JPH01234542A - Aluminum clad fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To provide the title fin material with excellent buckling resistance to the heating for brazing and high heat conductivity by regulating an Al alloy contg. specific amounts of Mn, Fe and Si and contg. specific numbers or above of secondary phase grains in the structure at the time of heating to the core and cladding Al or an Al alloy thereto. CONSTITUTION:The core of a composite fin material is formed with an Al alloy contg., by weight, 0.6-2.0% Mn, 0.05-0.8% Fe and <=0.6% Si. The core contains, per mm<3>, 30X10<9> pieces or above of secondary phase grains in the structure when heated for 10min at 610 deg.C. An Al surface material having >=99.9% purity or an Al alloy surface material contg. 0.03-0.35% Zr is clad to the one face or both faces of the core to form the clad fin material for a heat exchanger. By this method, excellent sagging resistance and high-temp. buckling resistance can be obtd. and a fin can be thinned.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fin material for an aluminum heat exchanger that is assembled by brazing, and more specifically, it exhibits excellent buckling resistance during brazing heat exchange and The present invention relates to a fin material for an aluminum heat exchanger that has high thermal conductivity and is suitable for improving heat exchange efficiency (cooling efficiency).

(Prior art) Aluminum heat exchangers, which are generally assembled by brazing, consist of passages (hereinafter referred to as tubes) through which a refrigerant such as water passes, and fins that absorb or dissipate heat. Depending on the application, extruded flat multi-hole tubes, press-formed plates made of pre-zinc sheets clad with Al-Si brazing material as a skin material, or electric resistance welded flat tubes are used. Further, as the fin material, a plating sheet in which both sides of a core material 1 are clad with a skin material 2, as shown in FIG. 1, or a bare fin material (bare material) without cladding with a skin material is used.

A specific example of a brazed aluminum heat exchanger is shown in FIGS. 2 and 3. Fig. 2 shows a Doron cup evaporator, in which press-formed plates 3 made of plastic and single sheets are stacked to form a tube, and corrugated fins 4 made of bare material or plastic sheets are stacked on top of each other to form a tube.
It is a combination of Figure 3 (A) shows an evaporator, which is a combination of an extruded flat multi-hole tube 13 and a corrugated fin 14 made of a plating sheet, and Figure 3 (B) shows a condenser, which is a combination of an extruded flat multi-hole tube 13 and a corrugated fin 14 made of a plating sheet. The corrugated fins 24 are combined, and the figure (c) shows a radiator, in which an ERW flat tube 33 (on the outside of the tube filler metal comes) and bare fin material 3
It is combined with 4. The tubes and corrugated fins of these heat exchangers are assembled by flux brazing, vacuum brazing, or inert gas atmosphere brazing at a temperature of about 600°C.

By the way, in conventional aluminum heat exchangers assembled by brazing, Al-Mn alloys with relatively good buckling resistance are used as fin materials, such as JIS 3003 alloy (Al ~0.05 ~ 0.20 wt). %Cu-1
,0~1.5 wt%Mn alloy [hereinafter wt% is simply %
]) or JIS3203 alloy (A-1,0-1
．． 5% Mn alloy) as the core material, and A-3i on both sides.
Alloy brazing filler metal (A4-5 to 12% Si alloy), Al-3,
i-Mg alloy brazing filler metal (Au-5~12%5i~0.
5-2% Mg alloy) etc. with a thickness of 0.1-0.
2mm thread sink sheet or thickness 0.1~0.2m
A bare material made of the above-mentioned 3003.3203 alloy of m is used.

On the other hand, in recent years, heat exchangers, especially those for automobiles, have become lighter and more compact, and there is a need for thinner fins and improved heat exchanger performance, that is, improved heat exchange efficiency (cooling capacity). It's coming.

Therefore, there is a desire to develop a fin material that does not deteriorate in high-temperature buckling resistance even when thinned and has excellent thermal conductivity.

