JPH0230742A - Manufacture of aluminum alloy fin material for brazing - Google Patents

Abstract

PURPOSE:To obtain the title fin material having excellent strength and heat conductivity and having good sagging resistance at the time of brazing with good balance by subjecting an Al alloy ingot having specified Si and Fe to homogenizing treatment, hot rolling and cold rolling under prescribed conditions. CONSTITUTION:An Al alloy ingot contg., by weight, 0.3 to 1% Si and 0.05 to 0.3% Fe is cast. The Al alloy inogot is subjected to homogenizing treatment at <=550 deg.C and is thereafter subjected to hot rolling. The ingot is then subjected to final process annealing including one or more times of process annealing on the way and is thereafter cold-rolled at 15 to 60% rolling rate.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention has good processability when manufacturing heat exchangers for automobiles, that is, radiators, evaporators, condensers, etc., and has little deformation during assembly and brazing heat. Furthermore, the present invention relates to a method for manufacturing an aluminum alloy fin material with excellent thermal conductivity after brazing.

(Prior Art) Since Al has good workability, excellent corrosion resistance, and is lightweight, it has been widely used in heat exchangers for vehicles and various industries in recent years. Among these heat exchangers, for example, a radiator is normally made of a flat tube made of an electric resistance welded tube made of corrugated bare fin material (1) with a thickness of about 0.1 m and a brazing material clad on the outer circumferential surface, as shown in Figure 1. (2) are stacked alternately and fixed to each other by brazing, and both ends of the tube material (2) are attached to a header (3), and a tank (4) is attached to each header (3). Heat exchange is performed by opening both ends of the tube into the tank (4) and passing the heat medium from one tank (4) through the flat tube material (2).

In addition, as shown in Figure 2, condensers and evaporators are usually made by corrugating a plating sheet clad with brazing material and having a thickness of about 0.16 seconds to make a fin material (5), and then forming a flat extruded multi-hole tube (6) into a fin material (5). The tubes are bent into a serpentine shape, fin materials (5) are placed in the gaps between the tubes, and the tubes are brazed and fixed to each other, and heat exchange is performed by passing a heat medium through the multi-hole tube (6).

The fin material used in such Al alloy heat exchangers is conventionally JIS 6951 alloy (0.20~0.50w).
t% (hereinafter simply referred to as %) 3 i −0,15 to 0.
40%CIJ -0,40-0,8%M9-Ai) and J
IS 3003 alloy (0.05~0.20% CLJ-1
, 0 to 1.5% Mn-81), etc., and prevents the occurrence of through-pitting corrosion due to corrosion from the outer surface of tube materials, etc. that form heat transfer passages (external air corrosion). In order to impart a sacrificial effect to the fin materials for the purpose of this, elements such as ln, Sn, and In that make the potential of Al less noble are sometimes added to these fin materials.

The following properties are generally required of the fin material.

■Appropriate strength for processing at room temperature, such as corrugating and assembling with tube material. For this reason, materials that have been work-hardened by cold working are usually used. (For example, H14 treated material of JIS 3003 alloy is 14
(Has a strength of ~18KIf/-) ■The core with the fin material and tube material assembled is restrained with a jig during brazing heating, but since it is held at a high temperature of approximately 600°C, the core may deform. In order to prevent this, the product must have appropriate high-temperature strength.

■Have good thermal conductivity to ensure heat exchange performance.

In the case of bare fin materials, the manufacturing method of such Al alloy fin materials for brazing is usually a process of homogenizing the ingot obtained by casting an Al alloy molten metal with a predetermined composition, followed by rapid hot rolling followed by cooling. It is carried out by sequentially performing inter-rolling → intermediate annealing treatment → final cold rolling.

(Problem to be solved by the invention) However, the bare fin material manufactured in this way has the above-mentioned ■,
It is difficult to say that either of the required characteristics (1) and (2) are sufficient. For example, in recent years, there has been a strong need for automobile heat exchangers to be more compact and lightweight, and to meet this demand, thinner fin materials have been desired. However, when the fin material is made thinner, the cross-sectional area required for heat release decreases, so it is necessary to improve the thermal conductivity of the fin material, but in the case of conventional JIS 3003 alloy, the strength However, the thermal conductivity is lower among Al materials due to the solid solution of Mn added as a component (compared in terms of electrical conductivity, JIS 3003 alloy has a thermal conductivity of 40%).
In the case of pure Al, it was 60% lAC3) compared to AC3, which was a problem.

