JPH0971833A - Aluminum alloy brazing sheet strip with excellent electric resistance workability - Google Patents

Abstract

(57) [Abstract] (Correction) [Problem] Aluminum alloy brazing sheet strip material for heat exchanger tube material that does not crack during electric resistance sewing. SOLUTION: Al containing Si, Cu, Fe, Mn
Deformation resistance at 760K and 800K at a strain rate of 10 / s is σ ₇₆₀ (MPa) and σ ₈₀₀ (MPa),
Deformation resistance at absolute temperature T (K) above 800K σ _T (MP
a) is log (2σ _T ) ≦ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ) /
Let T1 (K) be the minimum temperature at which T-19 · log σ ₇₆₀ +20 · log σ _800, and log (1.1 σ _T ) ≤ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ).
/ T-19 · log σ ₇₆₀ the minimum temperature at which the +20 · log σ ₈₀₀ when the T2 (K), and an Al alloy temperature difference between T1 and T2 is 20K or less the core material, Mg on one side thereof, An aluminum alloy brazing sheet strip having a three-layer structure excellent in electric resistance workability, in which an Al alloy containing Zn, In, Sn is clad as a sacrificial material, and an Al alloy brazing material is clad on the other side.

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 for a heat exchanger used as a tube material for a heat exchanger of an automobile or the like, and more specifically to an aluminum alloy brazing tube made into a tube by electric sewing. The present invention relates to a sheet strip, and the brazing sheet strip of the present invention has high electric resistance workability and can be thinned.

[0002]

2. Description of the Related Art A heat exchanger such as a radiator has a plurality of flat tubes (1) integrally formed with corrugated thin fins (2) as shown in FIG. The flat tube (1) is opened at both ends into a space composed of the header (3) and the tank (4), and high-temperature refrigerant is passed from the space on one tank side through the flat tube (1). The refrigerant is sent to the other space on the side of the tank (4), and heat is exchanged in the tubes (1) and fins (2) to circulate the refrigerant having a low temperature again.

[0003] The tube material of such a heat exchanger is, for example, JIS3003 alloy (Al-0.15wt% Cu-1.1wt% M
n) is used as a core material, and a JIS 7072 alloy (Al
-1 wt% Zn), and usually J
A brazing sheet clad with a brazing material such as IS4045 alloy (Al-10wt% Si) is used as a tube material by electric resistance welding, and is integrally assembled by brazing together with other members such as fins that have been corrugated. . As the brazing method, a flux brazing method, a nocolock brazing method using a non-corrosive flux, etc. are performed, and brazing is performed by heating to a temperature of around 600 ° C.

[0004] In recent years, heat exchangers have been reduced in weight and size, and for that purpose, it has been desired to reduce the thickness of the material. In order to reduce the thickness of the tube material, first, it is necessary to improve the strength by the reduction of the material thickness and ensure the corrosion resistance. On the other hand, some high-strength alloys have been proposed, and a method of improving the strength by adding a large amount of Si or Cu to the core material alloy or a method of improving the strength by adding Mg to the sacrificial material is considered to be a promising method. Has been done. However, in recent years, due to the increase in strength as described above, problems that have not heretofore arisen have occurred as the wall thickness has been reduced. This is a problem caused by the electric sewing process.

That is, it has been found that when the tube material is made thinner, the crushing as shown in FIG. Furthermore, it was also found that when such crushing occurs, microcracks often occur. It was found that the pressure resistance strength of the electric resistance welded pipe was lowered due to the shape and microcracks as shown in FIG. 2, and the repeated pressure resistance life of the heat exchanger was extremely reduced. In addition, micro cracks in the tube cause liquid leakage and corrosion, making it unusable as a product.

[0006] The tube material is first formed into a cylindrical shape, and electric resistance welding is performed along the opposite edge portions. At this time, since the welded portion is pressed from both sides during welding, it is crushed, and then crushed. When this electric resistance machined tube is cooled and then processed into a flat tube, the shape as shown in FIG. 2 is obtained.

Therefore, as a result of the inventors' investigation on the cause of crushing during electric resistance welding, the tube is pressed from both sides of the welded portion during electric resistance welding.
High-temperature strength (deformation resistance) of the brazing sheet core material is small in high-strength alloys, and as the thickness of the brazing sheet decreases, the stress received from both sides increases even if the pressing force from both sides is the same, resulting in crushing. It has been found that is likely to occur.

