JPH03162543A - High strength brazing sheet for al heat exchanger structural member - Google Patents

Abstract

PURPOSE:To offer the brazing sheet showing high strength and excellent corrosion resistance after brazing by specifying the compsn. of each Al alloy forming a core material, a surface material and a brazing filler metal. CONSTITUTION:The compsn. of a core material is regulated to the one constituted of, by weight, 0.1 to 0.3% Si, 0.2 to 0.5% Fe, 0.45 to 0.7% Cu, 0.8 to 1.5% Mn and the balance Al with inevitable impurities. Either face of the core material is clad with a surface material of an Al alloy contg. 0.55 to 1.5% Mg and 0.35 to 0.6% Zn, and the other face of the core material is clad with a brazing filler metal of an Al alloy contg. 7.5 to 11% Si and 0.3 to 1.5% Mg to form a brazing sheet for an Al heat exchanger structural member. In this way, good corrosion resistance and sufficient strength can be obtd. and its thinning can be attained. If required, one or 2 kinds of 0.05 to 0.2% Cr and 0.05 to 0.2% Zr are furthermore incorporated into the core material, and 0.05 to 0.15% Bi is moreover incorporated into the brazing filler metal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides high-strength materials suitable for use as structural members such as pipe materials and header plate materials when manufacturing Aff heat exchangers by vacuum brazing. The present invention relates to a brazing sheet that has the following characteristics and also has excellent corrosion resistance.

[Conventional technology]

Previously, the same applicant filed Japanese Patent Application No. 88753 (1987) (
JP-A No. 82-227058), in weight% (
% indicates weight %), Cu: 0.3 to 1%, Mn: 0.
8-1. 5%, Zr: 0.05 to 0.2%, and the rest is Al and unavoidable impurities.
．． 2 ~ 0.5%, Zn: 0.1 ~ 0.3%,
A skin material made of an Al alloy having a composition containing An! with the remainder consisting of Al and unavoidable impurities, and on the other side of the core material, An! An application has been filed for a brazing sheet for Al heat exchanger structural members, which is clad with a brazing filler metal made of -Si-based alloy.

[Problem to be solved by the invention]

On the other hand, as various vehicles have become faster, smaller, and lighter in recent years, there is a tendency for the structural members of the /'47 heat exchangers that make up these vehicles to be thinner. Although aluminum alloys exhibit good corrosion resistance, they do not have sufficient strength, and at present it is not possible to achieve a satisfactory thickness reduction in this respect.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors focused on the above-mentioned conventional plating sheet, and improved its strength.
As a result of research aimed at further improving corrosion resistance, we found that the core material that makes up the plating sheet has a SI: 0.1 to 0.3% and a Fe content of 0.2 to 0.
．． 5%, Cu: 0.45 to 0.7%, Mn: 0.
11 to 1.5%, and optionally further contains Cr:o. 05-0.2%, Zr: 0.
0 5 ~ 0. 2% or two of Mg:0, and the remainder is Afl and unavoidable impurities, and the skin material clad on one side of the core material is made of .55 to 1.5%, Zn: 0.35
~0.6%, with the remainder consisting of Al and unavoidable impurities, and a brazing filler metal clad on the other side of the core material, S1:7.5~11 %, Mg: 0.3-1.5
%, and if necessary, B1: 0.05 to 0.15%, and the remainder is l? The resulting plating sheet has high strength and excellent corrosion resistance, and when used as a structural member of an IJ heat exchanger, This not only makes it possible to make the wall thinner, but also allows it to exhibit excellent performance over a long period of time.

This invention has been made based on the above knowledge, and the reason why the compositions of the Al alloys constituting the core material, skin material, and brazing material of the plating sheet are limited as described above will be explained below. do.

A, core material (a) 31 The Sl component combines with Aj) and Mn to form an A,Q-Mn-St-based compound that is finely dispersed in the base material,
It has the effect of improving the strength of the core material, but its content is
, L%, the desired strength improvement effect cannot be obtained, and on the other hand, if the content exceeds 0.3%, corrosion resistance will decrease, so the content should be set at 0.1 to 0.3%. Established.

(b) Fe Similar to S+, the Fe component forms fine /J-Fe compounds and has the effect of improving the strength of the core material, but if its content is less than 0.2%, the desired strength cannot be achieved. High strength cannot be obtained,
On the other hand, if the content exceeds 0.5%, the corrosion resistance will similarly decrease, so the content should be increased from 0.2 to 0.
It was set at 5%.