(Means for Solving the Problems) In view of this, and as a result of various studies, the present invention has developed a method for manufacturing an Al alloy fin material for brazing that has a good balance of both strength and thermal conductivity properties, instead of JIS 3003 alloy. It is.

That is, one of the manufacturing methods of the present invention is to homogenize an Al alloy ingot containing 0.3 to 1.0% Si and 0.05 to 0.3% Fe, with the remainder being Al and inevitable impurities at a temperature of 550°C or lower. After the treatment, hot rolling is performed, and then intermediate annealing is performed at least once during cold rolling, and after the final intermediate annealing, cold rolling is performed at a rolling rate of 15 to 60%. It is something to do.

Another method of the present invention is 3i0.3 to 1.0%
, Fe0.05-0.3% and Z r 0.01-0.
After homogenizing an Al alloy ingot containing 3% Al and the remainder Al and unavoidable impurities at a temperature of 550°C or lower, it is hot rolled and then cold rolled at least once. Perform intermediate annealing, and after final intermediate annealing 15
It is characterized by cold rolling at a rolling reduction of ~60%.

Another method of the present invention is 3i0.3 to 1.0
% and Fe0.05-0.3%, and further contains Zn0
．． 2-2.0%, Sn0.01-0.1%, ■n0.
Contains one or more types selected from oi to 0.1%, and the remainder Af! After homogenizing the /1 alloy ingot, which consists of
It is characterized by performing intermediate annealing twice, and cold rolling at a rolling rate of 15 to 60% after the final intermediate annealing.

Furthermore, another method of the present invention is S0.3-1.
0%, Fe0.05-0.3% and Zr0.01-0.
3% and further Z n0.2-2.0%.

Sn0.01~0.1%, In0.01~0.1%
An Al alloy ingot containing one or more selected from the following and consisting of the remainder Al and unavoidable impurities is homogenized at a temperature of 550°C or less, then hot rolled, and then cold rolled. The process is characterized in that intermediate annealing is performed at least once, and after the final intermediate annealing, cold rolling is performed at a rolling ratio of 15 to 60%.

(Function) First, the reason why the alloy components of the pair fin material are limited as described above will be described below.

The addition of Si has the effect of improving the strength of the fin material,
The content was limited to 0.3% to 1.0%, which was 0.3%.
If it is less than 1.0%, the above effect will not be obtained, and if it exceeds 1.0%, the melting point will decrease, sag during brazing will become noticeable, and the thermal conductivity will also decrease.

The addition of Fe is effective in improving the strength of the fin material, and the content is limited to 0.05% to 0.3%.
If it is less than 0.3%, the above effect will not be obtained, and if it exceeds 0.3%, the grain size will become fine and sag during brazing will become noticeable.

The addition of Zr coarsens the grain size and is therefore effective in improving the strength and sag resistance of the fin material, and is particularly effective in preventing deformation at high temperatures. And its content is 0.01~0
゜3% was limited to 0. If the content is less than 0.3%, the above effect will not be obtained, and if it exceeds 0.3%, the effect will not only be saturated, but also the plastic workability will be reduced.

This is because the addition of Zn, Sn, and In makes the potential of the fin material more base and increases the sacrificial anode action. oi ~0. t%,
The reason why the content is limited to 1 to 0.1% is that below the lower limit, the above effect is not obtained, and above the upper limit, the effect is saturated. Note that these may be added singly or in combination.

Furthermore, such fin materials contain Mn and Cu, which have the effect of reducing conductivity but improving strength.

Mg, Cr, etc. may be added in a total amount of 0.4% or less.

Next, the reason why the method for manufacturing the pair fin material having such components is limited as described above will be described.

Homogenizing the ingot at a temperature of 550°C or lower reduces the segregation of the ingot and reduces the Fe content in solid solution.

This is to precipitate 3i and Zr, and if the temperature exceeds 550°C, the precipitates of Fe, 3i and Zr will become coarse and the sag resistance and high temperature strength of the fin will decrease.

The temperature is preferably 450'C or higher, and the treatment time is preferably 1 to 24 hours.