Incidentally, buckling during brazing heating is a problem that has arisen as fin materials become thinner, and many studies have been made in the past regarding buckling of laminated material fins. As a result, it was revealed that the brazing components diffuse into the core material during brazing addition heat, which causes buckling.As a countermeasure, recrystallization is completed before the brazing material melts and becomes coarse. The use of core materials that produce recrystallized grains is being practiced.

(Problem to be Solved by the Invention) However, although fin materials made of Al-M n-based alloys such as JIS 3003 alloy and 3203 alloy have relatively excellent buckling resistance, they do not have sufficient buckling resistance when made thin. Moreover, it cannot be said that the thermal conductivity is necessarily high, and therefore, when this fin material is used, it causes poor heat dissipation of the heat exchanger.

In addition, alloy fin materials with compositions close to pure aluminum have been proposed in recent years to improve thermal conductivity, but such alloys have low high-temperature strength and poor buckling resistance (
The fins tend to deform during brazing heat, making it difficult to reduce the thickness of the fins.

Therefore, it is an object of the present invention to produce aluminum that has excellent buckling resistance (sagging resistance) during brazing heat addition even when the wall thickness is reduced, and also has high thermal conductivity and can improve the thermal efficiency of heat exchangers. Our goal is to provide fin materials.

(Means for Solving the Problems) In order to solve the above problems, the present inventors conducted various studies focusing on the mechanism of buckling at high temperatures. I found out what was happening.

(1) Non-uniform strain distribution that occurs during corrugation molding of the fin material affects recrystallization behavior during brazing heating, resulting in a non-uniform recrystallization state and impairing buckling resistance. (For relatively thick fin materials, slight changes in recrystallization behavior do not impair buckling resistance.) (2) Fin buckling begins to occur at temperatures around 250°C, where recrystallization begins, and Until the temperature at which the crystallization ends.

(3) Furthermore, when the fin material is heated to a temperature of about 560° C. or higher, buckling occurs even if recrystallization is completed (even if there is no diffusion of the brazing material components). This corresponds to a kind of high-temperature creep phenomenon.

Therefore, as a result of further intensive research, the present inventors found that A.
The buckling resistance can be improved by limiting the composition of the l -M n-based alloy and making the material so that it has a predetermined number or more of second phase particles at the brazing temperature. The core material is aluminum or Zr0 with a purity of 99% or more.
．． It was discovered that an aluminum composite fin material clad with an aluminum alloy containing 03 to 0.35% as a skin material meets the above objectives (having buckling resistance and high thermal conductivity), and based on this knowledge, the present invention was developed. It has been completed.

That is, the present invention has the following properties: 1. Mn 0.6-2.0%, Fe 0.
05-0.8%, A containing 0.6% or less of Si
I-M n-based alloy, when heated at 610°C for 10 minutes, the second phase particles are generated in the structure at 30X per mm3.
An aluminum composite fin material for a heat exchanger, characterized in that the core material is an aluminum alloy containing 10" or more, and one or both sides of the core material is clad with an aluminum skin material with a purity of 99% or more, and 2 , Mn 0.6-2
．． A containing 0%, Fe 0.05-0.8%, Si 0.5% or less! ;L-M n-based alloy, 61
When heated at 0°C for 10 minutes, 1 second phase particle was added into the tissue.
The core material is an aluminum alloy having 30x109 or more per mm", and Zr0.0:l is applied to one or both sides of the core material.
This is an aluminum composite fin material for a heat exchanger, characterized in that it is clad with an aluminum alloy skin material containing ~0.35%.

In other words, the present invention is an aluminum composite fin material in which an alloy with excellent buckling resistance is used as a core material, and this is clad with a skin material with excellent thermal conductivity.

The reasons for limiting the components and their content in the core material used in the fin material of the present invention are as follows.

