US2033710A - Copper alloys - Google Patents

Description

Patented Mar. 10, 1936 UNITED STATES PATENT OFFICE COPPER ALLOYS Franz R. 'Hensel. Indianapo Ind., and Earl I.

Larsen, Newark, N. 1., assignors to Westinghouse Electric &

Manufacturing Company,

East Pittsburgh, Pa, a corporation of Pennsylvania 4 Claims.

This invention relates to alloys and particularly to copper base alloys which have improved mechanical, thermal and electrical properties.

Certain metals have been alloyed with copper to produce an alloy having better mechanical properties but generally such alloys have been quite inferior to copper as conductors of electricity and it has been difllcult to duplicate the resulting characteristics.

An object of this invention is to produce an alloy of copper in which hardening elements are distributed throughout the resulting alloy in a finely divided state, improving the mechanical properties of the alloy and maintaining a high electrical and thermal conductivity comparable to that of copper.

This application is a division of Serial No. 714,614, filed March 8, 1934, and directed to Copper alloys.

In order to produce a copper base alloy which will have desired mechanical and electrical properties, metals are added which can be precipitated to effect a dispersion of fine particles throughout a copper melt. It has been discov- 'ered that a copper alloy containing even small proportions of chromium and cadmium has excellent mechanical and electrical properties when suitably heat treated.

The introduction of the chromium into molten copper to form a solution is diiilcult, for chromium dissolves slowly in copper and the amount finally dissolved is small. The free chromium differs in density from copper and tends to segregate in the melt and to result in lack of homogeneity in the resulting solid product. More- .over, chromium being lighter than copper it is diflicult to keep the chromium submerged for the time required to dissolve it. The chromium tends to rise to the surface of the melt where oxides are formed that contaminate the product.

In practice, finely divided chromium may be added to the copper melt in the form of a compacted mass or mixture in order that the chro mium will be dissolved in and not tend to segregate irom the copper melt. One of the preferred forms in which the. chromium is added to the copper melt is as a cake, pellet or rod compacted from intermixed copper and chm-- mium powders.

In producing the cake, pellet or rod of intermixed copper and chromium powders, the coper and chromium melts are powdered to approximately 100 mesh size and then thoroughly mixed and compressed to suflicient density to flnnflno of the chromium from molten copper. A pressure of about 60,000 lbs. per sq. inch on the intermixed copper and chromium powders produces a mass which has a density 01' about 8.5. Lower pressures and densities, however, may be employed.

Another method of preparing the powdered copper and chromium metals in the form desired is to alternately compress the powdered mixture under a pressure of 4000 lbs. per sq. inch and then heat the compressed mass in areducing atmosphere to sinter the particles. A modification of this method is to heat the compressed mass in a reducing atmosphere to approximately the melting point of copper and to quickly strike the mass a hard blow as in a die under a punch press.

The finely divided chromium powder may also be enclosed in copper tubes of suitable size instead of in the form of compressed and sintered masses hereinbefore described. The copper tubes which contain the chromium powder are swaged to suitable compactness for addition to the molten metal. Such articles may be employed as hardening and scavaging additions to other alloys.

Satisfactory copper chromium alloys containing up to 5% of cadmium have been produced which have high mechanical properties and good electrical conductivity. The cadmium may be added to the copper melt either in the form or pure cadmium or it may be added in the form of a fine powder compressed with the finely divided, chromium and copper powders into a compact mass or mixture such as the cake, pellet or rod hereinbefore described.

Generally, the alloying content of the alloys prepared in accordance with this invention comprises from .l% to 5% cadmium with about .l% to 5% chromium and the balance copper. The relative amounts of cadmium and chromium content in the copper base alloy is adjusted according to the hardness or strength and conductivity desired.

These copper base alloys have excellent mechanical and electrical properties and may be employed in making sand castings of complicated design. In casting the alloys where the chromium content is above 1.5% there is a tendency for the chromium to separate and segregate and float to the top of the casting and to thus produce unsound castings. This segregational effect of the high chromium content in the alloy may be reduced by the use 01' rapidly cooled types of molds. Slower cooled types of molds may be employed where the chromium content of the alloy is about .5%. The alloys formed by such an addition have good pouring qualities and when suitably heat treated have excellent mechanical and electrical properties.

chanically operated welding electrodes, or as welding wheels, or as current collecting nozzles on automatic arc welding heads. Further, an

important use for these high strength alloys is a cylinder head for internal combustion motors such as for automobile engines. Thesefields re- FRANZ R. HENSEL. EARL I. LARSEN.

C'ERTIFICAT OF CORRECTION.

