JPH08246117A - High strength aluminum brazing sheet and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Structure] Si: 0.05-0.80 wt%, Fe: 0.05-0.6 wt
%, Cu: 0.1-1.0 wt%, Mn: 0.6-1.6 wt%: Mg:
0.05-0.5wt%, Cr: 0.3wt% or less, Zr: 0.3wt%
Hereinafter, an aluminum alloy containing Ti: 0.3 wt% or less of one kind or two kinds or more, the balance being Al and unavoidable impurities is used as a core material, and an Al-Si alloy brazing material is provided on one surface,
In producing a high-strength brazing sheet made of a laminated material provided with an aluminum alloy material having a sacrificial effect on the other surface, the ingot is not subjected to homogenization treatment or at 500 ° C. or less. A method for producing a high-strength aluminum brazing sheet in which heating before hot rolling is performed at 500 ° C. or less, hot rolling, cold rolling / annealing is performed, and a final cold rolling rate is 20 to 80%. [Effect] This brazing sheet has high strength after brazing, excellent brazing properties, less diffusion of brazing due to brazing, and excellent corrosion resistance after being formed into a tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy brazing sheet and a method for producing the same, and more specifically, it may be a brazing sheet which is made into a tube by electric sewing or the like, or a brazing sheet used as a header material as it is. High strength after attachment,
(EN) A brazing sheet having excellent brazing properties, less diffusion of brazing due to brazing, and excellent corrosion resistance after forming a tube, and a method for producing the brazing sheet.

[0002]

2. Description of the Related Art A heat exchanger such as a radiator is shown in FIG.
As shown in FIG. 2, a corrugated thin fin (2) is integrally formed between a plurality of flat tubes (1), and both ends of the flat tubes (1) are a header (3) and a tank (4). Open to the space constituted by the above, and the high temperature refrigerant is sent from the space on the side of one tank through the inside of the flat tube (1) to the space on the side of the other tank (4), and the tubes (1) and fins (2) The refrigerant that has been heat-exchanged at the portion of and has become low in temperature is circulated again.

The tube material and the header material of such a heat exchanger have, for example, JIS3003 alloy as a core material, and as a lining material on the inside of the core material, that is, on the side which is constantly in contact with the refrigerant.
A JIS7072 alloy is used, and a brazing sheet in which a normal brazing material is clad is used on the outer side of the core material, and the brazing sheet is integrally assembled by brazing together with other members such as corrugated fins. Such a brazing sheet must satisfy the required properties of excellent brazing property, low diffusion of braze, and excellent corrosion resistance.

By the way, in recent years, heat exchangers have been in the direction of weight reduction and downsizing, and therefore, thinning of materials has been desired. However, when the conventional material is thinned, the thickness of the material is reduced, resulting in insufficient strength. Therefore, A
High strength alloys such as l-Mn-Cu alloys have been proposed.

[0005]

However, even with these, sufficient strength is not obtained. This is because the components of the high-strength alloy itself are restricted from the viewpoints of brazing property and corrosion resistance, and there is brazing that is heated to around 600 ° C as the final process of the product, so that the strength such as work hardening is improved. This is because the mechanism of is not available.

[0006]

In view of this, the present invention is a brazing sheet having high strength after brazing, excellent brazing property, less diffusion of brazing due to brazing, and excellent corrosion resistance after being formed into a tube. And (1) Si: 0.05-0.80 wt%, Fe:
0.05-0.6wt%, Cu: 0.1-1.0wt%, Mn: 0.6-1.6wt
%: Mg: 0.05-0.5 wt%, Cr: 0.3 wt% or less, Z
r: 0.3 wt% or less, Ti: 0.3 wt% or less, one or two or more types, with the balance being an aluminum alloy consisting of Al and unavoidable impurities as the core material, and an Al-Si alloy brazing material provided on one side In producing a high-strength brazing sheet made of a laminated material having an aluminum alloy material having a sacrificial effect on the other surface, the core material is not subjected to homogenization treatment of the ingot, or 500 ° C or less. The high-strength aluminum brazing is characterized in that heating before hot rolling is performed at 500 ° C. or lower, hot rolling, cold rolling and annealing are performed at a final cold rolling rate of 20 to 80%. Sheet manufacturing method, and (2) Si: 0.05-0.80 wt
%, Fe: 0.05-0.6 wt%, Cu: 0.1-1.0 wt%, Mn:
0.6-1.6 wt%: Mg: 0.05-0.5 wt%, Cr: 0.3w
An aluminum alloy containing one or more of t% or less, Zr: 0.3 wt% or less, and Ti: 0.3 wt% or less, and the balance being Al and inevitable impurities, the metal structure of which is 0.
02-0.2 μm intermetallic compound with number density of 10-2000
Aluminum alloy material containing particles / μm ³ as the core material
The present invention provides a high-strength aluminum brazing sheet characterized by comprising a laminated material having an l-Si alloy brazing material provided on one surface and an aluminum alloy material having a sacrificial effect on the other surface.

