JPH028340A - Aluminum alloy material for high strength spacer bar of heat exchanger and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture the title alloy material having high proof stress by subjecting an alloy material constituted of Mn, Cu, Si, Fe and Al to homogenizing treatment at specific temp. for specific time and subjecting it to hot extrusion. CONSTITUTION:An alloy material contg. 1.0 to 1.7% Mn, 0.05 to 0.40% Cu, 0.15 to 0.80% Si, 0.2 to 0.6% Fe and the balance Al with impurities is subjected of homogenizing treatment at 400 to 530 deg.C for 2 to 48 hr and to hot extrusion. By this method, its proof stress is regulated to >=8kgf/mm<2> to obtain the Al alloy material for a spacer bar of a high strength heat exchanger. In the use of the Al alloy material, the construction of a heat exchanger can easily and accurately be finished without buckling at the time of construction.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a spacer and
The present invention relates to a method of manufacturing an aluminum alloy material used for bars.

[Prior art] Aluminum heat exchangers are manufactured by assembling tube plates made of fins formed from rolled plate material into corrugated shapes, spacer bars cut from extruded sections, and plating sheets, and then brazed at 580 to 600°C. This is how the heat exchanger part is manufactured.

The aluminum alloy used for the heat exchanger fins is pure aluminum, A I, because as mentioned above, brazing is heated to 580 to 600 degrees Celsius during assembly, which reduces its strength, and from the viewpoint of corrosion resistance. -Mn based 3003 alloy and Al-ZnMg based 7072 alloy were used.

Also, although the spacer bar does not directly participate in heat exchange, it must have strength and corrosion resistance, and the same material as that used for the fins was used.

[Invention or problem to be solved] Heat exchangers for liquefied natural gas and liquefied oxygen evaporators and petrochemical plants have recently become larger, so long spacer bars are made of extruded materials such as 3003 alloy. If the yield strength is about 5 kgr/1 m2, the bending occurs, making handling difficult, making assembly complicated, and reducing assembly accuracy. One way to prevent buckling is to increase the cross-sectional shape, but there is a restriction that this cannot be increased due to the thermal efficiency of the exchanger.

Therefore, in the present invention, the yield strength of the hot extruded material is 8 kg1'/+u
The present invention provides an aluminum alloy material for high-strength heat exchanger spacer/bars having a diameter of m2 or more.

[Means for Solving the Problems] The present invention solves the above problems and consists of the following inventions.

(1) Mn: 1.0-1.7%, Cu:
0.05-0.40%, Si: 0.15-0.8
0%, Fe: 0.2-0.6%, remaining A
An aluminum alloy material for spacers and bars for high-strength heat exchangers, which is made of aluminum and impurities and has a yield strength of 8 kg1'/m112 or more.

(2) Mn: 1.0-1.7%, Cu:
0.05-0.40%, Si: 0. I5~0.8
0%, Fe: 0.2-0.6%, remaining A
An alloy material consisting of l and impurities is heated at 400 to 530℃ for 2 to 4
A method for producing an aluminum alloy material for a spacer/bar for a high-strength heat exchanger, which has a yield strength of 8 kgf/12 or more by performing an 8-hour homogenization treatment and hot extrusion.

The reasons for limiting the above alloy components and manufacturing conditions are as follows.

Mn: Mn forms a solid solution in aluminum during casting and contributes to improving strength. If it is less than the lower limit, this effect will be small, and if it exceeds the upper limit, there will be problems such as deterioration of extrudability or crystallization of giant intermetallic compounds. Therefore, the Mn content is set to 1.0 to 1.7%.

Cu: Addition of a trace amount of Cu contributes to improving strength. Below the lower limit, this effect is small, and above the upper limit, the corrosion resistance decreases. Therefore, the Cu content is 0.05 to 0.4
%.

Si: Addition of Si contributes to improving strength. Below the lower limit, this effect is small, and above the upper limit, the extrudability decreases. Therefore, the Si content is set to 0.15 to 0.8%.

Fe: Fe forms Al-Fe-Mn system crystallized products during casting, so if Feff1 exceeds the upper limit, solid solution Mn
As En decreases, the strength also decreases.

If it is less than the lower limit, crystal grains tend to become coarse. Therefore, the Fe content is set to 0.2 to 0.6%.

Homogenization treatment conditions: When the homogenization treatment temperature of the ingot exceeds 530°C, the structure of the extruded H is likely to recrystallize, resulting in a decrease in strength.

