JPH06145862A - Heat exchanger made of al alloy constituted of high strength fin material - Google Patents

Abstract

PURPOSE:To provide a heat exchanger made of an Al alloy constituted of a high strength fin material. CONSTITUTION:The thinned fin material by which the thickness of a heat exchanger made of an Al alloy assembled by brazing is regulated to 30 to 80mum is constituted of an Al alloy having a compsn. contg., by weight, 0.2 to 1.2% Mg, 0.4 to 0.8% Si and 0.15 to 0.4% Fe, contg. one or >=two kinds among 0.1 to 2% Zn, 0.01 to 0.05% In and 0.01 to 0.15% Sn and furthermore contg., at need, one or >=two kinds among 0.02 to 0.2% Ti, 0.02 to 0.2% Cr, 0.02 to 0.15% Zr and 0.05 to <0.5% Mn, and the balance Al with inevitable impurities and having a fine structure in which, viewed in the section perpendicular to the rolling direction, one or more pieces of continuous grain boundaries are present over the whole width from one side to the other side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al alloy heat exchanger having a high strength and therefore made of a fin material which can be thinned to a thickness of 30 to 80 .mu.m.

[0002]

2. Description of the Related Art Conventionally, Al alloys have been widely used for heat exchangers such as evaporators and radiators of automobiles, and condensers.
Alloy heat exchangers can be used for various Al alloy pipe materials and various A
l alloy fin material is flux brazed in a state where at least one of the pipe material and the fin material is clad with a brazing material of an Al-Si alloy containing Si: 6 to 13% by weight to form a brazing sheet. It is also well known that it is manufactured by assembling and brazing using a vacuum brazing method, a vacuum brazing method, or an inert gas atmosphere brazing method.

[0003]

On the other hand, in recent years, there have been severe demands for downsizing and weight reduction of heat exchangers, and accordingly, the fin material constituting the heat exchangers also has a thickness of 30 to 80 μm.
Although it is strongly required to reduce the wall thickness to m, in the case of the conventional Al alloy fin material, the desired thickness cannot be reduced because the strength after being assembled into the heat exchanger by brazing is not sufficient. is the current situation.

From the above viewpoints, the present inventors have conducted research to develop an Al alloy heat exchanger composed of an Al alloy fin material having high strength after brazing and assembling. The weight ratio of the fin material of the Al alloy heat exchanger (hereinafter,% means% by weight), Mg: 0.2 to 1.2%, Si: 0.4 to 0.8
%, Fe: 0.15 to 0.4%, Zn: 0.1 to 2%, In: 0.01 to 0.0
5%, Sn: 0.01 to 0.15%, one or more of them are contained, and if necessary, Ti: 0.02 to 0.2%, Cr: 0.02. ~ 0.2
%, Zr: 0.02 to 0.15%, Mn: 0.05 to
A having a composition of less than 0.5%, one or more of which is Al, and inevitable impurities.
The final cold rolling rate is 80% or more when the sheet is made into a fin material by hot rolling under normal conditions and cold rolling with intermediate annealing if necessary. Or the final cold rolling is 80
% Of the rolling rate, the resulting fin material is brazed to the heat exchanger by brazing when the annealing is carried out at a predetermined temperature within a range of 200 to 250 ° C. for a predetermined time. As observed in a section perpendicular to the rolling direction in the assembled state, one or more continuous crystal grain boundaries were thinned over the entire width from one side to the other side.
The research results show that it has a microstructure that exists with a thickness of μm, and that it has significantly higher strength than the conventional fin material that has only intermittent and sparse grain boundaries. I got it.

The present invention has been made based on the above-mentioned research results, and in an Al alloy heat exchanger assembled by brazing, the constituent thickness thereof is 30 to 80.
μm thinned fin material, Mg: 0.2 to 1.2%, Si: 0.4 to 0.8
%, Fe: 0.15 to 0.4%, Zn: 0.1 to 2%, In: 0.01 to 0.0
5%, Sn: 0.01 to 0.15%, one or more of them are contained, and if necessary, Ti: 0.02 to 0.2%, Cr: 0.02. ~ 0.2
%, Zr: 0.02 to 0.15%, Mn: 0.05 to
Less than 0.5%, one or more of which are contained, and the balance consisting of Al and unavoidable impurities, and
It is characterized in that it is composed of an Al alloy having a fine structure in which one or more continuous grain boundaries are present over the entire width from one side to the other side when observed in a cross section perpendicular to the rolling direction. It is a thing.

