US2289593A

US2289593A - Alloy

Info

Publication number: US2289593A
Application number: US350780A
Authority: US
Inventors: Charles B Sawyer; Bengt R F Kjellgren; Gerald G Christensen
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-08-03
Filing date: 1940-08-03
Publication date: 1942-07-14
Anticipated expiration: 1959-07-14

Description

July14, 1942. C, a SAWYER EN; 2,289,593

' ALLOY Fiied Aug. s, 1940 Afro/mfr Patented July 14, 1942 v2,2zas93 Charles B. Sawyer, Cleveland Heights, Bengt R.` A F. Kjellgren, University Heights, and Gerald G Christensen, Cleveland, Ohio Application August 3, 1940, Serial No. 350,780

1o claims..y (cl. 14s-e2) This invention relates to beryllium copper a1- loys containing nickel, and it relates more especially to such alloys in which the copper is more than about 90%, and the nickel' and beryllium together amount to. lesshthan about 5%.

Beryllium copper alloys containing nickel form" *the subject of several patents which have been fgrantedinthe past. United States Patent No.

1,393,984,1ssued to yCorson, is the earliest United States patent which relates to .alloys of the type here under` i consideration. It. `discloses ternary copperberylliumnickel f alloys whichl may con- .tain up toA about` 2% beryllium and up to as `much as v40% nickel. Other patents issued subsequently have dealt with other ranges of beryllium and nickel in ternary alloys, while still others have been concerned with quaternary alloys in .which the nickel and beryllium ranges have been diversified, and in` which various fourth-metal alloying additions have `been in-` cluded. `While a Wide range of mechanical properties .can be obtained in these prior alloys, depending on the l relative proportions of the 'various alloyingelements of each, few of the alloys have possessed maximum'electrica'l conductivities .of much over fifty per cent of that of copper. The

few that have` conductivities in excess of this Y latter `value contain` relatively large amounts of alloying ingredients which are .considerably more expensive than nickel, and in` addition possess certain metallurgicall characteristics `which militate againsttheir use under some conditions.

f moderate hardness` with resistance' to wear or" alloy of the class described which may be cast readily into intricate shapes.

kIt is another object to provide` an improvedA alloy of the class described which may be fabricated readily from the cast condition vby means Y of any of the usualprocesses of forging. rolling,` hammering, drawing, extruding, etc.

Numerous industrial/devices and 'apparatus4 require parts which -are'made of material havim; good electricalconductivity and possessing abrasion. Weldingelectrodes` of'various types exemplify such uses..v Copper e alloys' have, in general, beenmost successful, in meeting the needs of such applications. `Few copper base1 alloys. however, have adequatehardness together4 loys are more than adequatetov meet the requirel with adequate `electrical conductivity. It has been known for a number of years that copper may be heat-hardened when itis alloye'd with small amounts of beryllium.v The values .of hardness obtainable in suchbina'ry-beryllium copper alments of the appucations Imentioned, above.

It is a primary objectfof -this invention to pro- I vide an improved beryllium copper alloy in which nickel is the basic third-'metal addition but in which fourth-metal additions may also be included either to enhance the effects of the nickel or to improve the'alloy in some of its metallurgi'` cal aspects Without diminishing appreciably the advantages to begained from the primary nickel addition.

It is another primary object to provide an alloy r of the class described which possesses improved electrical conductivity.

YIt is another primary object to provide an agehardened alloy ofthe class described. which possesses high electrical conductivity together with desirable mechanical ,properties such as strength, hardness, proportional limit, fatigue limit, abrasion resistance, etc.

It-is another object to provide an improved alloy of the class described which is suitable for use as an electrical conductor in'both the ascast unheat-treated condition, and in its numerous heat-treated conditions.

It is a further object to provide a pressure welding electrode composed of 'an improved agee hardened alloy of the class described.