[0008]

As a result of intensive studies in view of such circumstances, the present invention has developed an aluminum alloy brazing sheet strip for a heat exchanger, which has excellent strength after brazing and does not cause cracks due to electric resistance welding. It is a thing.

That is, according to the present invention, Si: more than 0.2 wt% and 1.0 wt% or less, Cu: more than 0.3 wt% and 1.0 wt% or less,
Si + Cu: more than 0.7 wt% and 1.6 wt% or less, Fe: 0.05
more than wt% and less than 2.0 wt%, Mn: more than 0.3 wt% and 2.0 wt
% Or less, aluminum alloy consisting of balance aluminum and unavoidable impurities, with a strain rate of 10 / s of 76
Deformation resistance at 0K is σ ₇₆₀ (MPa), deformation resistance at 800K is σ ₈₀₀ (MPa), absolute temperature T of 800K or more
The deformation resistance σ _T (MPa) at (K) is log (2σ _T ) ≦ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ) /
Let T1 (K) be the minimum temperature at which T-19 · log σ ₇₆₀ +20 · log σ _800, and log (1.1 σ _T ) ≤ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ).
/ T-19 · log σ ₇₆₀ + 20 · log σ ₈₀₀ , where T2 (K) is the minimum temperature, an aluminum alloy having a temperature difference between T1 and T2 of 20K or less is used as a core material, and Mg is provided on one surface thereof: Contains more than 0.05 wt% and less than 2.5 wt%, Zn: more than 0.5 wt% and less than 6.0 wt%, In: 0.0
Over 02wt% and under 0.3wt%, Sn: over 0.002wt%
It has a three-layer structure in which one or more of 0.3 wt% or less is clad as an sacrificial aluminum alloy consisting of the balance aluminum and unavoidable impurities, and a brazing material consisting of an aluminum alloy is clad on the other side. This is an aluminum alloy brazing sheet strip with excellent electric resistance workability.

According to another aspect of the present invention, Si: 0.2 wt%
Over 1.0 wt%, Cu: over 0.3 wt% 1.0 wt%, Si + Cu: over 0.7 wt% 1.6 wt%, Fe:
Over 0.05wt% and under 2.0wt%, Mn: over 0.3wt%
Contains less than 2.0wt%, Mg: over 0.05wt%, 0.5wt%
Below, Cr: more than 0.03 wt% and 0.3 wt% or less, Zr: 0.03
more than wt% and less than 0.3wt%, Ti: more than 0.03wt% and 0.3wt%
%, An aluminum alloy containing one or more of the following, and the balance aluminum and unavoidable impurities, and the deformation resistance at 760K at a strain rate of 10 / s is σ ₇₆₀
(MPa), the deformation resistance at 800K is σ ₈₀₀ (MPa), and the deformation resistance σ at an absolute temperature T (K) of 800K or higher.
_T (MPa) is log (2σ _T ) ≦ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ) /
Let T1 (K) be the minimum temperature at which T-19 · log σ ₇₆₀ +20 · log σ _800, and log (1.1 σ _T ) ≤ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ).
/ T-19 · log σ ₇₆₀ + 20 · log σ ₈₀₀ , where T2 (K) is the minimum temperature, an aluminum alloy having a temperature difference between T1 and T2 of 20K or less is used as a core material, and Mg is provided on one surface thereof: Contains more than 0.05 wt% and less than 2.5 wt%, Zn: more than 0.5 wt% and less than 6.0 wt%, In: 0.0
Over 02wt% and under 0.3wt%, Sn: over 0.002wt%
It has a three-layer structure in which one or more of 0.3 wt% or less is clad as an sacrificial aluminum alloy consisting of the balance aluminum and unavoidable impurities, and a brazing material consisting of an aluminum alloy is clad on the other side. This is an aluminum alloy brazing sheet strip with excellent electric resistance workability.

First, the alloy composition of the brazing sheet strip of the present invention will be described. The core alloy used in the present invention is a high strength alloy. That is, the core material has Si: more than 0.2 wt% and 1.0 wt% or less, Cu: more than 0.3 wt% and 1.0 wt% or less, Si + Cu: more than 0.7 wt% and 1.6 wt% or less, Fe:
Over 0.05wt% and under 2.0wt%, Mn: over 0.3wt%
An aluminum alloy containing 2.0 wt% or less and the balance aluminum and inevitable impurities, or Mg: more than 0.05 wt% and 0.5 wt% or less, Cr: 0.03 wt%
%, 0.3 wt% or less, Zr: 0.03 wt% or more, 0.3 wt%
The following is an aluminum alloy in which one or more of Ti: 0.03 wt% and 0.3 wt% is added. The role of each additive element in the core alloy will be described below.

