US2266482A - Age hardenable, nickel-iron-chromium-titanium alloy possessing controlled thermoelastic properties - Google Patents

Description

new, 1941.

N. B. PILL'ING ET AL 2,266,432 AGE HARDENABLE, NICKEL-IRON-CHROMIUM-TITANIUM ALLOY POSSESSING CONTROLLED THERMOELASTIC PROPERTIES Filed Oct. 27, 1939 EF'F'ECTIVE NICK EL: PER CENT L0 Q3 3022 m0 Fzwaiumo wmak/mwmiwh CHROMIUM PER CENT no 215002 .0 FzmUEuuO wmzk mmuimr 5 T R60 Y mg m m m W T 2 M P N mm w Patented Dec. 16, 1941 'AGE HARDENABLE, NICKEL moN chao- MIUM TITANIUM ALLOY rossassmc. CONTROLLED THERMOELASTIC raor- ERTIES Norman B. Pilling, Westiield, and Albert M.

Talbot,,Fairhaven, N. J., assignors to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware Application October 27, 1939, Serial No. 301,581

Claims.

The present invention relates to improved I age-hardenable controlled modulus alloys and to age hardened articles of manufacture made therefrom, and more particularly, to age harden able controlled modulus iron-nickel-chromium alloys and articles of manufacture made therefrom for use in precision devices of resilient nature.

It is well known that the accuracy of precision devices of resilient nature, for example, 'chronometers, weighing scales, etc., changes in temperature. It has been suggested that these defects could be overcome by using materials made of alloys of substantially constant or controlled elastic modulus containing about 30% to 38% nickel, up to 12% chromium, and the balance iron.- It is also known that part of the chromium may be replaced by one or more of the members of the group consisting of tungsten, molybdenum, vanadium, aluminum and silicon in amounts ranging from traces, e. g. 001% up to 4% or even more. These metals, like chromium, lower the temperature coeilicient of the modulus of elasticity of iron-nickel alloys containing about 35% nickel so that the coefficient'has a value of zero or is slightly negative or positive as desired, when measured at usual temperatures. Tungsten, molybdenum and vanadium also served to increase the base hardness of the alloys. These alloys are frequently referred to as controlled or constant modulus alloys. By constant modulus, we mean that the temperature coefllcient of the modulus .of elasticity is substantially zero. Alloys referred to as "controlled modulus alloys will have a small positive or negative value for the temperature coeiiicient of modulus of elasticity as is required to give the best overall result and will are affected by include those showing a zero change in modulus with temperature. Generally speaking, these modulus changes refer to changes observed at temperatures ranging from ordinary atmospheric temperatures up to about 200 F. Since these alloys are austenitic, they can be hardened only by cold work and as a consequence, many potential applications have been hindered by the fact that the alloys did not possess the high strength and other mechanical properties required in these applications. Attempts to obtain the desired mechanical properties by cold working about 75% to 90% did not produce completely satisfactory material. when carried out into industrial scale operation. Serious difliculties were also constantly encountered in cold working the alloys to the required heavy cold .into practical and economic reductions. Even excessive amounts of cold work yield only moderately good mechanical properties and entail serious difficulties inproduction and subsequent fabrication.

Although many attempts were made to remedy the aforementioned shortcomings, none as far as we are aware, was entirely successful, produced satisfactory results and could be carried industrial scale operation.

We have discovered certain iron-nickel-chromium-titanium alloys which can be age hardened and in which the'nickel, chromium and titanium are critically related to yield controlled or substantially constant thermo-elastic properties akin to those exhibited by the alloys of the Elinvar-type but exhibiting markedly superior mechanical properties, particularly high proportional limits. Titanium is added in critical and controlled amounts and a compensating adjustment is made in the nickel and chromium contents in special proportions to balance said nickel and chromium against titanium and any carbon which is present. The age hardening characteristics facilitate manufacture and avoid the necessity of the excessive cold working required with e-existing materials.

t is an object of the present invention to provide improved age'hardenable and age hardened controlled modulus iron-nickel-chromiumtitanium alloys which contain controlled and adjusted proportions of nickel, chromium and titanium and in which the nickel and chromium are balanced against the titanium and any carbon present in the alloy.