After the homogenization treatment, hot rolling is carried out according to a conventional method, and the reason for performing at least one intermediate annealing in the subsequent cold working is that the material can be recrystallized, and the appropriate conditions are 360″CX2hr. It is.

In addition, the final cold working rate after the final intermediate annealing is set to 15 to 60%, which gives the material appropriate strength and improves corrugation properties.The core assembly not only prevents buckling when assembled, but also
This is because it has the effect of improving sag resistance during brazing, and if the processing rate is less than 15%, the recrystallization of the fin material will not be completed during brazing heat and sag will become noticeable.
If it exceeds 0%, recrystallized grains during brazing will become fine and high temperature strength will decrease.

Note that the Al alloy according to the present invention is homogenized and used as a core material, and one or both sides of the core material are coated with Aλ-3i series or A, f! -3i -5 to 1 My-based brazing filler metal per side
The method according to the present invention, in which annealing and rolling are carried out under the above-mentioned conditions, can also be used when manufacturing a plating sheet fin material clad with a cladding ratio of 5%.

(Example〕 Next, examples of the present invention will be described.

Example (1) After casting an ingot obtained by casting an Al alloy molten metal having the composition shown in Table 1 by a conventional method, the ingot was subjected to the homogenization treatment shown in Table 2, and then hot-cast at 500'C. Rolled to a thickness of 3.
5. After that, intermediate annealing and cold rolling were performed,
Thereafter, final cold rolling was performed at the rolling rate shown in Table 2 to obtain a final plate thickness of 0.10. A pair of fin materials were prepared.

On the other hand, use a He1 alloy ingot with the composition shown in Table 1 as a core material, apply the same processing conditions as the above pair fin material, and clad both sides of the core material with JIS 4343 alloy brazing filler metal at a cladding ratio of 10%. A fin material was prepared using a plating sheet of 0.16 Mll1.

These paired fin materials and plating sheet fin materials were heated in the atmosphere at 600°C x 10 m1n, which is the brazing condition, and then the tensile strength and electrical conductivity were measured, and the results are shown in Tables 3 and 4. Indicated. Furthermore, as shown in FIG.
) from the edge of the block jig (8) to the fin material (7) made of the paired fin material and plating sheet.
With the other end protruding horizontally with a length of 50 I/lfn, heat it under the conditions of 600'c x 10 min to obtain the sag amount (1), that is, the fin material made of the pair fin material and the plating sheet (7). The amount of sag at the other end was measured, and the average value of the amount of sag for each three pair fin materials of each composition is also listed in Tables 3 and 4.

As is clear from Table 1 and Table 3, all of the pair fin materials produced by the method of the present invention have a tensile strength of 7'Jf/mA after heating, and an electrical conductivity of 52%lAC3 or more. Further, the sag acid content during heating is 18 seconds or less, and has good characteristics.

On the other hand, in comparison method Nα12, the Al alloy composition is JI
Since S3003 alloy is used, the tensile strength and sag amount are excellent, but the electrical conductivity is poor. Comparative methods Nα13 to Nα15 in which the processing conditions deviate from those of the present invention have excellent tensile strength and electrical conductivity, but have extremely large amounts of sag.

Therefore, when manufacturing a heat exchanger using the paired fin material obtained by the method of the present invention, it is possible to significantly improve performance and make it more compact by adjusting the fin shape such as the fin pitch and corrugation height. .

Furthermore, as is clear from Table 4, all of the fin materials made from plating sheets according to the method of the present invention are good in terms of tensile strength, electrical conductivity, and sag acid. On the other hand, the fin material Nα produced by the plating sheet according to the comparative method
It can be seen that No. 32 has poor conductivity, and No. 33 to No. 35 have a significantly large amount of sag.

Example (2) In order to confirm the sacrificial effect of the pair fin material obtained by the method of the present invention, the Al alloy shown in Table 5 was processed under the processing conditions shown in Table 2 to obtain a plate with a thickness of 0. i.

A pair fin material of m was produced. Next, JIS 4343 alloy (7.5%Si-/l) was added to the JIS 3003 alloy core material.
A tube material with a thickness of 0.41M1 consisting of an electric resistance welded tube clad with brazing filler metal at a 10% cladding ratio on the outer periphery and a corrugated fin made by corrugating the above pair fin material were combined, and a fluoride-based flux was used to immerse the tube material in a sieve gas. 600℃
A core in which the fins and tubes, which are part of the radiator, are combined, was manufactured by heating and brazing at a temperature of 10 mm.