[0012] Si contributes to the improvement of strength, but tends to cause cracks during electric resistance sewing. When Si is 0.2 wt% or less, the strength improving effect is not sufficient, and when it exceeds 1.0 wt%, the condition of the core material of the present invention described later cannot be satisfied. Therefore, S
i exceeds 0.2 wt% and 1.0 wt% or less, but especially 0.8
Stable electric resistance characteristics are exhibited at wt% or less.

Cu exists in the alloy in a solid solution state after brazing and improves the strength. When Cu is 0.3 wt% or less, the strength improving effect is small. If it exceeds 1.0 wt%, the melting point will be lowered, the material will melt during brazing, and the conditions for the core material of the present invention described below will not be satisfied.

Furthermore, Si and Cu are Si + Cu: 0.7
The range is over 1.6 wt% and over wt%. Si + Cu
This is because when it is 0.7 wt% or less, the electric resistance workability is good without considering the conditions of the present invention (described later). Also, S
When i + Cu exceeds 1.6 wt%, the conditions of the present invention described later cannot be satisfied regardless of the metal structure of the core material, and good electric resistance sewing cannot be performed.

Fe distributes a coarse intermetallic compound in the alloy to make the crystal grains of the brazing sheet of the present invention fine and prevent cracking during electric resistance sewing. If the amount is 0.05 wt% or less, the above effect is not sufficient, and if added in excess of 2.0 wt%, the formability is lowered and the brazing sheet is cracked during electric resistance sewing.

[0016] Mn is an essential element for distributing a fine intermetallic compound in the alloy and improving the strength without lowering the corrosion resistance. If the amount is 0.3 wt% or less, the above effect is not sufficient, and if added in excess of 2.0 wt%, the formability is lowered and the brazing sheet is cracked during electric resistance sewing.

Mg is a solid solution in the alloy and Mg ₂ Si
Exists as a fine precipitation phase of and improves the strength. 0.05
If it is less than wt%, there is no effect, and if it exceeds 0.5 wt%, when brazing using a non-corrosive flux, the flux reacts with Mg and brazing becomes impossible.

Cr, Zr, and Ti all have the function of forming a fine intermetallic compound and improving the strength of the alloy.
However, if each of them is less than 0.03 wt%, there is no effect, and if each of them exceeds 0.3 wt%, the formability is lowered and the brazing sheet is cracked during processing such as assembly.

Further, elements other than the above, such as B added for refining the structure of the ingot, may be contained if the content is 0.05 wt% or less.

The above are the components of the core alloy of the present invention.
Such alloy composition itself is conventionally known. The core material of the present invention is characterized in that it has the above alloy composition and has a deformation resistance of ₇₆₀ at a strain rate of 10 / s at 760K.
(MPa), the deformation resistance at 800K is σ ₈₀₀ (MPa), and the deformation resistance σ at an absolute temperature T (K) of 800K or higher.
_T (MPa) is log (2σ _T ) ≦ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ) /
Let T1 (K) be the minimum temperature at which T-19 · log σ ₇₆₀ +20 · log σ _800, and log (1.1 σ _T ) ≤ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ).
/ T-19 · log σ ₇₆₀ + 20 · log σ _{800 When the} minimum temperature is T2 (K), the material is characterized by the temperature difference between T1 and T2 being 20K or less. The workability is improved. The reason for this will be described below.

When the inventors conducted a detailed investigation on the condition of crushing during electric resistance sewing, it was found that crushing is difficult to occur depending on the alloy composition, and that the same alloy may or may not be crushed depending on the manufacturing process. I found it.
As a result of further detailed study, it was found that the hot deformation resistance of the core material drastically decreased at the portion where the crushing occurs, and the present invention was completed.

The hot deformation resistance of the aluminum alloy is It can be represented by. Therefore, when the strain rate is constant, the vertical axis is the deformation resistance in logarithm, and the horizontal axis is the reciprocal of the absolute temperature, the relationship of the above equation can be represented by a straight line as shown in FIG.

