US2254598A - Hot pressed or extruded alloys - Google Patents

Description

Patented Sept. 2, 1941 2,254,598 HOT PRESSED R EXTRUDED ALLOYS Reginald S. Dean, Salt Lake City, Utah, assignor to Chicago Development Company, Chicago, 111.,

a corporation of Illinois No Drawing. Application April 29, 1940.

Serial No. 332,287

6 Claims.

My invention relates to alloys of zinc, copper and manganese and is, particularly concerned with such alloys as contain a predominating proportion of zinc. My invention also relates to the fabrication of such alloys so as to provide the desired properties therein to a substantially maximum degree.

I have discovered that such alloys,- the composition of which is described hereinafter in detail, may readily be hot pressed or extruded and the resulting alloy, in the hot pressed or extruded form, possesses unusual and valuable properties.

A conventional type of alloy used for extrusion or hot pressing is a brass containing 60% copper and 40% zinc. The advantages of the alloys of my invention may be pointed out rather strikingly by contrasting them with said brass. At least many of the alloys of my present invention extrude at a much lower temperature, for example at about 400 degrees C., as contrasted with about 750 degrees C. for the brass. This results in a much longer life of the extrusion or hot.

pressing dies and, of course, greater economy of operation. In their hot pressed o,r extnuded form, the alloys of my invention have far better physical properties than the brass. For example, in many cases their tensile strengths are of the order of 50% greater than that of the brass, and their densities less than that of the brass, in some cases only about 80% of that of the brass. The wear resistance of the alloys of my present invention is also, at least in most cases, substantially greater than that of the brass.

The alloys of my invention contain relatively high proportions of zinc and ratios of manganese to copper of at least unity, and particularly relativelyhigh ratios of manganese to copper. The alloys fall within the general range of about 2% to about 15% copper, about 50% to about 75% zinc, and the balance substantially manganese, in each case, however, the manganese being present ".n amounts at least equal to, and preferably substantially greater than, the copper. Small proportions, for example, up to about 5% of other alloying constituents such as lead or tin maybe .utilized where special characteristics are desired, such as increased machinability or frictional resistance, but, in general, the alloys contain substantially only copper, zinc and manganese, such other elements as are present being introduced only as impurities. I may point out, however, that, for best results, the manganese employed should be electrolytic manganese or other highly pure manganese containing, preferably, not more than 0.1% of other metals or elements asimpurities, and the copper and zinc used should also be of highly pure grade, preferably electrolytic.

The alloys proper, prior to being extruded or point of the alloy so formed and zinc can be added directly to this alloy without appreciable volatilization. While any manganese of high purity, that is, containing not more than about 0.1% of metallic or other impurities, may be used in the production of useful alloys in accordance with my invention, for the best results, as previously noted, electrolytic manganese should be utilized both because of the relatively great readiness with which-the alloys are made in accordance with the preferred process and also because of the especially satisfactory properties of the alloys made with electrolytic manganese.-

The following is an illustrative example of an alloy made in accordancewith my invention. It

will be understood that the same is but one embodiment, which is to be interpreted as illustrative and in no way limitative of the full scope of the invention. Other alloys can be made within the composition range defined having at least many of the properties and advantages of that hereinbelow specifically described.

EXAMPLE 87.5 parts zinc and 12.5 parts copper were melted together'and, while maintaining the mixture in a substantially molten condition but below the boiling point of zinc, 25 parts of relatively finely divided electrolytic manganese were stirred in. When homogeneity was obtained, the alloy .was cast in ingots. The alloy so produced contained about 20% manganese, about zinc and about 10% copper. The alloy was extruded at 400 degrees C. Various of its properties are set forth in the following table: 4

Tensile strength 106,000 lbs/sq. in. Yield point 89,000 lbs/sq. in. Modulus of elasticity 15 M. lb./sq. in./in. Specific damping capac- 4 ity-per cent l 0.01 Electrical resistance 128 microns/cm. Coeificient of linear expansion-20-100 deg. C; 25.2x10- cm./cm./.C. Density 7.2 Rockwell hardness C-9 Elongation 2.5% in 2 inches The heat conductivity of'the alloy was very low,

degrees C. are satisfactory in most cases. Temperatures above 450 degrees C. may also be used but, in this temperature range, care must be exercised not to exceed the melting point which,

in the case of many of the alloys of my present invention, is between 450 degrees C. and 500 degrees C. Furthermore, when operating in the higher temperature ranges, the extruded product tends to take on an oxidized coating. While this coating does not appear to affect the valuable properties of the alloys, it may be objectionable -from the standpoint of finish or appearance,

and the extrusion temperatures should, therefore, be selected to avoid this undesirable result.

Within the composition range given, the higher zinc alloys, especially, for example, alloys eontalning 01 the order of about 65%to about 75% zinc, about 17% to about 23% manganese and about 8% to about 17% copper, are of great use in making various kinds of objects. In this particular range, the objects produced are, moreover,

relatively inexpensive due to the presence of the large proportion of the relatively cheap metal zinc. The alloys in this range may be produced with considerable advantage over alloys heretofore known and used for generally similar purposes.

The unusual combinations of properties of the alloys of the present invention render said alloys highly useful in the arts. Their high resistance and low melting point make many of them desirable for electrical fuses. The simplicity with which they maybe fabricated into various kinds of shapes by extrusion or hot pressing operations,

combined with the strength and hardness of the finished products,.make them valuable for the construction 01' ratchets and other machine parts subject to wear. The very low vibration damp- .ing' capacity makes the extruded alloys useful for vibration transmitting members in various sorts of machines. Their corrosion resistance, coupled with the ease of fabrication by extruding or hot pressing, and their low specific gravity compared to brass,'make the alloys valuable for the fabrication of valve bodies, gears, pinions, spuds and many other parts which, at present, are made from hot pressed, brass. What I claim as new and desire to protect by- 2. A hot pressed or extruded alloy containing.

about 70% zinc, about 20% manganese, and

about 10% copper.

3. A hot pressed or extruded alloy containing about 70% electrolytic zinc, about 20% electrolytic manganese, and about 10% electrolytic copper.

4. A hot pressed or extruded alloy of zinc,

copper, and manganese, said alloy containing from about 8% to about 17% copper, from about 65% to about 75% zinc, and the balance substantially all manganese.

5. A hot pressed or extruded alloy consisting substantially of zinc, copper and manganese, wherein the zinc comprises from about to about 75%, the copper from about 8%' to about 17 and the manganese from about 17% to about 23%.

- 6. A gear comprising a hot pressed or extruded alloy of zinc, copper, and manganese comprising about to about zinc, about 8% to about 17% copper, and the balance substantially all electrolytic manganese, said manganese being present in proportions at least equal to that of the copper.

' REGINALD S. DEAN.