(c) Cu The Cu component solidly dissolves in the base material and makes the potential of the core material noble, and this is maintained even after vacuum brazing, so the core material becomes nobler than the skin material and brazing material. As a result, the surface of the plating sheet acts as a sacrificial anode material, which protects the core material from corrosion, and particularly improves the pitting corrosion resistance of the core material. If the content is less than 45%, the desired effect cannot be obtained; on the other hand, if the content is 0.
．． If it exceeds 7%, local corrosion such as intergranular corrosion is likely to occur in the core material, so the content should be reduced to 0.45 to 0.7%.
It was determined that

(d) Mn The Mn component not only improves high-temperature strength and prevents deformation during brazing, but also suppresses the penetration of brazing metal into the core material during brazing, thereby preventing a decrease in the corrosion resistance of the core material. However, if the content is less than 0.8%, the desired effect will not be obtained, while if the content exceeds 1.5%, the processability will decrease. Its content is 0
．． It was set at 8-1.5%.

(e) Cr and Zr These components have the effect of further improving high-temperature strength and preventing penetration of brazing filler metal when coexisting with Mn, so they are included as necessary. If the content is less than 0.05%, the desired effect of improving the above action cannot be obtained;
If it exceeds 2%, workability will be impaired, so the content of Fiut should be reduced to Cr20. 05 ~0
．． 2%, and Zr: 0.05 to 0.2%.

B. Skin material (a) Mg Mg component has the effect of improving corrosion resistance by being dissolved in the base material, but if its content is less than 0.55%, the desired corrosion resistance cannot be secured; Content is 1.5
If the content exceeds 0.55%, the amount of evaporation during brazing will increase rapidly and cause furnace contamination.
It was set at 1.5%.

(b) Zn The Zn component has the effect of forming a solid solution in the base material and making the corrosion form completely soluble, thereby suppressing the occurrence of pitting corrosion, but if its content is less than 0.35%, the desired resistance cannot be achieved. Pitting corrosion cannot be ensured, and even if the white content exceeds 0.6%, pitting corrosion will easily occur again, so the white content should be reduced to 0.
．． It was set at 35-0.6%.

C. Brazing filler metal (a) Si Si To some extent, the melting degree of the filler metal is lowered and a predetermined fluidity is imparted to the filler metal at a brazing temperature of usually about 600°C to form a sound brazed part. However, if the content is less than 7.5%, the liquid phase ratio near the brazing temperature will be low and sufficient fluidity will not be obtained, while the same will occur if the content exceeds 11%. In addition, the fluidity decreases and the composition becomes hypereutectic, and the primary Sl grains become coarser, reducing workability.
．． It was set at 5~U%.

(b) Mg Mg evaporates from the surface of the filler metal during brazing,
By combining with oxygen in the atmosphere, the so-called getter effect increases the actual degree of vacuum in the atmosphere, suppresses the growth of an oxide film on the surface of the brazing material, and thereby improves brazing properties. If the content is less than 0.3%, the desired effect cannot be obtained, while if the content exceeds 1.5%, the amount of evaporation of Mg will be too large and cause furnace contamination. The amount was determined to be 0.3-1.5%.

(e) BI Bl has the effect of further lowering the melting point of the brazing filler metal and further increasing the fluidity of the brazing filler metal, so it is included as necessary, but its content is less than 0.05%. However, if the content is 0. If i exceeds 5%, corrosion of the wax core material during brazing will be accelerated, so the content was set at 0.05 to 15%.

〔Example〕

Next, the praising seat of the present invention will be specifically explained using examples.

Al alloys 1 to 19 for core material, Al alloys A to 19 for skin material, and Al alloys a to g for brazing material, each having the composition shown in Table 1, were melted by a normal melting and casting method. After producing and casting an ingot, and subjecting this ingot to face milling and homogenization heat treatment under normal conditions, Al alloys 1 to 1 for core material are prepared.
19' has a board thickness of 8m1 and is for leather material. J alloy A-H'
Al alloys a to g for brazing metal are each hot-rolled to 3III1, and the hot-rolled sheets of Al alloys A-H' for skin material and Al alloys a to g for brazing metal are cold worked to form plates. Thickness: 1m scratch, these plate thickness: 8 inch Al alloy for core material 1
~19' hot-rolled plate and plate thickness: 1mm A47 for skin material
Using cold-rolled plates of alloys A to H' and Al alloys a to g for brazing metal, these plates were stacked with the core material sandwiched between them according to the combinations shown in Table 2, and hot rolled. After cladding, by performing cold rolling (final rolling ratio = 30%) while appropriately applying intermediate annealing, the present invention plating sheets 1 to 12 and comparative plating sheet 1, each having a plate thickness of 0.3 mm, were prepared. ~10 were produced, respectively.

