DE2342633B2 - Use of a magnesium-based alloy for corrosion-resistant parts - Google Patents

Description

The invention relates to the use of an alloy based on magnesium with proportions of aluminum, Zinc, manganese, titanium, zirconium and small additions of beryllium, iron, nickel, silicon and Copper.

In DE-OS 14 33 108 silicon-containing magnesium alloys with improved properties, in particular with regard to the fine grain of the cast structure, the strength and the corrosion resistance are described as further components among other things Can contain aluminum, zinc, manganese, titanium, zirconium, vanadium and chromium. To classify the The grain structure depends on the ratio between manganese and silicon, which depends on the absolute values for the amounts of these two components present, e.g. B. 0.75 and 3.80 for fine

Table 1

Chemical composition, in%

Grain structure and 0.46 to 32.5 for coarse grain structure can be. The corrosion resistance achievable according to these values was tested with 3% NaCl solution in a 30 liter bath, the volume of the after a certain time has elapsed, the developed gas is evaluated as a measure of the corrosion resistance became. Although aluminum is listed as a component, Table II of the laid-open specification shows that after the evaluation criteria there good corrosion resistance durability is achieved when the magnesium alloy Manganese, zinc and silicon, possibly also titanium Grain structure also not derivable.

From the German standard DIN 1729 from May 1963, Sheet 2 magnesium-aluminum-zinc alloys are known, the other alloy components, z. B. May contain manganese and permissible additions of silicon, copper, iron, nickel, calcium.

While magnesium-manganese alloys with approximately similar permissible admixtures contain the indication "corrosion-resistant", the Mg-Al-Zn alloys do not provide anything about corrosion resistance testified. There is therefore no DIN regulation Indication that could suggest the present invention.

For use in fresh air under sea and tropical climate conditions and for short-term use Use in sea water requires that the Alloys not only have a sufficiently good tensile strength and elongation at break, but also a high one Have corrosion resistance.

There are corrosion-resistant alloys based on magnesium of the type Mg-Al-Zn-Mn as well as one

η alloy known, which also contains titanium (U.S. Patent 23 * 0 795).

Components of this alloy are given in Table 1 below.

Mg Al Zn Mn Ti Highest concentration

Ni Cu Fe Si Be Zr

rest 7.5-9 0.2-0.8 0.15-0.5 rest 7.5-9 0.3-1.0 0.15-0.7 rest 4-6 1-2 0.1-1

0.05-1 0.001
0.001

0.040
0.005

0.007
0.003

0.08 0.01

0.002 0.002

It is a disadvantage of the alloys listed that their corrosion resistance is relatively low.

The present invention is based on the object while eliminating the disadvantages mentioned to specify a magnesium-based alloy for use under the conditions set out above.

According to the invention, the object is achieved by the use of the there specified in the claim designated alloy dissolved. The usage according to the invention ensures a higher corrosion resistance compared to the known alloys.

Execution examples for the l "rlilulling angegelien.

H e i s ρ i c I I

I.im. ¹ ciTiiidimgsgcmäl) / u using alloy

7.7%

2.0%

0.5%

0.005%

0.3%

0.007%

0.0007%

0.03%

0.02 »/«

rest

Aluminum,

Zinc,

Manganese,

Titanium,

Zirconium,

Iron,

Nickel,

.Silicon,

Copper,

Magnesium.

The Corrnsionsgcschwiiuligkeit the alloy in Ciiiiss / ustiind and in the wäimebehaiuleHen state at Complete immersion in a 1% NaCl solution for 48 hours is 0.0180 mg / cn-'h. the Alloy corresponds in its resistance to corrosion in humid and ionic disease. as well as ncriodi-

Scheme dousing with sea water, for example, aluminum casting alloys of the type Al — Si — Mg.

The mechanical properties of the alloy in the heat treated condition are at room temperature as follows:

Tensile strength O ₆ = 23 -26 kp / mm ² , Elongation at break ό = 3–10%. Example 2

Contains an alloy to be used according to the invention

2% aluminum,

£ 2% zinc,

2.5% manganese,

0.5% titanium,

0.002% zirconium,

0.01% iron,

0.001% nickel,

0.08% silicon,

0.04% copper,

Remainder magnesium.

The rate of corrosion of the specified alloy in the as-cast state when completely immersed in a 3% NaCl solution over the course of 48 hours is 0.0100 mg / cm ² h. The mechanical properties of the alloy in the heat treatment state at room temperature are as follows:

Tensile strength Oi, = 18-20 kp / mm ² , Elongation at break ό = 8-10%. Example 3

Contains an alloy to be used according to the invention

12% aluminum, 0.01% zinc, 0.01% manganese, 0.0001% titanium, 2% zirconium, ίο 0.1% beryllium, '' 0.003% iron, 0.001% nickel, 0.01% silicon, 0.02% copper, Remainder magnesium.

The corrosion rate of the alloy in the heat-treated state when completely immersed in a 3% NaCl solution over the course of 48 hours is 0.0250 mg / cm ² h. The mechanical properties of the alloy in the heat-treated state are as follows at room temperature:

Tensile strength a _b = 21-23 kp / mm ² , elongation at break ό = 2-3%.

The composition of the alloy according to the invention ensures high corrosion resistance of the products when used in fresh air, under sea and tropical climate conditions and for short-term use Use in sea water with a sufficiently high level of mechanical properties.

Claims (1)

Claim: Use of an alloy consisting of 2 to 12% aluminum, O ₁ U1 to 23% zinc, 0.01 to 23% manganese, 0.0001 to 03% titanium, 0.002 to 2.0% zirconium and admixtures of up to 0.1 % Beryllium, up to 0.1% iron, up to 0.001% nickel, up to 0.08% silicon, up to 0.04% copper and the remainder of magnesium for parts that are cast or heat-treated with a tensile strength of 18 to 26 kp / mm ² and an elongation at break of 2 to 10% have a corrosion rate when immersed in 3% NaCl solution of 0.010 to 0.025 mg / cm ² · h and against chemical attack in sea or tropical climates or when used briefly in sea water are corrosion resistant.