The Mn content in the core material of the fin material of the present invention is from 0.6 to
It shall be 2.0%. Mn improves the strength of the alloy. Furthermore, A-stand-Fe-Mn, A-stand-Mn-3i or Al-
It produces Fe-Mn-3i-based crystallized or precipitated phases, and when properly controlled, has the function of improving buckling resistance.

If the amount of Mn added is less than 0.6%, the effect is small;
If it is added in an amount exceeding 2.0%, giant crystallized substances tend to form, impairing the formability of the fin.

The amount of Fe added is 0.05 to 0.8%.

Fe is A l-F e -M n or A l -F
producing a crystallized or precipitated phase of e-Mn-Si system,
When these are properly controlled, it has the effect of improving buckling resistance. Furthermore, Fe itself has the function of increasing high temperature strength and improving buckling resistance. Fe addition amount is 0.0
If it is less than 5%, the above effect will not be achieved, and if it exceeds 0.8%, the amount of crystallized or precipitated phases will increase, resulting in decreased formability and difficulty in corrugating.

The amount of Si added is 0.6% or less. Si is An-Fe
-Has the function of promoting the precipitation of a Mn-3i-based precipitate phase. If it exceeds 0.6%, the melting point of the alloy will decrease and the high temperature strength will decrease.

In the core material of the fin material of the present invention, elements other than the above are:
For example, in order to refine the ingot structure, Ti of 0.05% or less is used.
or B can be added. In addition, In (0,05~
0.2%), Sn (0.01~0.1%), Zn
(0.3 to 2%) may be selected to add one or more kinds. In order to further increase the strength, Cu (0.2% or less), Zr (0.2% or less)
, Cr (0.3% or less), N1 (0.6% or less), etc. may be added. Addition of such elements does not affect the characteristics of the fin material of the present invention unless the distribution state of the second phase particles is outside the range described below.

Next, the core material of the fin material of the present invention is a material that contains 30×10 9 or more second phase particles per 1 mm 3 in its structure when heated at 610° C. for 10 minutes. The second phase particles refer to intermetallic compound particles present in the aluminum alloy, and are crystallized phases separated by rolling or precipitated phase particles precipitated during homogenization treatment or annealing. The particle size is in the range of 0.001 to 3 mm, more specifically, most of the crystallized phase is in the range of 0.5 to 3 mm, and the precipitated phase is in the range of 0.001 to 3 mm.
, ooi~0.5J. These second phase particles have a large effect on buckling behavior, and if the amount is 30 x 109 particles per mm or more when heated at 610 °C for XIO minutes,
Reduces the sensitivity of processing degree to buckling behavior of fin material. In other words, by corrugating, even if the amount of strain is uneven, it will not be affected by it, and buckling will not occur due to it.

In addition, the second phase particles have the effect of reducing buckling that occurs as recrystallization progresses, but 30X10 particles per 1 mm3
If the number is less than 9, the effect is not sufficient.

Furthermore, the core material of the fin material of the present invention has a
It shows relatively large recrystallized grains around 0°C. This is due to the effect of interfering with recrystallization by the precipitated phase, which results in secondary buckling that occurs at temperatures around 560°C (corresponding to high-temperature creep characteristics, the smaller the grain size, the easier it is to deform). and does not cause buckling due to diffusion of wax from the tube material.

The distribution of second phase particles in the core material is measured using a transmission electron microscope. That is, the film thickness of the sample to be measured is determined using an isometric stripe, and the area in each field of view and the number of second phase particles therein are measured and determined. The number of particles may be measured after the fin material is manufactured, but since the processed material from which the fin material has been manufactured has many dislocations and it is difficult to distinguish the second phase particles, the fin material is heated under brazing conditions. Heating (e.g. 1 at 610°C)
It is preferable to heat the sample for 0 minutes) and then cool it to room temperature and measure at room temperature. In the case of the fin material of the present invention, the additional heat of brazing is 600
Since the process is carried out at a high temperature around °C, the second phase particles that existed before heating will be solidified again by the brazing heat, and the number of particles will decrease, but will not increase. After heating at 610℃ for 10 minutes, 30 x 10” pieces/
In a fin material in which there are m rn' or more second phase particles, a larger number of second phase particles are always present even before heating.

