US2156348A - Copper-zinc alloys - Google Patents

Description

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Patented May 2, 1939 PATENT OFFICE COPPER-ZINC ALLOYS Wolf Johannes Miiller and Moritz Niessner, Vienna, Austria, assignors to Oesterreichische Dynamit Nobel Aktiengesellschaft, Vienna, Austria, a .firm of Austria No Drawing. Application June 29, 1935, Serial No. 29,102. In Austria July 21, 1934 3 Claims.

It is known that gamma-brass, that is to say copper zinc alloys'with a copper 'content of about 31-40%,1. e. alloys which are characterised by a low copper content, are more resistant to corrosion than the brass alloys of the alpha and alpha and beta region with for instance 68-72% and more of copper, i. e. ahigher'copper content. The technical employment of gamma-alloys poor in copper is however impossible, since these alloys are extremely hard and brittle and are consequently not machinable.

From such alloys as is described in our prior Patent Nos. 2,006,598 and 2,006,599, it has been disclosed that it is possible, by the addition of a few percent of a metal soluble in gamma-brass or alloyable therewith, such as nickel or, with more advantage cobalt, preferably by a simultaneous addition of nickel and cobalt, to obtain alloys, which possess the good resistance to corrosion of gamma-alloys poor in copper, but are also capable of being worked up, that is to say can be treated with machine tools and can also Such alloys with an addition of approximately 340% of cobalt, nickel or the like individually or in mixture, that is to say for instance pure copper-zinc alloys with a minimum content of nickel of approximately 7-8% or of cobalt of approximately 5-6% have extremely good technical properties, and when cobalt and nickel are used simultaneously it is possible with a much smaller cobalt content to obtain the same effects as with the use of cobalt alone. Consequently alloys that are deficient in copper, even those most deficient, can be made utilisable for industrial purposes or as constructional material for the production of articles, if the copper-zinc alloys are alloyed with cobalt, nickel or the like individually or in mixture.

The present invention is based on the discovery that such copper-zinc alloys containing cobalt,

nickel or the like, which contain copper in such an amount that they have a homogeneous mixed crystal or solid solution structure-that is to say in a binary system copper-zinc alloyswith approximately 31-40% copper--, can be substantially improved in their properties by the addition of other metals, i. e. metals which are soluble in the solid solution of the alloy and are added or alloyed in an amount that is not greater than corresponds to their solubility in the solid solution. It has been found that such alloys can be made capable of being moulded in the cold state, i. e. rolled, pressed and drawn in the cold state by the addition of such metals in amounts which are soluble in the solid solutions so that the solid solution formation is maintained and the occurrence of a heterogeneous structure is avoided. Such metals are for instance aluminium, tungsten, tin, chromium, selenium, tellurium, titanl-- um, silver, silicon, iron, manganese, lead, molybdenum, zirconium etc. individually or two or more such metals combined as desired, and of thesemetals, the best effect is obtained 'by those which cause-an increase in fineness of the grain, that is to say more especially manganese, iron, lead,

silver. Phosphorus also produces this effect. By

such additions the region of the solid solution can also be somewhat extended with respect to that of the binary alloy, and alloyswith asomewhat higher copper content for instance with 45% copper content, which come in the beta and gamma region in the binary alloy, can be made suitable for purposes for which they would otherwise be impossible owing to their copper content, such as for instance for cold rolling or for a drawing process.

In particular suitable are alloys with a copper content of at least 35%; such alloys, as compared with alloys with less copper content, have the advantage of better workability.

By addition of such metals the alloy can be I improved in colour, more especially made whiter, and also favourably influenced as regards other properties, more especially made tougher, thus improving the capacityfor being machined.

It is easily possible by empiric means to determine for each metal the amount which produces the most favourable effects.

It is more especially advisable to use the metals of the iron group,'more particularly manganese. 46

- be assumed as more than 4% manganese.

which as compared with other metals, for instance as compared with aluminium, has the efiect that with an increasing content, i. e. up to about 10%, there is an approximately proportional improvement in the capacity of working up cold, whereas for instance aluminium in amounts of about 0.3% has an extremely favourable action, but in amounts of more than 1. shows a diminished efiect.

The more deficient the alloy is in copper, the greater addition of manganese is necessary, and the lower limit for alloys deficient in copper must The higher the content of manganese, the better is the capacity for being worked up cold, and one can go up to an addition of about 15% manganese. Suitable is an alloy which beside manganese, contains iron up to the limit-of solubility. which, depending on the composition of the alloy', may be 1 to 1.5%.

The addition of manganese has also the effect however that the addition of cobalt and nickel or the like can be reduced.

It is advisable to add very small amounts of phosphorus to such alloys, whereby a very considerable increase in the fineness of the grain oi the alloys can be obtained.

The cobalt or nickel content or content of cobalt and nickel in such alloys according to the invention may be between about 3-12%.

Examples Suitable alloys according to the invention with manganese as added metal have for instance the following composition, it being clearly specified manganese content is smaller in the alloys of relatively high copper content than in the alloys of relatively low copper content.

however that the invention is naturally not limited to these examples:

Percent by weight What we claim is: 1. A corrosion resistant copper-zinc alloy,

which is workable in the cold state, containing copper in an amount of 30 to 45%, at least one metal of the group cobalt and nickel in an amount of 3 to 12% and in addition thereto manganese in an amount 4 to 15%, the zinc, constituting substantially the the remainder.

2. An alloy according to claim 1 wherein the 3. An alloy according to claim 1 -containing less than copper.-

WOLF JOHANNES Mt'irLLER. 35

MORITZ N'IESSNER.