FI114400B - Zinc alloy cast in hot chamber - Google Patents

Abstract

Alloy containing, in percentage by weight, (a) either 15-20 Al and 8-10 Cu, or 25-30 Al and 15-20 Cu; and (b) 0.01-2 Si, 0-0.1 Mg, 0-0.5 Ti, 0-0.5 Cr, 0-1Mn, 0-0.5 Nb and 0-0.1 of a metal or a mixture of rare earth metals, the remainder being zinc. The alloy has excellent creep and tensile strength, when it contains 15-20 Al and 8-10 Cu weight percent, and excellent creep and tensile strength when it contains 25-30 Al and 15-20 Cu.

Description

1,114,400

This invention relates to a zinc-based alloy containing Al and Cu that can be cast in a hot chamber machine.

Such an alloy is described in "SÄE technical paper series 930788. ACuZinc: Improved zinc alloys for die casting application, M.D. Hanna and M.S, Rashid. International Congress and Exposition Detroit, 10 Michigan, March 1-5, 1993". This known alloy, called "ACuZinc 5", contains 5.0 - 6.0% Cu, 2.8 - 3.3% Al and 0.025 - 0.05% Mg, the remainder of Zn (all percentages given in this patent application are% by weight). The creep resistance of this alloy, although slightly higher than that of Zamak or ZA alloys cast for a long time in a hot chamber, is still relatively low.

It is an object of the present invention to provide an alloy such as the one described above which has a better creep resistance i '. 20 than the aforementioned known alloy.

Therefore, according to the invention, the alloy contains% by weight of t: either 15 to 20 Al, 8 to 10 Cu, 0.01 to 2 Si, * * 0 to 0.1 Mg, 0 to 0.5 Ti, 0 to 0 , 5 Cr, 0 - 1 Mn, 0 - 0.5 Nb * ·. and 0 to 0.1 rare earth or a mixture thereof, hereinafter referred to as the "I variant," or 25 to 30 Al, 15 to 20 Cu, 0.01 to 2 Si, 0 to 0.1 Mg, 0 to 0, 5 Ti, 0 -0.5 Cr, 0-1 Mn, 0-0.5 Nb and 0-0.1 rare earth or alloy thereof, this alloy is hereinafter referred to as Variant II, the remainder being zinc and zinc and above 30 inevitable impurities in said alloy elements.

:, · In fact, it has now been found, on the one hand, that these two variants of V'i, when liquid at temperatures below 460 ° C, have such a low reactivity with steels that so-35 can be cast in a hot chamber, and Fourth I has good creep strength and excellent tensile strength in casting, while Variant II has excellent creep strength and good tensile strength. The above AI and Cu concentrations must be respected; otherwise, the melting point of the alloy 5 rises above 450 ° C, which causes the alloy to no longer be cast in the hot chamber because its reactivity with the casting tools becomes too high at over 460 ° C. If the silicon content is less than 0.01%, tensile strength and creep strength 10 will decrease. When the silicon content is above 2%, the alloy becomes too doughy and reactive when melted.

It is useful to recall here that the following alloy species have already been described: a) 17-19 Al, 4.5-5.5 Cu, 0.9-1.3 Si, 0.8-1.2 Mg, 15 Zn (CS application 135,802) b) 28.6 Al, 3.1 Cu, 1 Si 0.1 Ca, 0.2 Ni, remaining Zn (GB application 769 483) c) 20-40 Al, 0- 5 Cu, 0 to 1 Si, 0 to 0.1 Mg, 0.25 to 2, at least one rare earth metal, the remainder of Zn (U.S. Pat. No. 4,789,522) d) 55 Al, 8 Cu, 6.5 Si, 4.5 Be, 0.12 Ni, 0.6 Ca, remainder, ··, Zn (U.S. Pat. No. 287,008) • · 'Among these known alloys, alloys a) and »· 5. c) are closest to the alloy of the invention. The alloy a) 25 Cu content is too low and Mg content too high to be cast in the hot chamber. The Cu .. content of the alloy c) .. is also too low; furthermore, it is extremely difficult to produce an alloy containing 0.25 to 2%; rare earth metals and would not be in an oxidized state, because these metals have a high affinity for oxygen.

»*

Variation I preferably contains 15-18% Al and 15-17% Al.

In variant II, the best concentrations of AI and Cu are 25.5-28.5% and 15-18%, respectively.

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The best Si concentration in these two variants is 0.1-1%. These two variants may contain: - up to 0.1% Mg to improve inter-crystalline corrosion resistance, if necessary; 5 - up to 0.5% Ti, up to 0.5% Cr, and up to 1% Mn to improve forensic properties if necessary; - up to 0.5% Nb to improve external corrosion resistance, where appropriate, to retard white salt formation; and 10 - up to 0.1% of the rare earth or their alloy to reduce the surface tension of the alloy when melted, if necessary.

If the Mg content is greater than 0.1%, it will make the alloy doughy melt and brittle solid. Alloy 15 also becomes dough-like when the above Ti, Cr and Mn contents are exceeded. 0.5% higher Nb concentrations and 0.1% higher rare earth concentrations are difficult to achieve because of the high affinity of these elements for oxygen.

