JPH10502705A - Hot chamber castable zinc alloy - 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

The present invention relates to a zinc-based alloy containing Al and Cu that can be cast under pressure in a hot-chamber machine. Such alloys are described in the document SAE Technical Paper Series 930788, ACuZinc: An Improved Zinc Alloy for Use in Mold Casting, MD Hannah and MS Rashid, International Conference and Exhibition Detroit. , Michigan, March 1-5, 1995 ". This known alloy is called "ACuZinc5" and contains 5.0-6.0% Cu, 2.8-3.3% Al and 0.5% Mg. 025-0.05%, with the balance being zinc (all percentages herein are% by weight). The creep resistance of this alloy is substantially better than the creep resistance of Zamak or ZA alloys that have been cast in hot chambers for a long time, but is still relatively low. It is an object of the present invention to provide an alloy as described above which has a better creep resistance than the known alloys described above. To this end, according to the invention, the alloys are in weight%: Al15-20, Cu8-10, Si0.01-2, Mg0-0.1, Ti0-0.5, Cr0-0.5, Mn0. -1, Nb0-0.5 and one rare earth metal or metal mixture 0-0.1 (this composition is hereinafter referred to as variant I) or Al25-30, Cu15-20, Si0.01-2, Mg0-0 0.1, Ti0-0.5, Cr0-0.5, Mn0-1, Nb0-0.5 and any one of rare earth metals or metal mixtures 0-0.1 (this composition is hereinafter referred to as variant II) The balance is zinc and zinc and impurities unavoidably present in the alloying elements. Indeed, on the one hand, the two variants in the liquid state at a temperature not exceeding 460 ° C. have a low aggressiveness approaching steel, such as can be cast in a hot chamber, and, on the other hand, In the cast state, variant I has been found to exhibit good creep resistance and excellent tensile strength, and in the cast state, variant II has excellent creep resistance and good tensile strength. The Al and Cu contents described above must be adhered to, otherwise the melting point of the alloy rises above 450 ° C., so that the alloy becomes too corrosive to casting equipment above 460 ° C. So it can no longer be cast in a hot chamber. If the silicon content is less than 0.01%, the tensile strength and creep resistance deteriorate. A silicon content of more than 2% makes the alloy too pasty and too corrosive in the molten state. It is appropriate to report here that the following alloys have already been described: (a) 17-19 Al, 4.5-5.5 Cu, 0.9-1.3 Si, 0. 8-1.2 Mg, balance Zn (CS-A-135802) (b) 28.6 Al, 3.1 Cu, 1 Si, 0.1 Ca, 0.2 Ni, balance Zn (GB-A-768483) ) (C) 20-40 Al, 0-5 Cu, 0-1 Si, 0-0. 1 Mg, 0.25-2 At least one rare earth metal, balance Zn (US-A-4789522) (d) 55 Al, 8 Cu, 6.5 Si, 4.5 Be, 0.12 Ni, 0. 6 Ca, balance Zn (US-A-287008). Of these known alloys, alloys (a) and (c) are closest to the alloy according to the invention. Alloy (a) has a Cu content that is too low to be castable in a hot chamber and a Mg content that is too high. Alloy (c) also has an extremely low Cu content and, even in the oxidized state, prepares alloys containing 0.25-2% of these rare earth metals due to the high affinity of the rare earth metals for oxygen. It is extremely difficult to do. Variant I advantageously contains 15-18% Al, preferably 15-17%. The preferred Al and Cu contents of variant II are 25.5-28. 5% and 15-18%. The preferred Si content of both variants is 0.1-1%. Both variants:-up to 0.1% Mg, if necessary, to improve intergranular corrosion resistance;-up to 0.5% Ti, if necessary, to improve ductility. Up to 0.5% and Mn up to 1%;-if necessary, to improve the resistance to external corrosivity, ie up to 0.5% Nb to delay the formation of white salts; and If necessary, rare earth metals or metal mixtures may be included up to 0.1% to reduce the surface tension of the alloy in the molten state. With an Mg content of more than 0.1%, the alloy becomes pasty in the molten state and brittle in the solid state. The alloy also becomes a paste if it deviates from the above ranges for Ti, Cr and Mn. Nb contents greater than 0.5% and rare earth metal contents greater than 0.1% are difficult to use due to the high affinity of those elements for oxygen. The Zn, Al and Cu used to prepare the alloy each have a purity ≧ 99. It is desirable to have 99%, ≧ 99.95% and ≧ 99.99%. This is because the presence of impurities in the alloy has been found to adversely affect fluidity and mechanical properties. Preference is given to using zinc with a purity of 99.995% and aluminum with a purity of 99.97%. If the alloy contains a metal with a very high affinity for oxygen, such as Y, at least some of the metal may be present in an oxidized state. The good creep resistance of variant I of the alloy according to the invention and the excellent creep resistance of variant II are illustrated by a series of comparative tests described below, the results of which are shown in the accompanying drawings. Two known alloys, Zamak 5 and ACuZinc5, correspond to two alloys according to the invention, a first alloy corresponding to variant I, hereinafter referred to as "X27", and a variant II, hereinafter referred to as "X28" Was tested with a second alloy. The composition of these alloys is as follows:-Zamak 5: 4% Al, 1% Cu, 0.04% Mg, balance Zn;-ACuZinc 5: 3% Al, 5.5% Cu, 0.04% -X27: 17% Al, 9.5% Cu, 0.5% Si, balance Zn; -X28: 27% Al, 16.5% Cu, 0.1% Si, balance Zn. Specimens of these alloys were cast in a hot chamber machine. The general casting conditions were as follows:-Cycle time: 12 seconds-Bath temperature: 420-460 ° C-Pressure applied to the metal: 50 MPa-Piston speed: 1.2 m / s-Nozzle diameter: 9 0.5 mm-Mold temperature: 180-250 ° C. The shape and dimensions of these specimens are those specified by the European Zinc Processing Technical Committee for specimens used in tensile tests on sheets and foils made from zinc and zinc alloys. The specimen was subjected to a creep test at 100 ° C. under a load of 40 MPa. A creep curve showing the elongation (unit,%) measured as a function of time (unit, time) is shown in the accompanying drawings. It has been shown that the alloy according to the invention, in particular the variant II, is better resistant to creep than the known alloys. The excellent tensile strength and very high hardness of variant I and the good tensile strength and moderate hardness of variant II of the alloy according to the invention are shown by the data summarized in the table below. The tensile test was performed on a test piece having a thickness of 3 mm manufactured as described above at a tensile speed of 1 cm / min at room temperature. The present invention also relates to a method for producing an article comprising a zinc-based alloy containing Al and Cu by casting under pressure in a hot chamber machine, wherein said alloy is an alloy of the present invention; The casting is performed at a temperature equal to or less than 460 ° C. While the alloy of the present invention may be cast in a hot chamber, it may optionally be cast in a cold chamber and under atmospheric pressure. Therefore, the present invention relates to a method for producing an article comprising a zinc-based alloy containing Al and Cu by casting under pressure in a cold chamber machine or by gravity casting, wherein said alloy comprises Characterized in that it is an alloy of The invention further relates to a method of using the alloy according to the invention as an anti-friction material.

