JPS63186847A - Aluminum alloy for heat exchanger - Google Patents

Abstract

PURPOSE:To develop an Al alloy having excellent characteristics as a core for the core plate of a radiator having excellent strength, corrosion resistance and bending workability, by adding specific ratios of alloy elements to Al. CONSTITUTION:The Al alloy contg., by weight, 1.0-1.5% Mn, 0.30-0.60% Cu, 0.10-0.50% Mg, 0.05-0.35% Cr and 0.05-0.35% Zr, or furthermore contg. one or two kinds of 0.05-0.35% Ti and 0.05-0.35% V with impurities of Fe and Si regulated to <=0.5% is melted to produce. Said Al alloy ingot is subjected to a homogenization treatment at 500 deg.C for 8hr and is worked to a plate material. The plate material is used as the core for the core plate of the radiator. The core plate material of the Al alloyed radiator having the excellent strength, bending workability and corrosion resistance, particularly pitting resistance can be thus obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to an aluminum alloy core material used for a core plate material of an aluminum alloy radiator assembled by brazing and a core material of a laminate type heat exchanger. Related to alloys with excellent strength, workability, and corrosion resistance.

[Prior Art] The manufacturing method of an aluminum alloy radiator includes mechanical assembly and brazing assembly. In the former case, a galvanized iron plate is used as the core plate material, and in the latter case, an aluminum alloy containing relatively high M9 content and relatively high strength, such as 6951 alloy, is used as the core material of the core plate material. . The thickness of the plate material in this case is 1.2 to 1.4 mm.
and relatively thin.

On the other hand, in the case of fluoride flux brazing, which has recently been in the spotlight, MC is used as an additive element in the core material of the core plate.
Brazing of materials with I reduces the properties, thus limiting the amount of MCI. For this reason, 3003 alloy is being used instead.

Furthermore, 3003 alloy has conventionally been used as the core material of brazing sheets for laminated heat exchangers. However, materials using this alloy, such as JIS BA8P
With the C13003-4004 double-sided clad material, the vacuum brazing strength does not reach t2 kg/mm2, so it is difficult to reduce the thickness for weight reduction.

On the other hand, as a material for heat exchangers that has higher strength than the above-mentioned 3003 alloy, for example, 3004.3005.6951 is required, but these alloys have advantages and disadvantages in terms of properties such as workability and corrosion resistance, and are not suitable for use as heat exchanger materials. could not be fully achieved.

[Problems to be Solved by the Invention] Currently, when manufacturing radiators, when mechanically caulking and joining the core plate and the plastic tank, the caulking part may be adjusted, and at this time, the caulking work is necessary due to rework etc. is repeated. FIG. 1 shows a state in which the end of the core plate 1 and the mounting part of the plastic tank 2 are joined by caulking.
When repairing the caulked part, the caulked pawl 3 is pulled up in the direction of the arrow, and after the prescribed repair is completed, the caulking is performed. At this time, alloys with relatively high strength (for example, 6951
For core plates whose core material is made of
Cracks or the like occur in the bent portion 4 of the product, making it unusable as a product.

On the other hand, alloys with relatively good bending properties (for example, 3
003, etc.), the strength of the alloy itself is low and the plate material cannot be made thinner (plate thickness 1
．． 4 to 1.8 mm), making it impossible to reduce the weight of the radiator.

Therefore, in order to solve the above problems, the present invention provides 30
Aluminum alloys, which have higher strength and better corrosion resistance than alloys with good bending workability such as 03 alloy, and have the same or better repeated bending workability, are used as core materials for radiator core plates. The purpose is to provide

In general, the present invention is intended to solve the above-mentioned problems of the prior art and to provide an aluminum alloy with high strength, excellent formability and corrosion resistance.

[Means for Solving the Problems] In order to solve the above problems, the structure of the present invention is an Al alloy for heat exchangers whose composition is limited as follows,
and a praising sheet using the same.

That is, the present invention provides (1) Mn: 1.0 to 1.
5%, Cu: 0.30-0.60%, MC1:
0.10-0.50%, C:, r: 0.05-0
．． Aluminum for a heat exchanger made of an aluminum alloy containing 35% and Zr: 0.05 to 0.35%, the remainder being substantially Al, and impurities, especially Fe and Si, each of 0.5% or less Alloy and (2) Mn
: 1.0-1.5%, Cu: 0.30-0.60%
, M]: 0.10 to 0.50%, Cr: 0.0
5-0.35% and Zr: 0.05-0.35%
Including Sarani T! : 0.05-0.35% and HV
: Contains 0.05 to 0.35% of one or two types, the rest is substantially Al, and contains impurities, especially Fe and S.
The aluminum alloy for heat exchangers is made of an aluminum alloy in which i is 0.5% or less.

