US2136918A - Copper alloys - Google Patents

Description

Nov. 15, 193s; F. R. HENSEL ET AL 1 2,136,918

COPPER ALLoYs Filed sept. '15, 1957 Waarna/v /n/ 7///f/f/vf.ss[%j l ATTORNEY Patented Nov. 15, 1938V 1 lCOPPER ALLOYS Franz B. Hensel and Earl I. Larsen, Indianapolis,

Ind., assignorsto P. B. Mallory & Co., Inc., Indianapolis, Ind., a corporation of Delaware Application September 15, 1937, Serial No. 164,039

1 Claim.

This invention relates to copper alloys.

An object of the invention is to produce an improved copper base alloy.

Another object is to produce a copper-tin base 5 alloy which can be age hardened.

Other objects of the invention will be appar# ent from the following description taken in connection with the appended claim.

The present invention comprises the combination of elements, methods of manufacture and the product thereof, brought out and exemplified in the disclosure hereinafter set forth, the scope of the invention being indicated in the appended claim.

In the drawing: Figure 1 is a graph having curves, illustrating the improvement in the hardness and electrical conductivity of the alloy of the present invention during age hardening;V v Figure 2 is a graph showing the effect of cold working after quenching from high temperatures and subsequent aging at a temperature of 450 degrees C.; and

Figure 3 is a graph showing the effects of cold working the quenched and aged alloy.

While a preferred embodiment of the invention is described herein, it'is contemplated that considerable variation may be made in the method of procedure and the combination of elements, 30 ithout departing from the spirit of the inven- Copper-tin alloys are frequently used at the present time for the purpose of current carrying springs, special trolley wires and electrical conductors of various types. These alloys, while having numerous advantages, when used at low temperatures, are not entirely satisfactory when used at even moderately high temperatures, such as 300-350 degrees C. Furthermore, in order to obtain a reasonably high hardness, it is necessary .to add a tin contentv ranging from 5-10%. This high percentage of tin, which is held in solid solution by the copper decreases the electrical conductivity enormously.

According to the present invention, copper-tin base alloys are improved by the addition of zirconium. The improved alloys can not only be \made of greater hardness than prior copper-tin alloys, but are also capable of retaining their hardness at high temperatures. v

According to the preferred method of carrying out the present invention, an alloyis made containing copper, tin and zirconium in substantially the following proportions:

Per cent 'Iln 0.1-10 Zirconium 0.05-5 Copper Balance.

Itis possible likewise to improve the characteristics of other copper-tin alloys by the addition of zirconium, particularly copper-tin alloys con- ,i

taining small percentages of phosphorus. Such alloys are generally known as phosphor bronzes and usually contain from about 0.01 vto 1.0% phosphorus. In general, copper-tin base alloys, containing small proportions of silver, zinc, magnesium, calcium, lithium, silicon, beryllium, cadmium, iron, nickel, cobalt, manganese, can be improved by the addition of zirconium in substantially the proportions indicated above.

The addition of zirconium to the above alloys renders them susceptible to age hardening.

The alloy can be made accordingto standard alloying methods, such as melting the copper and adding the desired amount of tin. Afterwards the zirconium may be introduced in any suitable form, such as pure zirconium wrapped in foil, or a hardener alloy or zirconium powder mixed with copper powder and compressed to a high density.

After the alloy has been lprepared. according to the standard alloying methods, the heat treatment `may be carried out as follows:

The alloy in the form of a billet or -a sand casting or any other desired form, is raised in temperature to above l7,00 degrees C. The alloy is then quenched from this high temperature and subsequently aged at temperatures below 700 degrees C. This heat treatment results in a con- `siderable improvement in the hardness of the alloy. For example, an alloy of Per cent Zirconium 0.5 Tin 0.5 Copper Balance.

having a Rockwell B hardness of 21, after quenching, may be given a Rockwell B hardness of 60 by the heat treating process. This is shown` in a curve of Figure l. Another remarkable effect of the heat treatment is the marked improvement of the electrical conductivity. With the alloy combination of 1/2% tin and 1/2% zirreached.

1f a certainamount of cold working is applied after quenching, this same alloy will reach a higher hardness after aging. If it is, for instance, reduced 60% in thickness, the hardness after aging is 79 Rockwell B.

If the alloy is completely age hardened and cold worked afterwards, a Rockwell B hardness of over 70 can be easily obtained with 25% reduction.

In many applications, it is not necessary to `retainthe high electrical conductivity of and higher tin contents may be employed. In this case, the increasein hardness is much more pronounced and materials can be produced which areideally suited for springs. Due to the fact that the material will not anneal until high temperaturesvare reached, these springs will have conium an electrical conductivity of 63% was a decreased tendency to creep in service and the material may be subjected to higher temperatures than was heretofore possible.

Usually the phosphor bronzes were susceptible to annealing and the annealingv temperature was a function of the amount of cold work. In other words, if the material was severely cold worked, the annealing temperature would be comparatively low. With the addition of zirconlum, all of these disadvantages are entirely overcome and a'material ispproduced which will not soften until the aging temperature is reached. Furthermore, if the. material hasbeen softened,` its hardness can be restored by a heat treating process. This is very important, 4be. .cause in some cases, the metal might have been reduced in thickness to the desired dimensions and further reductions are undesirable. In such Vvleases an Ordin/ary phosphor-copper spring ,would lbe useless, whereas the present inventionv proturing process. l

properties and Yelectrical properties are 'Ihe alloys have a high resistance to corro- -sion and a reduced tendency to oxidation.

The alloys are well suited for any electrical or mechanical luse at room temperatures and also at elevated temperatures, 'since the physical maintained at such elevated temperatures for indenite periods.

The alloys are also suited for the manufacture of bronze castings which may be used for such applications as commutator segments, collector rings, structural parts of electrical machinery.

In addition, the alloys are well suited for welding electrode tips as used in resistance welding and forwelding wheels.

Another important use of these high strength alloys` is in the manufacture of parts used for internal combustion engines Where high heat conductivity is needed in combination with high strength.

While the present invention as to its objects and advantages has been described herein; as carried out in specifcembodiments thereof, it is not desired to Vbe limited thereby, but it is ingtended to cover the invention broadly, within the spirit and scope of the appended claim.

What is claimed is: l An age-hardened alloy containing about 0.1 to 10% tin, about 0.05 to 5% zirconium, and the balance substantially all copper, characterized by a combination of high hardness and high electrical and heat conductivity and further characterized by the fact that its hardness and Vconductivity is not permanently adversely affected by temperatures in the order of 400-450 degrees C.

' FRANZ R. HENSEL.

EARL I. LARSEN.

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