US2034561A - Copper and copper base alloys - Google Patents

Description

March 17, 1936. c. H. DAVIS COPPER AND COPPER BASE ALLOYS Filed Oct. 13, 1934 216 920 M g m ATTORNEYS Patented Mar. 17, 1936 UNITED STATES PATENT OFFICE COPPER AND COPPER BASE ALLOYS Application October 13, 1934, Serial No. 748,193

1 2 Claims.

This invention relates to articles made of copper and copper base alloys improved with respect to resistance to corrosion or intercrystalline parting in the metal, particularly in steam, by the addition of a certain amount of cadmium.

It has been found in certain types of steam service, especially at temperatures above 212 F. C.) and pressures above atmospheric, that the steam and (or) gases commonly associated with steam in ordinary manufacturing or commerce cause certain copper base alloys to disintegrate or crack.

Notable failures of copper and copper base alloys have occured while in use, as portions of expansion joints in the steam lines in large cities, such as New York and Boston. The early or unexpected failure of copper or copper base alloys in these locations is a. serious menace to commerce and health. An intensive study of the causes of such failures in copper base alloys was initiated with'the result that by a novel' method of testing in steam, certain alloys have been discovered to be particularly resistant to the action of steam at elevated temperatures.

The disintegrating action of the steam or gases in the steam mentioned in the previous paragraphs is especially pronounced at the boundaries of the grains of the alloys; separating said grains or crystals by destroying the cohesion and bond that normally holds the alloy crystals together in a strong, unified mass. Certain copper base alloys, when under stress, or when alternately stressed and unstressed, have been shown more susceptible to this disintegrating action of steam and (or) gases in steam than other copper base alloys. Commercially pure copper itself is susceptible to this action just described and fails quickly under the higher unit stresses.

. The effect of steam at elevated temperatures upon copper and certain copper base alloys is known to the engineers in charge of aforesaid steam lines and to certain of the engineering and metallurgical professions, but it has beenfurther demonstrated in a novel method of laboratory test.

Wires of copper and many copper base alloys have been subjected while under stress, or while alternately stressed and unstressed, to the action of steam. It was found by said tests that representative wrought copper base alloys from the following alloy systems, while under stress, are susceptible to a greater or less degree to the disintegrating action of steam, and this indicates the remaining alloys of these systems are also so susceptible to this disintegrating action. These systems include, in addition to the commercially pure copper:

Commercial copper-silicon alloys up to at least 5 indicates that practically all copper base alloys are improved at least to some extent by the presence of cadmium in the alloy with respect to resistance to corrosion in steam.

The tests were made in a cylindrical steam chamber with normal pressure pounds per sq. in. gauge pressure, equivalent to a temperature of about C. The steam was analyzed and the impurities determined. The copper base alloy specimens were in the form of .036" diameter wire and these passed through glands sealed with asbestos packing in each head of the cham- 85 her so that a load of any size might be applied to stress the wires. The loads varied from no load up to 80% ofthe ultimate strength of thespecimens. Tests made under intermediate loads, such as 5%, 10%, 20%, 30%, 40%, etc. of the ultimate strength of the specimens revealed that the length of life of the specimens under test in steam varied proportiontally with the amount of load or stress applied during the test. Hence, tests were conducted at stresses both under and over the yield point, elastic limit and (or) proportional limit of many specimens. The usual procedure was to keep the steam turned on at all times but to remove the load for a certain period of the specimens and extending inward until the 66 remaining cross-section of sound metal fractured because of the increased unit stress.

Another type of failure was discovered where the grains parted in the interior of the specimens with no apparent connection with the surfaces. Certain specimens failed by one or the other of these types of intergranularseparation, while others failed by a combination of the two types of parting.

In order to present concrete evidence of the behavior of several selected copper base alloys in the testing apparatus described in the above paragraphs, examples of these alloys are now listed. The specimens were in the steam chamber in about 130 lbs. per sq. in. steam pressure (180 C.) and each specimen was stressed individually to of its ultimate tensile strength.

The above actual steam tests and many other similar tests have demonstrated the superiority In many instances apparatus fabricated of these cadmium-bearing copper base alloys may need to be joined by welding. It has been found that such welds can be and are preferably made from similar cadmium-bearing welding, or filler rods, for it is important that welding joints be as resistant to the disintegrating action of steam as the metals welded.

