US2011259A - Nonferrous alloy - Google Patents

Description

Patented Aug. 13, 1935 UNITED STATES PATENT OFFICE "NONFERROUS ALLOY William B. Price, Waterbury, Conn., assignor to Scovill Manufacturing Company, Waterbury, Conn., a corporation of Connecticut No Drawing. Application December 9, 1931, Serial No. 579,985

4 Claims.

than with prior alloys of the same metals having 7 higher percentages of copper and less of zinc. Also, while such prior alloys are very resistant to corrosion under ordinary conditions, yet at the high temperatures of annealing they form a slight scale which necessitates treatment with a pickling solution such as 10% sulphuric acid, solution.

By reducing the percentage of copper and increasing the percentage of zinc, while maintaining the same ranges of percentages of aluminum and nickel, the new alloy is so bright and free from scale that it is unnecessary to pickle it. A product of this kind is particularly suitable for architectural purposes, especially for exterior sidings or panels.

The alloys of the present invention consist chiefly of copper, zinc, nickel and aluminum, although, of course, in commercial production slight amounts of other metals may be present without injuriously affecting the advantageous properties of the alloy. For example, a slight percentage of lead not exceeding 2% of the whole will be advantageous where the product is to be machined as, for example, by turning.

For a material which is to have a good tensile strength particularly at relatively high temperatures, the most advantageous results are obtained with an alloy consisting chiefly of copper, zinc, nickel and aluminum, in which the relative proportions of the four metals are substantially as follows:

An alloy of this composition when extruded into bars and rolled to what is known as 8 numbers hard, gave, on testing, a Brinell hardness number 98. Different samples cut from this strip and annealed at different temperatures, as stated below, gave the following results:

Annealed at 500 0.

600 C. Brinell N o 84 69 This is to be compared with prior alloys having the same percentages of nickel and aluminum but with 80% copper and 17% zinc. The latter alloy when formed in the same way and tested after rolling gave a hardness of 95 Brinell and on annealing the samples gave the following results:

Annealed at It will be observed that the hardness of the new alloy with more zinc and less copper was higher than that of the prior alloy under each condition specified, and what is particularly significant is the fact that the drop in hardness by annealing at the customary annealing temperature of 500 C. was only 14 numbers Brinell with the new alloy, whereas it was 25 numbers Brinell with the prior alloy having 80% copper.

Other samples of the new alloy of similar composition were made and on analysis showed the following composition: A

Copper 70.56, nickel 1.42, aluminum 2.13, zinc by difierence 25.89 which, of course, might include a slight amount of impurities.

Comparative tests of this new alloy with the prior alloy of the same metals having copper higher and zinc lower were made for tensile strength, elongation and reduction of area at Per cent different temperatures. The prior alloy had the Copper following composition: Copper 80.16%, nickel Zinc 27 1.00%, aluminum 2.07%, zinc, by difference, Nickel 1 16.77%. The results of these comparative tests Aluminum 2 were as follows:

Temperature C. 25 250 375 500 625 750 J 875 T '1 st tbs:

ewe mg 91,600 74,100 51,000 24,000 5,100 2, 700 652 100,500 89,000 50,700 10,000 7,100 4.200 2,000 New 110 l6 z 4 30 40 a7 Priorill y 14 4 40 49 101 142 Reduction of area:

New alloy 66 2 5 v 32 51 40 Prior alloy 48 12 49 52 89 It will be observed that although the tensile strength of the new alloy at temperatures of 250 and below is somewhat less than that of the prior alloy, yet at temperatures ranging from 375 to 500 C. the tensile strength is greater and therefore the new alloy is particularly suitable for use under conditions where it must withstand working stresses at temperatures in the neighborhood of 375 C. to 500 C. This is confirmed also by the figures as to elongation and reduction of area.