The inventors plotted the deformation resistance at each temperature for the core material of the brazing sheet in the above graph. As a result, as shown in the example of Fig. 4, the graph is shown as a solid straight line at a temperature near 800K, but is deformed from the broken straight line that surrounds the straight line near 800K near the melting point (solidus line) temperature of the alloy. I found that the resistance dropped. Then, it was found that the tendency of this decrease differs depending on the alloy composition and the metal structure, and correspondingly, the state of occurrence of crushing of the brazing sheet at the time of electric resistance sewing differs. That is, depending on the alloy composition and the metal structure, there may be a relationship as shown in FIG.
In this case, crushing is less likely to occur during electric resistance sewing. This will be briefly described below.

First, in the strip for electric resistance welding, the welded portion is pressed from both sides, and the deformation resistance in the vicinity of the melted portion is greatly related to the occurrence of cracks. The temperature distribution near the welded portion is such that the temperature decreases as the distance from the welded portion increases. Therefore, when the temperature range in which the deformation resistance decreases is wide as described above, the region in which the deformation resistance decreases decreases and the crushing is likely to occur. The present invention is based on such a background.
The conditions for becoming a material having excellent electric resistance workability are quantified as follows.

That is, since the temperature (reciprocal number) and the deformation resistance (logarithm) can be represented by a straight line on the graph between 760K and 800K, each absolute temperature T on the line that covers it is shown.
Deformation resistance sigma _t in the knowing the deformation resistance of 760K and 800 K, (each sigma _760, when the _{σ 800) log σ t = 15200} (log σ 760 -log σ 800) / T-19
・ It can be expressed as log σ ₇₆₀ +20 ・ log σ ₈₀₀ . This is indicated by a broken line in FIG. On the other hand, the relationship between each temperature near the melting point temperature and the deformation resistance can be expressed as a solid line.

In FIG. 6, assuming that the actual deformation resistance at each temperature T of 800 K or more is σ _T , log (2σ _T ) ≦ log
Minimum temperature that gives σ _t (ie log (2σ _T ) = log σ
The temperature) to be _t and _{T1, log (1.1σ T) ≦} log σ
Minimum temperature that becomes _t (ie log (1.1 σ _T ) = log σ
The temperature difference between T1 and T2 (T1-T2) corresponds to the deformation resistance lowering region range in the vicinity of the welded portion, where T2 is the temperature at which _t is reached. And the temperature difference between T1 and T2 is
If it is less than 20K, crushing does not occur, but if it exceeds 20K, crushing occurs.

In the present invention, the temperature difference between T1 and T2 is 20 in the composition range of the core material alloy described above.
Although the electric resistance workability is improved by setting the temperature to K or less, in order to reduce the temperature difference between T1 and T2 to 20K or less, the homogenization treatment, hot rolling conditions, and annealing conditions should be optimized. Good.
The range of conditions becomes wider as the amount of Si + Cu is smaller and narrower as the amount of Si + Cu is larger. Since specific conditions differ for each alloy, they will be described later by giving examples in Examples. Basically, it can be achieved by increasing the homogenization treatment temperature and the continuous annealing temperature when performing the intermediate annealing by the continuous annealing method, and by decreasing the homogenization treatment temperature when performing the intermediate annealing by the batch annealing method. . further,
When performing the stabilizing annealing, it is desirable to reduce the cold rolling rate after the intermediate annealing and lower the annealing temperature.

The deformation resistance is measured by a plane strain compression test as shown in FIG. The test piece was subjected to the homogenization treatment under the same conditions as the strip, and then the total
Rolled at 60% or more, and annealed under the same conditions as the strip. This is because when the rolling process is less than 60%, the ingot structure remains and the measured deformation resistance value does not correspond to that of the electric resistance welded pipe. This is because the homogenization treatment and the annealing affect the cracking property during electric resistance welding, and therefore accurate evaluation cannot be performed unless the same heat is applied to the material. Further, the temperature rising rate at the time of measuring the deformation resistance at each temperature needs to be 5 K / s or more. Below 5K / s,
The characteristics may not correspond because it is too small compared to the rate of temperature rise of the strip during ERW processing. The processing amount is up to about 0.3, and the deformation resistance is the maximum deformation load at that time divided by the area where the jig and the test piece are in contact. Strain rate is 10 /
Let s.