It is .another object of the present invention to provide improved age hardenable and age hardened iron-nickel-chromium alloys of the Elinvar-type containing controlled and balanced amounts of nickel, chromium and titanium and characterized by improved mechanical properties, including high proportional limits and'tensile strength while achieving a substantially constant or controlled temperature coefficient of modulus of elasticity.

I It is a furtherobject of the present invention to provide, as articles of manufacture precision devices including resilient elements made of special age hardened ferrous austenitic alloys containing controlled and specially balanced amounts of nickel, chromium and titanium.

The invention contemplates a method of producing age-hardenable and age-hardened controlled modulus iron-nickel-chromium alloys and containing controlled amounts of titanium 2 2,aee,4sa

and articles of manufacture for use in precision but upon a relationship of chromium-like metal devices of resilient nature made therefrom, and to titanium. In addition to titanium, the alloys Ds8essing substantially constant thenno-elastic may contain carbon, especially in industrial pracmodulus combined with high mechanical propertice. While not a necessary element, commerties in the age hardened condition, said process cial production methods often result in the introinvolving an adjustment, in special proportions duction of some carbon, e. g., along with the titaof the nickel content and the chromium content nium addition alloy. Carbon may be present in to compensate for the alteration in thermoamounts up to about 0.2%, but it is preferred to elastic properties caused by the presence of maintain the carbon at low levels, e. g., up to titanium. m .0896, in order that: the maximum benefits of Other objects and advantages of the present titaniumbe realized. The amounts of nickel and invention will become apparent to those skilled in of chromium or chromium-like metals are dethe art from the following description taken in pendent upon a relationship of carbon and titaconiunction with the accompanying drawing in nium which has been termed herein the "nonwhich: carbidic titanium. For practical purposes, the Fig. 1 is a graph illustrating the eflect of varynon-carbidic titanium is the total titanium coning the eil'ective nickel content upon alloys content in weight percent less four times the carbon taining sufflcient chromium to exhibit negative content in weight percent. The eifective nickel m i nts; and content of the alloys provided by the present in- Flg. 2 is a graph depicting the effect of vary- 2o vention should be maintained within the range of ing the chromium content upon another series about 34.5% to about 37.5%, or 39%, and the of alloys made in accordance with the present .titanium content within the range of about 1% invention. to 4%. The total nickel content of the alloys Broadly stated, the inverfithgi1 prgiiges iionmay be expressed by the following formula: nickel-chromium alloys 0 e var- W 1 which contain controlled and critical amounts of Total NL'Eflectfive (Non'cubmic TD titanium and which after age hardening heat where K has a value of about 2.4. The total chrotreatmentpossess markedly increased mechanical mium percentage is expressed by the following properties combined with controlled sir substanformula: tially constant thermo-elastic proper es, e. g., a .10 zero thermo-elastic coemcient. A strictly con- %Ttal cr+%Nn'mb1dic n 4% 9% stant modulus alloy is not always desirable, since The alloys of the present invention hav the in practical applications, dimensional changes in approximate mmposiflon t forth in the followthe structure may require a slightly negative or m Tam positive thermo-elastic coefllcient, in order to Table I secure a minimum temperature coefllcient for the whole device. The present invention provides Element Percentage alloys with constant or controlled coefficients of modulus of elasticity over a wider range of temperatures than is ordinarily obtained and, in; addition, higher mechanical properties are obtained with greater ease of production and subsequent manufacture. Mechanical properties, especially proportional limit which is generally of I controlling importance in resilient elements, in The total nickel content 118118113 falls within t excess of those obtainable by cold working the nge of about 36% to about 47%. As p inted ordinary alloys are produced in the alloys pro- 011% ie e. some carbon is usually p e vided by the present invention. e. 8., .0 to 0.07%, and preferably less than The compositions that have been found to deabout It is to be understood that carbon velop the above-mentioned desirable characteristo may e completely absent o m y be P s 0111! tics an properties are essentially alloys of iron, in traces or small amounts of the order of 0.001%. nickel and chromium to which about 1% to about In addition, the alleys y 5 co tain S all 4% of titanium has been added. It has been unts of minor elements and imp r s and found that when titanium is added to the Elinvarwhen We in the p i a i n and claims that type alloys, the thermo-elastic properties are adthe balance 18 "balance 15 Substantially versely affected and are not as expected or deiron, We include Within the e p n sired. We have discovered that the composition minoreonstituehbs and impurities. Such 38 Cobalt, of the titanium-containing alloys must be selectmanganese. Zirconium. silicon, aluminum, Sulfur. ed in accordance with certain special relation- Phosphorus and other elements n y P ships b tw th l i m t t t th B0 ent in such materials in commercial practice. various elements must be balanced against each Thus, the alleys may contain from traces, -5 other inspecial proportions to control the temup to about 1% of silicon. p to about perature coefllclent of the modulus of elasticity. a anese. up to about 1% aluminum. etc. It has been found that the thermoelastic proper- 511mm. and aluminum. is l as r e ties are not solely dependent upon the total nickel Often associated with the iitanium used 88.811 for a fixed chromium content ofithe alloys, as in addition material. a sa es is o ten pr e the case of grdinary anoys of t Elmvaratype, for the purpose of improving the forgeability. As but are dependent upon the portion of the nickel pointed out hereinbefore, the chr y be nt t which ha b term d herein the eflfecreplaced by other elements which have an eifect tive nickel content. Likewise, the thermo- 701811111191) chromium-like elastic properties for a fixed nickel content are in nts from traces, say 0.001 p to about not solely dependent upon the total percentage 4%. or even more, as is well known to those skilled of chromium-like metal, i. e., chromium plus any in the art and when we refer to chromium in the vanadium, tungsten, molybdenum, aluminum or claims we do not desire to exclude the presence silicon present as a replacement for chromium, oi! small amounts of chromium-like metals as asoeasa.