In commercial practice the percentage of nickel in the alloy may vary from 1 to 1 and the aluminum from 2 to 2 /2% while still retaining the advantages of the invention as to satisfactory tensile strength and hardness of the resulting product under working temperatures as high as 500 C. as, for instance, in equipment for steam plants working at modern high pressures and consequent relatively high temperatures, this result being attained by keeping the percentage ofcopper below 80% and correspondingly increasing the zinc. It has been found that with nickel and aluminum within the ranges stated hereinabove the, copper may vary considerably from the 70% of copper employed in the best embodiment of the invention, provided, however, it be not lower than 60%. At this lower limit of copper, with nickel 1 to 1 aluminum 2 to 2% and zinc, including any impurities or slight amounts of other metals, by difference, ranging from 36 to 37, it will be found that the alloy comes through the annealing process in a very bright condition so that where color of this kind is desired, the lower percentage of copper may be employed, but with some reduc-' tion in tensile strength as compared with the alloy having 70% copper.

n the other hand, as the percentage of copper is increased from 70% toward 80%, the color is not quite so bright after annealing, the tensile strength at temperatures around 375 to 500 C. is not as high as that of the 70% alloy, and the hardness is less than that of said 70% alloy, but at temperatures below 375 C. the tensile strength is relatively higher. Therefore, to attain the advantages of the present invention the copper should be kept within the range of 60 to about 80% of the total of the four metals, copper, zinc, nickel and aluminum, and any impurities or additional metals should be kept below I Hence, the zinc should not be less than 16 A% and not more than 38% of the complete alloy, the lower figure allowing for the impurities or other metals such as some lead. In the best embodiment of the invention, as hereinbefore set forth, the impurities should be reduced to a minimum, for example, so as to total not more than half of one percent of the total alloy.

Although as pointed out above, the alloy consists chiefly of copper, zinc, nickel and aluminum, and the proportions may range as stated, viz: copper 60-79, zinc, about 38 to 16 A%, aluminum 1 to 2/z%, nickel 1 to 2 yet to obtain the best balance of the properties for commercial purposes, viz: good tensile strength, hardness and freedom from scale after annealing, it is well to keep closer to the ideal formula employing 70% copper, l to 2 aluminum, 1 to 2 nickel and the'balance substantially all zinc, except for i yipurities which, if present, should not exceed Where, however, the material is to be used for exposed architectural purposes, and a durable golden color is demanded while the tensile strength need not be so high, the ideal composition for such purpose will have copper about 60 to 65 percent, aluminum 1 to 2 nickel 1 to 2 impurities, including lead, not to exceed and the balance zinc.

In practice it is suflicient tomaintain the nickel and aluminum within the ranges stated and to maintain the copper within a range of about 5% each side of the ideal, that is to say within the range of 65% to 75%, the zinc constituting substantially all of the remainder, that is, about 20 to 33 percent of the whole. If there are any impurities or other metals such as lead, they should not exceed one percent, and the percentage of zinc should be reduced an equivalent amount.

An alloy embodying the present invention has all the advantages of the previously known high copper alloys consisting chiefly of copper, zinc, nickel .and aluminum in regard to corrosion resistance, lack of tendency to season crack and ease of extrusion into rods or tubes at relatively low temperatures and relatively low pressures. It has a tensile strength nearly as high at low temperatures, say from 25 C. to 250 C. and is much improved as to tensile strength in the range of 375 to 500 C. Its hardness is also higher at all temperatures.

What is claimed is:

1. An alloy consisting essentially of copper, aluminum, nickel and zinc, in proportions substantially as follows:

Per cent Copper 60 to 75 Aluminum l to 2 Nickel l to 2 Balance zinc except for impurities.

2. An alloy consisting essentially of copper, aluminum, nickel and zinc, in proportions substantially as follows:

Per cent Copper 70' Aluminum 1 to 2 Nickel 1 to 2 /2 Balance zinc except for impurities.

3. An alloy having the following composition:

Per cent Copper 60 to 75 Aluminum 1 to 2 /2 Nickel 1 to; 2 /2 Lead /2 to 1% Balance zinc, except for impurities.

Per cent Copper 60 to 70 Aluminum 1 to 2 Nickel 1 to 2 Lead, to modify machinability 0 to 1% Zinc constituting the remainder, except for traces of impurities.

WILLIAM 13. PRICE.