It is desirable that the Zn, Al and Cu used. alloy, would be of equivalent purity. *, equivalent to> 99.99%, 99.95% and 99.99%, as observed. It is noted that the presence of impurities in the alloy adversely affects its flowability and mechanical properties. Preferably zinc with a purity of a 99.995% and aluminum with a purity of a 99.97% are used.

. : It is clear that when an alloy contains metal, it has a very high affinity for oxygen, such as:. Therefore, at least one portion of this metal may be in oxidized form.

The good creep strength and the excellent creep strength of Variant I of the invention according to the invention are shown below in the descriptions of the comparative test series, the results of which are given in the enclosed tau-35 lock.

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Two known alloys, Zamak 5 and ACuZink 5, and two alloys of the invention were tested, the first according to Variant I, hereinafter referred to as "X27" and the second according to Variant II, hereinafter referred to as "X28".

Composition of these alloys: - Zamak 5: 4% Al, 1% Cu, 0.04% Mg, remaining Zn; ACuZinc 5: 3% Al, 5.5% Cu, 0.04% Mg, remaining Zn; - X27: 17% Al, 9.5% Cu, 0.5% Si, end Zn; 10-X 28: 27% Al, 16.5% Cu, 0.1% Si, end Zn.

Specimens of these alloys were cast on a hot-seat machine.

The general conditions for casting were as follows: - cycle time: 12 seconds

15-bath temperature: 420-460 ° C

- metal pressure: 50 MPa - piston speed: 1.2 m / s - trough diameter: 9.5 mm

- mold temperature: 180-250 ° C

j _ 20 These specimens have the same shape and dimensions. ··, the dimensions of test specimens used for tensile tests of zinc sheets and 1-sheet and zinc alloys as described by the Technical Committee of the European Zinc Producers.

1,, The test pieces were subjected to a creep test at 100 ° C under a load of 40 MPa. Creep curves giving elongation (in%) as a function of time (in hours),. , is shown in the attached table.

:, · It is found that the alloys according to the invention, and in particular the alloy according to variation II, are much more resistant, · 1.30 more virulent than the known alloys.

The alloy of the variant I according to the invention; · The excellent tensile strength and very high hardness and the good tensile strength and suitable hardness of the alloy of Variant II are shown in the 35 results in the table below.

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Table

Alloy Tensile Strength Vickers Hardness (MPa) (5 Kgf)

Zamak 5,286,105 ACuZinc 5,270 5 X27 435 181 X28 276 140

Tensile tests were performed at room temperature at a tensile speed of 1 cm / min on test pieces of 10 to 3 mm thickness prepared as described above.

The present invention also describes a process for making parts of a zinc-based alloy containing Al and Cu by casting under pressure in a hot-chamber machine, characterized in that the alloy set is an alloy of the invention and that the casting is performed at a temperature equal to or less than 460. ° C. Since the alloy according to the invention can be "cast in a hot chamber, it may be forced to be cast in a cold chamber and gravity."

* · · 20 The present invention thus also describes a process for making parts of a zinc-based alloy containing Al and Cu by casting under pressure in a cold chamber; machine or gravity, this process is characterized in that the alloy is an alloy of the invention.

The present invention also describes the use of an alloy according to the invention as an anti-friction material.

i t »t I · t I • · * · *» 1 ·

Claims (9)

1. Zinc-based alloy, which contains Al and Cu and which can be molded under pressure in a hot-chamber machine, characterized in that it contains as a percentage by weight 15-20 Al, 8-10 Cu, 0.01-2 Si , 0 - 0.1 Mg, 0 - 0.5 Ti, 0 - 0.5 Cr, 0-1 Mn, 0 - 0.5 Nb and 0-0.1 rare earth metal or a mixture thereof, the remaining part zinc and in zinc and in the alloys mentioned above are inevitable impurities. 2. Zinc-based alloy containing Al and Cu and which can be molded under pressure in a hot-chamber machine, characterized in that it contains in percent by weight 25 - 30 Al, 15 - 20 Cu, 0.01 - 2 Si , 0 - 0.1 Mg, 0 - 0.5 Ti, 0 - 0.5 Cr, 0-1 Mn, 0 - 0.5 Nb and 0 - 0.1 rare earth metal or a mixture thereof, the remaining part are zinc and in zinc and in: "the above-mentioned elements of the alloy inevitable impurities: ** 20. 3. An alloy according to claim 1, characterized in that it contains 15-18 and preferably 15-17 AI. An alloy according to claim 2, characterized in that it contains 25.5 - 28.5 Al and 15 - 18 Cu. 5. An alloy according to any of claims 1-4, characterized in that it contains 0.1 - 1 Si. : An alloy according to any one of claims 1-6, characterized in that it contains Zn, Al *. and Cu having a purity of> 99, 99%,> 99, 95% and> 99.99% respectively. 11440C Process for the production of articles of a zinc-based alloy containing Ά1 and Cu, by casting in a hot-chamber machine, characterized in that the alloy is an alloy according to any of claims 1-6 and that the casting is carried out at 460 ° C. or a temperature below it. Process for the preparation of articles of a zinc-based alloy containing A 1 and Cu, by casting in a hot-chamber machine or by gravity casting, characterized in that the alloy is an alloy according to any one of claims 1 to 6. Use of an alloy according to any one of claims 1-6 as an anti-friction material. • · i · * «k» <·