It isanother object to provide van improved `are introduced into the binary alloys. y

pointed out in the patent referred 'to above that However, such binary alloysv do Anot .have suitable electrical conductivities. Furthermore; such binary alloys are unduly expensive `since beryllium contents of around 1.0% Vor more are necessary to provide the- .hardening effect. It has also been known for a number of vyears'that the amount of beryllium required tol harden` copper `can be materially reduced Lif various third metals Corson nickel is a third-metal addition to beryllium copper which Ahas this effect. Other workers have shown that several other elements also have the same kind of effect.'` When the properites of these various ternaryberyllium copper alloys became known, it seemed likely that they would'be able to meet thefrequirements of hard, ness and electrical conductivitywhich are involved in the previously mentioned applications.

It has been found, however, that few of the -ternary alloys or even of the more complex alloys of copper and beryllium have values of ele'ctrical conductivity and hardness which are desired. In the beryllium-copper-nickel alloys in particular, Corson has indicated -that conductivities of around 33% may-be expected in such alloys after they have beenworked and precipitation-hardened to a, condition which gives the alloy suitable mechanical properties. i The hardness of the alloy `has been indicated to be around Brinell. It has commonly been considered that while greater hardness values might be ob,- tained in the Corson alloys, conductivities in excess of the value stated could not be expected,

'this being on the general theory that as the hardness is increased, Athe conductivity is decreased. However, in investigating the low beryl- 'in" a restricted range. of values.

lium alloys ot Coxon-Anelli, we lhave foun that exceptionally good electrical conductivities can be obtained along with desirablevalues of l hardness by 'suitably proportioning the beryllium and nickel-contentsoi the alloys.

` This invention is based on the discovery that an improved alloy results if the nickel and beryllium contents are proportioned to fall with- The improved alloy which results is characterized by high electrical conductivity, particularly after a precipitation heat-treatment. and by a desirable range oi' mechanical and metallurgical properties which adapt it for use in numerous tields of application. Preferred compositions lying within the limits ot the Iinventionare particularly adapted j for use as pressurefexerting welding electrodes. Qther preierredcompositions are adapted for use in unheat-treatedcastings which should, in use, strength, hardness and good electrical or-thermal conductivity. Still other preferred compositionsl are adapted for use in applications which require exceptionally high electricalor thermal conductivity with only mod,- erate strength or All compositions. falling within the limits of the invention are characterized by their susceptibility to precipitation hardening heat-treatments, and by their capacity for being fabricated by the usual metal working methods and apparatus. When the alloys are so fabricated and suitably heat-treated, they even hig er 'values of electrical conductivity than can obtained in the as-cast heat-treated metal. l

',The invention will be `understood more fully lium, by increasing the nickel proportionatelyiasYV the beryllium/ content is increased. This is merely a general statement. however, ior it will be observed lthat it does not apply strictly to the whole iield of the invention. It will be noted particularly, however. that the increase in'nickel content is nearly a linear function of the in. crease inberylliumcontent in the particular region which is adjacent to the diagonal line M -M'. Anl investigation of this region has shown that an optimum ratio prevails between the nickel and beryllium contents. It has `been through reference to \the accompanying drawing which illustrates graphically th'e approximate limits of the invention together with typical values of electrical conductivity which may be obtained lin as-c` t age-hardened alloys having suitable propo ions between the beryllium and nickel contents' thereof. 'lhe limits of the inf vention aref-,marked by thev closed traverse ABCDEFGHJQ.' and the electrical conductivities of alloys falling within theapproximate ileld of invention are shownby means of contours which mark theapproximate outer limits of regions in which may befobtained at least the electrical conductivity which is indicated by the index number of each contour.l It will be understood that the indexnumber represents the conductivity measuredin per cent of the conductivity oi' standard, copper. Thus, an index number of 50 indicates that in'therileld bounded by the "50 contour, electrical conductivlties of 50% or more are obtainable. 'I'he conductivitles indicated inthe drawing were measured at abopt 23 C., and represent-values which may be obtained in an as-cast, unworked alloy having the indicated beryllium and nickel contents. Prior to measurement, each composition was subjected to an age-hardening heat-treatment consisting tained in alloys containing asnuch as .8% beryl- 4following formula:

foundthat the ratiol maybe expressed by the nickel minus 0.25=

beryllium 5 When the proportions of nickel andk beryllium comply approximately with this formula, better values ofelectrical conductivity can be secured than in alloys which do not comply therewith.

