DE1608193A1 - Magnesium alloy - Google Patents

Description

Patent attorneys Dipl.-Ing. E Weickmann, Dr. Ing.A. Weickmann

Dipl.-Ing. H.Weickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. R A.Weickmann, Dipl.-Chem. B. Huber

0, no. 20199 OL 811

8 MUNICH 27, DEN

MÖHLSTRASSE 22, CALL NUMBER 48 3921/22

Norsk. Hydro-Slektrisk Kvaelstofaktieselskab

Oslo / Norway

Magnesium alloy

The invention relates to alloys based on magnesium, which Contains aluminum and caleium.

Alloys of this type with high creep resistance at slightly elevated temperatures, for example in the range from 125 to 175 ° C., are known. Such alloys normally contain 2 to 10 wt .- # ,, aluminum 0.001 to 0.5 / * manganese, 0.5 bis.- 2.5 $ calcium, up to 4 io zinc, up to 0.5 $ copper and up to O ₉ 5 $ silicon, the remainder, apart from impurities *, consisting of magnesium. However, these alloys have drawbacks that greatly impair their practical utility and, in some cases, prevent their industrial use. The major disadvantage consists in the formation of troughs in the GnB ₉ in particular

009849 / Ό41-3.

in pressure injection molding.

Ea has already been proposed to eliminate the tendency to heat cracking of these alloys by adding at least 0.01 Wt .- $, preferably 0.015 to 0.050 wt .- $ iron can be added. However, this was not found to be very satisfactory.

It has also been found that the tendency to heat cracking of magnesium-based alloys which contain aluminum and calcium can be significantly reduced if the zinc content in the alloy is reduced to a much lower level than previously used. According to the invention, the maximum zinc content is limited to 0.6 ° J>, preferably to a maximum of 0.5 fo _f . . Particularly preferred is a zinc content between 0.1 and 0.3 wt is - $> of the alloy and very satisfactory alloys contain 7.5 to 9.5 $> aluminum, 0.7 to 1.0 $ calcium and from 0.1 to 0.3 # zinc.

Numerous alloys have been made, their compositions are in the range given below:

aluminum 8th until 10 # manganese 0.10 to 0.30 fo Calcium 0.6 up to 1.0 i> zinc not About 0.20

The remainder, apart from impurities, consists of magnesium. These alloys were used in an industrial pressure injection molding

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Device cast to make commercial parts known to be prone to thermal cracking. It has been found that these alloys for thermal cracking were not susceptible than similar conventional magnesium alloys containing Al and Zn but do not contain calcium (alloys AZ91) and with respect to ".-Des. Creep resistance at 15O ⁰ G with a higher zinc content having ealciumhaltigen alloys comparable are. the hardness and tensile properties of the alloys erfindungsgemäßeu is comparable with those of AZ91 at room temperature. _v

Other alloys were then made, their compositions fell in the following area;

aluminum 6 - 10 ■ J6 manganese 0.10-0.50 Galeium 0.6 - 1.0 io zinc not more than 0.46

Rest of magnesium, apart from impurities.

These alloys have been used for chilled casting using a modified (improved) test shell of the in Foundry 45, Issue 26 (1958) pages 761 to 765 described type. It was found that alloys are not more susceptible to heat cracks are common alloys that do not contain calcium (AZ91 alloys) and in terms of creep resistance

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15O ⁰ O are comparable with the calcium-containing alloys with a higher zinc content. The hardness and tensile properties of these alloys according to the invention were found to be comparable to those of AZ91 at room temperature.

For comparison purposes, alloys were prepared whose compositions were in the following areas:

Aluminum $ 6-10

Manganese $ 0.10-0.30>

Calcium 0.6 - 1.0 $

Zinc 0.61 - 1.0 ^

Rest of magnesium, apart from impurities. The alloys were cast in the same test pan as used in the above-mentioned alloys, i.e. both in an industrial pressure injection molding machine and in a modified (improved) test shell of the type described in Foundry 45, Issue 26 (1958) pages 761 to 765. Here a significant tendency towards heat cracking was found.

In addition, the following series of tests were carried out, which also the advantages of the alloy according to the invention over the show known calcium-containing alloys with a higher zinc content.

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Three different magnesium-based alloys have been used for die casting to produce parts of various shapes (given below). These alloys were ι

Alloy I i 9 # Al, (no Oa), 0.8 <fo Zn, 0.2 $ Mn, alloy II ί 9 # Al, 0.8 $ Ca, 0.15 $ Zn, 0.2 # Mn, Alloy ΙΙΙϊ 9 ί> Al ,. 0.8 $ Oa, 0.8 ^ Zn, 0.2 # Mn, remainder magnesium, apart from impurities.

, The four types of parts shown in the table below were die cast from each of alloys I, II and III namely in amounts between 30 and 2500 castings lay. The results are shown in the table below

Casting I II III

a) valve cover no no considerable heat

Heat cracks Heat cracks in places where

the wall thickness changes

b) typewriter. «■. Warmth on the right cover angled corners

c) Housing "'very little- considerable Nei

Ge tendency to heat cracks to heat (80 $ of the castings "ripped unusable)

d) Ash tray * few cracks - few cracks - strong cracks in

se to sharp to schso? - large number fen corners fen corners' ■

* This Ash Tray®j which has a multitude of ribs and sharp Had corners, was especially designed as a crack-sensitive casting for test purposes.

00 98 4.9 / 0413 Λ - 6 -

Additional experiments using the above-described alloys I, II and III with small amounts of Si and varying amounts of Mn ¹ revealed no discernible effect of silicon or manganese on the Wärmerißneigung.

Alloy I has, as can be seen from the table above is good heat cracking properties, but these alloys have is known to have a relatively low creep resistance in contrast to the new alloys II, which combine good heat cracking properties and good creep resistance. The table also shows that the known alloys III, which have good creep resistance, are poor in properties Have heat cracking.

The alloys according to the invention can easily be used for pressure injection molding and, as can be seen from the above, show a greatly reduced tendency to heat cracking while using the maintain high creep resistance (fatigue strength), which characterizes the well-known calcium-containing alloys based on magnesium.

The alloys can be made resistant to oxidation by the usual addition of a small amount of beryllium without noticeably impairing their desired properties will.

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The fact that a certain zinc content in the invention Alloy is preferred is based on the beneficial effect of zinc on the general casting properties of alloys of the present kind »

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Claims (5)

Patent claims 1. Magnesium-based alloy, consisting of 2 to 10 wt .- ^ AIu-? minium, 0.001 to 0.5 # manganese, 0.5 to 2.5 # calcium, up to 0.5 > copper, up to 0.5 # silicon and up to 0.6 # zinc, with some zinc preferably being present is, balance magnesium, apart from impurities. 2. Alloy according to claim 1, characterized in that it contains up to 0.5 # zinc. 3. Alloy according to claim 2, characterized in that it contains 0.1 to 0.5 1 ° zinc. 4. Alloy according to claim 3, characterized in that it Contains 7.5 to 9.5 aluminum and 0.7 to 1.0 56 calcium. 5. Alloy according to one of the preceding claims, characterized due to a low usual content of beryllium than Antioxidants. 009849/0413