First, the structure of the brazing sheet of the present invention will be described. In the core material of brazing sheet,
Si in the alloy contributes to the strength improvement by two roles. One is to promote the precipitation of Mn, increase the amount of intermetallic compounds described later, and improve the strength. The other has a type of age hardening after brazing with Mg. For this reason Si
Is less than 0.05%, the above effect is not sufficient and 0.8
If it exceeds 0%, the diffusion of the brazing becomes large at the time of brazing heating, the brazing property is deteriorated, and the corrosion resistance of the tube is also deteriorated. Therefore, Si is 0.05% or more and 0.80
% Or less, but particularly 0.3 to 0.7% shows stable characteristics.

Fe forms an intermetallic compound with Mn and contributes to the improvement of strength. If the amount is less than 0.05%, the effect is not sufficient, and if it exceeds 0.6%, a large amount of coarse crystallized substances are generated during casting, and the recrystallized grain size of the core material during brazing heating becomes small, resulting in brazing. Sex decreases.

Cu exists in the alloy in a solid solution state and improves the strength. Further, it has the function of making the potential of the core material noble and improving the corrosion resistance. The function is not sufficient if Cu is less than 0.1%, and if added over 1.0%, the melting point of the alloy is lowered and the alloy is melted during brazing and heating.

Mn is an essential element for distributing the intermetallic compound, which is the main point of the present invention, in the alloy. If the amount is less than 0.6%, it is not sufficient, and if added in excess of 1.6%, the formability is deteriorated and the brazing sheet is cracked during processing such as assembly.

Mg is a solid solution in the alloy and Mg ₂ Si
Exists as a fine precipitation phase of and improves the strength. If the amount is less than 0.05%, it is not sufficient, and if added over 0.5%, when brazing using a non-corrosive flux, the flux reacts with Mg and brazing cannot be performed.

In the present invention, this alloy is further added with a value of 0.
3% or less of Cr, 0.3% or less of Zr, and 0.3% or less of Ti are added by one kind or two or more kinds. All of these elements have the function of forming a fine intermetallic compound and improving the strength of the alloy. However, if the content of each exceeds 0.3%, the formability is lowered and the brazing sheet is broken during processing such as assembly.

The alloy may be added with B for refining the ingot structure or Ni for the purpose of improving strength. The addition amount of each of these elements is preferably 0.05% or less.

The brazing sheet of the present invention contains a fine intermetallic compound of about 0.02 to 0.2 μm in a metal structure at a number density of about 10 to 2000 / μm ³ , and more preferably 100 to 1800. contains. This intermetallic compound has the following functions. First, the strength is improved by dispersion hardening. Further, the recrystallized grains generated during the brazing heating are made coarse and pancake-like to reduce the diffusion of the brazing material into the core material and improve the corrosion resistance of the core material. Then, the action of trapping the diffusing element at the interface of the particles has the action of preventing the composition of the core material from changing due to diffusion during brazing. The particles having the above-mentioned action are intermetallic compounds having a size of about 0.02 to 0.2 μm before the brazing heating, and particles smaller than that are dispersed because they are re-dissolved in the matrix during the brazing heating. It does not have the effect of hardening and the effect of preventing the diffusion of elements during brazing. Also,
Larger particles do not have the effect of dispersion hardening and also do not have the effect of making recrystallized grains, which occur during brazing heating, coarse and pancake-like. Therefore, in the present invention, 0.0
The characteristics are improved by distributing the intermetallic compound of 2 to 0.2 μm.

The intermetallic compound referred to here is measured by a transmission electron microscope, the particle diameter is the maximum diameter, and the number density is determined by correlating the film thickness of the observation part with the equal thickness interference fringes and the observation area. It is a thing. When the core material has dislocations and it is difficult to measure the particles, the measurement was performed after performing strain relief heating at 500 ° C. for about 10 s. This is because the particle distribution hardly changes even if such a measurement is performed. The core material used as a brazing sheet usually contains the above particles in an amount of less than 10 particles / μm ³ .