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Claims (1)

[Claims] 1. 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 metals or metal mixtures, the balance being zinc and zinc E) an impurity unavoidably present in lead and the alloying elements. Containing Al and Cu, which can be cast under pressure in a multi-chamber machine Lead-based alloy. 2. 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. 5Nb and 0-0.1 rare earth metal or metal mixture, the balance being zinc and It is an impurity unavoidably present in zinc and the above alloying elements. Contains Al and Cu, which can be cast under pressure in a hot chamber machine Alloy based on zinc. 3.15-18% by weight, and preferably 15-17% by weight of Al The alloy according to claim 1, wherein: Contains 4.25.5-28.5% by weight Al and 15-18% by weight Cu 3. The alloy according to claim 2, wherein: 5. The method according to claim 1, wherein the composition contains 0.1-1% by weight of Si. 2. The alloy according to claim 1. 6. Zn, Al and Cu have a purity of 99.99%, 99.95% and 9 respectively. 7. The composition according to claim 1, wherein said composition has 9.99%. alloy. 7. By casting under pressure in a hot chamber machine, Al and Cu A method for producing an article comprising a zinc-based alloy comprising The gold is an alloy according to any one of claims 1 to 6, and the casting is Characterized in that it is carried out at a temperature equal to or lower than 60 ° C. Construction method. 8. Casting under pressure or gravity casting in a cold chamber machine Manufactures articles consisting of zinc-based alloys containing Al and Cu Wherein the alloy is an alloy according to any one of claims 1 to 6. The above-mentioned manufacturing method, wherein 9. The alloy according to any one of claims 1 to 6 is used as an anti-friction material. how to.