu, 0.1-0.8% Fe, 0.05-1.1% Zn, and optionally one or more of 0.01-0.30% Cr, 0.01-0.30% Zr, 0.01-0.30% Ti, and 0.1-1.2% Mg, with the remainder being Al and unavoidable impurities. The component contents of the composition are adjusted to satisfy the relational expression: [%Mn] + [%Fe] + |(1-[%Si])/[%Si]|≦2.6.

[casting]
The aluminum alloy having the above composition is produced by melting, for example, by semi-continuous casting.
When casting is performed at a normal casting speed, Al-Mn-Fe compounds grow between the start of casting and solidification, and large intermetallic compounds of 200 μm or more tend to form. To prevent this, it is desirable to perform the cooling rate of the alloy at 640°C to 670°C during casting at a rate of 0.1°C/s to 10°C/s. This makes it possible to effectively prevent the formation of large intermetallic compounds of 200 μm or more. Note that 640°C to 670°C is the temperature at which the above compounds grow.
If the cooling rate is less than 0.1°C/sec, giant intermetallic compounds are likely to be generated. If the cooling rate is 10°C/sec or more, the generation of giant intermetallic compounds is effectively suppressed, but the susceptibility to cracking increases and manufacturability decreases. More preferably, the cooling rate in the above temperature range is 0.5°C/sec to 5°C/sec.

[Homogenization treatment]
The resulting alloy may be subjected to a homogenization treatment.
In the homogenization treatment, the obtained alloy can be subjected to homogenization treatment at a temperature of 400°C to less than 600°C and for a treatment time of 3 to less than 12 hours. This results in a finely dispersed state of intermetallic compounds with a circle equivalent diameter of about 100 nm to 500 nm, which is suitable for obtaining the desired characteristics. If conditions other than the above temperature and treatment time are applied, the desired distribution state of intermetallic compounds cannot be obtained, and the strength decreases. In addition, at 600°C or higher, there is a risk that the material will melt during the homogenization treatment. A more preferable temperature is 420°C to 580°C.

"Hot rolling"
Separately, the brazing alloy and the sacrificial alloy are cast and hot rolled to a predetermined thickness in a conventional manner, and then laminated with a core ingot and hot rolled to produce a clad material.
The brazing alloy contains, by mass%, 2.0 to 13.0% Si, and further contains
Fe: 0.8% or less, Zn: 5.0% or less, Cu: 1.0% or less, Mn: 2.0% or less,
An example of a composition containing Cr: 0.50% or less, Zr: 0.30% or less, Ti: 0.30% or less, Ni: 1.5% or less, Mg: 2.0% or less, Sr: 0.2% or less, Na: 0.2% or less, V: 0.2% or less, Bi: 1.0% or less, Sb: 1.0% or less, Sn: 1.0% or less, with the remainder being Al and unavoidable impurities. Each component other than Si may be 0%.
The aluminum alloy for the sacrificial material may be, by mass%, Si: 1.5% or less, Fe: 0.8% or less, Zn: 0.4 to 10.0%, Cu: 1.0% or less, Mn: 2.0% or less, Cr: 0.50% or less, Zr: 0.30% or less, Ti: 0.30% or less, Ni: 1.5% or less, Mg: 3.0% or less, Sr: 0.2% or less, Na: 0.2% or less, V: 0.2% or less, Bi: 1.0% or less, Sb: 1.0% or less, Sn: 1.0% or less, with the remainder being Al and unavoidable impurities. Each component may be 0%.

Here, it is preferable that the soaking treatment before hot rolling of the clad material is performed at a temperature of 400°C to 550°C for 1 to 10 hours. At a temperature higher than this, the dispersed particles precipitated during the homogenization treatment are redissolved, and the material strength decreases. In addition, in order to crush the giant intermetallic compounds generated during casting during hot rolling, it is preferable to perform 15 or more passes of rolling so that the thickness of the exit side is reduced by 20 mm or more compared to the thickness of the entry side. In addition, by performing this condition, the crushed intermetallic compounds become about 1 μm in size, which effectively acts as a nucleation site, and the distribution state of the intermetallic compounds is optimized, thereby improving the r value of the plate material.
If the reduction amount or number of passes is less than this, the large intermetallic compounds formed during casting remain, and the subsequent manufacturability is reduced. On the other hand, a reduction amount of more than 30 mm is effective in crushing the large intermetallic compounds, but promotes cracks in the plate width direction, which reduces manufacturability. Therefore, it is more preferable to set the reduction amount per pass to 20 mm to 30 mm, and the number of passes to 15 or more.

"Cold rolling"
The aluminum alloy clad material that has been hot rolled can be cold rolled. Although not particularly specified, it is preferable to carry out the cold rolling at a rolling reduction rate per pass of 10 to 40%. Outside this range, manufacturability decreases.

