US 3061426 A
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Oct. 30, 1962 C. G. BIEBER CREEP RESISTANT ALLOY Filed Feb. 1, 1960 1'86 000! X SSEIELLS ATTORNEY 3,061,426 CREEP RESISTANT ALLOY Clarence G. Bieber, West Roselle Park, N.J., assignor to The International Nickel Company, Inc., New York, N.Y., a corporation of Delaware Filed Feb. 1, 1960, Ser. No. 6,001 4 Claims. (Cl. 75-171) The present invention relates to strong heatand corrosion-resistant alloys and, more particularly, to strong, heatand corrosion-resistant nickel-chromium-cobalt alloys.
Heretofore, the art has endeavored to provide castable alloys which may be subjected in use to temperatures in excess of about 1700 F. in corrosive atmospheres and which maintain adequate strength and ductility under these conditions. In order to be completely satisfactory, the alloys must not depend upon scarce or expensive elements in order to obtain the required strength at high temperatures. Although attempts were made to overcome the foregoing difficulties and other disadvantages, none, as far as I am aware, was entirely successful when carried into practice commercially on an industrial scale.
It has now been discovered that by the use of a specially coordinated combination of readily obtainable elements, it is possible to produce alloys having substantially enhanced properties when exposed in use to high stresses at elevated temperatures of the order of about 1700 F. and higher.
It is an object of the present invention to provide a novel alloy having substantially enhanced characteristics at elevated temperatures and particularly at temperatures in excess of about 1700 F.
Another object of the invention is to provide a novel heat-resistant article having substantially enhanced characteristics at temperatures in excess of about 1700 F.
The invention also contemplates providing a novel turbine structure having substantially enhanced characteristics at temperatures in excess of about 1700" F.
It is a further object of the invention to provide a novel turbine blade having substantially enhanced characteristics at temperatures in excess of about 1700 F.
Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawing in which the FIGURE is a graph relating stress and a parameter commonly known as the Larson-Miller parameter.
Generally speaking, the present invention contemplates novel nickel-chromiurn-cobalt alloys and articles, structures, etc., made therefrom having substantially enhanced characteristics at elevated temperatures, and, particularly when subjected to temperatures in excess of about 1700 F comprising about 6% to about 12% chromium, about to about 30% cobalt, about 1% to about 8% molybdenum, about 0.2% to about 2% vanadium, about 4% to about 9% aluminum, about 0.5% to about 6.5% titanium, about 8% to about 12% aluminum plus titanium, about 0.001% to about 0.1% boron, about 0.01% to about 0.25% zirconium, about 0.01% to about 0.5% carbon, with the balance being essentially nickel. The term balance essentially is used to include in addition to nickel in the balance of the alloy, small amounts of impurities such as sulfur, phosphorous, etc., and incidental elements such as niobium, tantalum, manganese, silicon, copper, iron, etc., in amounts which do not adversely affect the novel advantageous characteristics of nitecl States Patent ice the alloy. The novel alloys of the present invention can contain up to about 5% niobium, up to about 2% copper, up to about 1% silicon, up to about 2% manganese, up to about 0.2% calcium, up toabout 4% tantalum and up to about 10% iron and more advantageously, up to about 2% iron The alloys of the present invention exhibit excellent lives to rupture at elevated temperatures, for example, up to at least about hours lifewhen tested under a load of 35,000 pounds per-square inch (p.s.i.) at 1700 F. in combination with a reasonable amount of ductility, for example, at least about 4% elongation under the aforestated conditions. The alloys can be used in the as-cast condition but can advantageously be treated by heating for about /2 to about 4 hours at a temperature of about 2100 F. to about 2200 F. under an inert atmosphere such as helium, argon, etc. The alloys are then cooled rather rapidly to a temperature below about 1700 F. while maintaining them in an inert atmosphere. The alloys and articles made therefrom may be aged in service or may be aged byheating for about 1 to about 20 hours at temperatures of about 1400 F. to about 1700 F. It is characteristic of the alloys of the present invention that they can be readily cast and that they give excellent mold reproduction making them especially suited for use in the precision casting process. The alloys are usually melted from either "a calculated charge or from remelt stock under an inert atmosphere (including vacuum) and are cast at temperatures between about 2500 F. and about 3100 F. into molds preheated to about 1000 F. to about 1800 F. If melted at atmospheric pressure a final treatment with calcium silicide prior to casting is advantageous. When produced in this manner, alloys in accordance with the invention may be subjected in use under oxidizing conditions to temperatures up to about 2100 F.
In carrying the invention into practice, it is most advantageous to maintain the composition of the novel alloys within the limited range set forth in Table I.