If the homogenization treatment temperature is 530°C or less, the structure of the extruded material is difficult to recrystallize, so the strength will increase, or if the homogenization treatment temperature is less than 400°C, the extrudability will decrease. Therefore, the homogenization treatment temperature is set at 400 to 530°C. Moreover, if the time is less than the lower limit, extrudability deteriorates, and if it exceeds the upper limit, recrystallization tends to occur and the strength may decrease. Ideally, it will take 2 to 48 hours.

[Example] Next, the present invention will be explained based on specific examples.

Example 1 Alloy materials having the compositions shown in No. 1 and No. 13 shown in Table 1 were cast into a 150 nvφ mold, treated under various homogenization conditions, and then heated to a cross section of 5+ at a normal extrusion temperature.
Extruded to corner +4 of nmX 10n+n+. The tensile test was carried out in accordance with the No. 9A test piece specified in JIS Z 2201, by gripping both ends of the extruded material as it was. The results are shown in Table 1. In Table 1, Nos. 1 to 12 are examples in which the homogenization treatment conditions and extrusion temperature were changed for alloy materials of the same composition, Nos. 1 to 7 are examples of the present invention, and Nos. 8 to
12 shows a comparative example.

In addition, Nos. 13 to 18 are examples in which the homogenization treatment conditions and extrusion temperature were changed for other alloy materials of the same composition.
~1G represents an example of the present invention, and No. 17.18 represents a comparative example.

No. 9 with a lower homogenization temperature has a yield strength of 9.7
Although it is as high as kgf/mm2, the extrusion force becomes large and extrusion is difficult, which is not preferable. In addition, N
No. 8 is also unfavorable because it is difficult to obtain a yield strength of 9.1 kgf/m river 2 or to extrude it.

In addition, No. where the homogenization temperature was raised higher than 530°C,
In the case of lo-12, 17, and 18, the yield strength is 5.
9, 56, 4.9, 6.0, 5,7, which is unfavorable.

On the other hand, in the case of the embodiments of the present invention, the yield strength is 8 kgr.
/mm2, and other test results were also good, making it suitable as an aluminum alloy for high-strength heat exchanger spacer bars.

Example 2 The same tests as in Example 1 were conducted using aluminum alloys with various compositions, and the results are shown in Table 2.

In Table 2, Nos. 19 to 22 are examples of the present invention;
, 23 to 28 show comparative examples.

No. 23 has a low Mn content of 0.7% and a yield strength of 8k.
gr/mm' could not be obtained. No. 24 has a high Fe content and low Cu content, so the yield strength is 8k.
gr/mm' could not be obtained.

No. 25 had a high Fe content and low Cu and Si contents, so it was not possible to obtain a yield strength of 8 kgf/mm 2 .

No. 26 had a low Si content and a poor soaking temperature, so it was not possible to obtain a yield strength of 8 kgf'/mm'.

No. 27 has a high Si content and a low Fe content, so the target value of yield strength is 9.1 kgf/mm2, but the extrudability is poor due to the high Si content, and the Fe content is also low. Since the amount is small, the crystal grains become coarse and corrosion resistance decreases, which is not preferable.

No. 28 can obtain proof stress of 8 kgf/mm2 or more,
Since the Cu content is high, corrosion resistance decreases, which is not preferable.

On the other hand, in the case of the examples of the present invention, the yield strength is 8 kg.
1'/mm2 and other test results were also good, making it suitable as an aluminum alloy for high-strength heat exchanger spacer bars.

[Effect of the invention] According to the present invention, the force resistance of the hot extrusion mill is 8 kgf/+I1m.
A high-strength material with the above properties can be obtained, and can be used for heat exchanger spacer bars without bending during assembly.
It is possible to easily assemble a heat exchanger and finish it with high precision.

Patent applicant: Sumitomo Light Metal Industries, Ltd. Agent Patent Attorney Hidetake Komatsu Agent Patent Attorney Hiroshi Asahi

Claims (2)

[Claims] (1) Mn: 1.0-1.7%, Cu: 0.05-0.
40%, Si: 0.15~0.80%, Fe: 0.2~
An aluminum alloy material for a spacer bar for a high-strength heat exchanger, characterized by containing 0.6%, remaining Al and impurities, and having a yield strength of 8 kgf/mm^2 or more. (2) Mn: 1.0-1.7%, Cu: 0.05-0.
40%, Si: 0.15~0.80%, Fe: 0.2~
An alloy material containing 0.6% and the remaining Al and impurities is homogenized at 400 to 530°C for 2 to 48 hours,
A method for producing an aluminum alloy material for a spacer/bar for a high-strength heat exchanger, characterized in that the material has a yield strength of 8 kgf/mm^2 or more by hot extrusion.