When the second phase particles of the core material are distributed in this manner, the strength of the fins of the brazing thermal bridge is also slightly improved. This is due to the dispersion-strengthening effect of a large number of dispersed particles, but this effect also prevents the strength of the heat exchanger itself from decreasing due to thinning of the fins.

The aluminum used as the skin material of the first invention is A
n Purity should be 99% or more. Specifically, JISI 100 alloy, 1050 alloy, etc. can be used. The higher the purity of the A pattern, the higher the thermal conductivity. If the An purity is less than 99%, the thermal conductivity will not be sufficiently improved.

The aluminum alloy used as the skin material of the second invention is an Al-Zr alloy. In this case, the Zr content is 0.03 to 0.35%. Zr significantly improves the high temperature buckling resistance without impairing the thermal conductivity of the alloy.

If the Zr content is less than 0.03%, the effect is not sufficient, and if it exceeds 0.635%, coarse crystallized substances of the AJlj-Zr system are produced, resulting in poor formability as a fin material. In addition to Zr, the alloy used as the skin material in the present invention contains, for example, 0.05% or less of Ti or B to refine the ingot structure, and 0.1% or less to provide a sacrificial anode effect. S
n, In, 0.6% or less Zn, 0.5% or less Ca, 0.7% or less Fe, 0.3% or less Cu to improve buckling resistance (sagging resistance). , 0.5% or less of Si and Mn may be added, respectively. However, since these elements reduce the thermal conductivity of the fin material, it is desirable that the amount thereof be as small as possible.

The aluminum composite fin material of the present invention is formed by cladding a core material having the above composition and second phase particles and a skin material having the above composition, but the cladding in this case may be either double-sided cladding or single-sided cladding.

Further, the cladding ratio (in the case of double-sided cladding, the sum of the cladding ratios on both sides) is preferably 10 to 60%. The aluminum composite fin material of the present invention has improved thermal conductivity by cladding the core material with excellent buckling resistance with a skin material with good thermal conductivity for the entire fin. If the conductivity is not sufficiently improved and it is too high, the proportion of the core material will decrease and the buckling resistance will be insufficient. In addition, the fin material of the present invention is tempered in a hard state (H material instead of 0 material), and in detail, it is used in a hard state (H material instead of 0 material), and in detail, it is used as a hard plate (HIX) by so-called final cold rolling or partially annealed after final cold rolling. It is used in the form of a hard plate (H2X).

(Example) Next, the present invention will be explained in more detail based on examples.

A double-sided clad fin material as shown in FIG. 1 was prepared using aluminum alloy core materials and skin materials having the compositions shown in Table 1 and the cladding ratios shown in the same table.

In FIG. 1, numeral 1 is a core material, and 2 is a skin material.

The fin material was produced by welding and temporarily fixing a skin plate to a core ingot, followed by homogenization treatment, hot rolling, and then a combination of cold rolling and annealing.

Of these processes, hot rolling requires 300 to 350
℃, and the final thickness of the hot rolled sheet was 3.5+wm. In addition, the homogenization treatment was carried out at 400 to 600°C for 1 to 48 hours, and the annealing was carried out at 320 to 600'C for 1 to 48 hours. I controlled it. Through these steps, the final plate thickness is 0.1
A thin fin material sample with a thickness of 0 mm was obtained. Table 1 shows the distribution of second phase particles in the core material of each fin material sample. Here, the distribution of the second phase particles was determined using a transmission electron microscope after heating the fin material for 610'cxlO minutes, cooling it to room temperature.