Table I Element Range, percent Chromium 8-12 Cobalt 10-20 Molybdenum 2-5 Vanadium 0.25-1.50
Aluminum I 5-8 Titanium 1-6 Aluminum-l-titanium 9-1 1 Carbon 0.10.3 Boron 0.005-0.05 Zirconium 0.05-0.1 Nickel Balance Alloys within the limited range set forth in Table I exhibit lives to rupture in excess of about 100 hours when subjected to a load of 35,000 p.s.i. at 1700 F. and elongations in the range of about 3% to about 20% under the same testing conditions. It is advantageous to maintain a relationship between the vanadium and carbon contents of the alloys as set forth both broadly and in the more advantageous aspects in such fashion that the percentage of vanadium is at least twice the percentage of carbon. Examples of alloy compositions within the scope of the present invention are set forth in Table II together with an outstanding composition selected from the prior art alloys.
Table 11 Per- Per- Per- Per- Per- Per- Per- Per- Per- Pen Per- Y N cent cent cent cent cent cent cent cent cent cent cent Cr 00 Mo Al V 'Ii Cb 1 C Zr Ni 1 10 15 3 5. 1 4. 5 0.18 0.02 0.05 Bal.
10 3 5. 5 1 5. 0 0. 18 O. 02 0.05 Bal.
12 15 2 5. 5 1 4. 5 0. 18 0. 02 0. 05 Del.
10 15 3 5. 5 1 5. 5 0.18 0.02 0.05 Bel.
10 15 3 5. 7 1 4. 5 0.18 0. 02 0. O5 Bal.
10 15 3 5. 5 0.5 5.0 0.18 0.02 0. 05 Bal.
12 5 6 0.6 0.12 0. O2 0. 50 Bal.
1 Including small incidental amounts of tantalum. 1 Including small incidental amounts of manganese, sillicon, iron, etc.
Alloy No. A is representative of the best commercial alloys of the prior art. Alloys set forth in Table II were produced in various conditions as set forth in Table III and were stress-rupture tested under the conditions set forth in Table IV.
Table III Treatment designation Processing 1 treatment A.M. as cast.
V.M. as cast.
A.M. 2 hours at 2,150 F. V.M. 2 hours at 2,150 F.
A.M.=Melted at atmospheric pressure under argon. V.M.= Melted under vacuum.
The results of life-to-rupture tests conducted on alloys set forth in Table II which were heat treated as set forth in Table III and tested under the conditions set forth in Table IV, are presented in Table V. Standard specimens having gage sections 0.250 inch in diameter and 1.0 inch in length were used for these test purposes.
Table V Test condition Time to fracture, hours Elongation,
Processing t percen Alloy No. treatment WWW.
Hen- -er ws w es eprpr s crumqwumumoocncnow O It is characteristic of the alloys of the present invention that they exhibit, in addition to high strength at elevated temperatures, good resistance to thermal shock. When tested by repeatedly subjecting airfoil turbine blade sections to an intermittent heating and cooling cycle comprising heating in a flame for one minute to 1800 F. and then cooling in air for one minute, the alloys of the present invention withstand many thousand cycles without failure. For example, one alloy in accordance with the present invention withstood 5850 cycles prior to failure as indicated by the formation of the first crack 0.125 inch in length. Under same conditions prior art alloys in commercial use fail in one to two thousand cycles.
Referring now to the drawing, it is to be observed that the stress rupture characteristics of an alloy in accordance with the present invention containing about 10% chromium, 15% cobalt, 3% molybdenum, 5.5% aluminum, 5.0% titanium, 0.18% carbon, 0.02% boron, 0.05% zirconium, 1% vanadium and the balance cssentially nickel, which was heat treated at 2150 F. for two hours and then air cooled, can be illustrated in the manner suggested by Larson and Miller (see Transactions of the A.S.M.E., 1952, volume 74, pages 765-771). It is to be noted that the figure shows a master curve for the aforementioned alloy obtained by plotting stressx 1000 p.s.i. against P (parameter). Parameter P is obtained from experimental data by the use of the following formula wherein P=parameter,
T =absolute temperature in Rankine,
log t=common logarithm of the time to rupture in hours; and
C=a constant having a value of 25.
Table VI Rupture strengths, Temperature, F. p.s.i.
In addition to excellent rupture strengths the alloys of the present invention also exhibit excellent short-time tensile characteristics at temperatures ranging from room temperature up to and including 1800 F. Short-time tensile characteristics measured on the short-time high temperature test scale for alloy No. 1 as set forth in Table II are presented in Table VII.