5 In practice, the castings made from the copquire a metal of high electrical and thermal con- 5 per base alloys are aged by suitable heat treatductivity combined with high strength at somement to develop the mechanical and electrical what elevated temperatures. These alloys are properties of the alloy. A method which has been found suitable for use at normal or low temperafound to be satisfactory for developing the proptures as required for transmission wires.

erties of the alloy is to heat the casting to be- It is, of course, to be understood that various 10 tween 600 C. and 1000 C., quench or quickly modifications may be made in the alloying concool it and then reheat it to between 250 C. and stituents and heat treatment as above described 600 C. Where feasible, an intermediate cold without in any way departing fromthe spirit of working step may be interposed between the the invention, as set forth in the appended claims.

quenching and ageing steps. We claim as our inventionz. 15

. Alloys whose alloying contents arewithin the 1. An alloy comprising about .1% to 5% chroranges hereinbefcre described when heat treatmium, about .1% to 5% cadmium and the baled in the above manner have excellent mechanance copper. 1 ical and electrical properties. An alloy compris- 2. An alloy comprising 1% to chromium, 2%

:0 ing cadmium as high as 2% with about 1% chroto cadmium and the balance copper. 0 mium and the, balance copper when quenched 3. An age hardened copperbase alloy comprisfrom 950 C. had a hardness of 59 Brinell. After ing from .1% to 5% chromium, from .1% to 5% this alloy has been aged at 450 C., the alloy has cadmium with the balance copper which has been a hardness of 116 Brinell. When quenched, the quenched from a temperature of between 600 alloy has a conductivity of only 50% of that of C. and 1000" C. and reheated to and aged at a 25 copper but after ageing. tests conducted show that temperature of between 250 C. and 600 C. to dethe conductivity of the alloy has increased to 90% velop hardness and conductivity. of that of copper. 4. An age hardened copper base alloy compris- Alloys prepared from these alloying elements ing from .1% to 5% chromium, from .i% to' 5% a 80 and within the ranges given above are particucadmium with the balance copper which has been larly useful in the manufacture of large castings quenched from a temperature of between 600 such as commutator segments and collector rings C. and 1000" C., cold worked. and then reheated dy amo electric machines, t e lloys havto and aged at a temperature of between 250 ing high strength and high conductivity are par- 0. and 600 C. to develop hardness and conducticularly adapted to be employed astips for metivity. 35

March 10, 1 936.

Patent No. 2,033,710. I

FRANZ R. HENSEL, ETAL.

I-t is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, lines 19 and 20, claim 2, for "to" read of; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

'Signed and sealed this 26th day of' January, A. D. 1937.

Henry Van Arsdale (Seal) Acting Commissioner of Patents .5%. The alloys formed by such an addition have good pouring qualities and when suitably heat treated have excellent mechanical and electrical properties.

chanically operated welding electrodes, or as welding wheels, or as current collecting nozzles on automatic arc welding heads. Further, an

important use for these high strength alloys is a cylinder head for internal combustion motors such as for automobile engines. Thesefields re- FRANZ R. HENSEL. EARL I. LARSEN.

C'ERTIFICAT OF CORRECTION.

5 In practice, the castings made from the copquire a metal of high electrical and thermal con- 5 per base alloys are aged by suitable heat treatductivity combined with high strength at somement to develop the mechanical and electrical what elevated temperatures. These alloys are properties of the alloy. A method which has been found suitable for use at normal or low temperafound to be satisfactory for developing the proptures as required for transmission wires.

erties of the alloy is to heat the casting to be- It is, of course, to be understood that various 10 tween 600 C. and 1000 C., quench or quickly modifications may be made in the alloying concool it and then reheat it to between 250 C. and stituents and heat treatment as above described 600 C. Where feasible, an intermediate cold without in any way departing fromthe spirit of working step may be interposed between the the invention, as set forth in the appended claims.

quenching and ageing steps. We claim as our inventionz. 15

. Alloys whose alloying contents arewithin the 1. An alloy comprising about .1% to 5% chroranges hereinbefcre described when heat treatmium, about .1% to 5% cadmium and the baled in the above manner have excellent mechanance copper. 1 ical and electrical properties. An alloy compris- 2. An alloy comprising 1% to chromium, 2%

:0 ing cadmium as high as 2% with about 1% chroto cadmium and the balance copper. 0 mium and the, balance copper when quenched 3. An age hardened copperbase alloy comprisfrom 950 C. had a hardness of 59 Brinell. After ing from .1% to 5% chromium, from .1% to 5% this alloy has been aged at 450 C., the alloy has cadmium with the balance copper which has been a hardness of 116 Brinell. When quenched, the quenched from a temperature of between 600 alloy has a conductivity of only 50% of that of C. and 1000" C. and reheated to and aged at a 25 copper but after ageing. tests conducted show that temperature of between 250 C. and 600 C. to dethe conductivity of the alloy has increased to 90% velop hardness and conductivity. of that of copper. 4. An age hardened copper base alloy compris- Alloys prepared from these alloying elements ing from .1% to 5% chromium, from .i% to' 5% a 80 and within the ranges given above are particucadmium with the balance copper which has been larly useful in the manufacture of large castings quenched from a temperature of between 600 such as commutator segments and collector rings C. and 1000" C., cold worked. and then reheated dy amo electric machines, t e lloys havto and aged at a temperature of between 250 ing high strength and high conductivity are par- 0. and 600 C. to develop hardness and conducticularly adapted to be employed astips for metivity. 35

March 10, 1 936.

Patent No. 2,033,710. I

FRANZ R. HENSEL, ETAL.

I-t is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, lines 19 and 20, claim 2, for "to" read of; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

'Signed and sealed this 26th day of' January, A. D. 1937.

Henry Van Arsdale (Seal) Acting Commissioner of Patents