It has been pointed out above that the contours of the drawing mark approximate outer limits of areas of composition which contain alloys capable of possessing electrical conductivities of indicated values. ciated, however, that while the contours are based on and derived from conductivity measure.- ments of numerous alloys which fall within the scope of the invention, yet the contours are only' careful estimates of fields of alloy compositions,

expressed graphically rather than verbally. They should be regarded more in the nature of guides to the ileld of composition which represents the invention, rather than being regarded as exact graphical delineations of precise critical boundaries between iields of composition. In other words, it should be' recognized that the contours may be subject to some degree of correction as the number of conductivity measurements 'of distinct alloyA compositions is extended throughout the ileld of the invention.

Through reference to the drawing it will bev observed that when lines are drawn to connect the points A, B, C, D, E, F, G, H, J, and A in succession, a closed traverse is formed which encloses the field of discovery which represents the invention. Furthermore, it will be observed that the area of compositions so enclosed includes alloys which, for the most part, have electrical conductivlties of-50% or more after they have been subjected to the particular heat-treatment on which the drawing is based. Included within the closed traverse ABCDEFGHJA are other areas which include alloys capable of being heattreated so as to possess electrical conductivlties l of,v for example, 60%, 65%, or 70% or more. Specific 'examples selected from these various areas are described below, where it will be seen that the alloys possess other desirable mechanical properties in addition to' these exceptionally high conductivlties.

One area containing compositions whichare of particular merit is the area bounded by the traverse ABCDEFGA. 4Another area which constitutes. av preferred portion of the invention is the area which includes alloys containing from about .75% nickel to about 2.0% nickel with beryllium contents `falling within the limits of the invention as marked by the traverse ABCDEFGHJA. Still another preferred range lies within the closed .traverse ABCDEFGHJA, but includes alloys which contain from about .75% nickel to about 2.0% nickel, and from about 0.20% beryl-l It should be appre` com to about .45% beryllium. ancora .een or alloys having meritior particular uses is the field of the invention whichl lies between about .05% beryllium and about .20% beryllium, with asso,

ses

heated at 900.- C. for one hour and quenched, and reduced` in'area about 00% by coldedravving. The material was then tested in the afs-drawn vcondition and in several ass-drawn and heatniclrel between about .25% and about l.'l5%. 5 treated conditions with thefollowing results; Still another compositional ileld containing al- A Table lll loys having outstanding properties is the held marlred by traverse BCDEFGB with nichel con@ TG SH@ wel@ me tents above about 2%. n preferred range within L) (p gl L) mnd: this latter neld is bounded by the traverse and l by nichel contents or more than about 2% and Pefcem less than about 3.75%." The following speelde Asdrwn 72.000 07.000 39-0 1 s examples selected from each oi these indicated ggg g1 Zggg iglg c4713 fields will provide a more complete understand- -Asdrawnand aged 211mm@ 500 G- 115,000 80.000 M0 lng of the merits of the alloys oi the invention. 1'5 Y Taatu irais-cast alloys L,

Tensile Yield alcnga- Elec. Banen Be Ni Treatmnt (p. s. 1.) (p. s. 1.) tion cond. hardness l iercent .69 3.30 Quenched from 900 C.; aged 2 hours 500 C f 50.9 Quenched from 900 C.; aged 2hours 400 C. j 48. l.v .4s-cast; not heat-treated; 45, 0 ..59 2.78 As-cast; not heat-treated 40.5 Quenched from 900 C.; aged v2 hours 50 C I 5l. 4 .23 1.47 As-cast; not heat-treated 45,5 Qucnched from 900 C.; aged Zhours 550 C 57. 7 .23- 1.48 As-cast; not heat-treated 42 Qnenched from 900C.; aged 1 hour 450 C 86, 500 52, 500 53 .22 1.49 `As-oast; not heat-treated 30,000` ,000 39 A Quonched from l,000 C.; aged 2 hours 500 C- 80, 000 00, 000 61. 5 200 .28 1.139 Quonched from 900 C.; aged 2hours 500 0-.... ,000 60,000 53.0 200 .13 .74 As-cast;n0theattreated 49.0

