JPH0696754B2 - Method for manufacturing aluminum brazing sheet - Google Patents

Description

The present invention relates to a method for producing an aluminum brazing sheet for use in a drone cup type oil cooler, intercooler, evaporator, etc., after being processed by press molding or the like. In addition, the diffusion of the brazing material to the core material side at the time of joining by the brazing heat is reduced, and the brazing property and the corrosion resistance are improved.

[Conventional technology]

The Delon cup type evaporator is shown in Fig. 2 (a).
As shown in (b), press plates (2) and (2 ') formed by press-molding a brazing sheet having a plate thickness of 0.5 to 1 mm are laminated to form refrigerant circulation paths (3) and (3'), and a corrugated gate is formed. It is made by combining with fins (1) and joining by brazing. JIS 3003 alloy or JI for brazing sheet
S 6951 alloy is used as core material, and both sides of JIS 4004 alloy and JI
A brazing material made of S4104 alloy clad with 5 to 15% is used, which is a soft material (O
Material) is widespread.

Such a brazing sheet is manufactured as follows. First, cast a core material, for example JIS 3003 alloy, then 600
Homogenization is performed at a temperature of about ℃. Then brazing material, for example
After casting JIS 4004 alloy, it is hot-rolled to a predetermined plate thickness. This brazing material is clad on both sides of the above core material, and the temperature is 500 ° C.
It is made into an integral three-layer material by hot compression rolling at a temperature of about three.
This is subjected to intermediate annealing and cold rolling at a temperature of 360 to 400 ° C to obtain a final plate thickness, and then finally annealed at a temperature of 360 to 400 ° C to obtain a soft material.

To produce a brazing sheet with excellent press formability, the homogenization temperature is increased, the grain size of the final annealed material is refined, and the cold rolling rate is set to 80% or more to promote the softening and final re-annealing. We are trying to make the crystal grains finer. The recrystallized grain size of the core material is about 50 to 200 μm.

[Problems to be Solved by the Invention]

When a conventional perfect O material is press-molded, a processing strain of 0 to 20% is added, and this strain amount varies depending on the location. this
When the brazing heat is applied to about 600 ° C, the phenomenon that the brazing material diffuses abnormally to the core material side occurs in the low working degree (5-10%) region where recrystallization of the core material does not sufficiently occur Reduce sex. Further, when the thickness of the core material decreases due to the diffusion of the brazing material and preferential corrosion of the brazing material portion occurs due to corrosion, the corrosion resistance life of the core material also shortens in proportion to the reduction in the plate thickness.

A brazing sheet using an Al-Mn-Cu alloy as a core material can use a brazing material as a sacrificial material, but when the brazing material diffusion increases, the sacrificial layer increases but the core material decreases and the corrosion resistance tends to deteriorate significantly. There is a problem.

[Means for Solving the Problems]

The present invention, in view of this, results of various studies, to reduce the brazing material diffusion of the corrosion-resistant brazing sheet with Al-Mn-Cu-based alloy as the core material, a method for producing an aluminum brazing sheet with improved brazing and corrosion resistance. Was developed.

That is, the present invention is at least Mn 0.3 to 2.0 wt% (hereinafter wt% is%
Abbreviated) and Cu of 0.2 to 1.0% as an aluminum alloy as a core material, and in the production of a brazing sheet in which an aluminum brazing material is clad on one side or both sides,
After homogenizing at a temperature above 560 ° C, aluminum brazing material is clad on one or both sides of the core material and subjected to hot rolling, followed by cold rolling at a rolling rate of 20 to 70%,
Finally, the annealing treatment is performed at a temperature of 300 to 480 ° C.

[Action]

In the present invention, the core material composition is basically Mn 0.3 ~ 2.0%
It consists of an aluminum alloy containing 0.2 to 1.0% Cu, and contains Fe 0.7% or less and Si 0.6% or less as impurities. To further improve the strength, Mg 0.5% or less, Cr 0.3% or less, Zr0 0.3% or less, Zn 0.3
% Or less and Ti 0.2% or less, any one kind or more can be added. Also, for the brazing material, Al-for vacuum brazing
JIS 4004 alloy or JIS 4104 alloy is used as the Si-Mg brazing material, and as the Al-Si brazing material for flux brazing.
Use JIS 4343 alloy or JIS 4045 alloy.

Therefore, the reason for limiting the Mn content of the core material in the present invention to 0.3 to 2.0% is that Mn improves the strength and pitting corrosion resistance of the core material, and if the content is less than 0.3%, the effect is not satisfactory. This is because when it exceeds 2.0%, the strength and pitting corrosion resistance are improved, but the plastic workability is significantly reduced. Also, the Cu content is limited to 0.2 to 1.0% because Cu improves the strength and pitting corrosion resistance of the core material as well as Mn, and also makes the potential of the core material noble and protects the core material from the potential difference with the brazing material. However, if the content is less than 0.2%, the effect is insufficient, and if it exceeds 1.0%, not only the effect of potential depletion is saturated, but also the corrosion resistance of the core material itself is increased. This is because it deteriorates.

The present invention, after homogenizing the core material at a temperature exceeding 560 ° C., performs hot rolling by clad an aluminum brazing material on one or both surfaces of the core material, and then cold rolling at a rolling rate of 20 to 70%. It is rolled and finally annealed at a temperature of 300 to 480 ° C to obtain a brazing sheet.