In addition, the fin material made from the plating sheet shown in Table 4 was corrugated, sandwiched between the gaps of the meandering extruded multi-hole tube as shown in Figure 2, and the two were bonded together by brazing and heating under the same conditions as above. manufactured the core.

A 720-hour CASS test was conducted on each of the above cores according to JIS H8681 to check whether through-pitting corrosion had occurred in the tube material or not, and the depth of the pits that had occurred in the tube material was measured using the depth of focus method. ,
These results are also listed in Tables 5 and 4, respectively.

In addition, fin material N made by plating sheet according to the comparative method
A core made by corrugating α33 to N0.35 and combining it with a meandering extruded multi-hole tube was crushed when heated by brazing, and could not be subjected to the CASS test.

As is clear from Table 5, the pair fin material produced by the method of the present invention has the same sacrificial effect as the pair fin material produced by the conventional method.

Further, as is clear from Table 4, the sacrificial effect of the fin material by the brazing sheet according to the method of the present invention after brazing is similar to the sacrificial effect of the fin material by the brazing sheet 1 according to the comparative method.

〔Effect of the invention〕

As described above, according to the present invention, the conventional JIS 3003 alloy fin material and the pure Al used for the fins of household air conditioners can be improved.
It is now possible to manufacture a fin material that has a well-balanced combination of both properties, i.e., excellent strength and thermal conductivity, and good sag resistance during brazing, thereby producing a compact heat exchanger with excellent heat exchange performance. As a result, it has remarkable effects such as greatly contributing to the weight reduction and cost reduction of the heat exchanger.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional perspective view showing an example of a radiator;
FIG. 2 is a side view showing an example of an evaporator, and FIG. 3 is a side view showing a sag test method. 1...Pair fin material 2...Flat tube material 3...Header 4...Tank 5... ...Fin material 6...Extruded multi-hole pipe 7...Pair fin material and plating sheet 8...Block jig

Claims (4)

[Claims] (1) Si0.3-1.0wt% and Fe0.05-0
．． After homogenizing an Al alloy ingot containing 3wt% with the remainder being Al and unavoidable impurities at a temperature of 550°C or lower, hot rolling is performed, and then cold rolling is performed at least once. A method for producing an aluminum alloy fin material for brazing, which comprises performing intermediate annealing and cold rolling at a rolling rate of 15 to 60% after final intermediate annealing. (2) Si0.3-1.0wt%, Fe0.05-0.
An Al alloy ingot containing 3 wt% and 0.01 to 0.3 wt% of Zr, with the remainder being Al and unavoidable impurities was heated at 550°C.
After homogenizing at the following temperature, hot rolling is performed, and then at least one intermediate annealing is performed before cold rolling, and after the final intermediate annealing, cold rolling is performed at a rolling rate of 15 to 60%. A method for manufacturing an aluminum alloy fin material for brazing, which comprises rolling. (3) Si0.3-1.0wt% and Fe0.05-0
．． 3 wt%, further Zn0.2 to 2.0 wt%,
Sn0.01~0.1wt%, In0.01~0.1w
After homogenizing an Al alloy ingot consisting of one or more selected from t% and the remainder Al and unavoidable impurities at a temperature of 550°C or less, hot rolling, and then cold rolling. A method for producing an aluminum alloy fin material for brazing, which comprises performing intermediate annealing at least once during rolling, and cold rolling at a rolling rate of 15 to 60% after the final intermediate annealing. (4) Si0.3-1.0wt%, Fe0.05-0.
3wt% and Zr0.01~0.3wt%, further containing Zn0.2~2.0wt%, Sn0.01~0.1w
After homogenizing an Al alloy ingot, which contains one or more selected from 0.01 to 0.1 wt% of In and 0.01 to 0.1 wt% of In and the remainder is Al and inevitable impurities, at a temperature of 550°C or less. An aluminum alloy for brazing, characterized in that it is hot rolled, then subjected to at least one intermediate annealing during cold rolling, and cold rolled at a rolling rate of 15 to 60% after the final intermediate annealing. Method of manufacturing fin material.