T l VII 0.01% to about 0.25% zirconium, about 0.01% to about 0.5% carbon with the balance being essentially nickel. Test mm 9 at 5933 r g longation, Reduction 2. An alloy for use as castings and characterized by p r are S 152%,? percent 133; having a life to rupture of at least about 100 hours when 5 exposed at a temperature of 1700 F. to a load of 35,000 Room temp 115,000 135,750 10.3 13.1 pounds per square inch containing about 8% to about 39%; igj 2: 31% "151; 12% chromium, about 10% to about cobalt, about $882? 9 228 igg ggg Z 8 2% to about 5% molybdenum, about 9% to about 11% %:ggg:g 1331358 g8 10 aluminum plus titanium, about 5% to about 8% alu- 11000: 1011000 1211750 414 3:1 minum, about 1% to about 6% titanium, about 0.25% to @885 g: 1358 52%? 2:: 3:; about 1.50% vanadium, about 0.005 to about 0.05% boron, about 0.05% to about 0.1% zirconium, about 0.1% Additional alloys in accordance with the present invenr to about 03% Carbon With the balance being essentially tion are set forth in Table VIII. nickel.
Table VIII Alloy No. Percent Percent Percent Percent Percent Percent Percent Percent Percent Percent Or 00 Mo Al i V O B Zr Ni 3. 41 2. 99 5.95 5.05 0. 97 0.14 0.014 0.04 Bal. 14.54 3.00 6.10 5. 36 1.01 0.15 0. 01s 0. 05 Bal. 8.8 3.13 6.00 5.5 0.97 0.15 0. 023 0. 05 Bal. 14.74 3.03 5.96 3.33 0.94 0.19 0.017 0.0 Bal.
1 Including small incidental amounts of silicon, manganese iron, etc. Each of the aforementioned alloys Nos. 10 to 13 which 3. An alloy for use as castings and characterized by were vacuum melted and heat treated at 215 0 F. for 2 having a life to rupture of at least about 100 hours when hours and then cooled, exhibited a 100 hour rupture life exposed at a temperature of 1700 F. to a load of 35,000 under the specific stress-temperature conditions as set forth pounds per square inch containing about 8% to about in Table IX. 12% chromium, about 10% to about 20% cobalt, about Table IX 2% to about 5% molybdenum, about 9% to about 11% aluminum plus titanium, about 5% to about 8% alu- Stress fo -100 minum, about 1% to about 6% titanium, about 0.25% Alloy 5 1 32?- fig rultllfe 35 to about 1.50% vanadium, about 0.005% to about 0.05% boron, about 0.05 to about 0.1% zirconium, about 0.1% m 1 900 14 000 to about 0.3% carbon, with the balance being essentially 11 11900 131000 nickel, the carbon and vanadium contents of said alloy g 838 2 888 40 being so related that the vanadium percentage is at least twice the carbon percentage. 4. An alloy for use as castings and characterized by a 'Idhe P lgllventlon pacrlnFularly i zg i g g z z prolonged life to rupture when exposed at elevated temrotors etc. The novel alloys of the present invention oxldlzl-ng atmosphere contammg about 6% to about 12% chromium, about 5% to about 30% cobalt, about 1% to gay also be used as extruslon d1es, valves, valve seats, about 8% molybdenum, about 8% to about 12% minum plus titanium, about 4% to about 9% aluminum, f gggggg g g f g gfi fjg if;$ 5233 about 0.5% to about 6.5% titanium, about 0.2% to about stood that modifications and variationshnay be restored 5O 2% Vanadlum about F about 01% g about to without departing from the spirit and scope of the in- 001% to about 9 Zirconium t to 0 vention, as those skilled in the art will readily understand. carbon Wlth h balance bemg e ssentlany l Such modifications and variations are considered to be the carbon and Vanad1 um contents of sald alloy bemg so within the purview and Scope of the invention and related that the vanad1um percentage 1s at least twice the pended 1 j carbon percentage.
I claim: 1. An alloy for use as castings and characterized by a References Cited m the file of thls Patent prolonged life to rupture when exposed at elevated tem- UNITED STATES PATENTS p r t r to the combmed e e of pp Stress and an 2,912,323 Bieber et a1 NW 10, 1959 ox1d1z1ng atmosphere contammg about 6% to about 12% 920 956 b 1 J 12 1960 chromium, about 5% to about 30% cobalt, about 1% to Is at et about 8% molybdenum, about 8% to about 12% alu- OTHER REFERENCES mmum plus t1tan1um, about 4% to about 9% alummum, about 0.5% to about 6.5% titanium, about 0.2% to about Journal Of Metals, VOL September 1953 (Nisbet 1:) 2% vanadium, about 0.001% to about 0.1% boron, about (pages 1149-1165 relied upon).
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,061,426 October 30, 1962 Clarence G. Bieber It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Columns 3 and 4, Table II, eleventh column, line 10 thereof,- for 0.50" read 0.05 columns 5 and 6, Table VIII, tenth column, line 3 thereof, for "0.05" read 0.04
Signed and sealed this 21st. day of May 1963,,
ERNEST w. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents