US2357190A - Copper base alloys - Google Patents

Description

Patented Aug. 29, 1944 I Frank Charles Evans, Farnham Common, England,

Langley, England assignor to Langley Alloys Limited,

N Drawing. Application December 9, 1941, Se-

rial No. 422,295. 1940 3 Claims.

This invention relates to copper base alloys with more especial reference to alloys hardenable by heat treatment and containing small proportions of nickel or chromium and silicon.

Heat treatable copper base alloys containing 0.5-5% nickel, 0.l-1.25% silicon corresponding to about one quarter of the nickel content,'and optionally containing also proportions of magnesium have been proposed and are hardenable as a result of heat treatment consisting generally in quenching from TOO-900 C. followed by ageing between about 400-600 C., but it is found in, practice that these alloys are diflicult to handle and there is a large proportion of failures after heat treatment owing to embrittlement of the alloy due to the hardening constituent separating out on the grain boundaries.

The present invention has for its principal object'to remove this disadvantage and to provide for the addition of grain refining elements which facilitate casting and result in improved structures.

In accordance with the present invention copper base alloys hardenable by heat treatment consist of copper. with nickel, and silicon, and

also as grain refining elements cerium, with or without titanium, which have been found to inhibit embrittlement, thereby greatly facilitating the conduct of the heat treatment, and enhancing the grain structure of the product.

In the practice of the invention applied to copper alloys containing 0.5-5% nickel, 0.1-1.25% silicon with or without magnesium, the grain refining element, cerium and, it may be titanium, are included in proportions ranging from 0.05-0.5%, and not only is the casting facilitated and the structure of the products improved as a result of the grain refining action on the alloy, but cerium has the additional advantageous property of de-oxidizing and scavenging the copper, when treated with an addition of 0.25%

cerium, with or without titanium, will give in the heat treated condition an ultimate tensile In Great Britain April 16,

- been completely eliminated.

stress of 35 tons/sq. in., and-an elongation of thereby showing that embrittlement has The'presence of the additional elements in the proportions mentioned does not bring about any reduced electrical conductivity in the heat treated alloy and it will be understood that the normal heat treatment procedure is followed,

melt, thus freeing it from obnoxious oxides and that is to say, the alloy as cast is quenched from '700-900.C. and then artificially aged or precipitation hardened for about five hours at 400- 600 C.

In the case of forgings the heat treatment is preceded by hot working at a temperature above 800 C. and the alloy may be cold worked after quenching and either before and/or after the artificial Such alloys with the additions of cerium, and it may be titanium, after forging and heat treatment with or without intermediate or final cold working, have been found suitable for the valve guides in internal combustion engines and other applications where resistance to wear and strength at high temperaturesare of importance.

By the present invention the casting, fabrication and heat treatment of hardenable copper alloys is greatly facilitated and uniform products of enhanced grain structure and properties are obtained.

What I claim is:

1. Copper base alloys hardenable by heat treatment containingfrom 0.5% to 5% nickel, from 0.1% to 1.25% silicon, from 0.05% cerium, and from 93% to 99% copper.

2. Copper base alloys according to claim 1 containing 2.6% nickel and 0.9% silicon, with 0.25% cerium and sufficient copper to make 100%.

3. Copper base alloys according to claim 1 including also from 0.05-0.5% titanium.

FRANK CHARLES EVANS.

ageing or. precipitation hardening