JPH0611896B2 - Aluminum alloy brazing sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Object of the Invention (Industrial field of application) The aluminum alloy brazing sheet according to the present invention has high strength even after brazing and is excellent in corrosion resistance, and is made of aluminum heat used as a radiator or heater core for automobiles. It can be used as a plate material for heat exchanger tubes and seat plates of exchangers.

(Prior Art) As a heat exchanger used as a radiator or a heater core, a heat exchanger as shown in FIG. 2 is known. This heat exchanger includes a large number of flat heat transfer tubes 1 and 1, a large number of fins 2 and 2, and a curved portion of each fin 2 and 2 to each heat transfer tube 1,
An upper tank 6 and an outlet pipe each having an inlet pipe 5 via a seat plate 4 at both upper and lower (or left and right) end portions of a core portion 3 which is alternately stacked in a state of being in contact with a flat side surface of And a lower tank 8 having

For example, when heat is dissipated from the engine cooling water by such a heat exchanger, when the cooling water which has taken the heat of the engine and rises in temperature is sent from the inlet pipe 5, this cooling water is transferred to the upper tank 6.
From the bottom to the lower tank 8 while flowing in the large number of heat transfer tubes 1 and 1, heat is exchanged between the large number of fins 2 and 2 forming the core part 3 and the air flowing in the front-back direction of the drawing. After the temperature is lowered by performing the above, the gas is sent out from the outlet pipe 7.

Conventionally, such a heat exchanger has been made of copper or brass, but in recent years, it has become more and more often made of inexpensive and lightweight aluminum.

However, aluminum is more likely to corrode than copper or brass, and it is not possible to obtain sufficient durability as a heat exchanger as it is, therefore, JP-A-55-95094, JP-A-55-123996, and JP-A-56-56 As disclosed in JP-A-44742, JP-A-58-173396, etc., an aluminum alloy skin material containing a large amount of zinc is provided by being laminated (clad) on a core material of an aluminum material to be protected against corrosion. It has been attempted to prevent corrosion of an aluminum material which is a core material by sacrificially corroding an aluminum alloy skin material containing a large amount of zinc.

Many of such aluminum heat exchangers have JIS3
003 material (0.05-0.2% copper, 1.0-1.5
% Of manganese, the remainder being unavoidable impurities and aluminum) as a core material, and an aluminum alloy brazing sheet in which a brazing material of an aluminum-silicon alloy is laminated on one or both surfaces of the core material as a skin material. It is used.

When this brazing sheet is used as it is for a radiator heat transfer tube or a seat plate, engine cooling water, which is a heat medium, comes into contact with it to cause corrosion, and in the case of a thin sheet, corrosion progresses through the skin material. However, a through hole may be formed in the core material. For this reason, J
A sacrificial anode is formed by laminating an aluminum-zinc alloy represented by IS7072 material (containing 0.8 to 1.3% of zinc, with the balance being inevitable impurities and aluminum) to form a sacrificial anode, and a heat exchanger as a core material. As the brazing sheet, a brazing sheet is used to prevent the occurrence of fatal corrosion. Other aluminum laminates for heat exchangers that have been known in the past are basically used in the same manner to prevent corrosion that would be fatal as a heat exchanger from occurring in the core material. .

(Problems to be Solved by the Invention) However, the aluminum alloy brazing sheet used in the conventional heat exchanger has the following disadvantages.

That is, in the case of the core material of the conventional laminated material for heat exchanger represented by JIS3003 material, the tensile strength of the softened material after brazing is relatively small at about 11 to 12 kg / mm ^2, and therefore, after brazing In order to obtain sufficient strength, it is necessary to increase the thickness of the material sheet, and the effect of reducing the weight of the heat exchanger by using the aluminum alloy cannot be fully exerted.

In addition, JIS3003 material is used as a core material for corrosion protection. When an aluminum alloy containing a large amount of zinc is laminated on the core material, the corrosion resistance of the core material can be achieved, but the corrosion amount of the skin material of the aluminum alloy containing a large amount of zinc. Will increase considerably. Particularly, when silicon (Si) or copper (Cu) is added to the aluminum alloy forming the core material for the purpose of improving the strength of the core material, these silicon and copper are the components of the heat exchanger. Diffusion in aluminum alloy such as JIS7072 material forming the sacrificial anode by heating when brazing each member,
Inflow. Then, along with this diffusion and inflow, the amount of corrosion of the sacrificial anode is increased.

When the amount of corrosion of the aluminum alloy to be sacrificed and corroded increases in this way, corrosion products are generated in large amounts, which causes clogging of the heat transfer tubes 1 and 1 constituting the heat exchanger, which deteriorates the performance of the heat exchanger. It is not preferable because it also becomes.