Next, A constituting the heat exchanger of the present invention
The reason why the component composition of the 1-alloy fin material is limited as described above will be described. (A) Mg and Si Both of these components contain fine Mg ₂ S on the substrate after brazing.
Although it has the effect of precipitating as an i compound and improving the strength of the fin material, if the contents thereof are less than Mg: 0.2% and Si: 0.4%, the desired strength improving effect cannot be obtained. On the other hand, if the content of Mg exceeds 1.2%, the hot workability deteriorates, and if the content of Si exceeds 0.8%, the amount of solid solution in the base increases. Since the electrical conductivity (thermal conductivity) decreases with the addition of Mg, the content of Mg: 0.2 to 1.2% and that of Si:
It was set to 0.4 to 0.8%.

(B) Fe Fe component is Al-Fe- which is finely and uniformly dispersed in the matrix.
Although it has an effect of improving the strength of the fin material by forming a Si compound, if the content is less than 0.15%, the desired strength improving effect cannot be obtained, while if the content exceeds 0.4%. However, since the effect of further improving the strength cannot be obtained, the content thereof is set to 0.15 to 0.4%.

(C) Zn, In, and Sn All of these components have the action of forming a sacrificial anode effect by making a solid solution in the base material to make it electrochemically base, thereby preventing corrosion of the pipe material. The contents are Zn: 0.
Less than 1%, In: less than 0.01%, and Sn: 0.0
If it is less than 1%, the desired effects cannot be obtained, while the contents are Zn: 2% and In: 0.05%, respectively.
And, if Sn: 0.15% is exceeded, not only the corrosion progresses rapidly but also the thermal conductivity decreases, so the contents are Zn: 0.1-2% and I, respectively.
n: 0.01 to 0.05%, and Sn: 0.01 to
It was set at 0.15%.

(D) Ti, Cr, Zr, and Mn All of these components have the effect of further refining the recrystallized grains after brazing and further improving the strength, so they are contained as necessary. However, their contents are Ti: less than 0.02%, Cr: less than 0.02%, Z, respectively.
If r: less than 0.02% and Mn: less than 0.05%, the desired strength-enhancing effect cannot be obtained, while the contents are Ti: 0.2%, Cr: 0.2%, and Zr, respectively. :
Even if the content exceeds 0.15% or the Mn becomes 0.5% or more, a coarse intermetallic compound is formed and the strength is reduced.
0.02-0.2%, Cr: 0.02-0.2%, Z
r: 0.02 to 0.15%, and Mn: 0.05 to
It was determined to be less than 0.5%.

Al constituting the heat exchanger of the present invention
The alloy fin material is obtained by subjecting a slab having the above composition to cold rolling while applying hot rolling under normal conditions and intermediate annealing as described above to obtain a cold rolled sheet having a predetermined thickness, and then applying (a ) 8
Final cold rolling at a rolling rate of 0% or more, (b) rolling rate:
After the final cold rolling of 80% or more, by annealing at a temperature of 200 to 250 ° C. for 4 to 10 hours, and performing the above step (a) or (b) to obtain a thickness of 30 to 80 μm. It is manufactured.

Next, the heat exchanger of the present invention will be described in detail with reference to examples. An Al alloy melt having the composition shown in Tables 1 and 2 was prepared by a usual melting method, and a water-cooled mold was used to obtain a width of 200 mm and a length of 400 mm.
Thickness: cast into a slab having a dimension of 50 mm, and this slab is heated to a predetermined temperature within a range of 480 to 580 ° C. for 4 to 15
Homogenizing treatment is carried out under the condition of holding for a predetermined time within the range of time, thickness: 5 mm is chamfered, hot rolled sheet with thickness: 5 mm is obtained by hot rolling under all the following normal conditions, and then Repeated cold rolling while adding intermediate annealing to 0.0
A cold-rolled sheet having a predetermined thickness within the range of 75 to 0.6 mm is formed, and this cold-rolled sheet is subjected to final cold rolling at the rolling ratios shown in Tables 3 and 4, and subsequently, the same table is selectively used. Annealing was performed under the conditions shown in Nos. 3 and 4 to produce the inventive Al alloy fin materials 1 to 17 and the comparative Al alloy fin materials 1 to 9 having the thicknesses shown in Tables 3 and 4, respectively.

