JPH0250935A - Brazing sheet made of aluminum for heat exchanger member - Google Patents

Abstract

PURPOSE:To increase strength after brazing in the title brazing sheet and to improve its corrosion resistance by regulating the core material of a brazing sheet made of Al for a heat exchanger member to an alloy having specific compsn. and cladding at least the one face with an Al alloy contg. >=5wt.% Si. CONSTITUTION:In the brazing sheet made of Al, the alloy having the compsn. contg., by weight, 0.4 to 1.2% Si, 0.15 to 1.0% Fe, 0.4 to 1.0% Cu, 0.5 to 1.2% Mn, 0.05 to 0.8% Mg and 0.05 to 3.0% Ni, furthermore contg. either one or more kinds in the range of 0.001 to 0.5% Cr, 0.001 to 0.3% Zr, 0.001 to 1.5% Hf, 0.001 to 0.5% Ti and 0.0001 to 0.1% B and the balance Al with inevitable impurities is regulated to the core material. At least the one face of the core material is then clad with an Al alloy brazer material contg. >=5wt.% Si. As the result, the brazing sheet has well-balanced characteristics such as strength after brazing heating, brazability and repeated bendability and furthermore has good corrosion resistance in particular, by which the thinning and lightening of a heat exchanger are realized.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an aluminum brazing sheet for heat exchanger members, particularly tube materials, header materials, etc., mainly used for brazing heat exchangers. It has improved strength and pitting corrosion resistance.

(Prior art) Many conventional heat exchangers, especially automotive heat exchangers such as fugiators, heaters, oil coolers, air conditioner evaporators, and condensers, are made of A1 alloy.
It is mainly assembled by the wax (T&Pue method).For example, a laminated type evaporator used as an evaporator for oil coolers and air conditioners is shown in Figure 3.The tank plate (9) and fins (10) that are press-formed are shown in the figure. It is assembled by brazing.

JIS 1000 series alloys are used as materials for these heat exchangers.

JIS 3000 series alloy or these alloys as core material A
1-5: A brazing sheet in which a brazing alloy alloy is cratted on one or both sides is used.

In addition, JIS 1070 alloy is used for the inside where cooling water circulates, such as the header material and tube side of the radiator.

JIS 7072 alloy, A, e-Zn-M9 alloy, etc. are clad as a sacrificial anode layer to prevent silk pitting corrosion.

In addition, the header material used for the tank part of the radiator is made mechanically by bending the claws (11) of the header +J (12) through the rubber backing (13) and the resin tank (14) as shown in Figure 4. It's tight. Such header materials are required to have strength and the ability to be re-caulked when repairing the caulked portion if it becomes loose.

(Problems to be Solved by the Invention) In recent years, there has been a demand for thinner heat exchanger members in order to reduce the weight and cost of heat exchangers. Therefore, attempts have been made to develop various alloys. However, materials for heat exchangers, especially those manufactured by brazing methods, are
The strength at approximately 600'C) and the strength after brazing are both high.
There is a need for pipes to have a variety of required performances, such as pitting corrosion resistance after brazing.

Brazing with JIS 3003 alloy, which has been conventionally used for the core material, has low strength after heating, making it difficult to reduce the thickness. Furthermore, when a high-strength JIS B951 alloy is used as a core material, it is highly susceptible to intergranular corrosion, and when used as a header material, re-caulking properties are poor and cracks are likely to occur at bent portions.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has developed an aluminum brazing sheet for heat exchanger members that has good brazing properties, excellent strength and pitting corrosion resistance after brazing.

That is, one of the brazing sheets of the present invention has Si0.4 to
1.2wt% (hereinafter wt% is abbreviated as %).

Fe 0.15-1.0%, Cu0.4-1.0%
, Mn0.5-1.2%, My0.05-0.8%, N
10.05 to 3.0%, and further contains Cr0. OOl ~
0.5%, 7r0.001~O13%, Hto, ooi
~1.5% 2 pieces 0,001~0.5%, 130.00
An A1 alloy brazing filler metal containing one or more types within the range of 01 to 0.1%, with the remainder being Al and unavoidable impurities as a core material, and at least one side thereof containing 5% or more of Si. It is characterized by being clad.