Comparative plating sheets 1 to 10 are Al alloys for core materials 13' to 13' in which a certain amount of ffl (marked with * in Table 1) of any of the constituent components is outside the scope of the present invention.
19' and/or AD'alloys F' to H' for skin materials, respectively.

Next, from these various plating sheets, a tensile test piece with the dimensions of parallel part length: l (lmm) x total length: 5 (lm3) and plane size L: 50mm x 70m
m corrosion test pieces were cut and these test pieces were subjected to conditions corresponding to the vacuum brazing conditions, i.e. I
After heat treatment under the conditions of holding the temperature at 600° C. for 5 minutes in a vacuum atmosphere of RR, it was subjected to a test.

The corrosion test was conducted using C(1~: 100ppm, SO4
': loOppm, HCO-: 100ppII
Corrosion at 80°C containing 1 ppm of Cu2 was carried out under the conditions of immersion for 30 days in a 30-day solution, and after the test, the corrosion loss and maximum pitting depth were measured with the corrosion products removed. The selection results are shown in Table 2.

〔Effect of the invention〕

From the results shown in Table 2, the plating sheets 1 to 12 of the present invention all exhibit high strength and excellent corrosion resistance after brazing, whereas the comparative plating sheets 1 to I
As seen in O, if the content of any of the Al alloys of the core material and skin material that constitutes this is out of the scope of this invention, at least one of the strength and corrosion resistance is inferior. It is clear that

As mentioned above, the plating sheet of the present invention has high strength, so when it is applied as a structural member of an Al heat exchanger, it can be made sufficiently thin and has excellent corrosion resistance. Therefore, it has industrially useful properties, such as exhibiting excellent performance over an extremely long period of time.

Claims (3)

[Claims] (1) Si: 0.1-0.3%, Fe: 0.2-0.5
%, Cu: 0.45-0.7%, Mn: 0.8-1.5
%, with the remainder consisting of Al and unavoidable impurities.
A skin material made of an Al alloy having a composition containing Zn: 0.55 to 1.5%, Zn: 0.35 to 0.6%, and the remainder consisting of Al and unavoidable impurities, and the above core material. On the other side, there is a solder made of an Al alloy containing 7.5 to 11% of Si, 0.3 to 1.5% of Mg, and the remainder consisting of Al and unavoidable impurities (weight percent). High-strength brazing sheet for structural members of Al heat exchangers, made of cladding material. (2) Si: 0.1-0.3%, Fe: 0.2-0.5
%, Cu: 0.45-0.7%, Mn: 0.8-1.5
%, and further contains Cr: 0.05-0.2%, Zr: 0.05-0.2%
Mg:0.
Al containing 55 to 1.5%, Zn: 0.35 to 0.6%, and the remainder consisting of Al and inevitable impurities.
A skin material composed of an alloy, and the other side of the core material, contains Si: 7.5 to 11%, Mg: 0.3 to 1.5%, and the remainder consists of Al and inevitable impurities. A high-strength brazing sheet for an Al heat exchanger structural member, which is clad with a brazing filler metal made of an Al alloy having the following composition (the above weight %). (3) Si: 0.1-0.3%, Fe: 0.2-0.5
%, Cu: 0.45-0.7%, Mn: 0.8-1.5
%, with the remainder consisting of Al and unavoidable impurities.
A skin material made of an Al alloy having a composition containing Zn: 0.55 to 1.5%, Zn: 0.35 to 0.6%, and the remainder consisting of Al and unavoidable impurities, and the above core material. On the other side, Si: 7.5-11%, Mg: 0.3-1.5%, Bi
: 0.05 to 0.15%, and the remainder is Al and unavoidable impurities. Strength brazing sheet. (4) Si: 0.1-0.3%, Fe: 0.
2-0.5%, Cu: 0.45-0.7%, Mn: 0.
8 to 1.5%, furthermore, Cr: 0.05 to 0.2%, Zr: 0.05 to 0.2%
Mg:0.
Al containing 55 to 1.5%, Zn: 0.35 to 0.6%, and the remainder consisting of Al and inevitable impurities.
A skin material made of an alloy, and on the other side of the core material, Si: 7.5-11%, Mg: 0.3-1.5%, Bi
: 0.05 to 0.15%, and the remainder is Al and unavoidable impurities. Strength brazing sheet.