Somewhat higher mechanical properties may be above indicated or as will have the same desired effect as chromium on the thermoelastic properties.

In carrying the invention into practice, it is preferred to maintain the titanium within, the

of minor elements which may be present as a.

result of commercial practice include about 0.06%

carbon, about 0.5% silicon, about.0.6% manganese, about 0.3% aluminum.

In order that those skilled in the art may have a better understanding of the present invention, illustrative examples of constant modulus alloys produced in accoi dance with the present invention are given in the following Table H.

\ Table 11 Element Alloy 1 Alloy 2 Alloy 3 Alloy 4 Nickel "percent" 40 42 44 42 Ghromium do 6 5. 4 4. 7 5. 2 Titanium .do 2. 3. 25 2. 5 Car :1 do 0.06 0.06 0.06 0.00 Moly m d0 0. 45

The influence of eilective nickel content upon the temperature coefllcient of one series of alloys is illustrated in Fig. 1. Fig. 2 shows the effect of chromium upon the temperature coemcient of the modulus of rigidity of an alloy containing 42% nickel, 2.6% titanium, 0.45% molybdenum,

chromium in various amounts and the balancement at 1250 F. for 4 hours and furnace cooled.

iron which has been subjected to an aging treat- The values given herein for the temperature co-, efficient of the modulus'of rigidity, i. e., the thermo-elastic coeflicient, were determined by a torsion pendulum while the ambient temperature was changed through a series of values. ,The proportionate change in moduli with temperature in relation to the moduli at 0 F. determines the temperature coefllcient.

For maximum mechanical properties, the alloys of the present invention are preferably subjected ate cold working operation nd subsequently aged at temperatures between about 1100 F. and 1350 F. The usual solution treatment is acto a solution treatment prior to a modercomplished by heating at about 1700 F. to about 1750 F. and rapidly cooling, e. g., oil quenching. Blow cooling from the aging temperatures is desirable from a standpoint of stability of properties.

