JPH0299325A - High strength al alloy clad material for working fluid contact structural member of heat exchanger excellent in pitting resistance - Google Patents

Abstract

PURPOSE:To obtain excellent pitting resistance and to extend use life by constituting a core material composed of a specific composition and a skin material composed of a specific composition clad to the single surface or both surfaces of said core materials and brought into contact with a working fluid. CONSTITUTION:A core material is constituted of an Al-alloy having a composition containing 0.3-1.5% of Mn, 0.3-1.2% of Si, 0.3-1% of Cu and, if necessary, further containing 0.03-0.15% of Zr and composed of the remainder Al and inevitable impurities and clad to the single surface or both surfaces of the core material while a skin material brought into contact with a working fluid is constituted of an Al-alloy having a composition containing 0.3-1.5% of Mn, 0.3-1.2% of Si and, if necessary, 0.03-0.15% of Zr and composed of the remainder of Al and inevitable impurities. By this method, a high strength Al-alloy clad material for the working fluid contact structural member of a heat exchanger excellent in pitting resistance is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a structural member of various heat exchangers, such as pipe bodies and header plates that come into contact with a working fluid such as tap water circulating inside the heat exchanger. The present invention relates to a high-strength Al alloy clad material that exhibits excellent pitting corrosion resistance when used as a material.

[Conventional technology]

As heat exchangers have become lighter and smaller in recent years, their structural members such as tubes and header plates are also required to be thinner. In terms of weight % (hereinafter % indicates weight %), Mn: 0.3 to 1.5%, sx': 0.
7-1.2%.

Cu: 0.1-0.6%.

A high-strength AN alloy has been proposed, which has a composition containing 100% of phosphorus, with the remainder consisting of AN and unavoidable impurities.

[Problem to be solved by the invention]

However, although the above-mentioned Al alloy materials have high strength, they are relatively electrochemically noble, so they tend to suffer from pitting corrosion rather than general corrosion. At present, before a through hole is formed in a member, the life of the member is set to a relatively short period of use in consideration of safety.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors focused on the conventional high-strength Al alloy mentioned above, and conducted research in order to impart excellent pitting corrosion resistance to it without reducing its high strength. As a result, when using the conventional high-strength Al1 alloy as a core material, one or both sides of this core material, that is, when used as a structural member of a heat exchanger, the surface that comes into contact with the circulating working fluid has high strength. In order to ensure that the Mn and S1 contents are the same as the core material, Cu is
By not containing oxides and making the core material electrochemically more base than the core material, the sacrificial anode effect can be sufficiently exerted on the core material, and the corrosion can be made into a general corrosion type to prevent the occurrence of pitting corrosion. When clad with a suppressed Al alloy as a skin material, the resulting Aj7 alloy clad material exhibits excellent pitting corrosion resistance while maintaining high strength, making it possible to significantly extend the service life. We obtained the knowledge to do so.

This invention was made based on the above knowledge, and the core material has Mn: 0. :3-1.5%, St:
0.3-1.2%.

Cu: 0.3-1%.

Contains, and if necessary, Zr: 0.03-0.15%.

The skin material, which is clad on one or both sides of this core material and is in contact with the working fluid, is composed of an Al convex metal having a composition containing 1) and the remainder consisting of 1) and unavoidable impurities. 1.5%, Si: 0
．． 3-1.2%.

Contains, and if necessary, Z　r　: 0.03-0.15%.

This is a high-strength A47 alloy cladding material for working fluid contact structural members of heat exchangers with excellent pitting corrosion resistance, which is made of Al convex metal with a composition of It is something that you have.

Next, the reason why the composition of one alloy constituting the core material and the skin material in the Al alloy cladding material of the present invention is limited as described above will be explained.

(a) Mn and Si content in the core material and skin material In either case, these two components have the effect of forming fine Al-Mn-3t compounds that are uniformly dispersed in the base material and improving strength. However, the content is Mn:0.
If the Mn content is less than 3% and S1: less than 0.3%, the desired high strength cannot be secured, while if the Mn content exceeds 1.5%, workability will decrease. Moreover, if the St acid content exceeds 1.2%, the melting point will drop and not only will partial melting occur during brazing, but also the strength and corrosion resistance will decrease. , the content is Mn: 0.3 to 1.5%, respectively.
.

SI: Set at 0.3 to 1.2%.

(b) Cu content in the core material In order to ensure high strength in the cladding material, it is necessary to add Cu to the core material.
Therefore, in the cladding material of the present invention, the content of Cu in the core material, which normally accounts for 90% in the thickness direction, is set to 0.3 to 1% to ensure high strength. Since pitting corrosion is likely to occur due to the Cu content, the skin material cladding is made electrochemically less noble than the core material without containing Cu as an alloying component to prevent corrosion from occurring on the entire surface. As a result, the cladding material has high strength and excellent pitting corrosion resistance, and as mentioned above, the core material containing Cu as an alloy component is more durable. Since it is electrochemically more noble than a skin material that does not contain Cu as an alloy component, the skin material exhibits a sacrificial anode effect and provides good corrosion protection for the core material. Therefore, if the Cu content of the core material is less than 0.63%, it is not possible to achieve the desired strength improvement by solid solution strengthening of the substrate, while if the content exceeds 1%, the hardness will improve,
The content should be reduced to 0 as it may reduce processability.
．． It was set at 3-1%.