Another one of the brazing sheets of the present invention is Si0.
4-1.2%, Fe0.15-1.0%, Cu
0.4-1.0%, Mn0. , 5-1.2%, M70
．． 05 to 0.8%, Ni 0.05 to 3.0%, and further Or0.001 to 0.5%, Zro
, ool ~0.3%, Hf0.001 ~1.5
%, T i 0.001 ~ 0.5%, B0
, 0001 to 0.1% of any one or two or more types, with the remainder AJ2 and unavoidable impurities as the core + O, and one side of the A1 alloy brazing filler metal containing 5% or more of Si. clad and 50m from the core material on the opposite side.
It is characterized by being clad with an A1 alloy skin material having a base potential of V or more.

[For production]

In the present invention, the composition of the core material is limited as described above.
This is due to the following reasons.

3i is a solid solution in the matrix when brazing is heated, improving strength, and when brazing is cooled after heating and left at room temperature after cooling, extremely fine M9zSl is precipitated together with M7, forming a core material. Improve strength. However, the reason why the 3i content was limited to 0.4 to 1.2% was 0.4%.
This is because if it is less than 1.2%, the strength of the brazing will not be sufficient, and if it exceeds 1.2%, the solidus temperature will be low and there is a risk that the brazing will melt when heated.

"e makes the crystal grains of the core material finer and improves the formability, especially as a header material.It improves the repeated bendability.However, the reason why we limited the Fe content to 0.15 to 10% is
．． This is because if it is less than 15%, the effect is not sufficient, and if it exceeds 1.0%, the corrosion resistance of material H will deteriorate.

Cu forms fine precipitates of the /'1-Cu series, A1-CL)-M9 series, and the wax contributes to strength after heating, and improves corrosion resistance by adjusting the potential of the material. However, the reason why the Cu content was limited to 0.4 to 1.0% was 0.4%.
If it is less than 1.0%, the effect will not be sufficient, and if it exceeds 1.0%, the repeatability will deteriorate and there will be a risk of melting during brazing (brazing).

Mn improves strength, and its content should be increased from 0.5 to
The reason for limiting it to 1.2% is that if it is less than 0.5%, the effect will not be sufficient, and if it exceeds 12%, giant intermetallic compounds will be generated during casting, reducing the ductility of the ÷A material and reducing the repeated bending property. This is to reduce the

During brazing, MJ dissolves into solid solution in the matrix upon heating, contributing to improved strength.Furthermore, when brazing is left at room temperature after heating, fine precipitates of MHz3i are generated, contributing to improved strength. Therefore, My content is 0105~0.8
% because if it is less than 0.05%, the effect will not be sufficient, and if it exceeds 0.8%, the brazing properties will decrease.

Ni is Aj! This produces fine 3Ni precipitates, which improves the strength of the core material and improves corrosion resistance and fatigue strength. However, the reason why the Ni content was limited to 0.05 to 3.0% was 0.0% to 3.0%.
This is because if it is less than 0.05%, the effect is not sufficient, and if it exceeds 3.0%, the repeated bendability will decrease.

Cr, Zr, Hf, Oi, [3 has the effect of making the tJ material group i uniformly fine and improving the material strength without impairing the repeated bendability, and also reduces the potential difference around the grain boundaries due to the precipitation of insoluble compounds. Relaxation improves corrosion resistance. However, the content is Cr 0.001~0.5%, Z
ro,ool ~0.3%.

H-ro, ooi~1.5%, Ti0.001~0.5
%, Bo, oooi to 0.1%.If it is less than the lower limit, the effect will be insufficient, and if it exceeds the upper limit, coarse metal will be formed during casting. This is necessary because the ductility and repeated bendability of the core material decrease due to the formation of intermediate compounds.

In the present invention, at least one side of the core material having the above composition is clad with an A1 alloy braze containing S+5% or more. This is because the temperature is high and sufficient brazing is difficult. Usually, a brazing filler metal containing 5 to 15% Si is used, and in addition, Be is added for the purpose of improving brazing properties.

A small amount of B+, My, etc. may be added. The brazing material is clad on one or both sides of the core material in an amount of 3 to 30%, preferably 3 to 15%, of the total board thickness.

Furthermore, the present invention is to clad one side of the core material having the above composition with an A1 alloy brazing material containing 5% or more Si, and clad the other side with an A1 alloy skin material having a potential 50 mV or more more base than the core material. Can be done. By crating the A1 alloy, which has a lower potential than the core material, this alloy layer acts as a sacrificial layer for cathodic protection and protects the core material. This is because the potential difference should be kept at 50 mV or more, but a sufficient effect cannot be obtained if it is less than 50 mV. Note that this sacrificial layer is preferably clad in a range of 1 to 20%, preferably 2 to 10% of the total board thickness.