Next, the significance of adding additional elements to the aluminum alloy mentioned above will be described.

Mn, Cu has the effect of increasing the strength of the core material, and is added to reinforce the strength-improving effect of Mg, which is added together. If both elements are added in excess of their upper limits, the corrosion resistance and repeated bending workability of the core material will deteriorate.

On the other hand, if the amount is less than the lower limit, the above effects will be small.

Mg is the main strength-enhancing element in the core material, and the degree of strengthening increases as the number of additions increases. However, if the amount added exceeds 0.50%, the brazing properties of the fluoride flux decrease, and the repeated bending workability of the core material also deteriorates. On the other hand, if the addition is lower than 0.10%, the reinforcing effect is small and the reinforcing effects of Mn and other elements are not utilized.

Cr, Zr They have the effect of increasing material strength without impairing repeat bending workability, so they are added to reinforce the reinforcing effect of MQ. However, when both elements exceed 0.35%, giant intermetallic compounds are formed, which deteriorates bending workability, makes it difficult to form a plate material, and deteriorates corrosion resistance. the other 0.0
If the amount is less than 5%, the above effects will be small.

Ti,v has the effect of increasing the strength of the material without impairing its repeated bending workability, so when the amount of MQ added is lowered within the above range to improve brazing properties and workability, When it is necessary to further increase the strength, one or two types are added.

However, if both amounts exceed 0.35%, the corrosion resistance will deteriorate, and if it is less than 0.05%, the above effects will be small.

Both 3i and Fe are impurities, and if they are contained in amounts greater than 0.5%, the corrosion resistance of the core material will deteriorate.

Examples of the present invention will be listed below in comparison with comparative examples.

[Examples] Example 1 Table 1 shows examples of aluminum alloys used for the core material of the radiator core plate according to the present invention. In addition, as a comparative example, aluminum alloys used for concentric materials are also listed.

Table 1 Core alloy composition (wt%) For each ingot piece of each example alloy in Table 1, 50'C
After homogenization treatment of X ahr, this was used as a core material, and a 4343 alloy piece was placed on one side as an aluminum alloy, and a 7072 alloy piece was placed on the other side as a sacrificial anode, and each cladding ratio was 10% in the final product plate. Polymerization was carried out to give the following properties, and a soft core plate material having a thickness of 1.2 mm was manufactured by adding hot working and cold working.

After applying fluoride flux to the solder surface of each core plate material obtained in this way and heating it at 600°C for 5 minutes in a nitrogen gas atmosphere, the mechanical properties of each core plate material were Table 2 shows the properties and the number of repeated bending tests. The core plate material numbers in this table correspond to the alloy numbers in Table 1.

As shown in FIG. 2, the repeated bending test method involves gripping the top and bottom of the core plate material sample 5 with an upper jig 6 and a lower jig 7, bending it alternately to 90 degrees, and repeating this bending. This method determines the number of times the sample is bent until it breaks.

Table 2 East Number of repeated bending cycles until breakage Furthermore, using inverted T-shaped test pieces made from each core plate material, fluoride flux was applied and brazing properties were tested. The evaluation is shown in Table 3.

The inverted T-shaped brazing test method is as shown in Figure 3.
A 3003 alloy plate 9 is placed upright on the core plate material 1 placed horizontally with the surface of the 4343 alloy solder 8 facing upward, and one end of its lower side is placed on it, and the other end is placed between the core plate material 1 and the plate material 1 with a diameter of 2 mm. A gap is created between the rod 10 and the plate material 1, and brazing is performed by heating in this state, and the brazing is performed by measuring the valley filling length X B of the solder.

In addition, in order to further confirm the corrosion resistance as a core plate material, the
The 343 alloy solder side and the 7072 alloy side were sealed separately with silicone rubber, and a corrosion test was conducted on each side. For the 7072 alloy surface, (ASTMX
1o+1oppm cu > 8 alternately using an aqueous solution
0'CX ahr←→The test was conducted by immersion for 1 month in a cycle of maximum temperature x 16hr, and 1
It was set as the CASS test (JIS D-0201).