"Annealing during rolling"
It may be performed during cold rolling to continue the cold rolling. It can be performed in a batch annealing furnace at a temperature increase rate of 30 to 70°C/hour at 200 to 450°C for a treatment time of 3 to 10 hours. If the temperature exceeds 450°C, secondary recrystallization may occur, resulting in non-uniform recrystallized grains.
Alternatively, a continuous annealing furnace (heating rate of 50° C./s or more, treatment temperature of 400° C. or more, treatment time of 60 s, cooling rate of 200° C./s or less) may be used.

"Final plate thickness"
Although not particularly specified, a range of 0.5 mm to 3.5 mm is exemplified.

"Annealing"
The aluminum alloy clad material after the cold rolling can be subjected to final annealing, which can be performed in a batch annealing furnace at a temperature increase rate of 30 to 70° C./hour to 200 to 400° C. for a treatment time of 3 to 10 hours.
Furthermore, when a continuous annealing furnace (heating rate of 50°C/s or more, treatment temperature of 400°C or more, treatment time of 60 s, cooling rate of 200°C/s or less) is used, the crystal grains after annealing become finer, thereby improving the strength and formability.
If necessary, final rolling may be performed after annealing in the range of 10 to 40%.
In the above description, final annealing is performed after cold rolling. However, in this embodiment, final annealing is not performed after cold rolling, and the steel sheet can be used in its as-rolled state.

In the aluminum alloy clad material that has undergone the above-mentioned process, the distribution density of dispersed particles of 100 ^nm to 500 nm in the core material is 1.0 x ¹⁰ to 5.0 x ¹⁰ per mm2, and compounds of 200 μm or more are distributed at 1 particle or less per ¹⁰ mm2.

In addition, the aluminum alloy clad material after production, after annealing or as rolled, has a tensile strength of 150 MPa to 250 MPa, and an average value r _ave calculated from r values measured in directions of 0°, 45°, and 90° with respect to the rolling direction of 0.6 or more.
The aluminum alloy of the present invention is not limited to a specific application, but can be suitably used, for example, as a plate material for a heat exchanger.

The aluminum alloys for the core material (the balance being Al and unavoidable impurities) shown in Table 1 were prepared. The calculated values in the relational expression [%Mn] + [%Fe] + |(1-[%Si])/[%Si]| for each composition are shown in Table 1.
The casting method for this alloy was semi-continuous casting, and when the aluminum alloy object temperature passed through 640°C to 670°C, the cooling rate was controlled to a range of 0.5°C to 5.0°C/sec by adjusting the appropriate casting speed and cooling water amount. For cooling rates below 640°C, casting was performed at a normal casting speed. In Table 5, those in which the cooling rate was controlled to a range of 0.5°C to 5.0°C/sec in the range of 640°C to 670°C are indicated with ●, and those in which the cooling rate was controlled to less than 0.5°C/sec are indicated with △.

The brazing alloys shown in Table 2 and the sacrificial alloys shown in Table 3 were similarly produced by semi-continuous casting. The brazing alloys and the sacrificial alloys were cast under normal conditions. The brazing alloys and the sacrificial alloys were adjusted in thickness by hot rolling to have the clad ratios shown in Table 4, and then combined with the core alloys and hot rolled to produce clad materials.

The core alloy ingot was homogenized under the conditions shown in Table 5, and then combined with the brazing alloy and the sacrificial alloy as described above, and soaked at 500°C for 1 hour, and then hot rolled. The hot rolling conditions (number of passes when rolling with a reduction of 20 mm to 30 mm) are shown in Table 5.
The thickness of the hot rolled material was 8.0 mm, and then cold rolling was performed to obtain a cold rolled material with a plate thickness of 0.8 mm. For test material No. 21, intermediate annealing was performed during cold rolling. After hot rolling, the material was rolled to 3.0 mm by cold rolling, and then heat treatment was performed at 350 ° C. for 4 hours as intermediate annealing conditions. Then, a cold rolled material with a plate thickness of 0.8 mm was obtained by cold rolling.
After cold rolling to 0.8 mm, the material was subjected to final annealing at 350° C. for 3 hours (quality O material).
For some samples (Nos. 31 and 32), the final annealing was performed just before 0.8 mm, and samples were also prepared in which the thickness was reduced to 0.8 mm so as to achieve the specified cold rolling reduction (H-grade materials with final rolling reductions of 15% and 30%, respectively).

"Distribution of compounds"
Confirmation of compounds with a size of 200 μm or more The cross section of the produced aluminum alloy parallel to the rolling direction was mechanically polished, and the intermetallic compounds were observed with an optical microscope. Ten fields of view with an area of 0.35 ^mm2 were observed with an optical microscope at a magnification of ×100, and the circle equivalent diameter and distribution amount of the particles of the intermetallic compounds were calculated from 10 images obtained using image analysis software (e.g., ImageJ, developed by Wayne Rasband), and the results are shown in Table 5.