Next, the sacrificial layer of the brazing sheet produced by the present invention will be described. The sacrificial layer alloy of the present invention is M
g: more than 0.05 wt% and less than 2.5 wt%, Zn: 0.5
over wt% and below 6.0 wt%, In: over 0.002 wt% and 0.3
wt% or less, Sn: more than 0.002 wt% and 0.3 wt% or less, M
n: An aluminum alloy containing more than 0.05 wt% and less than 1.6 wt% and one or more species and the balance aluminum and unavoidable impurities.

The addition of Mg has a sacrificial effect and enhances the strength of the sacrificial layer alloy to improve the strength of the entire material. If the amount is less than 0.05 wt%, there is no effect, and if it exceeds 2.5 wt%, the melting point lowers and the alloy melts during brazing.

The addition of Zn gives the alloy a sacrificial effect. If the amount is 0.5 wt% or less, the effect is not sufficient and the amount is
If it exceeds 6.0 wt%, the melting point will be lowered, and even if the brazing alloy of the present invention is used, it will melt during brazing. In the case of the tube material of the present invention, since the core material contains a relatively large amount of Cu, Zn of 3.0 to 5 wt% is the most suitable amount.

The addition of In and Sn also gives a sacrificial effect to the alloy. If the amount is 0.002 wt% or less, the effect is not sufficient, and if the amount exceeds 0.3 wt%, the rolling workability of the alloy decreases.
It becomes unsuitable as a sacrificial layer used for a brazing sheet of three-layer material.

The sacrificial layer alloy elements of the present invention are as described above, but 3.0 wt% to 5 wt% Zn and 0.5 wt% to 2 wt% M are used.
Those containing g as an essential element and one or more other elements are most recommended from the viewpoint of strength and corrosion resistance. As an unavoidable impurity, Si is
The content is 0.5 wt% or less, but 0.1 wt% or less is preferable. Fe can be contained if it is 0.8 wt% or less, but 0.1 wt% or less is desirable. C for strength improvement
Elements other than the above, such as r, Zr, and Ti, are each 0.05 wt%
If it is the following, it may be contained as an impurity element.

Next, the brazing alloy of the present invention will be described. Al-Si such as 4343 alloy (Al-7.5 wt% Si) and 4045 alloy that have been used as brazing filler metals
It is possible to use a system alloy as a brazing material. Also,
You may use the low temperature brazing material as shown by Unexamined-Japanese-Patent No. 7-96385.

The alloy composition of the brazing sheet of the present invention has been described above. The constitution will be described below. The aluminum alloy brazing sheet strip for a heat exchanger manufactured by the present invention has a three-layer structure as shown in FIG. That is, the brazing sheet strip of the present invention comprises a core material (7) made of a high-strength aluminum alloy, a brazing material (6) on one side of the core material, and a sacrificial material (8) on the other side thereof. Is a strip for forming a tube with the brazing material on the outside and the sacrificial material on the side of the refrigerant passage. Moreover, the plate thickness of this brazing sheet strip is 0.3 mm or less, the clad ratio of the sacrificial layer is 5 to 30%,
The brazing material has a clad ratio of 5 to 30%.

The quality of the strip of the present invention may be adjusted so that the formability of electric resistance sewing and the diffusion resistance of brazing during brazing are excellent. Specifically, set the final cold rolling rate to 10
Approximately 80%, and it is desirable to heat-treat the sheet at the final thickness if necessary. In the present invention, the process after electric resistance sewing is not particularly limited. The heat exchanger may be manufactured by brazing as is conventionally done.

[0037]

The present invention will be specifically described below with reference to examples.

Example 1 A three-layer brazing sheet strip having a plate thickness of 0.25 mm for an aluminum alloy tube material having the composition and constitution shown in Table 1 was manufactured. The steps until obtaining the hot rolled coil are conventional. Specifically, the core alloy was DC cast to a thickness of 400 mm and then, as shown in Table 2, at 450 ° C to 6 ° C.
After homogenizing treatment in the temperature range of 00 ° C., after chamfering, the brazing material alloy sheet and the sacrificial layer alloy sheet prepared in advance were combined, and hot rolling was performed after heating. The brazing material has a clad ratio of 10% and the sacrificial material has a clad ratio of 15%. Further, Fe and Si are contained in the sacrificial material as impurity elements within the range of 0.01 to 0.2 wt%, respectively. The hot-rolled coil of this double-sided clad material was cold-rolled to various plate thicknesses and annealed under various annealing conditions shown in Table 2. Further, cold rolling was performed to 0.25 mm, and after the cold rolling, partial annealing was performed if necessary.

