JPS6032703B2 - Al material for brazing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pile material for brazing that maintains high temperature strength and has improved corrosion resistance.

AI is generally known as a material with good corrosion resistance, but when used as a brazed structure such as a heat exchanger, the Si in the brazing filler metal diffuses into the base metal, causing the Sj to become a core. There is a risk that intergranular corrosion may occur as a result of the formation of a local battery between the surrounding mountain village and the surrounding area. Therefore, although the following methods have been proposed as methods for preventing such corrosion, it is difficult to say that any of them are realistic measures. The known methods will be outlined below. ○｝ Method using elements that act as an anode (Zn, Sn, etc.) (1-i) Further cladding the surface of the cladding formed on the brazing material or core material with added materials such as Zn or Sn. Method (1-U) A method in which Zn, Sn, etc. are added to the brazing filler metal so that the brazing filler metal itself acts as an anode (1-Normal) A method for adding Zn, Sn, etc. to the brazing filler metal so that it acts as an anode (1-Normal) A method of using a material added with Zn, Sn, etc. in a part and protecting other components by its anodic action '21 A method of improving and strengthening the grain boundary diffusion resistance of the N base material against Si A method in which a third component is added to the material to modify the base material so that it acts cathodically in comparison to the brazing material.

However, method (1-i) has the disadvantage that manufacturing conditions become complicated and production costs rise.

Furthermore, although the method of using Zn among (11U) has a remarkable effect of improving corrosion resistance, due to the high vapor pressure of Zn, it evaporates and scatters during brazing, causing contamination of the furnace. be. And in the method of using Sn instead of Zn,
Although the problem of evaporation and scattering can be avoided, it has the disadvantage that workability is reduced, and rolling is difficult, so it is not practical. Furthermore, the method (1-bait) cannot protect members that do not come into direct contact with the fin material, such as a hetuda tank, so it must be said that it is an extremely incomplete method. In addition, as an improvement and strengthening method for ■ and [3i, for example, Cu, F
Attempts have been made to add E, Cr, Z neck, etc., or to change heat treatment conditions such as soaking, but no satisfactory results have been obtained yet. This 3003 material has Mh as one of its main components, and as is well known, it has extremely good corrosion resistance, but under brazing conditions (i.e., under high temperature heating), it becomes extremely susceptible to intergranular corrosion. , some kind of modification is desired. On the other hand, the above 3
AI-Nh alloys such as 003 material and 3203 material [Mn:
1.0 to 1.5% (hereinafter % means weight %)] is inferior in high temperature strength, and while specifying the Mn content (0.5 to 1.5%), Cr, Ti There has also been an attempt to provide an aluminum alloy for brazing that satisfies both the properties of workability and high-temperature strength by blending Zr into the aluminum alloy (Tokukan Sho 50-118919).

However, the publication states that if the amount of Mn is too small, sufficient strength cannot be provided, and as will be described later, this statement does not match the findings of the present inventors. The same publication also states that if the amount of Mn is excessive (1.5% or more), a huge A1-Mn compound is formed and the workability deteriorates, but regarding the relationship between excessive Mn and intergranular corrosion susceptibility is not mentioned. The present invention has been made under these circumstances, and it is possible to suppress the diffusivity of Si in the base metal when forming a brazing filler metal, and to reduce its own intergranular corrosion susceptibility without sacrificing high strength properties. AI for brazing with low
The purpose is to provide materials.

The material according to the present invention has Mn of 0.003 to 0.
．． 3%, Cu in the range of 0.003 to 0.5%, and at least one of Zr, Cr, and Ti at 0.05 to 0.3%, and the remaining two at 0.3%. Including the following,
The gist is that the remainder consists of AI and unavoidable impurities. In other words, susceptibility to intergranular corrosion is lowered by keeping the amount of Mn blended as low as possible without losing high strength properties, and diffusion resistance is achieved by adding at least one of Zr, Cr, and Ti in an amount within a predetermined range. It depicts sexual improvement. Next, the reason for limiting the blending amount of each of these components will be described.