There is no particular limitation on the outer covering material, and a commonly used brazing material such as JIS 4004 or JIS 4045 may be used.
A typical example of the lining material is JIS7072 alloy, but the material is not limited to this. However, the potential of the lining material must be electrochemically base with respect to the core material. This is because, when pitting corrosion occurs in the lining material under the usage environment of the heat exchanger, it has an effect of preventing the pitting corrosion from spreading to the core material.

In the present invention, 1.5% of Mg is added to the above lining material.
It is preferable to add the following. This is to prevent the Mg contained in the core material from diffusing into the lining material and reducing the strength of the alloy.

The above is the brazing sheet of the present invention.

Next, the manufacturing process of the brazing sheet of the present invention will be described. As described above, the manufacturing process of the present invention is
It is a method for forming the distribution state of the intermetallic compound of the specific core material as described above, and the ingot is not subjected to homogenization treatment or is performed at 500 ° C. or lower, and heating before hot rolling is performed to 5
It is characterized in that the final cold rolling rate is 20 to 80% by performing hot rolling, cold rolling and annealing at a temperature of 00 ° C. or less.

The alloy ingot used in the present invention may be manufactured by a usual DC casting method. With conventional brazing sheets,
Homogenization treatment is performed on the ingot at a temperature of about 600 ° C., cooling is followed by chamfering, and an Al—Si alloy brazing material is clad on one surface and an aluminum alloy material having a sacrificial effect is clad on the other surface.
It was reheated to the hot rolling temperature (490 to 520 ° C.) and the combined rolling was performed. On the other hand, in the present invention, the ingot is not homogenized or, if it is performed, it is performed at 500 ° C or lower, and the heating before hot rolling is performed at 500 ° C or lower. The homogenization treatment and the heating before the hot rolling cause the solute element that is in a supersaturated solid solution in the ingot to precipitate. When the homogenizing treatment is not carried out, precipitation occurs due to heating in hot rolling, but if the heating temperature before hot rolling exceeds 500 ° C., the precipitated particles become coarse and the strength decreases. When performing homogenization treatment, the treatment temperature is 500
When the temperature exceeds ℃, the precipitated particles become coarse and the strength decreases, and when the heating temperature before hot rolling exceeds 500 ° C. thereafter, the precipitated particles become coarse and the strength decreases. Therefore, in the present invention, the ingot is not subjected to homogenization treatment, or 50
The heating is performed at 0 ° C. or lower, and the heating before hot rolling is performed at 500 ° C. or lower. The holding time in the case of performing the homogenization treatment is about 0.5 to 24 hours, and the holding time for heating before hot rolling is about 0 to 24 hours. The above are the conditions for the homogenization treatment and the heating before the hot rolling, but the chamfering and the matching may be performed during this period according to a conventional method, and there is no particular limitation.

Hot rolling may be carried out according to a conventional method,
The finished plate thickness is about 1.5 to 10 mm. After hot rolling, cold rolling and annealing are performed to obtain a predetermined product sheet thickness, and the final cold rolling rate is set to 20 to 80%. If the final cold rolling rate is less than 20% or more than 80%, the brazing material diffuses into the core material during brazing and the strength decreases.

Therefore, the final cold rolling rate is 20-80.
%, But the annealing at that time is performed batchwise, and the heating temperature is 450 ° C. or lower. Since annealing is performed in the presence of dislocations, diffusion progresses faster than homogenization treatment. Therefore, although fine particles are precipitated during annealing,
If the temperature exceeds 450 ° C., the particles become coarse. The holding time of annealing is about 0.5 to 6 hours.

As long as the condition of the final cold rolling rate is satisfied, the annealing may be performed twice or more during the cold rolling.