The brazing sheet of the present invention remarkably improves the strength of the core material, and also improves the corrosion resistance of the sacrificial anode material while sufficiently exhibiting the sacrificial anode effect due to the potential difference between the core material and the skin material. This is to eliminate such inconvenience.

b. Configuration of the Invention (Means for Solving the Problem) The aluminum alloy brazing sheet of the present invention should be anticorrosive as shown in FIG. 1 as in the case of the conventional heat exchanger-like aluminum alloy brazing sheet described above. The sacrificial anode layer 10 is formed on the surface of the core material 9 that is in contact with the cooling liquid.
A brazing material layer 11 for supplying a brazing material when brazing this brazing sheet to another aluminum alloy plate material is provided on the surface on the opposite side.

The core material 9 in this is 0.8 to 1.5% by weight of manganese (M
n), 0.6 to 1.3% by weight of silicon (Si), and 0.3 to
1.0 wt% copper (Cu), 0.2-0.5 wt% magnesium (Mg), 0.05-0.2 wt% zirconium (Zr), the balance aluminum (Al) and unavoidable impurities.

The sacrificial anode layer 10 covering the surface of the core material 9 in contact with the cooling water is 0.2 to 0.5% by weight of magnesium (Mg).
And zinc (Zn) in an amount of 0.1 to 0.3% by weight, and the balance is aluminum and inevitable impurities.

Furthermore, the brazing material layer 11 that covers the opposite surface of the core material 9 contains silicon as a main component and aluminum as the unavoidable impurities.

In the aluminum alloy brazing sheet of the present invention having such a configuration, the sacrificial anode layer 10 itself does not contain much zinc, and the amount of magnesium contained is limited. , With the heating during brazing,
Silicon or copper diffuses from the core material 9 into the sacrificial anode layer 10,
Even if it flows in, the corrosion amount of the sacrificial anode layer 10 does not increase but rather decreases.
It does not increase enough to block the heat transfer tubes that make up the heat exchanger.

Further, since the potential of the core material 9 containing manganese and copper is higher (noble) than the potential of the sacrificial anode layer 10 not containing these elements, the sacrificial anode layer 10 is used when the corrosion condition becomes severe. Corrosion of 10 prevents the core material 9 from being corroded.

Further, the tensile strength of the core material 9 containing manganese, copper, silicon, magnesium, and zinc is higher than that of JIS3003 material, and the strength of the heat exchanger manufactured using the brazing sheet of the present invention is also sufficiently high.

The amount of manganese, silicon, copper, magnesium and zirconium contained in the core material is set within the above range for the following reason.

That is, by adding manganese to the aluminum alloy, the corrosion resistance and high temperature strength of the aluminum alloy are improved, but this effect is insufficient when the manganese content is less than 0.8% by weight, and conversely Is more than 1.5% by weight, the workability of the material is deteriorated and cracks are likely to occur during molding. Therefore, the content is limited to the above range.

Silicon forms fine aluminum-manganese and silicon compounds that are uniformly dispersed by coexisting with manganese, and has the effect of dramatically improving high-temperature strength and room-temperature strength as compared with aluminum-manganese alloys. This effect is insufficient when the content of silicon is less than 0.6% by weight, and when it exceeds 1.3% by weight, the melting start temperature of the material is lowered, the high temperature strength is lowered, and the corrosion amount of the sacrificial anode layer is reduced. Is increased, so the above range is limited.

Further, copper is added in order to make the potential of the core material sufficiently higher than that of the sacrificial anode layer and to improve the strength of the core material. This effect is obtained when the content of copper is less than 0.3% by weight. If the content exceeds 1.0% by weight, on the other hand, the intergranular corrosion between copper and aluminum becomes strong, and the growth rate of local corrosion becomes remarkable, as in the case of manganese. Since the size of the sacrificial anode layer is increased, the metal is destroyed from the inside to easily form a through hole, and the corrosion amount of the sacrificial anode layer is increased.

Magnesium is added to further improve the strength of the core material, but its effect is not sufficient if the magnesium content is less than 0.2% by weight, while the content is 0.5% by weight. If it exceeds, the intergranular corrosion resistance of the material becomes strong,
Since the growth rate of local corrosion is remarkably increased and a through hole is easily generated, the range is limited to the above range.

Like zirconium, zirconium is added to make the potential of the core material sufficiently higher than the potential of the sacrificial anode layer and to improve the strength of the core material at high temperature. If the content is less than 0.05% by weight, the content is insufficient. On the contrary, if the content exceeds 0.2% by weight, the workability during press molding is deteriorated, so the content is limited to the above range.

Next, the amounts of magnesium and zinc contained in the sacrificial anode layer are set within the above ranges for the following reason.

That is, magnesium can improve the corrosion resistance to water of the aluminum alloy by adding an appropriate amount, and in addition to preventing the diffusion and inflow of silicon and copper from the core material in the coexistence with zinc (Zn), As described above, the range in which the corrosion resistance can be expected is 0.2 to 0.5% by weight. If it is less than 0.2% by weight, the corrosion resistance cannot be expected. If added in addition, the corrosion resistance is rather lowered, so the content is limited to the above range.