The brazing sheet of the present invention has the above-mentioned structure.Flux brazing is done by the method, inert gas atmosphere brazing is done by the method, vacuum brazing is done by the method, and various brazing methods are used for radiator header material, tube material, evaporator, play 1. It can be used as a brazing sheet for heat exchanger members such as materials.

〔Example〕

Example (1) An alloy having the composition shown in Table 1 was cast by DC casting to a thickness of 70M.
Width 300. An ingot of
After homogenizing at 80°C for 3 hours, J
IS 4004 alloy (A, l!-3i alloy) brazing filler metal,
Cladding is applied to 15% of the total plate thickness on one side, and the thickness is 0.6mm by hot rolling and cold rolling. It was made into a plate material. This was subjected to finish annealing at 400'C for 2 hours to produce a brazing sheet. The core material in Table 1 was JIS 3003 alloy, and the core material in U was JIS 6951 alloy.

This brazing sheet was press-formed, assembled, and brazed into a plate 1 for a laminated evaporator having the shape shown in FIG. 3 as a material. An internal pressure of 0 to 151 fgf/- was repeatedly applied to this evaporator, and the number of repetitions until leakage occurred was measured. As a corrosion resistance evaluation, the core was subjected to a CASS test and the maximum pitting depth was measured after 200 hours. Brazing was carried out by heating to 610°C for 5 minutes under a vacuum of 5 x 10-5 Torr. Tensile tests were conducted on materials that had been annealed A and were left at room temperature for 10 days after brazing. The results are not shown in Table 2.

As is clear from Tables 1 and 2, compared to the brazing sheet Nos. 1 to 10 of the present invention, the comparative brazing sheet N is out of the range of core material composition of the brazing sheet of the present invention.
o, 11 to 19 and conventional brazing sheet No. 2
0.21 indicates that brazing is inferior in any one or more of the following properties: strength after brazing, repeated pressure fracture resistance, and corrosion resistance. Note that the comparative brazing sheet Nα11 melted under brazing heat, and the annealed sheets of No. 12.15°17 and No. 19 had poor press workability and could not be formed into the shape of an evaporator.

Example (2) An alloy having the composition shown in Table 1 was cast by DC casting to a thickness of 70#.
Width 300. An ingot of
After homogenizing at 80'C for 3 hours, J
IS 4045 filler material (Au-3i alloy) is used as a skin material on the other side, and JIS 7072 filler material is used as a skin material on the other side, each cladding is 10% of the total plate thickness, and hot rolled and cold rolled. A plate material with a thickness of 1M was obtained. This was subjected to finish annealing at 400°C for 2 hours to produce a brazing sheet. In addition, the middle and lower parts of Table 1 are JIS 300.
JIS 6951 excess was used as the core material for U.

Using these brazing sheets as test materials, we measured the mechanical properties of annealed materials, brazed materials after heating, and brazed materials that were left at room temperature for 10 days after heating. evaluated. These results are shown in Table 3.

Brazing properties are evaluated using the core vJ' as shown in Figure 1 (a).
(1) (7) Brazing sheet clad with IIS 7072 alloy skin material (3) on the bottom surface and JIS 4045 brazing filler metal (2) on the top surface (width 30#1I11.Length 50
#) At the center of the upper surface of the JIS 3003 alloy plate (4) (
A stainless steel wire (5) with a diameter of 3 Irun was interposed at one end and fixed vertically. After pre-treatment, a fluoroaluminum thins suspension was applied and dried for 610 minutes in a N2 gas atmosphere.
Brazing was performed at C for 5 minutes, and the gap filling length (×) of the brazing material was measured as shown in FIG. 1(b). In this test, a gap filling length of 15# or more was judged to be good.

Corrosion resistance evaluation is 50 in width and 100 in length. After brazing the brazing sheet for 5 minutes at 610'C in a N2 gas atmosphere, seal the JIS 4045 alloy brazing material surface and end surface, and apply CAS to the JIS 7072 alloy skin surface.
An S test was conducted to measure the maximum pitting depth after 500 hours. In addition, after removing the brazing material and skin material from the heated brazing sheet, the natural potential of the core material was measured in a 5% NaC +2 aqueous solution (25° C.) using a saturated calomel electrode as a reference.

In addition, the re-caulking property was evaluated at 610'C in a N2 gas atmosphere.
Brazing was performed for 5 minutes using a heated brazing sheet with a width of 30# and a length of 200#, and a repeated bending test was conducted.

