JPH01180937A - Al alloy excellent in self-color characteristic in welding construction zone - Google Patents

Abstract

PURPOSE:To provide an Al alloy excellent in rollability and formability and having uniform black color tone in self-color anodic oxidation in a weld zone by limiting respective contents of Si, Mg, and Fe. CONSTITUTION:An alloy having a composition consisting of, by weight, 0.5-4.0% Si, Mg and Fe in the amounts limited, respectively, to <=0.5% and <=0.3%, and the balance containing essentially Al is prepared. By the above constitution, no phase change according to cooling velocities occurs in this alloy after welding and, as a result, the whole alloy can be formed into uniform black color when this alloy is subjected to self-color anodic oxidation treatment after welding using the same alloy, and further, this alloy also has superior rollability and formability. Accordingly, this alloy is an Al alloy suitable for use in manufacturing kettles, vessels, etc., to be subjected to self-color anodic oxidation treatment.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is for welded structures, and in particular, natural color development of welded structures suitable for manufacturing kettles, containers, etc., which is caused by anodization treatment. This invention relates to an A-pattern alloy with excellent properties.

[Prior Art] Conventionally, Al--Fe alloys have been mainly used as alloys that are naturally colored black by anodizing.

However, when the above Al-Fe alloy is welded, the difference in cooling rate between the welded part and other non-welded parts causes a change in the precipitated phase (FeA or 3 → FeA or 6), and the welded part is anodized. When applied to natural color development, uneven coloring occurred, such as not turning black. As a specific example, when welding the spout of a kettle to the kettle, there were problems such as the welded part turning white and causing uneven coloring.

Therefore, in the past, parts that could not be welded with the same metal were joined using a mechanical caulking structure.

[Problems to be Solved by the Invention] The present invention solves the problems of the prior art as explained above, and eliminates color unevenness when the welded structure is anodized and colored black. The purpose of the present invention is to provide an A1 alloy that exhibits excellent natural color development in welded structural parts that does not occur.

[Means for solving the problems] The present invention contains Si in an amount of 0.5 to 4.0% by weight (hereinafter abbreviated as %), Mg in an amount of 0.5% or less, and Fe in an amount of 0.3%.
The gist lies in the AJJ alloy, which is regulated as follows and has excellent natural color development in welded structures, characterized in that the remainder is substantially made up of A-texture.

[Function] The inventor of the present invention discovered that when naturally colored black by anodizing treatment after welding, for example, in the case of A-Fe alloy, the color tone differs due to the difference in precipitated phases (FeAu: + and FeAu6). That is, they focused on the fact that color unevenness occurs when the cooling rate of a welded part after welding is different from that of a non-welded part, and completed the present invention.

That is, in the present invention, by selecting an Al-3i alloy that does not undergo phase change depending on the cooling rate after welding, when the alloy is welded and then naturally colored by anodizing treatment, the entire alloy is uniformly colored. It could be made black.

Note that the Al-3i alloy of the present invention becomes black due to the precipitation of Si, and M g 231 and Fe-3i
The contents of Mg and Fe must be regulated in order to suppress the generation of heterogeneous precipitates, such as system precipitates, that prevent blackness.

The content range of the elements contained in the alloy of the present invention and the reasons for limiting the range are described below.

*Si is 0.5 to 4.0%.

Si is the main element that causes natural color development, and the higher the Si content, the blacker the color. On the other hand, if the Si content exceeds 4.0%, the size of the Si grains becomes coarse, which reduces formability such as drawing and bending. In addition to damaging the surface finish, machinability and surface gloss also deteriorate. Further, if the Si content is less than O-5%, the desired black color cannot be obtained. Therefore, the Si content is reduced to 0.
5 to 4.0%.

-Restrict Mg to 0.5% or less.

Mg combines with Si to form a compound called Mg23i, which reduces the natural coloring effect of Si, so the Mg content is 0.
Regulated at 5% or less.

-Restrict Fe to 0.3% or less.

Fe combines with Si to generate Fe-3i-based compounds,
Since it reduces the natural coloring effect of Si, the content is regulated to 0.3% or less.

The present invention will be specifically described below with reference to Examples.

[Example] An ingot having the composition shown in No. 1 Mugi was melted and cast according to a conventional method to create an ingot measuring 400 mm. Next, one side 5
After both surfaces were exposed at m m t, soaking treatment was performed at 410°C for 4 hours. Furthermore, it was hot rolled to a plate width of 8 mmt, and then cold rolled to a finished plate of 2 mmt.

A bento box-shaped container was made by bending the O material obtained by annealing the above sample at 350°C for 1 hr.
Matching metal welding was performed using the TIG welding method. Thereafter, 30 μm of aluminium sulfate was applied to the entire body using a conventional method, and the natural coloring of the base metal and welded areas was investigated. Table 2 shows the results.

In Table 1 and Table 2, samples N001 to No.
No. 3 is an alloy that satisfies the composition range of the present invention;
Alloys No. 2 and No. 2 had excellent rollability and formability, and the natural color tone of the welded area was black. Also, sample N
Although the rollability and formability of No. 003 were inferior to those of No. 1, No. 2, and No. 2, they were still good, and the natural color tone of the welded portion was also black.

In contrast to the above-mentioned alloys of the present invention, Nos. 4 to 9 are comparative alloys.

Sample No. 4 contains only a small amount of Si than the Si content in the range of the present invention, so it has good rollability and formability, but the anodized natural coloring part of the welded part and base metal part is poor. The color tone was white-gray.

In sample No. 5, the Si content was higher than the range of the present invention, and the rollability and formability were poor.

In sample No. 6, the Fe content was higher than the Fe content range of the present invention, and the rollability and formability were somewhat good, but the natural color tone of the welded part was gray and color unevenness occurred. .

Sample No. 7 had a Mg content higher than the range of the present invention and had good rollability and formability, but the color tone of the anodized natural color was gray in both the base metal part and the welded part.

In sample No. 8, both Mg and Fe contents were higher than the range of the present invention, and the rollability and formability were somewhat good, but the natural anodized color tone of the welded part was gray, and color unevenness occurred.

N089 has good rollability and formability because the Si content is lower than the range of the Si content of the present invention and the Fe content is higher than the range of the Fe content of the present invention, but the anode of the welded part The natural oxidation color tone became gray and uneven coloring occurred.

[Effects of the Invention] As explained above, according to the present invention, it is possible to improve the natural coloring of the welded structure, which has excellent rollability and formability, and the anodized natural coloring of the welded portion is evenly black. An excellent A pattern alloy can be provided.

Table 1 Sample material composition Table 2 Test results

Claims (1)

[Claims] It contains 0.5 to 4.0% by weight of Si (hereinafter abbreviated as %), Mg is restricted to 0.5% or less, Fe is regulated to 0.3% or less, and the balance is substantially made of Al. An Al alloy with excellent natural color development in the welded structure.