A characteristic of a number of these alloys is a reddish surface film noticeable after annealing or heating, especially on the surface of the lighter nickel-bearing alloys. This film appears to afford some protection against intercrystalline parting or corrosion.

In casting the aforedescribed copper base cadmium-bearing alloys the cadmium may be added as the metal or in any other suitable form of alloy. In other words it may be added as in usual casting shop practice. A satisfactory way is to Results of tests in steam of various copper bar alloys each stressed to 80% of its ultimate strength Alloy Failed at hours under Cuv Sn Cd Si Mn Ni Al Zn stress of the cadmium-bearing copper base alloys under stress in steam. My tests show other elements such as manganese, nickel, tin and arsenic, and combinations of these elements materially aid in preventing or inhibiting the action of steam and/or-gases in steam on copper and copper base alloys, and although we recognize the beneficial effects of the presence in certain copper base alloys for service in steam of such elements as manganese, nickel, tin and arsenic, I have discovered and demonstrated that cadmium is the most beneficial in a great many instances, and even improves the corrosion resistance to steam and/or gases when used with these elements. The following are examples.

Cadmium added to commercial copper Cadmium added to copper-tin alloys Cadmium added to copper-nickel-aluminum alloys Cadmium added to copper-nickel-aluminumzinc alloys Cadmium added to copper-silicon-manganese alloys Cadmium added to copper-nickel-silicon alloys Cadmium added to copper-nickel alloys Cadmium added to copper-silicon alloys Cadmium added to copper-aluminum alloys The cadmium is ordinarily in amount from 0.01% to approximately 1.50% of the alloy, although it may be as high as 3%, if desired."

add it as master alloy, say for example of copper and 10% cadmium. The resultant alloy may be cast in any suitable molds. Said castings may then be rolled, forged, 'hammered, drawn, extruded, etc. either hot or cold, and in most instances both hot and cold, into various forms, such as sheets, bars, rods, wire tube, and the like, by methods now well known and practiced in the copper alloy industry.

Some of the. uses to which the cadmium-bearing copper base alloys may be put include'conductors of electricity and of heat, particularly where steam is present, condenser tubes, expansion joints and the devices of the sort in steam lines, steam regulating devices or controls, 'corrugated seamless tubes, and flexible metal hose, bellows, diaphragms and other parts of steam or water controls and power devices, valves or traps, heater tubes, steam conductors, and reservoirs, tanks, vats and other containers of liquids at steaming temperatures, steam turbine blades and other parts, and all apparatus particularly designed for steam service or to resist the corrosive and disintegrating action of steam.

In the accompanying drawing are shown examples of various articles for use in steam and hot water service which are greatly improved for this service by my invention, as their life both stressed and unstressed when used in contact with steam or hot water is greatly increased by the use of these alloys containing cadmium as this greatly action of the steam and hot water and/or gases in steam.

In this drawing Fig. 1 is a longitudinal section of a pipe, tube or conductor which may be used for conducting steam and hot water;

Fig. 2 is a cross section thereof;

Fig. 3 is a longitudinal section of a portion of a bellows which may be used for expansion joints, controlled or regulating devices, etc. for steam and hot water service;

Fig. 4 is a cross section thereof;

Fig. 5 is a cross section of cupped, drawn or formed metal sheets telescoping each other and adapted for use in steam service and steam regulating devices;

Fig. 6 is a top plan view thereof;

Fig. 7 is a longitudinal section of an annular, corrugated, seamless tube which may be used in steam or hot water systems;

Fig. 8 is a transverse section thereof;

Fig. 9 is a partial longitudinal section and a partial side elevation of another type of a corrugated seamless tube;

Fig. 10 is a. transverse section thereof;

Fig. 11 is a side elevation of a boiler or container for steam or hot water;

Fig. 12 is a transverse section of a flexible diaphra Fig. 13 is a top plan view thereof;

Fig. 14 is a top section of a plane diaphragm;

Fig. 15 is a plan view thereof;

Fig. 16 is a partial longitudinal section and partial side elevation of another form of flexible metal tube or hose;

Fig. 17 is a transverse section thereof;

Fig. 18 is a flat sheet metal piece;

Fig. '19 is a similar strip curved to any desired shape; and

Fig. 20 is a perspective view of a tank or con- The device of Fig. 5 comprises two cupped sections 23 and 24 cupped, drawn or formed from sheet metal sheets of this alloy and are assembled in telescoping relation so as to adjust the position under various pressures, etc. in regulating devices for steam and hot water systems- They may be connected to the system by suitable pipe connections to the nipples 25.