[0039]

[Table 1]

[0040]

[Table 2]

Further, a sample having a thickness of 100 mm was taken from the DC ingot of each core material alloy homogenized under the conditions of Table 2.
After hot rolling to 30 mm, it was cold rolled to 15 mm and annealed under the conditions shown in Table 2 except the sheet thickness. A large number of test pieces with a thickness of 15 mm (as-rolled) x width 20 mm x length 10 mm were cut out from such a plate material and subjected to a plane strain compression test at various temperatures of 760 K, 800 K, and 800 K or higher to determine the temperature and deformation resistance. Asked for a relationship. The test heating rate is 50K / s
The compression area is 5 mm x 20 mm. The strain rate of the test is
The strain was set to 10 / s, the strain was processed to 0.3, and the maximum load was divided by the cross-sectional area to obtain the deformation resistance.

FIG. 9 shows an example of a graph of the relationship between the obtained temperature and the deformation resistance (Example 4 of the present invention). The straight line (1) in this graph connects the deformation resistances at 760K and 800K log σ _t = 15200 (log σ ₇₆₀ −log σ ₈₀₀ ) / T-19
・ Log σ ₇₆₀ +20 ・ log σ ₈₀₀ . Here, since log (2σ _T ) = log 2 + log σ _T , the temperature at the intersection of the broken line (2) having a smaller log 2 value than the broken line (1) and the graph is T1. Furthermore, since log (1.1σ _T ) = log 1.1 + log σ _T , the temperature at the intersection of the broken line (3) and the graph, which is smaller than the broken line (1) by log 1.1, is T2. Table 2 also shows T1, T2, and the temperature difference between T1 and T2 thus obtained.

(Example 2) Next, the plate thickness obtained in Example 1
A 0.25 mm coil-shaped plate was slittered to a width of 35.0 mm according to the size of the electric resistance welded pipe. The obtained strip is subjected to electric resistance sewing, and the obtained tube is up to 5M
The pressure was increased to Pa, and a pressure resistance test and cross-section observation for checking the occurrence of leakage were performed. In addition, N is applied to the obtained strip.
_A brazing heat was applied in _two gases to perform a tensile test. The results are shown in Table 3. The brazing heat is alloy number E,
580 ° C x 5 minutes for F and G, and 600 ° C x 5 minutes for other alloys.

[0044]

[Table 3]

Comparative Examples 9 to 12 are alloys within the composition range of the present invention, but the temperature difference between T1 and T2 exceeds 20K,
The electric resistance process causes cracks and crushing, resulting in low withstand voltage. Comparative Examples 13 and 14 are out of the ranges of the amounts of Si and Cu of the core material of the present invention, and cracks do not occur during electric resistance sewing, but the strength after brazing is low. Further, in Conventional Example 15 as well, cracks do not occur during electric resistance sewing, but the strength after brazing is low. On the other hand, in the example of the present invention,
Despite the high strength after brazing, no cracks were formed during electric resistance welding.

[0046]

Industrial Applicability As described above, the aluminum alloy material of the present invention does not cause cracks during electric resistance sewing, has high strength, and when a heat exchanger is manufactured, it can be reduced in size and weight and is industrially used. It has a remarkable effect.

[Brief description of drawings]

FIG. 1 is a partially sectional perspective view showing a radiator.

FIG. 2 is a cross-sectional view of an electric resistance welded tube showing a crushed state during electric resistance welding.

FIG. 3 is a diagram showing the relationship between the heating temperature and the deformation resistance of an aluminum alloy, in which the vertical axis represents the deformation resistance as a logarithmic value and the horizontal axis represents the absolute temperature as an inverse number.

FIG. 4 is a diagram in which the relationship between the heating temperature and the deformation resistance of the core material of the brazing sheet made of an aluminum alloy is plotted as in FIG.

FIG. 5 is a diagram showing a relationship between a heating temperature and a deformation resistance of a brazing sheet core material made of an aluminum alloy when cracks are less likely to occur during electric resistance sewing and when cracks are likely to occur.

FIG. 6 is a diagram showing the relationship between the heating temperature and the deformation resistance of an aluminum alloy for explaining the conditions of the present invention.

FIG. 7 is an explanatory diagram showing a method of plane strain compression test.

