DK141373B - Aluminum-zinc alloy, preferably for use as a bearing material, and process for making it. - Google Patents

Description

(11) PRESENTATION 141373 DENMARK on Nothing.'C 22 C 21/00 • (21) Application No 5975/70 (22) Filed on 24 Nov. 1970 (23) Løbedsg Nov 24 1970 (44) The application presented and

the presentation paper published on 5 January. I98O

DIRECTORATE OF

PATENT AND TRADEMARKET (3 °> Priority requested from it

Feb 5 1970, 1045/70, AT

(71) UNITED AUSTRALIAN REQUIREMENTS AND STAHLWERKE AKTIENGESELLSGHAFT, Muldenetrasee 5> Linz, AT.

(72) Inventor: Erich _Pelzel, Wettersteinstrasse D-8031 Puchheim * (near Munich), DE.

(74) Plenipotentiary in the proceedings:

The company Chas. Hude.

(54) Aluminum-zinc alloy, preferably for use as a bearing material, and process for making it.

The present invention relates to an aluminum-zinc alloy having an aluminum content of 38-75%, preferably 50-65%, a content of nickel and optionally a content of magnesium and copper and the residual zinc, and a process for their preparation.

Such alloys are primarily used as bearing materials for bearing bowls or similar bearing parts, whereby they are manufactured by casting or by suitable shaping from rolled sheets. In each case, a piece of castings is first manufactured, the structure of which largely determines the properties of the bed.

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The aluminum-zinc-based alloys initially mentioned, due to their high solidification range, are prone to reverse block annealing and, as a result, intercrystalline porosity occurs. Such pores are not, as was previously assumed, favorable for the bearing wear conditions. Porous bearings that are soaked with oil are only self-lubricating when pores of a certain size are regularly distributed over the bearing wear surface. If this is not the case, the porous locations of a sliding surface remove the oil film in the dense locations, which may lead to tearing of the bearing.

It is known that in case of simply shaped pieces of aluminum zinc alloy castings, by virtue of very rapid cooling of these during casting, good mechanical properties are obtained. However, it has not hitherto been possible to exploit the advantages obtained by the rapid cooling of the castings, as the reverse block rise also increases with increasing solidification speed and therefore pores also appear in increased numbers in the castings. Admittedly, the propensity for pore formation can be diminished by casting techniques, such as by increased placement of riser and casting pins and by keeping them fluid. However, the metal that solidifies in the risers and molding pins must be separated from the actual molded product, for example by means of a cutting burner, and ends up as scrap. Since the amount of metal that solidifies in the riser pipes and casting pins constitutes a significant portion of the total amount of metal to be cast to produce a molded product, the disadvantages caused by the scrap quantity and greater cost of casting are of great importance. Apart from such financial considerations, the casting technical measures also do not lead to a successful outcome.

The invention aims to overcome these disadvantages, and the alloy according to the invention of the kind mentioned in the preamble is characterized in that the nickel content is at least 0.05% and at most corresponds to the course of the eutectic gutter in the aluminum-zinc-nickel system. , where the maximum content of nickel at 38% aluminum is 0.6%, at 50% aluminum 1.1%, at 60% aluminum 1.7%, at 70% aluminum 2.4%, at 75% aluminum 2, 8% and constant runs between the values stated.

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This results in a pore-free and fine-grained structure of the molded product and an increase in its hardness.

Advantageously, the alloy may further contain 0.005-0.05% magnesium, thereby obtaining a further grain reduction. Furthermore, copper may be contained in an amount not exceeding 6.5% of the aluminum content. This additional component also causes a hardness increase.

The process for preparing the alloy of the invention is characterized in that the starting materials have a purity of at least 99.5% and are free of elements which form insoluble compounds with nickel, such as silicon or boron, and are free of elements which crystallize primarily and such as needles such as iron, manganese, titanium, vanadium, molybdenum, tungsten and carbon.

