US2230969A - Alloys - Google Patents

Description

" Patented Feb. 4-, 1941 UNITED STATES PATENT OFFICE ALLOYS Reginald 8. Dean, Washington, D. C., assignor to Chicago Development Company, Chicago, 111. a

corporation of Illinois No Drawing. Application July 8, 1939,

' Serial No. 283,464

6 Claims. (Cl. 75-178) liliy-invention relates to alloys .of copper, zinc n'd manganese and is a continuation-in-part of V 'r'ny prior application Serial No. 199,329, filedApril duction of hard, high tensile strength casting al-' 10 loys which may be produced relatively inexpensively, although many of the alloys within the composition range pointed out hereinbelow may be used for other purposes.

More specifically, my present invention relates to alloys containing relatively high proportions of zinc and ratios of manganese to copper of at least unity, and particularly relatively high ratios of manganese to copper. The alloys fall within the general range 2% to copper, to zinc, and the balance substantially manganese, in each case, however, the manganese being present in amounts at least equal to, and preferably substantially greater than, the copper. Small proportions of other alloying constituents may be utilized where special characteristics are desired, 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 at the outset, 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 as impurities, and the copper and zinc used should also be of highly pure grade.

At least most of the alloys in the composition range identified are somewhat ductile and very hard and strong. They may be produced in accordance with various procedures, but the most suitable and dependable method isfirst to-prepare an alloy of zinc and copper and sukequently add the manganese in theform of a fairly fine powder. I have found that if the substantially molten mixture is stirred at a temperature slightly below the boiling point of zinc, a homogeneous alloy is readily produced. While any manganese of high purity, that is, containing not more than about 0.1% of metallic impurities, may be used in the production of useful alloys in accordance with my invention, for the best results, I

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 so far as ductility and toughness are concerned.

Example 1.In accordance with one example, I melttogether parts zinc and 15 parts cop- 5 per, and, while maintaining the mixture in a substantially molten condition but below the boiling point of zinc, I stir in 25 parts relatively finely divided electrolytic manganese. When homogeneity-is obtained, the alloy is cast in in- 10 gots or it may be cast directly into sand or chilled molds or in a'die casting machine. The alloy so produced contains about 20% 'manganese, about 68% zinc and'about 12% copper. It has a hardness greater than Rc-15 as cast and a tensile strength greater than 150,000 pounds per square inch. Some of the additional properties and uses of alloys of this composition will be discussed hereinafter.

Example 2,- parts zinc and 10 parts copper are heated to about 870 degrees C. and 50 parts finely divided electrolytic manganese are introduced, with stirring, maintaining the temperature of the mixture below the boiling point of zinc. The alloy so produced contains about 60% zinc, about 6%% copper, and about 33%% manganese.

Example 3.6 parts copper and 94 parts zinc are heated together in accordance with the pre- 30 ceding example, and parts of electrolytic manganese are introduced. Following the procedure outlined in the preceding examples a highly useful alloy is produced containing about 50% manganese, 3% copper and 47% zinc.

Example 4.12 parts copper and 88 parts zinc are heated together and parts finely divided electrolytic. manganese are gradually introduced, maintaining the temperature slightly below the, boiling point of zinc and continuing heating and stirring until a homogeneous mixture is produced. The molten mixture either may be cast into ingots or directly into molds for the production of castings. The alloy so'produced contains 35.2% zinc, 60% manganese and 4.8% copper. 45

Preferably following the general procedure given in the preceding examples, alloys of various combinations of zinc-copper-manganese may be produced. At least most of them are suitable for die casting or for casting in chilled or sand molds. 50 The alloys so produced are, in general, readily machined, have a beautiful silver color, and are highly resistant to corrosion either by atmospheric conditions or by salt water. The hardness of at least most of the alloys ranges from Etc-15 5 tom-25. and the tensile strength from 150,000

pounds per square inch to 250,000 pounds per square inch. The elongation in two inches varies, in general, from 5% to 10%.

Within the composition range given, the higher zinc alloys, especially, for example, alloys containing of the order of about to zinc, about 20% manganese and about 10% to about 15% copper, are of great use in making all sorts of hardware and decorative 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 overother alloys having properties which render them suitable for the same general purposes.

The utility of the alloys of the present invention is by no means confined to such materials as hardware and decorative objects. Particularly when the proportion of manganese is at least about 20% and somewhat higher than 20%, and, for that matter, throughout the range given, castings of great strength and hardness are produced which are highly resistant to corrosion and, therefore, have-great advantage where such combinations of properties are required. Examples are parts of marine pumps and various valves and gears which are subjected to corrosive conditions.

While the alloys of my present invention are primarily designed for use as castings, some of them are sumciently ductile so that various types of forming operations may be utilized in manufacturing finished parts. The great tensile strength and hardness of the castings, however,

makes it possible to'employ the alloy as cast for large numbers of mechanical purposesyandwhere finished surfaces are necessary, as in valves and gears, or the like, the easy machineability of the castings makes it possible to finish them from the casting to any final shape desired. In using the alloys, they may be cast to shape as melted initially, or the ingots may be produced and subsequently remelted for production of castings.

What I claim asnew and desire to protect by Letters Patent of the United States is:

1. An alloy of 3.0% to zinc, 2% to 15% copper. and balance substantially pure manganese, the manganese being present in proportions at least equal to that of the copper.

2. A casting alloy containing about 70% zinc,

about 20% manganese, and about 10% copper.

3. A casting alloy containing about 70% zinc, about 20% electrolytic manganese, and about 10% copper.

4. A deformable alloy of manganese, zinc and copper, having a hardness of at least Rc-15 in the cast condition, said alloy containing from about 10% to about 15% copper, from about 65% to about 70% zinc, and the balance substantially pure manganese.

5. -An alloy of zinc, manganese and copper particularly suitable for the production of tough castings, said alloy comprising about 65% zinc, about 20% manganese and about 15% copper.

6. An alloy, particularly adaptable for castings, comprising 2% to 15% copper, 30% to 75% zinc, and-the balance substantially electrolytic manganese, said manganese being present in proportions at least equal to that-of the copper.

. REGINALD S. DEAN.