FIG. 8 is a sectional view showing the structure of the brazing sheet of the present invention.

9 is a plot of the relationship between the heating temperature and the deformation resistance of the aluminum alloy core material of Inventive Example 4, in which the vertical axis represents the deformation resistance in a logarithmic value and the horizontal axis represents the absolute temperature in the inverse number. FIG.

[Explanation of symbols]

 1 Flat Tube 2 Fins 3 Header 4 Tank 5 ERW Welding Part 6 Brazing Material 7 Core Material 8 Sacrificial Material 9 Test Piece (Aluminum Alloy) 10 Jig

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Kumazawa 1-1, Showa-cho, Kariya city, Aichi Prefecture Nihon Denso Co., Ltd. Within the corporation

Claims (2)

[Claims] 1. Si: more than 0.2 wt% and 1.0 wt% or less, C
u: more than 0.3 wt% and 1.0 wt% or less, Si + Cu: 0.7 wt
%, 1.6 wt% or less, Fe: 0.05 wt% or more, 2.0 wt%
The following is an aluminum alloy containing Mn: more than 0.3 wt% and 2.0 wt% or less, and the balance aluminum and unavoidable impurities, and the deformation resistance at ₇₆₀ K at a strain rate of 10 / s is σ ₇₆₀ (MPa), 800 K Deformation resistance at σ ₈₀₀ (MP
a), the deformation resistance σ _T (MPa) at an absolute temperature T (K) of 800 K or higher is log (2σ _T ) ≦ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ) /
Let T1 (K) be the minimum temperature at which T-19 · log σ ₇₆₀ +20 · log σ _800, and log (1.1 σ _T ) ≤ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ).
/ T-19 · log σ ₇₆₀ + 20 · log σ ₈₀₀ , where T2 (K) is the minimum temperature, an aluminum alloy having a temperature difference between T1 and T2 of 20K or less is used as a core material, and Mg is provided on one surface thereof: Contains more than 0.05 wt% and less than 2.5 wt%, Zn: more than 0.5 wt% and less than 6.0 wt%, In: 0.0
Over 02wt% and under 0.3wt%, Sn: over 0.002wt%
It has a three-layer structure in which one or more of 0.3 wt% or less is clad as an sacrificial aluminum alloy consisting of the balance aluminum and unavoidable impurities, and a brazing material consisting of an aluminum alloy is clad on the other side. Aluminum alloy brazing sheet strip with excellent electric resistance workability. 2. Si: more than 0.2 wt% and 1.0 wt% or less, C
u: more than 0.3 wt% and 1.0 wt% or less, Si + Cu: 0.7 wt
%, 1.6 wt% or less, Fe: 0.05 wt% or more, 2.0 wt%
Below, Mn: more than 0.3 wt% and containing 2.0 wt% or less, M
g: over 0.05 wt% and under 0.5 wt%, Cr: over 0.03 wt% and under 0.3 wt%, Zr: over 0.03 wt% and under 0.3 wt%,
Ti: One or two of more than 0.03 wt% and 0.3 wt% or less
An aluminum alloy containing at least one species and the balance aluminum and unavoidable impurities, with a strain rate of 10 / s.
The deformation resistance at 60K is σ ₇₆₀ (MPa), and the deformation resistance at 800K is σ ₈₀₀ (MPa).
The deformation resistance σ _T (MPa) at (K) is log (2σ _T ) ≦ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ) /
Let T1 (K) be the minimum temperature at which T-19 · log σ ₇₆₀ +20 · log σ _800, and log (1.1 σ _T ) ≤ 15200 (log σ ₇₆₀ −log σ ₈₀₀ ).
/ T-19 · log σ ₇₆₀ + 20 · log σ ₈₀₀ , where T2 (K) is the minimum temperature, an aluminum alloy having a temperature difference between T1 and T2 of 20K or less is used as a core material, and Mg is provided on one surface thereof: Contains more than 0.05 wt% and less than 2.5 wt%, Zn: more than 0.5 wt% and less than 6.0 wt%, In: 0.0
Over 02wt% and under 0.3wt%, Sn: over 0.002wt%
It has a three-layer structure in which one or more of 0.3 wt% or less is clad as an sacrificial aluminum alloy consisting of the balance aluminum and unavoidable impurities, and a brazing material consisting of an aluminum alloy is clad on the other side. Aluminum alloy brazing sheet strip with excellent electric resistance workability.