Mere aging without cold working will increase the mechanical properties. Excellent high mechanical properties are obtained by cold working prior to the aging heat treatment and this treatment is ordinarily preferred. In some instances it may be convenient, particularly with alloys containing about 1.5% to 2% titanium,to cold work after aging heat treatment. Material cold worked-with or without prior aging, requires a stress relief treatment to obtain stable thermoproperties; whereas excessive amounts of cold work (75 to 99%) are necessary to produce high mechanical properties in Elinvar-type alloys.

For ordinary purposes a titanium content of about 2.4% to about 2.8% is satisfactory for high mechanical properties as shown in Table III.

05 elastic properties. Amounts of cold work up to about 35% or about 50% reduction in cross section which are readily attainable, appear very suitable to produce excellent high mechanical Table III Y.s. 'r. s. cane. ma.

Alloy P. L.

Ordinary titanium-lree 84,000

Aged titaniumcontaming 123,000

159,000 0 ioxw 'I. S.- nsile stren th in pounds per square inch.

T. E. O.-thermo-e tic coelliclent per F.

M. R.-=modulus of rigidity in pounds per square inch. The ordinary constant modulus alloy, after water quenching from about 1750 F., was cold drawn 75% and treated for two hours at'about 650 F. The age hardened alloy (alloy 5) contained 42.4% nickel, 5% chromium, 2.4% titanium and balance iron including 0.06% carbon, 0.56% manganese, 0.56% silicon and impurities, and was water quenched from 1750 F., subsequently cold drawn 35%, heat treated two hours at 1l50'F. and furnace cooled.

High mechanical properties are obtained by aging at temperatures between about 1100 and about 1350 F. However, byvarying the treatment within this range it is possible to vary the temperature coefllclent of elasticity as'desired within certain ranges. For a given alloy, the higher the aging temperature, the higher the temperature coefficient of elasticity. Similarly, the longer the period of aging at a 'given temperature, the higher the temperature co'efli'cient of elasticity. Also, it appears that the, more the cold work, the lower the temperature coeflicient of elasticity. Slow cooling fromthe aging temperature usually resuits in appreciably higher proportional limits and more stable elastic properties. Table V shows the effect of varying the treatment upon the properties of alloy 5. The material in each instance was 'water quenched from 1750 F. prior .to receiving the various treatments shown in Table IV.

Table IV.

Cold Aging Aging Treatment work temp time '3 Cooling rate Percent F. Hours 35 l, 250 4 Furnace cooled. 35 1,150 4 Do. 35 1,150 2 Do. 50 1,150 2 Do.

'I.E.G. M. R.

+15Xl0 l0. i 10 +l0 l0 10.0)(10' '0 10.0Xl0 '5 l0' 09x10 See Table III ior k ey to symbols. v

The present invention provides a method of producing improved age 'hardenable iron-nickelchromiurn-titanium alloys, and articles of manufacture made therefrom, possessing predetermined high mechanical properties and predetermined controlled modulus and containing as essential ingredients about 1% to about 4% titanium, about 36% to about 47% nickel, a small but eilective amount up to about 9% chromium, and

the balance substantially iron, in which carbon may be present up to about 0.2%, which comprises incorporating in an iron-nickel-chromium alloy a selected titanium content within said range corresponding to the predetermined desired mechanical properties, for example, proportional limit, and being larger the higher said desired properties, the nickel content of said alloy being proportioned within said range in accordance with the following formula:

Total Ni=Eflective Ni-i-K (Ti-4X0) where the effective nickel .is selected within the range of about 34.5% to about 37.5%, K being a constant with a value of about 2.4, and Ni, Ti and C being respectively the weight percent of nickel, titanium and carbonfthe chromium content of said alloy being proportioned within said range in accordance with the following formula:

alloys provided by the present invention. Typical examples of such devices and elements or members include springs, for example, hair springs for watches and other chronometers, springs for weighing scales; tuning forks; Bourdon tubes; proving rings for testing machines, torsion and tension dynamometers, etc.