Confirmation of 100-500 nm compounds As described above, a cross section parallel to the rolling direction was subjected to cross-section polishing, and a field emission scanning electron microscope (FE-SEM; JSM-7900F manufactured by JEOL Ltd.) was used to observe secondary electron images at a magnification of 30,000 times in 10 fields of view with an area of ¹² μm2, and 10 images were obtained. From the obtained images, the circle equivalent diameter and distribution amount of the particles of the intermetallic compound were calculated using image analysis software, and are shown in Table 5.

[Tensile strength]
Tensile test No. 5 test pieces were taken parallel to the rolling direction according to the method of JIS Z2241, and the tensile strength was measured. The tensile strength was evaluated as follows: less than 140 MPa x, 140 MPa or more but less than 180 MPa ◯, and 180 MPa or more ◎. The results are shown in Table 5.

[Average r value]
The r-value was measured at a strain of minus 0.5% from the strain (uniform elongation) at which the tensile strength was obtained. The measurement method of the r-value was in accordance with the usual method. The direction parallel to the rolling direction was set as 0°, and r0° was measured. Similarly, r45° from the 45° direction and r90° from the 90° direction were measured.
The average r value was calculated as (r0° + r90° + 2*r45°)/4, and absolute values of 0.6 or greater and less than 0.7 were evaluated as O, values of 0.7 or greater were evaluated as ◎, and values less than 0.6 were evaluated as ×. The calculated values and evaluations are shown in Table 5.

[Moldability evaluation]
To evaluate formability, press molding was performed, taking into account punching and bending. Parts with particularly excellent dimensional accuracy were rated A, parts that met the standards otherwise were rated B as pass, and parts that were not excellent were rated C as fail. The results are shown in Table 5.

Claims (4)

On one or both sides of the core material made of an aluminum alloy,
Si: 2.0 to 13.0%; Fe: 0.8% or less;
Zn: 5.0% or less,
Cu: 1.0% or less,
Mn: 2.0% or less,
Cr: 0.50% or less,
Zr: 0.30% or less,
Ti: 0.30% or less,
Ni: 1.5% or less,
Mg: 2.0% or less,
Sr: 0.2% or less,
Na: 0.2% or less,
V: 0.2% or less,
Bi: 1.0% or less,
A brazing material containing one or more of Sb: 1.0% or less and Sn: 1.0% or less, with the remainder being Al and unavoidable impurities, or/and, in mass%,
Si: 1.5% or less,
Fe: 0.8% or less,
Zn: 0.4 to 10.0%
Cu: 1.0% or less,
Mn: 2.0% or less,
Cr: 0.50% or less,
Zr: 0.30% or less,
Ti: 0.30% or less,
Ni: 1.5% or less,
Mg: 3.0% or less,
Sr: 0.2% or less,
Na: 0.2% or less,
V: 0.2% or less,
Bi: 1.0% or less,
Sb: 1.0% or less, and Sn: 1.0% or less,
and the remainder being composed of Al and unavoidable impurities. One or more skin materials are laminated, the clad ratio of the core material being 60 to 97%, and the thickness of the clad material being 0.5 mm to 3.5 mm,
The core material comprises, in mass %,
Mn: 0.7 to 1.7%,
Si: 0.5 to 1.7%,
Cu: 0.1 to 1.2%,
Fe: 0.1 to 0.8%,
Zn: 0.05 to 1.1%,
The remainder is composed of Al and unavoidable impurities,
The component contents in the composition satisfy the relational expression [%Mn] + [%Fe] + | (1 - [%Si]) / [%Si] | ≦ 2.6,
The distribution density of dispersed particles of 100 nm to 500 nm is 1.0 x 10 ⁶ to 5.0 x 10 ⁶ per mm ² , and compounds of 200 μm or more are distributed at 1 particle or less per 10 mm ² ,
The aluminum alloy clad material has a tensile strength of 150 MPa to 250 MPa, and an average r _ave calculated from r values measured in the 0°, 45°, and 90° directions relative to the rolling direction of 0.6 or more.
1. An aluminum alloy clad material comprising: The composition of the core material further comprises:
In mass percent,
Cr: 0.01 to 0.30%,
Zr: 0.01 to 0.30%,
Ti: 0.01-0.30%, and Mg: 0.1-1.2%,
The aluminum alloy clad material according to claim 1, which contains one or more of the following: The aluminum alloy clad material according to claim 1 or 2, in which only the brazing material is laminated as the skin material, and the brazing material/core material is laminated on one or both sides of the core material in this order. The aluminum alloy clad material according to claim 1 or 2, in which the brazing material and the sacrificial material are laminated as the skin material, and the brazing material/core material/sacrificial material are laminated on both sides of the core material in this order.