First of all, regarding Nh, as the amount of Mn increases, the strength as a base material improves, but at the same time, the susceptibility to intergranular corrosion also increases, so after various researches, the maximum amount that can satisfy both of these properties at the same time is 0.3%. I discovered something. However, unless a content of 0.003% or more is ensured, high temperature strength cannot be fully exhibited. That is, even if the Mn content is 0.3% or less,
It was found that, unlike conventional knowledge, this did not cause a decrease in high temperature strength. Next, Cu has the effect of both refining crystal grains and improving strength, but if it exceeds 0.5%, corrosion resistance will deteriorate, so 0.5% is set as the upper limit. However, 0
．． When the grain density reaches 0.03%, both the effects of grain refinement and strength improvement are no longer exhibited. Finally, Zr, Cr and T
Although there are three elements i, even just one of these exhibits the function of improving diffusion resistance and strength. However, if the amount of these three types is less than 0.05%, the above effects cannot be obtained, and at least one of these types must be 0.05% or more. On the other hand, if the content of all three types exceeds 0.3%, there will be a problem of decreased workability. Next, the present invention will be described in more detail with reference to Examples. Although the following example describes a case where the material is used as a core material for a plating sheet, it goes without saying that it can also be used as a fin material and various other single component parts.
A core material having the following composition was prepared.

Sample No. 1 to 3 are the core materials of the present invention, and sample No. 3 is the core material of the present invention. 4~
6 is a comparative core material. Table 1 (Note: The remainder is AI and unavoidable impurities: *) This core material was clad with 15% brazing filler metal of the composition shown in Table 2 on both sides, and plated with a board thickness of 0.6 sail. I created a sheet.

Table 2 The central part of this plate was subjected to Eriksen processing in accordance with JIS Z-2247 (E-J Kusen Test Method) to form a recess on the depth 8 side.

6 in a N2 gas atmosphere (dew point: -60oo or less)
05q○ was heated for 2 minutes to obtain a test piece, and this test piece was subjected to a corrosion test using an accelerated anodic electrolysis test method. The test piece was set so that the most protruding tip corresponding to the recess on the back side faced the electrode. Corrosive liquid: 0. State aCI aqueous solution test current: 0.2 mA/, 16 hours Micrograph of the vertical cross section of the recess etched with Keller's solution (Ion sound)
are shown in Figures 1-6.

1 to 6 correspond to the sample pieces numbers 1 to 6, but the fourth
Although considerable corrosion is seen along the grain boundaries in Figures 1 to 6, almost no corrosion is seen in Figures 1 to 3, indicating that the grain boundary corrosion resistance is excellent. In Figures 4 and 5, Mn is blended in an excessive amount, so corrosion progresses as if it is dispersed along relatively dense grain boundaries, whereas in Figure 6, Cu
Since Cu is blended in an excessive amount, corrosion progresses along coarse grain boundaries, and the depth of corrosion is also large, indicating that an excessive amount of Cu actually deteriorates corrosion resistance. On the other hand, in the present invention, as mentioned above, maintaining high temperature strength is one of the important issues, so as shown in Table 3, the Mn content satisfies the conditions of the present invention (Samples No. 7 to 16). and conventional 300 needle material and 3203 material with high Mn content (sample No.
．． 17 to 19) and conducted the following experiments.

That is, a core material O consisting of the components shown in Table 3 was clad with 15% of each of the brazing filler metals having the composition shown in Table 2 on both sides to prepare a plating sheet having a thickness of 0.6. This was heated for 10 minutes at 550° C., just below the brazing temperature, and then cooled to room temperature and subjected to a tensile test, and the results shown in Table 3 were obtained. As shown in the same table, samples with a lower Mh content than the conventional JIS standard (No. 7 to 16)
), the high-temperature strength was not sacrificed, and it can be seen that the objective of the present invention of improving corrosion resistance while maintaining high-temperature strength was fully achieved. Table 3 (Western: remaining N and unavoidable impurities) Since the present invention is configured as described above, the brazing AI
Diffusion resistance has been improved while maintaining the strength of the base material, and the susceptibility to intergranular corrosion has been successfully suppressed to a sufficiently low level, resulting in a significant improvement in the corrosion resistance of brazed nail structures. became.

[Brief explanation of the drawing]

Figures 1 to 6 are microscopic photographs (10 stitches) in place of drawings. Nada bonito fly pseudo Nada sardine cloud ≦ stem Koji member horse mackerel Nada straw fly Kamomizo Nada Snow Shinreiso

Claims (1)

[Claims] 1 Contains Mn: 0.003 to 0.3% (meaning by weight %, the same applies hereinafter) Cu: 0.003 to 0.5% as an essential component, and also consists of Cr, Zr, and Ti 0.05 to 0.3% of at least one selected from the group;
An Al material for brazing, characterized in that it contains 0.3% or less of the remaining two types, with the remainder consisting of Al and unavoidable impurities.