[0024]

Next, the present invention will be described in more detail with reference to examples. Using the aluminum alloy having the composition shown in Table 1 as the core material or the lining material, brazing sheets having the configurations shown in Tables 2 and 3 were produced. JIS 404 for outer covering (brazing material)
5 alloy is used and the clad ratio is 10% for both brazing material and lining material
Is. As shown in Tables 2 and 3, in the production, the brazing sheet is changed in homogenization treatment, annealing conditions and the like. Distributions of intermetallic compounds are shown in Tables 2 and 3.
The brazing sheet coil (plate thickness 0.25 mm) obtained was subjected to a brazing heating test, a corrosion resistance test, and a tensile test after brazing heating. First, the brazing heating test is the reverse T shown in FIG.
After the non-corrosive flux was applied to the joint, the joint was heated in N ₂ gas at 600 ° C. for 5 minutes. The brazing property is evaluated based on the appearance, and less than that based on the conventional material, x,
The results are shown in Table 4, with the equivalent or higher being designated as ◯.
Furthermore, the cross section of the brazing sheet was polished to examine the erosion condition of the brazing material (outer covering material). Based on conventional material (about 40μ
m) Less than that was evaluated as ◯, and more than that was evaluated as x, and the results are shown in Table 4.

The corrosion resistance test was conducted by using a brazing sheet coated with a non-corrosive flux in N ₂ gas at 600 ° C. for 5 minutes.
After heating under the conditions described above, only the central portion of the surface of the lining material was exposed, all other surfaces were sealed, and a corrosion test was performed under the following conditions. That is, each brazing sheet after the sealing treatment is treated with 88 ° C. ASTM artificial water (100 ppm · Cl ⁻ , 100 ppm ⁺ CO ₃
^- and an aqueous solution containing 100 ppm · SO ₄ ^2-a) was immersed for 8 hours in was performed 90 cycles test to stand at room temperature × 16 h. After the completion of this cycle test, the corrosion products of each brazing sheet were removed with a mixed solution of phosphoric acid and chromic acid, and then the maximum pitting depth was determined by the depth of focus method using an optical microscope. The results are shown in Table 4.

The tensile test was carried out by heating a brazing sheet coated with a non-corrosive flux in N ₂ gas under the condition of 600 ° C. × 5 min and then allowing it to stand at room temperature for 4 days. The results are shown in Table 4.

From the results in the table, it can be seen that the brazing sheet according to the manufacturing method of the present invention has high strength and excellent brazing property, less diffusion of the brazing material into the core material, and excellent corrosion resistance.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

INDUSTRIAL APPLICABILITY As described above, the brazing sheet of the present invention has high strength after brazing, excellent brazing property, less diffusion of brazing due to brazing, and excellent corrosion resistance after being formed into a tube. It has a great effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing a radiator with a part cut away.

FIG. 2 is an inverted T-joint that has been brazed.

[Explanation of symbols]

 1 Flat tube 2 Fins 3 Header 4 Tank 5 Brazing sheet 6 JIS3003 alloy (bare material)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F28F 21/08 F28F 21/08 A

Claims (2)

[Claims] 1. Si: 0.05-0.80 wt%, Fe: 0.05-0.6
wt%, Cu: 0.1-1.0 wt%, Mn: 0.6-1.6 wt%: M
g: 0.05-0.5 wt%, Cr: 0.3 wt% or less, Zr: 0.
Aluminum alloy containing 3 wt% or less and Ti: 0.3 wt% or less of 1 type or 2 types or more, with the balance being Al and unavoidable impurities as a core material, and providing an Al-Si alloy brazing material on one side, sacrificial effect In producing a high-strength brazing sheet consisting of a laminated material having an aluminum alloy material having on the other side, the ingot is not subjected to homogenization treatment, or is performed at 500 ° C. or less, The method for producing a high-strength aluminum brazing sheet is characterized in that the heating before hot rolling is set to 500 ° C. or lower, and hot rolling, cold rolling and annealing are performed thereafter, and the final cold rolling rate is set to 20 to 80%. . 2. Si: 0.05-0.80 wt%, Fe: 0.05-0.6
wt%, Cu: 0.1-1.0 wt%, Mn: 0.6-1.6 wt%: M
g: 0.05-0.5 wt%, Cr: 0.3 wt% or less, Zr: 0.
An aluminum alloy containing one or more of 3 wt% or less and Ti: 0.3 wt% or less, and the balance of Al and unavoidable impurities, the metal structure of which is an intermetallic compound of 0.02 to 0.2 μm. An aluminum alloy material containing 10 to 2000 pieces / μm ³ at a number density is used as a core material, an Al—Si alloy brazing material is provided on one surface, and an aluminum alloy material having a sacrificial effect is provided on the other surface. Characteristic high-strength aluminum brazing sheet.