Copper Base Alloy

Abstract

The present disclosure teaches an improved copper base alloy containing iron and tin and a material selected from the group consisting of phosphorous and zinc and mixtures thereof. The alloys of the present invention are characterized by improved physical properties, in particular high strength and high conductivity.

Parent Case Text

This application is a continuation-in-part of copending application Ser. No. 648,946 for "Copper Base Alloy" by Charles D. McLain, filed June 26, 1967, now abandoned.

Description

As is well known in the art, copper is an excellent conductor of electricity. Numerous alloying additions have been proposed in order to increase the strength of copper. In so doing, the electrical conductivity of the copper is markedly reduced.

It is, therefore, highly desirable to provide a copper base alloy characterized by high conductivity and increased strength.

Accordingly, it is a principal object of the present invention to provide a copper base alloy characterized by high electrical conductivity and high strength properties.

It is a further object of the present invention to provide a copper base alloy with annealed physical properties which do not have a wide variation.

It is a further object of the present invention to provide a copper base alloy having the ability to attain various strength levels as a result of different annealing treatments, even when small amounts of impurities are present.

It is a further object of the present invention to provide an improved copper base alloy having a combination of high strength, high conductivity, and other excellent physical properties.

It is an additional object of the present invention to provide a copper base alloy which is inexpensive and wherein the excellent physical properties are easily obtainable.

Further objects and advantages of the present invention will appear from the ensuing specification.

In accordance with the present invention it has been found that an improved copper base alloy is provided which effectively achieves the foregoing objects and advantages. The alloy of the present invention comprises a copper base alloy consisting essentially of from 1.5 to 3.5 percent iron, from 0.02 to 0.10 percent tin, a material selected from the group consisting of phosphorus from 0.01 to 0.08 percent, zinc from 0.05 to 0.20 percent and mixtures thereof and the balance essentially copper. Throughout the ensuing specification all percentages are percentages by weight.

In accordance with the present invention, it has been surprisingly found that the foregoing alloys are characterized by numerous unexpected and surprising advantages. For example, the alloys of the present invention have an unexpected improvement in electrical conductivity. Namely, there is readily obtained an IACS electrical conductivity in excess of 60 percent IACS and generally over 70 percent IACS. Furthermore, the alloys of the present invention have excellent annealing characteristics, with the ability to attain various strength levels as a result of different annealing treatments. In addition, the alloys of the present invention attain high rolled temper strength levels. Still further the high electrical conductivity of the alloys of the present invention is coupled with excellent annealed tensile strength properties of approximately 55,000 p.s.i. and higher. The strength and physical properties of the alloys of the present invention are not significantly variable if small amounts of impurities are present. In addition to the foregoing, the alloys of the present invention are inexpensive and their excellent physical properties are easily obtainable.

The composition of the alloys of the present invention is as stated heretofore. The preferred iron content is from 1.8 to 2.9 percent and the preferred tin content is from 0.03 to 0.10 percent. The preferred zinc content is 0.05 to 0.15 percent.

In view of the high and in fact surprising physical properties of the alloys of the present invention, the percentage ranges of the alloying ingredients are important.

In addition to the foregoing, small amounts of additional alloying ingredients may be, of course, included in order to achieve particularly desirable results, for example, phosphorus from 0.01 to 0.10 percent and zinc from 0.05 to 0.20 percent. Also, small amounts of impurities may be tolerated.

The alloys of the present invention attain improvement over conventional alloys in a wide range of processing. Naturally, however, particular processing will result in variation in properties.

The manner of casting the material is not particularly critical, with conventional casting methods for these types of alloys being readily utilizable, it being noted that higher temperatures should be used in order to solutionize the iron. It is preferred to cast the alloy into billets of conventional size, subjecting them to hot working, as by rolling in the conventional size.