The comparative Al alloy fin materials 1 to 9 have a composition that does not contain any of the constituent components Mg, Si, and Fe, or have a final cold rolling rate of less than 80%. It is a thing.

Then, the various Al alloy fin materials obtained as a result of the composition of the core material are Al-1.0% Mn-0.1.
% Cu, and the composition of the brazing material clad with this is Al-9.5% Si. A flat tube material with an outer diameter of 24 x 3 mm formed by a brazing sheet with a thickness of 0.3 mm, in a nitrogen atmosphere. The heat exchangers 1 to 17 of the present invention and the comparative heat exchangers 1 to 9 were manufactured by brazing at a temperature of 600 ° C. for 5 minutes.

Next, A constituting the above various heat exchangers
The specimen was taken out from the l-alloy fin material, and the tensile strength was measured 7 days after brazing, and a vertical line was drawn across the entire width of 30 mm from one side to the other side in a cross section perpendicular to the rolling direction. The number of crystal grain boundaries that moved and intersected with the vertical line was observed, and the maximum number and the minimum number were measured. The measurement results are shown in Tables 5 and 6.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

[Table 6]

[0021]

From the results shown in Tables 1 to 6, the heat exchangers 1 to 17 of the present invention are made of the Al alloy fin material 1 which constitutes them.
It is apparent that each of Nos. 17 to 17 has a fine crystal structure, and thereby has high strength. on the other hand,
The comparative heat exchangers 1 to 9 are the same as the comparative Al constituting the same.
It is clear that the strength of the alloy fin materials 1 to 9 is relatively low because the alloy fin materials 1 to 9 have a coarse crystal structure or are made of an Al alloy that does not contain any one of Mg, Si, and Fe among the constituent components. Is. As described above, since the Al alloy heat exchanger of the present invention has the high strength that enables the Al alloy fin material constituting the heat exchanger to be thin, it is possible to sufficiently cope with the weight reduction and the size reduction thereof. is there.

Claims (2)

[Claims] 1. A brazing-assembled Al alloy heat exchanger, comprising: a thinned fin material having a thickness of 30 to 80 μm, by weight%, Mg: 0.2 to 1.2%, Si: 0.4 to 0.8
%, Fe: 0.15 to 0.4%, and Zn: 0.1 to 2%, In: 0.01 to 0.0
5%, Sn: 0.01 to 0.15%, one or more of them, and the rest is composed of an Al alloy having a composition of Al and inevitable impurities, and in the rolling direction. It is composed of a high-strength fin material characterized by having a fine structure in which one or more continuous grain boundaries exist over the entire width from one side to the other side when observed in a cross section perpendicular to it. Al alloy heat exchanger. 2. A brazed and assembled heat exchanger made of Al alloy, wherein the thinned fin material having a thickness of 30 to 80 μm, which constitutes the heat exchanger, is wt%, Mg: 0.2 to 1.2%, Si: 0.4 to 0.8
%, Fe: 0.15 to 0.4%, Zn: 0.1 to 2%, In: 0.01 to 0.0
5%, Sn: 0.01 to 0.15%, one or more of them are contained, and further, Ti: 0.02 to 0.2%, Cr: 0.02 to 0.2.
%, Zr: 0.02 to 0.15%, Mn: 0.05 to 0.5
%, Less than 1%, or 2 or more of them, and the rest being composed of an Al alloy having a composition of Al and inevitable impurities, and observing in a cross section perpendicular to the rolling direction. A heat exchanger made of an Al alloy having a fine structure in which one or more continuous grain boundaries are present over the entire width from one side to the other side.