The corrugated seamless tube 26 of Fig. 7 is made of thin flexible metal and may be used for conducting steam and water and other similar uses. The corrugations in this particular form are annular.

The seamless tube 21 of Figs. 9 and 10 is simi-' larly constructed except that the spirals rim helioally and may be used for conducting steam and other uses the same as the tubes of Figs. 7 and 8.

The element 28 in Fig. 11 shows diagrammatically a boiler, tank or other container for steam or hot water, and may be constructed in any desired manner, such as riveted or welded sheets, heads, etc.

The diaphragm 29 of Figs. 12 and 13 is made from a thin flexible sheet of metal alloy and may be corrugated as indicated at 30 and may be used for regulating devices, etc.

The diaphragm 3| of Figs. 14 and 15 is substantially the same except that it is plain instead of corrugated.

In Figs. 16 and 17 is shown a common type of helically wound interlocked flexible metal hose it being formed of a strip 32 shaped at one side by bending inwardly and laterally as shown at 33 and placed between outwardly bent portion 34 of the opposite edge of the next adjacent convolution, so that these convolutions are inter locked and are capable of certain relative movement to permit flexingof the tube. They may be used for conducting steam or hot water between relatively movable elements of a system and in other locations as found desirable.

The flat plate 35 of Fig. 18 may be used for any desirable purpose or for making various elements of the steam or hot water system.

The same is true of the irregular shape 36 of Fig. 19.

The tank 31 shown in Fig. 20 may be of any suitable construction that shown having side walls 38 and end walls 39 and a bottom wall not shown.

These elements illustrated are shown merely as examples of the large number of elements which may be improved by my invention whereby they have increased resistance to corrostion and disintegration when used in contact with steam and hot water.

In addition to imparting the resistance to corrosion and disintegration the cadmium also imparts resistance to creep" (gradual elongation) under stress even at the elevated temperatures met with in use with hot water and steam.

My preferred invention is therefore an alloy intended principally for service in steam and characterized by the presence of cadmium from 0.01 to approximately 3.0%. This alloy is usually wrought, either hot or cold, or both, but may be used in the cast condition or in a weld or braze.

Having thus set forth the nature of my invention, what I claim is:

1. An element for use in conveying or distributing steam or hot water fabricated from copper or a cop er base alloy in which the tendency to intercrys alline parting in the metal is reduced by the incorporation of a small percentage of cad- CHARLES H. DAVIS. 3

CERTIFICATE OE CORRECTION.

Patent No. 2,034,561, March 1'7, 1,9256e CHARLES H. DAVIS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 25, for the word inc'ricates" read indicate; line 42, for "proportiontally" read proportionally. The table, page 2, should be inserted between lines 17 and 18 of column 1; in the heading to the table, for "bar" read base, and in the table, test No. 18, strike out the dotted line in the last column and insert instead a zero; 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 8th day of December, A. D. 1956,

Miriam-y Van Arsdale (Seal) Acting Commissioner of Patents,

CERTIFICATE OF CORRECTION.

Patent we. 2,054,561. March 1'7, 1936.

CHARLES H. DAVIS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 23, for the word "indicates" read indicate; line 42, for "proportiontally" read proportionally; page 2, second column, line 51, for "wire tube" read wire, tubes; same page, the table should be inserted between lines 1'? and 18 of column 1; in the heading to the table, in the table, test No. 18, strike out the dotted line in the last column and insert instead a zero; page 3, second column, line 61, claim 2, strike out 'Eht article "a"; and that the said Letters Patent should be read with these corre ticns therein that the same may conform to the record of the case in the Pat ent Office.

This Certificate of Correction issued in lieu of Certificate of Correction issued December 8, 1936 so as to correct an error therein.

Signed. and sealed this 5th day of January, A. D. 195?.

: :Benfyyan Arena-1e (Seal) Acting Commissioner of Patents.

for "bar" read base, and

Images