Therefore, in the present invention, the homogenization treatment temperature of the core material is set to 560
The temperature above ℃ was limited in order to prevent the diffusion of the brazing filler metal by promoting the recrystallization of the brazing filler metal when brazing with a medium grain size (200 μm or less). When the temperature is 560 ° C or lower, the grain size becomes large and the recrystallization during brazing is delayed and the diffusion of the brazing material becomes large. Also, the press formability is not good. The holding time is preferably 1 hour or more. In addition, the cold rolling rate after hot rolling is set to 20
The limit of 70% is to have a partially recrystallized structure at the time of the next final annealing treatment, and if processing strain is applied during press working, all parts of the core material during brazing will be combined with the residual strain in the material. This is because it is easy to recrystallize with, and to uniformly reduce the diffusion of the brazing material.If the cold rolling rate is less than 20%, partial recrystallization does not proceed, the elongation of the material decreases and the press formability deteriorates. This is because if the content exceeds 70%, recrystallization of the material will proceed and the low work strain portion during press forming will increase the diffusion of the brazing material due to the additional heat of the brazing material. If the sheet thickness cannot be reduced by hot rolling to achieve the specified cold rolling rate, cold rolling and 360-400
The plate may be finished to a predetermined thickness by repeating intermediate annealing at ℃. However, the cold rolling rate at this time must be 50% or more. The final annealing temperature was set at 300 to 480 ° C to promote the partial recrystallization of the material, which corresponds to the cold rolling rate.
It is necessary to raise the temperature to about 480 ° C, and if the temperature is less than 300 ° C, partial recrystallization does not proceed, the elongation of the material is not secured, and the formability deteriorates.

The present invention can also be applied to the case where one surface is clad with a sacrificial material such as Al, Al-Zn, or Al-Zn-Mg, and the other surface is clad with a brazing material. That is, JIS 4343 brazing material on the outside of the header material of the radiator, Al-Zn system, JIS 7072 on the inside
By using a three-layer material clad with an alloy, the brazing property and corrosion resistance on the outside can be improved, and the sacrificial effect on the inside (water side) can be further enhanced.

[Example] A brazing sheet was manufactured by using the five kinds of core materials shown in Table 1. JIS 4004 alloy was used for the brazing material, and 15% was clad on both sides of the core material, and the plate thickness was 0.5 mm. Table 2 shows the homogenizing treatment, the cold rolling ratio, and the final annealing temperature in the trial manufacture of the brazing sheet.

Using the 10 types of brazing sheets thus prototyped, the moldability was evaluated by the Erichsen test. Ie 90
It was cut into mm squares and subjected to bulging molding with a ball head punch having a diameter of 20 mm based on JIS Z 2247A method, and the molding height when cracks were formed was measured, and the average value of 5 pieces was evaluated.

As shown in Fig. 1, brazing is made from JIS 3003 with a thickness of 1 m.
The brazing sheet (4) was erected vertically on the mother plate (5) of m and joined, and the T-joint fixed with the stainless wire (6) was used to perform brazing heat at 600 ° C. for 3 minutes in vacuum, and its flow coefficient Was measured and evaluated. As the brazing sheet, those processed by cold rolling at a working rate of 0, 5, 10, 15, 20% were used assuming press working of a Delon cup evaporator. For the flow coefficient, the initial brazing filler metal amount (A) was obtained from the cross section, the brazing filler metal amount (B) of the fillet portion after brazing was also obtained from the cross section, and evaluated by the average of three B / A values. The results are also shown in Table 2.

As is clear from Tables 1 and 2, the method No. 1 of the present invention
It can be seen that the brazing sheets according to No. 6 all have the same Erichsen value as the brazing sheets according to the conventional method No. 7, and have the same formability. Conventional method N
In the brazing test according to o.7, in the brazing test in which the processing rate was changed, the diffusion of the brazing material into the core material was increased and the brazing property was lowered at the processing degree of 5 to 10%, whereas the brazing sheet was deteriorated. It can be seen that the brazing sheets according to Nos. 1 to 6 have a small amount of diffusion of the brazing material into the core material and have excellent brazing properties at any processing degree.

On the other hand, the brazing sheet according to Comparative Method No. 8 with a soaking temperature of 550 ° C (× 3 Hr) has a low elongation and a low Erichsen value indicating press formability. The cold rolling rate is 10%
No brazing sheet according to No. 9 and the comparative method No. 10 in which the final annealing temperature is 290 ° C. did not proceed with partial recrystallization,
Erichsen value is small.

〔The invention's effect〕

As described above, according to the present invention, when brazing a brazing sheet whose workability is changed by press molding, diffusion of the brazing material into the core material is reduced, brazing property is stabilized, and corrosion resistance is improved. It is possible to achieve such a remarkable effect in industry.

[Brief description of drawings]

Fig. 1 is a perspective view of a T-joint for measuring a flow coefficient, Fig. 2 (a) and (b) show an example of a Delon cup type evaporator, and (a) is an enlarged perspective view of a main part. ) Is a side view. 1 ... Fins 2, 2 '... Press plate 3 ... Refrigerant circulation path 4 ... Blazing sheet 5 ... Mother board 6 ... Stainless wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location F28F 3/00 301 Z 9141-3L

Claims (1)

[Claims] 1. At least Mn 0.3-2.0 wt% and Cu 0.2-1.0 wt%
% Aluminum alloy as a core material, and in the production of a brazing sheet in which an aluminum brazing material is clad on one or both sides, after homogenizing the core material at a temperature exceeding 560 ° C., one or both sides of the core material Aluminum brazing material is clad, hot rolled, and then rolled
A method for manufacturing an aluminum brazing sheet, which comprises performing cold rolling at 20 to 70% and finally performing annealing treatment at a temperature of 300 to 480 ° C.