Table 3 also does not show the state of corrosion from each side as a result of these tests. Core plate material No. in Table 3, alloy No. in Table 1,
It corresponds to

Table 3 Intergranular Corrosion Occurrence Tables 1 to 3 clearly show that the aluminum alloy used for the core material according to the present invention has appropriate strength and corrosion resistance, and is excellent in repeated bending workability. The alloy is ideal as a core material for radiator core plates with mechanically swaged joints.

Example 2 Alloys shown in Table 1 and N as shown in Table 4 as comparative alloys
o, 19 (3004), No, 20 (3005
) Regarding the ingots of 20 types of alloys with the addition of 2 types of alloys,
After homogeneous heating (soaking) for 540'Cx 3 hours, AA4104 alloy as a cholera core material was combined on both sides with a thickness of 10% of the plate thickness, and a plate with a thickness of 0.5 mmt was obtained by hot and cold rolling. Manufactured.

Table 4 Additional comparative core material alloy composition (wt%) This plate was heated to 600°C in a vacuum of 2X 10' Torr for 10 days.
Table 5 below shows the tensile strength when rapidly cooled after heating for a minute.

Table 5 Tensile Strength after Vacuum Heating This plate material was softened at 380'C for 1 hour, and the critical drawing ratio and Erichsen value in the soft state were measured. Table 6 shows the results.

Table 6 Formability test results Electrical limit drawing ratio L, D, R-D/d However, d: Punch diameter D: Large trowel blank diameter that can be drawn The dimensions of the cylinder tested for pure deep drawing in Table 3 above are The dimensions of the cylinder on which the overhang diaphragm test was carried out are as shown in FIG. 5.

Furthermore, the results of a one-month corrosion test of the vacuum-heated plate are shown in Table 7 below.

However, the corrosion test conditions were as follows.

CASS test: JIS H-8681 Alternate wet and dry immersion test: After immersing in an aqueous solution containing 3% NaCl, temperature 40°C, pH 3 (adjusted with acetic acid) for 30 minutes, immersion in a dry atmosphere for 50 minutes.
C for 30 minutes, and then repeat the immersion in the NaCl aqueous solution.

Table 7 Corrosion black results [Effects of the invention] As can be seen from Example No. 1, the core material for the core plate of the radiator according to the present invention is made of Moegi's aluminum alloy, so it has a better performance than the conventional core material made of 3003 alloy. It has higher strength and better corrosion resistance.
On the other hand, the repeated bendability is also the same or even better. Therefore, in the repair of the core plate of a radiator, etc., the core plate using the core material of the present invention can be repeatedly caulked, and can also be adapted to thinning of the core plate. Roughly speaking, as is clear from Example No.
Compared to alloys, the strength is the same, but the formability and corrosion resistance are improved, and it is clear that the pitting corrosion resistance is particularly excellent.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view showing the caulking part of the plastic tank of the radiator, Figure 2 is a diagram to explain the repeated bending test method for the core plate material, and Figure 3 is the inverted T-shaped brazing test. Diagrams for explaining the method; (a) is a conceptual diagram of the state before brazing, and (b) is a conceptual diagram of the state after brazing, viewed in the horizontal direction. FIG. 4 is an explanatory diagram of the dimensions of the cylinder subjected to the pure deep drawing test, and FIG. 5 is an explanatory diagram of the dimensions of the cylinder subjected to the overhang test. 1... Core plate material, 2... Plastic tank, 3... Pawl, 4...
・Bending part, 5... Sample, 6... Upper jig, 7...
Lower jig, 8... brazing surface, 9... 3003 alloy plate. Patent applicant Sumitomo Light Metal Industries Co., Ltd. Nippondenso Co., Ltd. Agent Patent attorney Hide Komatsu Agent Patent attorney Hiroo Asahi Figure 1

Claims (2)

[Claims] (1) Mn: 1.0-1.5%, Cu: 0.30-0.
60%, Mg: 0.10-0.50%, Cr: 0.05
~0.35% and Zr: 0.05~0.35%,
The remainder is substantially Al, with impurities, especially Fe and Si.
An aluminum alloy for heat exchangers consisting of an aluminum alloy containing 0.5% or less of each. (2) Mn: 1.0-1.5%, Cu: 0.30-0.
60%, Mg: 0.10-0.50%, Cr: 0.05
~0.35% and Zr: 0.05~0.35%,
Furthermore, Ti: 0.05-0.35% and V: 0.05-0
．． Contains 35% of one or two types, and the rest is substantially Al
Among the impurities, especially Fe and Si are each 0.5
% or less aluminum alloy for heat exchangers.