That is, as shown in FIG. 2(a), the brazing sheet (7) is placed on a right triangular concave jig (6), and the
As shown in Fig. 2(a), press the right triangular convex jig (8) and bend it 90 degrees, and then return it to the straight state as shown in Fig. 2(a). Repeat this process until cracks appear. The number of times was measured. In the test, brazing was carried out immediately after heating and on those left at seedling temperature for 10 days after 7JO heating.

Tests were also conducted with the wax phase open and in contact with the concave surface of the jig.

As is clear from Tables 1 and 3, the brazing sheets No. 22 to Si of the present invention have a JIS 300 core material.
Conventional brazing sheet N using 3 alloys.

Compared to conventional brazing seams 1 to 42, which use JIS 6951 alloy for the core material, brazing has excellent properties such as strength after heating, brazing resistance, and repeated bendability in a well-balanced manner, and especially corrosion resistance. It turns out it's much better.

On the other hand, the core of the brazing sheet of the present invention (comparative brazing sheets 1 to 1 which are outside the range of composition A) is inferior in properties of one or more of the following.In other words, the comparative brazing sheet with a high Ni content Nα33.CIJ content Comparative brazing sheet No. 1 to No. 36 with a high content of Mn, all of which have poor repeated bending properties, and comparative brazing sheet No. 34 with a high content of Fe.
has poor corrosion resistance.

Also, comparative brazing sheet No. with high MSJ content,
No. 40 is not only inferior in repeated bending properties and gap-filling length brazing properties), but also inferior in corrosion resistance. Furthermore, comparative brazing sheet No. 35 with a high Cu content and comparative brazing sheet No. 39 with a low M9 content both have inferior strength. Comparative brazing sheet No. with high S1 content,
In No. 32, the core material melted during brazing during heating.

〔Effect of the invention〕

As described above, the brazing sheet of the present invention has a good balance of brazing strength after heating, brazing properties, repeated bendability, etc., and has particularly good corrosion resistance, making it possible to make heat exchangers thinner and lighter. It has a remarkable industrial effect.

[Brief explanation of the drawing]

Figure 1 (ah) (b) is an explanatory diagram of the gap filling test method for brazing material for evaluating the properties of brazing, and (a) is before brazing, (
b) shows after brazing. Figure 2(a). (b) is an explanatory diagram of a repeated bending test method for evaluating re-caulking properties, with (a) showing before bending and (b) showing after bending. FIG. 3 is a front view of the stacked evaporator, and FIG. 4 is a cross-sectional view showing the main part of the caulking part of the radiator tank. 1. Core material A1 Alloy soldering A1 Alloy leather fence JIS 3003 Alloy plate Stainless wire spacer Concave jig Brazing sea 1~ Convex jig Tank plate 1~ Fin radiator header (A claw radiator header material Rubber backing resin tank Diagram (a) Figure (b)

Claims (2)

[Claims] (1) Si0.4-1.2wt%, Fe0.15-1.
0wt%, Cu0.4-1.0wt%, Mn0.5-1
．． 2wt%, Mg0.05-0.8wt%, Ni0.0
Contains 5 to 3.0 wt%, and further contains Cr0.001 to 0.5
wt%, Zr0.001-0.3wt%, Hf0.00
1-1.5wt%, Ti0.001-0.5wt%, B
An Al alloy brazing material containing one or more of the above in the range of 0.0001 to 0.1 wt%, with the remainder being Al and unavoidable impurities as a core material, and at least one side thereof containing 5 wt% or more of Si. An aluminum brazing sheet for heat exchanger parts characterized by being clad with. (2) Si0.4-1.2wt%, Fe0.15-1.
0wt%, Cu0.4-1.0wt%, Mn0.5-1
．． 2wt%, Mg0.05-0.8wt%, Ni0.0
Contains 5 to 3.0 wt%, and further contains Cr0.001 to 0.5
wt%, Zr0.001-0.3wt%, Hf0.00
1-1.5wt%, Ti0.001-0.5wt%, B
A1 containing one or more types within the range of 0.0001 to 0.1 wt%, with an alloy consisting of the remainder A1 and unavoidable impurities as a core material, and one side thereof containing 5 wt% or more of Si.
Clad the alloy filler metal, and 5mm from the core material on the opposite side.
An aluminum brazing sheet for a heat exchanger member, characterized in that it is clad with an Al alloy skin material having a base potential of 0 mV or more.