Further, zinc is contained in order to suppress partial deep corrosion, so-called pitting corrosion, in the aluminum alloy in the coexistence with magnesium, make the potential base, and cause a sacrificial anode effect on the core material. However, this effect of suppressing pitting corrosion cannot be expected if the amount of zinc added is less than 0.1% by weight, and conversely, if added in excess of 0.3% by weight, the potential becomes too base and pitting corrosion is prevented. However, the amount of corrosion of the sacrificial anode layer increases, and a large amount of corrosion products may cause clogging of the heat transfer tube. Therefore, the amount is limited to 0.1 to 0.3% by weight.

Example Next, an experiment conducted by the present inventor will be described.

In the experiment, six kinds of aluminum alloys having compositions as shown in Nos. 1 to 6 of Table 1 were used as the core material 9, and the sacrificial anode layer 10 was made as shown in Nos. A to I of Table 2. Nine kinds of aluminum alloys having different compositions were used.

Of the six types of aluminum alloy shown in Table 1, NO.
Nos. 1 to 4 belong to the present invention, and NO.
Is an aluminum alloy prepared for comparison and is NO.5
Corresponds to JIS3003 material.

In addition, among the nine types of aluminum alloys shown in Table 2,
NO.A to F belong to the present invention, and NO.G to I
Is an aluminum alloy prepared for comparison, and NO.
G is equivalent to JIS1050 material, NO.I is JIS7
It corresponds to 072 material.

The total of 15 types of aluminum alloys shown in Tables 1 and 2 are the aluminum alloy for the sacrificial anode layer shown in FIG. A total of 15 types of brazing sheet test pieces as shown in Table 3 were prepared by coating the same thickness.
All the test pieces were manufactured by rolling.

Since each test piece has the same condition as the brazing sheet used for the actual heat exchanger, it is 60
After heating at 0 ° C. for 3 minutes, the tensile strength was measured for each test piece and a predetermined corrosion test was performed, and thereafter the corrosion amount and the maximum pitting corrosion depth were measured for each test piece.

Corrosion test, a chlorine ion (Cl ^-) 200 ppm of sulfate ions
(SO ₄ ²⁻ ) 60ppm, copper ion (Cu ²⁺ ) 1ppm, ferric ion (Fe ³⁺ ) 30ppm, each test piece is immersed in a corrosive liquid heated to 88 ° C, and the above corrosion is performed. The liquid was circulated at 60 / min for 8 hours and then allowed to stand for 16 hours, which was set as one cycle, and was performed for 30 days (30 cycles).

In determining the test results, the corrosion amount is less than 2.0 mg / cm ² , and the maximum pitting depth is 0, which is the thickness of the sacrificial anode layer. If it was less than 1 mm, it was considered good.

As a result, the aluminum alloy brazing sheet according to the present invention had a tensile strength of 19 kg / mm ² or more in any case, and had a sufficient strength for producing a heat exchanger.

Regarding the amount of corrosion, 1.82 mg is the most
/ cm ^2, which was less than the brazing sheet used for comparison.

Further, regarding the maximum pitting depth, even the deepest pitting corrosion was 0.1 mm, which is the same as the thickness of the sacrificial anode layer, and no corrosion reached the core material. Excellent results were obtained in comparison with most of them in which pitting corrosion that reaches the core material occurred.

c. EFFECTS OF THE INVENTION As described above, the aluminum alloy brazing sheet of the present invention can not only suppress the amount of corrosion to be small, but also suppress the occurrence of deep pitting that reaches the core material. Moreover, since the tensile strength after heating is sufficiently large, it is useful because it is possible to obtain an aluminum heat exchanger that is lightweight and has excellent durability, and that exhibits stable performance over a long period of time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an aluminum alloy brazing sheet of the present invention, and FIG. 2 is a front view showing an example of a heat exchanger manufactured using this brazing sheet. 1: Heat transfer tube, 2: Fin, 3: Core part, 4: Seat plate, 5:
Inlet pipe, 6: upper tank, 7: outlet pipe, 8: lower tank,
9: core material, 10: sacrificial anode layer, 11: brazing material layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuyuki Hashimoto 5-24-15 Minamidai, Nakano-ku, Tokyo Within Japan Radiator Co., Ltd. (72) Inventor Toyama Ken 85 Hiramatsu, Susono-shi, Shizuoka Mitsubishi Aluminum Co., Ltd. Technology Development Center (72) Inventor Noriaki Takahashi 85 Hiramatsu, Susono City, Shizuoka Prefecture Mitsubishi Aluminum Co., Ltd. Technology Development Center (56) Reference JP-A-56-16646 (JP, A) JP-A-60-141844 (JP) , A) JP 60-230953 (JP, A) JP 62-127192 (JP, A) JP 59-85837 (JP, A)

Claims (1)

[Claims] 1. A manganese content of 0.8 to 1.5% by weight;
6-1.3 wt% silicon, 0.3-1.0 wt% copper, 0.2-0.5 wt% magnesium, 0.05
0.1% to 0.2% by weight of zirconium, with the balance being aluminum and unavoidable impurities.
~ 0.5 wt% magnesium, 0.1 ~ 0.3 wt% zinc, the rest is a laminate of aluminum and unavoidable impurities, laminated on the other side, aluminum and silicon An aluminum alloy brazing sheet made by laminating the brazing material.