We are aware of the invention described in U. S. patents to Pilling and Merica, including U. S. Patent No. 2,048,167, and we do not claim any of the subject matter disclosed therein. The present invention is an improvement in the art of controlled and constant modulus ironnickel-chromium alloys.

Although the present invention has been described in conjunction with preferred embodiments, it is understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as

those skilled in the art will readily understand;

We claim:

1. As an article of manufacture. an age hardened iron-nickel-chromium-titanium alloy possessing a temperature coeflicient of modulus of elasticity having a small positive to negative value including zero and containing in weight percentage from 36% to 47% nickel; an eifective amount up to 9% chromium; 1% to 4% titanium; up to 0.2 carbon; the percentage of nickel, titanium and carbon being such that Total NiK(Ti-4XC) Cr+(Ti4XC) lies between 4% and 9%, K being a constant having a value of about 2.4%, and Ni, Cr, Ti and aaea ea C being respectively nickel, chromium, titanium and carbon in weight percentage; and the balance being substantially all iron whereby a novel age hardened iron-nickel-chromium-titanium alloy is obtained having a unique combination of properties including the aforesaid temperature coemcient of modulus of elasticity having a small positive to negative value including zero together with high mechanical properties.

2. As an article of manufacture, an age hardened iron-nickel-chromium-titanium alloy possessing a temperature coeillcient of modulus of elasticity having a small positive to negative value including zero and containing in weight percentage from- 38.5% to 45.3% nickel; 4.7% to6% chromium; 2% to 3.25% titanium; up to 0.08%. carbon; the percentage of nickel, titanium and carbon. being such that Total Ni-K(Ti4 C) 7 lies between 34.5% and 37.5%, and the percentage of ohromium, titanium and carbon being such tha Cr+(Ti-4 C) lies between 7% and 8%, K beinga constant having a value of about 2.4, and' Ni, Cr, Ti and C being respectively nickel, chromium, titanium and carbon in weight percentage; and the balance being substantially all iron whereby a novel age hardened iron-nickel-chromium-titanium alloy is obtained having a uniqu combination of properties including the aforesaid temperature coefllcient of modulus of elasticity having a small positive to negative value including zero together with high mechanical properties.

3. As an article of manufacture, a resilient element made of an age hardened iron-nickelchromium-titanium alloy having the composition set forth in claim 4. As an article of manufacture, a precision device including a resilient element made of an age hardened iron-nickel-chromium-titanium alloy having the composition set forth in claim 2.

5. As an article of manufacture, an age hardenable iron-nickel-chromium-titanium alloy possessing a temperature coefficient of modulus of elasticity having a small positive to negative value including zero and containing in weight percentage from 38% to 47% nickel: an eifective amount upto 9% chromium; 1% to 4% titanium; up to 0.2% carbon; the percentage of nickel, titanium and carbon being such the Total Ni'-K(Ti4xC) lies between 34.5% and 39%, and the percentage olfaohromium, titanium and carbon being such Cr+(Ti-4XC) lies betwen 4% and 9%, K being a constant having a value of about 2.4, and Ni, Cr, Ti and 0 being respectively nickel, chromium, titanium and carbon in weight percentage; and the balance being substantially all iron whereby a novel age hardenable iron-nickel-chromiumtitanium alloy is obtained having in the aged condition a unique combination of properties, including the aforesaid temperature coeillcient of modulus of elasticity having a small positive to negative value including zero togetherwith high mechanical properties.

NORMAN B. BILLING. ALBERT M. TALBOT.

D cember 16, 19 1- nommn-B. PIiELIIGQ-ET AL.

'It is hereby certified that error p fi p enr-e -"lig tb rinted epecificatioo of the above numbered patent requiring .oornebtion'nffdliowE Page 1p, first column, line 75, claim 1 for "2.1;? read--Z'QlL-e; "and-that the' said Let 'ters Patent should be read with this correction therein that the same may conform to the record ofl theeeise in'the latent Office.

Signed and sealed this 7th day of July A. 1912.

Patent No. 2,266, 4-82.

Henry Vati Aradale, (Seal) Acting comissioper' of Potenta.

Images