. Qucnched from l,000 C.; aged 2hours @500 0....I f 7310 Quenched from 900 C.; aged 4 hours 475 C. 51, 400 37, 250 71. 2 124 *Pounds per square inch. v

The following examplesillustratethe improvements in properties andv conductivity which can be obtained by subjecting the as-cast alloys of the invention to mechanical working treatments of various kinds.- v

An alloy containing .32% beryllium and 1.47% nickel was quenched from about 900 C. and vwas then forged cold to about 80% of its original cross-sectional area. The forged material was subsequently aged by heating it at 450 C. for two hours. Its electrical conductivity in this age-hardened condition was 69%. This may be compared with a. conductivityof about 55% in the as-cast condition after having been age-'- hardened by quenching from about 900 C. and

.Y reheating for two hours 'at 500 C.

A cast ingot analyzing .25% beryllium and The other half of the above lot of the .12.8" diameter cold-drawn materiall was heated atv 750 C. for one hour, quenched, and reduced in area'about40% `by cold-drawing. The following results indicate the nature of the material.

Table IV 'Tensile Yield Elec. (p. s. 1.) cond.

l v Peiv cent As drawn 72, 000 I 59.8 As drawn and aged 2 hours 450 C 80, 000 64, 000 70. 8

It will be noted that the worked alloys have very desirable properties in both the as-worked and in the .Worked and heat-treated conditions.

' It will also be noted that the electrical conduc- 1.33% nickel wasquenched after having beenheated for three hours at 900 C. The quenched ingot was then hot-rolled at about 900.C. to a.

diameter of 5/16 inch. The rolled material was again heated to 900 C. and quenched, and then cold drawn from lihe" to .178 diameter. The proportional limit of the latter material wasdetermined, V18" samples being used. The following table indicates the results' obtained under tivity of alloys of the invention may be improved considerably by working them, and especially by age-hardening the "quenched and worked material.

It 'will be understood from the above examples'. that the alloys 'of the invention possess diverse properties which make certain compositional groups vmore 'suitable for some `uses than for others. In general, alloys of the invention which contain less than about '2% nickel and more than ,about .2% beryllium are particularly adapted for use in electrical conductors of all kinds which various conditions of heat-treatment.

` TABLE 1I Tensile (p. s. i.) (p. EL i.)

As quenched from 900 C 43,000 4, 700 As quenched from 900 C.; aged 2 hours 40 C 91,000 46,000 As quenched from 900 C.; aged 2 hours 425 C 102, 500 55,800

require high electrical conductivity together with hardness and resistance to fatigue. yBy reason of-their high proportional limits, these alloys make good current-conducting springs. By reason of their hardness, strength, and electrical conductivity, they are especially good for use in pressureexerting-welding electrodes of all kinds, and for many useswhere abrasion` and wearresistance 'are desired. Motor and. generator slip-rings exemplify the latter uses.

Alloys of the invention which contain more than about.2% nickel are especially useful in making articles which are used in their as-cast condition and which need good electrical or thermal conductivities. The alloys are extreme fluid in thevmolten state-and can be readilycast into intricate shapes.l Furthermore, the alloys have nearly as good values of conductivity inthe -as-cast condition as in the usual heat-treated conditions. It will be understood, of course, that `the conductivity of an alloy in the as-cast condition is determined to a large extent by the casting conditions. If the molten metal is solidified in a chill mold, its conductivity will be somewhat low and its properties are more apt to approach the `properties of as-quenched material. If the metal is solidified in` a sand mold where it is cooled more slowly, the conductivity will be higher and the properties will approach the properties of material which has been age-hardened slightly.

