JPS6286141A - Aluminum alloy having superior pitting corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain an Al alloy having superior pitting corrosion resistance in water by adding specified amounts of Cu, Mn and Cr to Al. CONSTITUTION:This Al alloy consists of 0.05-0.8wt% Cu, 0.5-1.5wt% Mn, 0.05-0.35wt% Cr and the balance Al. The alloy has superior pitting corrosion resistance even when used in water, especially seawater having high corrosive action on Al alloys. The alloy also has satisfactory strength, so it can be utilized in various fields such as the fields of a ship, vehicles, construction and foodstuff.

Description

Detailed Description of the Invention "Industrial Field of Application" The present invention relates to an aluminum alloy with excellent pitting resistance, and more specifically, to an aluminum alloy with excellent pitting resistance. The present invention relates to an aluminum alloy with excellent pitting resistance that exhibits excellent pitting resistance in harsh usage environments and is often used in the fields of ships, vehicles, construction, food, etc.

[Jubei Edjutsu J Generally, aluminum and aluminum alloys! Because it has 11LH on its apical surface, it shows excellent corrosion resistance in the atmosphere and is widely used in daily necessities.

□However, in applications used in water environments, the 3×XX system (AI-Mn
These alloys are used because they exhibit relatively good corrosion resistance. However, it is not always satisfactory, and improvements are expected, especially in terms of pitting resistance.

[Problem to be Solved by the Invention 1] The present invention has been made as a result of intensive research conducted by the present inventor in view of the corrosion resistance of the conventional aluminum alloys explained above.
We have developed an aluminum alloy that exhibits excellent pitting corrosion resistance even when used in an aqueous environment, especially seawater, which is highly corrosive to aluminum alloys.

[Means for solving the problems] The aluminum alloy with excellent pitting resistance according to the present invention is characterized by: Cu 0.05-0.8 wt%, Mn 005-1,5
wt%, Cr 0.05-0.35 wt%, and the balance consists of Al and inevitable impurities.

The aluminum alloy with excellent pitting resistance according to the present invention will be described in detail below.

First, the components and component ratios of the aluminum alloy with excellent pitting resistance according to the present invention will be explained.

Cu is responsible for aluminum alloy electrically and chemically, and
It is an element that increases strength, and if the content is less than 0.05 wt%, this effect is not sufficient, and if the content is less than 0.8 wt%,
If the content exceeds %, susceptibility to intergranular corrosion increases. Therefore, the Cu content is 0.05 to 0.8 wt%
shall be.

Like Cu, Mn electrochemically nobles aluminum alloys and removes Fe, an unavoidable impurity.
Since Fe is fixed in the form of (MnFe), it is possible to reduce pitting that occurs as Fe becomes a soft point.Furthermore, it is an element that improves pitting resistance and increases strength at the same time, and its content is 0.
Below 5IIIL%, this effect is small, and
If the content exceeds 1.5 wt%, coarse intermetallic compounds will be formed and cause defects. Therefore, the Mn content is 0
．． 5 to 1.5u+L%.

C is an element that increases strength and improves corrosion resistance; this effect is not observed when the content is less than 0.000%, and the effect is saturated when the content exceeds 0.35wt%. Furthermore, it is not preferable because it produces coarse intermetallic compounds like Mn.Therefore, the Cr content is set to 0.05-0.35 wt%.

In addition to these essential components, elements such as Ti that refine the casting structure and improve castability can be included.

Note that Fe is an unavoidable impurity, and the content is 0.3wt.
It is desirable to limit the amount to less than %.

[Example J Next, an example of an aluminum alloy having excellent pitting resistance according to the present invention will be described.

Example An aluminum alloy having the components and proportions shown in Table 1 was melted by a conventional method, and after casting, it was hot-rolled to a thickness of 3n+m, and then cold-opened to a thickness of 0.5III.
I finished it at 111.

This cold-open rolled plate with a regular thickness of 0.5 cm was cut into a size of 7 cm x 15 cm and subjected to a salt spray test as specified in JIS Z 2371.

For each test plate after 2000 hours, corrosion products were removed with a 30% HNO3 solution, and the depth of pitting was investigated by microscopic observation. The pitting resistance was evaluated based on the pitting depth as follows.

Maximum pitting depth Evaluation 0.05μ or less ◎ 0.05~0.1μ 00.1~0.
Less than 15μ Δ0.15μ or more
x As shown in Table 1, it can be seen that the aluminum alloy with excellent pitting resistance according to the present invention has significantly improved pitting resistance compared to the comparative example.

[Effects of the Invention] As explained above, since the aluminum alloy with excellent pitting resistance according to the present invention has the above-mentioned structure, it has excellent pitting corrosion resistance and also takes into consideration strength. It can be widely used in the fields of ships, vehicles, construction, food, etc.

Claims (1)

[Claims] Cu0.05-0.8wt%, Mn0.5-1.5wt
%, Cr: 0.05 to 0.35 wt%, and the remainder consisting of Al and unavoidable impurities.