(C) The Zr content of core material and skin material is as follows:
Forms fine A II a Z r compounds that are uniformly dispersed in the base material to improve strength, and further promotes the formation of anisotropic coarse grains, thereby preventing deterioration in corrosion resistance due to penetration of molten solder. It is included as necessary because it has an Hm content of 0.15%, but if its content is less than 0.03%, the desired effect cannot be obtained.
%, workability deteriorates, so the content was set at 0.03 to 0.15%.

〔Example〕

Next, the cladding material of the present invention will be specifically explained using examples.

Al alloys A to J for core material and Al convex metal a for skin material, each having the composition shown in Table 1, by ordinary melting method
zh is melted and cast into an ingot, and after homogenization heat treatment and face side treatment are performed on these ingots under normal conditions, the Al alloy ingot for core material is hot rolled. Thickness: 11
+U hot-rolled plates, and the Al alloy ingot for skin material was hot-rolled and then cold-rolled to make cold-rolled plates with a thickness of 1111 mm, and these are shown in Table 2. After overlapping in the combination shown, hot rolling was performed to form a cladding material with a thickness of 2 mm, followed by cold rolling to a thickness of 0.5 mm, and then 2 mm thick at a temperature of 370°C. By performing final annealing under the condition of time holding, the present invention Al alloy cladding materials 1 to I
6 were produced respectively.

In addition, for the purpose of comparison, a cold-rolled plate with a thickness of 0.5 mm was obtained by cold rolling from the hot-rolled plate of the above-mentioned AJ gold alloy for core material ~ J, and final annealing was performed on this under the same conditions. Conventional Al alloy plate materials 1 to 1O were manufactured by the following methods.

Next, the resulting AjJ alloy cladding materials 1 to IG of the present invention and the conventional Al alloy sheet material 1-1 (Table 1) were subjected to conditions corresponding to vacuum brazing, that is, I
The tensile strength was measured under the condition of heat treatment in a lo'torr vacuum at a temperature of 600°C for 5 minutes. For board materials, one side is 2+.

A tap water immersion test was conducted in which Cu and 1 ppII were immersed for 1 hour in running tap water at a temperature of 30° C., and the maximum pitting depth of the exposed surface was measured.

These results are shown in Table 2.

[Effects of the Invention] From the results shown in Table 2, it can be seen that the Al alloy cladding materials 1 to 16 of the present invention were brazed in a manner similar to that of the conventional AN after treatment.
It has high strength equivalent to alloy plates 1 to 10, and conventional Al
It is clear that the alloy plates exhibit significantly superior pitting corrosion resistance compared to alloy plates 1 to 1O.

In addition, in the above example, an Al alloy clad material consisting of a core material and a skin material was described, but in practical use, an Al-5+ alloy brazing material is further clad on the core material side to form a plating sheet. Of course, it may also be applied.

As mentioned above, the Af1 alloy cladding material of the present invention has high strength and excellent pitting corrosion resistance, so it can be applied to working fluid contact structural members of heat exchangers, such as pipe bodies and header plates. The high strength of the case makes it possible to reduce the thickness of the heat exchanger, which contributes to the reduction in weight and size of the heat exchanger.Furthermore, the excellent pitting corrosion resistance makes it possible to significantly extend the service life over a long period of time. It brings about an interesting effect.

Claims (4)

[Claims] (1) A core material and cladding on one or both sides of the core material,
and a skin material in contact with the working fluid, the core material comprising:
In weight%, Mn: 0.3-1.5%, Si: 0.3-1.2%, C
U: 0.3 to 1%, and the remainder is Al and unavoidable impurities. , Si: 0.3 to 1.2%, and the remainder is Al and unavoidable impurities. High strength Al alloy cladding material for structural members. (2) A core material and cladding on one or both sides of the core material,
and a skin material in contact with the working fluid, the core material comprising:
In weight%, Mn: 0.3-1.5%, Si: 0.3-1.2%, C
U: 0.3 to 1%, further containing Zr: 0.03 to 0.15%, and the remainder is composed of Al and inevitable impurities, and the skin material be composed of an Al alloy having a composition containing Mn: 0.3 to 1.5%, Si: 0.3 to 1.2%, and the remainder consisting of Al and inevitable impurities, also in weight%. A high-strength Al alloy cladding material for a working fluid contact structural member of a heat exchanger, which has excellent pitting corrosion resistance. (3) A core material and cladding on one or both sides of the core material,
and a skin material in contact with the working fluid, the core material comprising:
In weight%, Mn: 0.3-1.5%, Si: 0.3-1.2%, C
U: 0.3 to 1%, and the remainder is Al and unavoidable impurities. , Si: 0.3 to 1.2%, and Zr: 0.03 to 0.15%, with the remainder being Al and inevitable impurities. A high-strength Al alloy cladding material for a working fluid contact structural member of a heat exchanger, which has excellent pitting corrosion resistance. (4) A core material and cladding on one or both sides of the core material,
and a skin material in contact with the working fluid, the core material comprising:
In weight%, Mn: 0.3-1.5%, Si: 0.3-1.2%, C
U: 0.3 to 1%, further containing Zr: 0.03 to 0.15%, and the remainder is composed of Al and inevitable impurities, and the skin material Contains Mn: 0.3 to 1.5%, Si: 0.3 to 1.2%, and further contains Zr: 0.03 to 0.15%, also in weight%, A high-strength Al alloy cladding material for a working fluid contact structural member of a heat exchanger having excellent pitting corrosion resistance, characterized in that the remainder is composed of an Al alloy having a composition consisting of Al and inevitable impurities.