The fin material sample thus obtained was made into a corrugated fin, and a Dron cup evaporator shown in FIG. 2 was manufactured as a prototype using this. In FIG. 2, numeral 3 is a press plate, and 4 is a corrugated fin. As the press plate 3, a platen plate having a thickness of 0.6H and made of a core material 3003 alloy and a brazing material 4004 alloy (cladding ratio of 15% on both sides) was used. The width of fin 4 is 100+s■,
For brazing, a vacuum brazing method was used. The sagging resistance of the obtained fin material, the cooling capacity of the evaporator, and the buckling resistance of the fin were measured.

The test method and judgment method are as follows. The results are shown in Table 2.

■Cooling capacity test JIS D 1618 (automobile air conditioner test method)
I followed the instructions.

■ Drooping test A sample piece of fin material with a width of 22 mm and a length of 60 mm was cut out, one end protruded 50 mm, and the other end was fixed in a cantilevered state. After heating at 610'C for 10 minutes, the front end of the protrusion dropped. The amount (mm) was measured. The one with less droop or droop resistance (buckling resistance) is better.

■Buckling Resistance Test In manufacturing the Doron cup evaporator shown in Figure 2, it is assumed that there will be no brazing defects between the fins and the press plate due to buckling of the fins during brazing, and the interval between the press plates (10 mm before brazing) is assumed. A comparison was made before and after brazing, and buckling resistance was judged to be good if the reduction amount was 0.3 mm or less, and if it exceeded 0.31 cm, it was judged to be poor.

Table 2 Note) Samples No. 67 and No. 018 could not be assembled into an evaporator.

As is clear from the results in Table 2, the aluminum alloy fin materials (Nos. 1 to 5) of the present invention have excellent drooping resistance and good buckling resistance as corrugated fins for evaporators, and It has high thermal conductivity that improves cooling capacity compared to the conventional evaporator (No. 9). On the other hand, the comparative examples (Nos. 6 to 8) have poor droop resistance and cannot be assembled into an evaporator, or have poor buckling resistance.

(Effects of the Invention) According to the present invention, an aluminum alloy fin material having excellent droop resistance and high temperature buckling resistance, and high thermal conductivity can be obtained. Therefore, the aluminum alloy fin material of the present invention allows for thinner walls and has excellent heat dissipation properties.
It becomes possible to manufacture smaller and lighter heat exchangers.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an example of a plating sheet for fins, Fig. 2 is a side view of a doron cup evaporator, Fig. 3 (a) is a perspective view of the evaporator, and Fig. 3 (b) is a side view of the evaporator.
is a perspective view of the condenser, and (c) is a side view (partially cut away) of the radiator. Explanation of symbols■...core material, 2...skin material, 3...press plate, 4...corrugate fin, 13.23.33...tube, 14.24.34-...corrugate fin patent applicant
Furukawa Aluminum Industry Co., Ltd. Figure 1 (A) Figure 2 Figure 3 Figure 1-1124] Bon Shusa P

Claims (2)

[Claims] (1) Mn0.6-2.0%, Fe0.05-0.8
%, Si containing 0.6% or less (or more wt%)
It is a Mn-based alloy, and when heated at 610°C for 10 minutes, the second phase particles are 30 × 10^9 per 1 mm^3 in the structure.
1. An aluminum composite fin material for a heat exchanger, characterized in that the core material is an aluminum alloy having at least 10% of aluminum, and one or both sides of the core material are clad with an aluminum skin material having a purity of 99 wt% or more. (2) Mn0.6-2.0%, Fe0.05-0.8
%, Si containing 0.6% or less (or more wt%)
It is a Mn-based alloy, and when heated at 610°C for 10 minutes, the second phase particles are 30 × 10^9 per 1 mm^3 in the structure.
An aluminum composite fin for a heat exchanger, characterized in that the core material is an aluminum alloy having Zr or more, and one or both sides of the core material are clad with an aluminum alloy skin material containing 0.03 to 0.35 wt% Zr. Material.