JP3800345B2 - 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

引張試験は、上記のように製造された厚さ３ｍｍの試験片に対し引張速度１ｃｍ／分で室温にて行われた。
本発明はまた、ホットチャンバー機内で加圧下鋳造することにより、ＡｌおよびＣｕを含有する亜鉛がベースの合金からなる物品の製造方法に関し、該方法は上記合金が本発明の合金であり、そして上記鋳造が４６０℃に等しいか、またはそれより低い温度で行われることを特徴とする。
本発明の合金はホットチャンバーにおいて鋳造され得るが、それは必要に応じ、コールドチャンバーにおいて、および大気圧下で鋳造され得る。
それ故に、本発明はコールドチャンバー機内で加圧下鋳造するか、または重力鋳造することにより、ＡｌおよびＣｕを含有する亜鉛がベースの合金からなる物品の製造方法に関し、該方法は上記合金が本発明の合金であることを特徴とする。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: Improved Zinc Alloy for Use in Die Casting, MD Hanna and MS Rashid, International Conference and Exhibition Detroit Michigan, March 1-5, 1993 ". This known alloy is called “ACuZinc5” and consists of Cu 5.0-6.0%, Al 2.8-3.3% and Mg 0.025-0.05%, the balance zinc (all in the present specification). % Is by weight). The creep resistance of this alloy is substantially superior to the creep resistance of Zamak or ZA alloys that have been cast in hot chambers for a long time, but is still relatively low.
The object of the present invention is to provide an alloy as described at the outset which has better creep resistance compared to the known alloys.
For this purpose, the alloys according to the invention are in weight percent: Al25-30, Cu15-20, Si0.01-2, Mg0-0.1, Ti0-0.5, Cr0-0.5, Mn0-1, Impurities that inevitably exist in zinc and zinc and the above alloying elements, containing Nb0-0.5 and one rare earth metal or metal mixture 0-0.1 (this composition is hereinafter referred to as variant II) It is.
In addition, the alloy of a reference example is weight%: Al15-20, Cu8-10, Si0.01-2, Mg0-0.1, Ti0-0.5, Cr0-0.5, Mn0-1, Nb0- 0.5 and 1 rare earth metal or metal mixture 0-0.1 (this composition is hereinafter referred to as variant I), the balance being impurities inevitably present in zinc and zinc and the alloying elements mentioned above .
In fact, on the one hand, the two variants that are in the liquid state at temperatures not exceeding 460 ° C. have low aggressivity that approximates steel such that they can be cast in a hot chamber, and on the other hand, casting It has been found that variant I exhibits good creep resistance and excellent tensile strength in the state and variant II exhibits excellent creep resistance and good tensile strength in the cast state. The Al and Cu contents described above must be adhered to, otherwise the melting point of the alloy will rise above 450 ° C, so that the alloy will be too corrosive to casting equipment above 460 ° C. So it can no longer be cast in the hot chamber. If the silicon content is less than 0.01%, the tensile strength and creep resistance deteriorate. A silicon content greater 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-769483)
(C) 20-40 Al, 0-5 Cu, 0-1 Si, 0-0.1 Mg, 0.25-2 At least one rare earth metal, the 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).
Among these known alloys, the alloy (c) is closest to the alloy according to the present invention. Alloy (a) has a Cu content that is too low to be cast in a hot chamber and a Mg content that is too high. Alloy (c) also has an excessively low Cu content and, even in the oxidized state, prepared an alloy containing 0.25-2% of these rare earth metals because of 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%, respectively. The preferred Si content of both variants is 0.1-1%. Both variants are
-Up to 0.1% Mg to improve intergranular corrosion resistance if necessary;
-Ti up to 0.5%, Cr up to 0.5% and Mn up to 1% to improve ductility if necessary;
-Nb up to 0.5% to improve resistance to external corrosion if necessary, ie to delay the formation of white salts; and-Surface tension of the alloy in the molten state if necessary May be included up to 0.1% of rare earth metals or metal mixtures.
With an Mg content greater than 0.1%, the alloy becomes pasty in the molten state and becomes brittle in the solid state. The alloy also becomes pasty 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 because of their high affinity for oxygen.
It is desirable that the Zn, Al and Cu used to prepare the alloys have a purity ≧ 99.99%, ≧ 99.95% and ≧ 99.99%, respectively. This is because it has been found that the presence of impurities in the alloy adversely affects fluidity and mechanical properties. Preferably, a purity of 99.995% zinc and a purity of 99.97% aluminum are used.
When the alloy contains a metal having a very high affinity for oxygen, such as Y, at least a portion of the metal may be present in an oxidized state.
The excellent creep resistance of variant II of the alloy according to the invention and the good creep resistance of variant I of the reference alloy are illustrated by the series of comparative tests described below, the results of which are shown in the accompanying drawings. ing.
Two types of known alloys, Zamak 5 and ACuZinc5, correspond to two types of alloys according to the present invention, a first alloy corresponding to variant I, hereinafter referred to as “X27”, and variant II, hereinafter referred to as “X28” And tested with a second alloy.
The composition of these alloys is as follows:
-Zakuma 5: 4% Al, 1% Cu, 0.04% Mg, balance Zn;
-ACuZinc5: 3% Al, 5.5% Cu, 0.04% Mg, balance Zn;
-X27: 17% Al, 9.5% Cu, 0.5% Si, balance Zn;
-X28: 27% Al, 16.5% Cu, 0.1% Si, balance Zn.
These alloy specimens were cast in a hot chamber machine.
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: 9.5 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 elongation (unit,%) measured as a function of time (unit, time) is shown in the accompanying drawings.
It has been shown that variant II of the alloy according to the invention is better resistant to creep than known alloys.
The excellent tensile strength and very high hardness of variant I of the reference alloy 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 at room temperature at a tensile speed of 1 cm / min on the test piece having a thickness of 3 mm produced as described above.
The 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 the method is the alloy of the invention and It is characterized in that the casting is carried out at a temperature equal to or lower than 460 ° C.
The alloy of the present invention can be cast in a hot chamber, but it can be cast in a cold chamber and under atmospheric pressure if desired.
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, the method comprising the above-mentioned alloy according to the present invention. It is an alloy of the above.

Claims (6)

25-30Al, 15-20Cu, 0.01-2Si, 0-0.1Mg, 0-0.5Ti, 0-0.5Cr, 0-1Mn, 0-0.5Nb and 0-0. Contains Al and Cu, which can be cast under pressure in a hot chamber machine, characterized in that it contains one rare earth metal or metal mixture, the balance being zinc and zinc and impurities inevitably present in the alloying element Alloy based on zinc. 2. An alloy according to claim 1, comprising 25.5-28.5 wt.% Al and 15-18 wt.% Cu. Alloy according to claim 1 or 2, characterized in that it contains 0.1-1 wt% Si. The Zn, Al and Cu used to prepare the alloy have a purity of 99.99% or more, 99.95% or more and 99.99% or more, respectively. Alloys described in 1. A method for producing an article made of a zinc-based alloy containing Al and Cu by casting under pressure in a hot chamber machine, wherein the alloy is according to any one of claims 1 to 4. A method characterized in that it is an alloy and the casting is carried out at a temperature equal to or lower than 460 ° C. A method for producing an article made of a zinc-based alloy containing Al and Cu by casting under pressure in a cold chamber machine or by gravity casting, wherein the alloy is any one of claims 1 to 4. A method according to any one of the preceding claims.

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