After casting the alloy should be hot rolled at an elevated temperature, i.e., from 800.degree. to 1,050.degree. C., with a temperature of about 950.degree. C. being preferred. The alloy should then be cold rolled to gage, with intermediate anneals, with cold reduction in excess of 50 percent between anneals being preferred. Annealing temperatures of from 400.degree. to 600.degree. C. are preferred, with annealing time at temperature preferably being a minimum of 2 hours. Longer times may be utilized, if desired, to improve electrical conductivity. Continuous strand annealing of strip or mill products will achieve the same high level of physical properties as with bell annealing, but will not achieve as high a level of electrical conductivity. Therefore, for development of both high annealed strength and electrical conductivity, final annealing and preferably in process annealing must be in batches with conventional furnace cooling, such as bell annealing.

Detailed processing and preferred processing parameters consonant with the foregoing are found in copending application Ser. No. 648,742 for "Process For Treating Copper Base Alloy," filed June 26, 1967 by C. D. McLain, now U.S. Pat. No. 3,522,112.

The present invention will be more readily understandable from a consideration of the following illustrative examples.

EXAMPLE I

Alloys were prepared in the following manner. High purity copper and high purity iron were melted together in a low frequency, slot-type induction furnace under a charcoal cover at approximately 1,200.degree. C. About 10 percent of the copper charge was held back and the melt was slightly overheated to about 1,300.degree. C. in order to put the iron into solution. High purity alloying additions were added when the molten mass was at about 1,300.degree. C. The balance of the copper was added and the melt brought to the pouring temperature of about 1,200.degree. C. The melt was then poured into a water-cooled ingot mold of 283/4.times.5.times.96 inches at a pouring rate of 21.3 inches per minute.

The alloys thus prepared had the following composition. --------------------------------------------------------------------------- TABLE I

Alloy Iron Phosphorus Tin Copper __________________________________________________________________________ 1 2.3% 0.03% 0.08% essentially balance 2 2.3% 0.03% -- essentially balance __________________________________________________________________________

EXAMPLE II

Alloys 1 and 2 prepared in example I were processed as follows. The alloys were hot rolled at from 900.degree. to 940.degree. C., followed by a water spray quench to room temperature. The materials were then cold rolled to 0.100 inch, bell annealed at 480.degree.-600.degree. C. (1 to 4 hours at temperature,) cold rolled to 0.050 inch, bell annealed at 460.degree.-480.degree. C. (1 to 3 hours at temperature,) and cold rolled to 0.025 inch gage and bell annealed at 440.degree.-480.degree. C. (1 to 3 hours at temperature.)

The alloys were then tested for physical properties, with the results being shown in the following table. ##SPC1##

The foregoing demonstrates that alloy 1, the alloy of the present invention, develops greater annealed strength levels than conventional alloy 2 at comparable electrical conductivity.

This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.

Claims

What is claimed is:

1. A high conductivity, high strength copper base alloy consisting essentially of from 1.5 to 3.5 percent iron, from 0.02 to 0.10 percent tin, a material selected from the group consisting of phosphorus from 0.01 to 0.08 percent, zinc from 0.05 to 0.20 percent and mixtures thereof and the balance copper.

2. A copper base alloy according to claim 1 containing both phosphorus and zinc.

3. A copper base alloy according to claim 1 in the flat rolled condition.

4. A copper base alloy according to claim 1 having an electrical conductivity of at least 70 percent IACS and an annealed tensile strength of at least 55,000 p.s.i.

5. A copper base alloy according to claim 1 having an electrical conductivity of at least 60 percent IACS.

6. A copper base alloy according to claim 1 wherein the zinc content is from 0.05 to 0.15 percent.

7. A copper base alloy according to claim 1 wherein the iron content is from 1.8 to 2.9 percent.

8. A copper base alloy according to claim 1 wherein the tin content is from 0.03 to 0.10 percent.

9. A copper base alloy according to claim 1 in the cold-rolled condition.

10. A copper base alloy according to claim 1 in the cold-rolled and annealed condition.