Optionally, magnesium is suitably introduced in the form of a specific heavy alloy, preferably in the form of an alloy with 5% aluminum, 3% magnesium and 92% zinc.

In the manufacture of moldings from the alloy of the invention, it is advantageous that the heat dissipation during solidification thereof be kept below 0.2 cal / sec / g, preferably between 0.05-0.1 cal / sec / g.

Moldings made from the alloy of the invention can be rapidly cooled from temperatures above 350 ° C to room temperature and then heat-treated for a period between 0.25 and 8 hours at temperatures between 90 ° C and 275 ° C. By means of this heat treatment, a separation of pure zinc crystals from the alloy is produced in finely divided form, whereby the slip resistance properties of bearing materials made from the alloy according to the invention can be substantially improved.

The alloy of the invention can be thermoformed at temperatures between 200 ° C and 400 ° C, but can also be cold formed. Thus, it is possible to make thin-walled bearing bowls by forming cold-rolled sheets consisting of the alloy according to the invention.

. In the following examples, mechanical properties of a variety of alloys according to the invention are given.

Example 1

Medium load bearing alloy, annealed for 1 hour at 150 ° C.

Composition: Al 50%, Zn 49.3%, Ni 0.7%.

Cast Hardness: IL, - 90 kp / mm2 "2 Hardness after annealing: Ηβ - 65 kp / mm ·

Example 2

Higher load bearing material, annealed for 1 hour at 150 ° C. Composition: Al 58%, Zn 40%, Ni 1%, Cu 1%.

Cast Hardness: H_ - 110 kp / mm2 “2 Hardness after annealing: H_, - 90 kp / mm B 2 After the addition of 0.03% Mg the hardness increases by 10 kp / mm.

Example 3

Bearing alloy, hot rolled at 280 ° C from 30 mm to 6 mm, annealed for 3 hours at 150 ° C.

a) Composition: Al 60%, Zn 38.3%, Ni 1.7% 2

Cast Hardness: Ηβ - 115 kp / mrr ^ Hardness after annealing: Ηβ ^ kp / mm b) Composition: Al 60%, Zn 38%, Ni 1.7%, Cu 0.3%

Cast Hardness: Hn - 130 kp / mm2 ** 2 Hardness after annealing: Ηβ - 85 kp / mm

Alloys a) and · b) were cold rolled and heat treated for 3 hours at 150 ° C. Where two values are given in succession, the first value indicates the result of the measurement parallel to the rolling direction, and the second value indicates the result of the measurement perpendicular to the rolling direction.

Claims (4)

5 1A1373 a) Cold rolled Heat treated flow limit (kp / mm2) 27 31 18 18 Breakage limit (kp / mm2) 3436 23 24 Extension (%) 10 15 20 20 Hardness Ηβ (kp / mm2) 70 55 b) Cold rolled Heat treated flow limit (kp / mm2) 36 34 22 23 2 Fracture limit (kp / mm) 4444 26 28 Extension (%) 55 15 20 Hardness Ηβ (kp / mm2) 95 70 Patent claim. An aluminum-zinc alloy, preferably for use as a bearing material, which has an aluminum content of 38-75%, preferably 50-65%, a content of nickel and optionally a content of magnesium and copper and the rest of zinc, characterized by: the nickel content is at least 0.05% and at most corresponds to the course of the eutectic gutter in the aluminum-zinc-nickel system, with the maximum content of nickel at 38% aluminum being 0.6%, at 50% aluminum 1.1%, at 60% aluminum 1.7%, at 70% aluminum 2.4%, at 75% aluminum 2.8% and constant progress between the values indicated. An alloy according to claim 1, characterized by a magnesium content of 0.005-0.05%. An alloy according to claim 1 or 2, characterized by a copper content of not more than 6.5% of the aluminum content. A process for making an alloy according to any one of claims 1-3, wherein the process of starting aluminum, nickel, zinc and optionally magnesium and copper is melted and the molten alloy is cast and solidified.