It has been indicated above that alloys containing between about .05% and .20% beryllium, and nickel between about .25% and 1.75% constitute another preferred eld of the invention. It will vbe observed from Table I that alloys in this'iield have moderate values of strength and hardness in age-hardened as-cast or worked conditions. In addition, they pOSsesS unusually high electrical and thermal conductivities. By reason of these .properties the alloys of the eld are especially suitable for making hammered or forged articles which require exceptionally high conductivities without unusually high strength or hardness. Many parts of electrical and thermal instruments. machines, and apparatus involve such requirements.

Those skilled in the art will appreciate that the merits of copper-beryllium-nickel alloys of the invention may be retained even though the alloys contain appreciable amounts of other metals or elements. Such other constituents may .be added to enhance the effects of the nickelberyllium proportions of the invention and/or to improve diverse metallurgical characteristics of the alloys without impairing one or more of the electrical, thermal or mechanical properties appreciably.

Reference has been made in the preceding speciflcation to the thermal conductivities of alloy compositions of thev invention. Inasmuch as it has long been'an established fact that thermal and electrical conductivities of most metals parallel .each other closely under most conditions,`

the electrical conductivities indicated throughout the specification may be regarded as beingclose approximations also oi relative thermal conductivity.

Having now disclosed `the invention, what we claim is:

1. A copper base alloy containing beryllium and nickel in amounts which fall substantially within the graphical area of composition bounded by the closed traverse formed by joining the following points in sequence: from .05% beryllium at .25% nickel, thence to .05% beryllium at 1.5% nickel, thence to .35% beryllium at 3.0% nickeL thence to .70% beryllium at 4.25% nickel,

'thence Yto .80% beryllium at 4.25% nickel, thence to 80% .beryllium at 3.75% nickel, thence 'to .475% beryllium at 2.0% nickel, thence to .55% beryllium at 1.25% nickel, thence to .30% beryllium at .25% nickel, thence to the starting point of .05% beryllium at .25% nickel, the balance being substantially all copper.

2. An alloy as claimed in claim 1 wherein the nickel and beryllium are present in approximately the following ratio: f

% nickel minus 0.25 5

% beryllium 3. An alloy as claimed in claim 1 wherein the beryllium content is between about .2% and .4%, and the nickel content is less than 2.0%.

4. An alloy as claimed in claim 1 wherein the nickel content is more than 2.0%.

5. An age-hardened copper base alloy containing beryllium and nickel in amounts which fall substantially within the graphical area of composition bounded by the closed traverse formed by joining the following points in sequence: from .05% beryllium at .25% nickel, thence to .05% beryllium at 1.5% nickel, thence to .35% beryllium at 3.0% nickel, thence to .70% 'beryllium at 4.25% nickel, thence to ,8% beryllium at 4.25% nickel, thence to .8% beryllium at 3.75% nickel, thence to .475% beryllium at 2.0% nickel, thence .to .55% beryllium at 1.25% nickel, thence to '.30%

beryllium at .25% nickel, thence to the starting point of .05% beryllium at .25% nickel, the balance being substantially all copper.

6. An age-hardened alloy as claimed in claim 5 wherein the nickel and beryllium are present in approximately the following ratio:

% nickel minus 0.25 5

% beryllium 7. An age-hardened alloy as claimed in claim 5 wherein the beryllium content is between about .2% `and .4% and the nickel content is less than ductivity of standard copper after the said alloy has been age-hardened by subjecting it to a solution heat-treatment at,about 900 C., quenching.'

and reheating for approximately two hours at 500 C.

9. A casting made ofthe alloy as claimed in claim 1 wherein the nickel content is between about 2% and 4.25%.v

10. A pressure-exerting welding electrode composed of an age-hardened alloy as claimed in 4claim 5, said electrode being characterized by an electrical conductivity of more than about 50% of the conductivity of standard copper after the said electrode has been age-hardened by subjecting it to a solution heat-treatment at about 900 C., quenching, and reheating for approximately two hours at 500 C.

CHARLES B. SAWYER. BENGT R. F. KJELIGREN. GERALD G. CHRISTENSEN.