US3677748A - Alloy - Google Patents

Abstract

A NICKEL-BASE ALLOY USEFUL AT ELEVATED TEMPERATURES UNDER STRESS WHICH CONTAINS IN PERCENT BY WEIGHT ABOUT 8% CHROMIUM, ABOUT 10% COBALT, ABOUT 0.1% CARBON, ABOUT 4% MOLYBDENUM, ABOUT 4.25% TANTALUM ABOUT, 6% ALUMINUM, ABOUT 1% TITANIUM, ABOUT 2% TUNGSTEN, ABOUT 1.5% HAFNIUM, ABOUT 0.08% ZIRCONIUM, ABOUT 0.015% BORON WITH THE BALANCE BEING ESSENTIALLY NICKEL.

Description

"United States PatentOfice 3,677,748 ALLOY John Hockin, Arlington Heights, 111., assignor to Martin Marietta Corporation, New York, N.Y. No Drawing. Filed Nov. 19, 1969, Ser. No. 878,233

Int. Cl. C22c 19/00 US. Cl. 75-171 Claims ABSTRACT OF THE DISCLOSURE The present-invention is concerned with an alloy and, more particularly, witha nickel-base alloy having improved high temperature strength as well as improved ductility at trough temperatures, e.g. about 1400 F.

In application Ser. No. 841,505, now abandoned in favor of Ser. No. 157,335 filed in the names of Carl H. Lund, John Hockin and Michael J. Woulds, there was claimed alloys having, in the cast condition, enhanced ductility characteristics at trough temperatures. These alloys had, as their essentially novel features, a generalized balanced composition and a content of hafnium of about 0.8% to about 5% by weight.

It has now been discovered that particularly advantageous alloys can be provided by specially restricting and interrelating ranges of alloying elements to provide novel, highly advantageous alloys.

It is an object of the present invention to provide novel, highly advantageous alloys.

It is another object of the present invention to provide novel, highly advantageous castings from said novel alloys.

Other objects and advantages will become apparent from the following description.

Generally speaking, the present invention contemplates nickel-base alloys consisting essentially of elements as tabulated in percent by weight in Table I.

3,677,748 Patented July 18, 1972 Alloys within the range of chemistry in Table I are made essentially by vacuum melting and casting and are particularly balanced such that the sum of the weight percentages of molybdenum plus tungsten total about 5% to about 7.25% and the sum of the weight percentages of titanium plus aluminum total about 7%. If desired, more hafnium, for example up to 5%, and more zirconium, for example up to 0.5%, can be included in the alloys. Advantageously, the alloys are cast as disclosed and claimed in the Lund et a1. application Ser. No. 841,408. It is also advantageous to limit the maximum impurities and tramp elements in alloys of the invention to about 0.1% or 0.2%.

Specific examples of thealloys of the present invention and an alloy A as claimed in the Lund et a1. application Ser. No. 841,505, now abandoned in favor of Ser. No. 157,335 are set forth in Table I1.

TABLE II Example Element I II III Alloy A 6. 00 6. 00 6. 00 6. 00 0.015 0. 015 0.015 0.015 0. l0 0. 10 0. 10 0. 10 10. O0 10. 00 10. 00 10. 00 8. 00 8. 0 0 8. 00 8. 00 5.00 4.00 3. 00 6.00 Bal. Bal. Bal. Bal. 4. 4. 25 4. 25 4. 25 1. 00 1. 00 1. O0 1. 00 l. 00 2. 00 3. 00 0. 10 0. 075 0. 075 0. 075 0. 075 1. 50 l. 50 l. 50 1. 50

The alloys of Table II were cast into specimens and identically treated. The test specimens were subjected to various tests, the results of which are detailed in Tables III and IV. Table 111 contains results of tensile tests at room temperature.

45 TABLE I TABLE III 1 Element Range Advantageous Examp 9 Alloy I I II II II III Chromium. 7.5% to s. About 8%. I obalt .5% to 1 5% U.T.S. (k.s.i.)- 157.0 166.2 157.9 103.0 167.0 169.9 154.. 0 8% to 0 0.2% YS (k.s.i.) 125.5 118.2 125.8 125.6 126.6 120.6 118.0 $2 {2% :3 2 2 Elongation (percent) 2 0 16. 0 .0 2 t6 e Red. inarea (percent). .5 3.3 5 Ti 0.8% to 1.2 W.-. 0.75% to3% HL. 0 8% to 3%.... About 1.5%. Zr. 0 05% to 0.1%- About 0:08%. 55 13 to 0.2 H .gbg i t 0.0 5%. Table 1V contains results of creep-rupture tests conducted a 9856 a a at 1800 1400" F. and 1600" F.

TABLE IV Example Alloy Alloy I I II II III III 1,s00 F.29 k.s.i.:

Life (hours) 44.0 45.2 54.9 62.5 46.5 40.5 32.6 Prior creep (percent)- 7. 26 6. 59 6. 08 5. 9 6. 93 9. 92 Elongation (pereent) 8.00 5. 50 6.00 7. 0 8.0 13.0 6 6 Red. in area (percent) 11.90 5.20 4.5 6.6 9.1 11.8 1,400 F.94 k.

Lite (hours) r 201.3 271.5 293.5 253 385.6 318.8 136.6 Prior creep (percent 4.02 8. 27 7. 35 5.41 5. 67 4. 32 5. 5 Elongation (percent) 9.50 9.50 9.0 7.00 6.50 5.00 Red.in area (percent) 10. 50 11. 10 10. 3 5. 6. 30 4. 50 1,600 F.35 k.s.i.:

Life (hours) 1, 932.5 2,578.8 1,942.5 1,260 Prior creep (percent)- 7.24 7.93 2.33 Elongation (percent) 8. 50 9.50 2.00 5.7 Red. in area (percent) 9. 20 6. 7 1. 40

Tables III and IV show that the alloys of the present invention and particularly Example II, an alloy illustrative of the most advantageous embodiment of the present invention, are highly advantageous when compared to alloy A, the most nearly comparable alloy known heretofore. Example II retains all of the advantageous ductility char acteristics ofalloy A at room temperature and 1400 F. while adding thereto increased strength at other temperatures of engineering significance. From the data of Tables III and IV it is apparent that the alloys of the invention will be highly useful as structures in gas turbine engines and in other'usages where resistance to stress at high temperatures is essential.

While the present invention has been described in conjunction with advantageous embodiments, those skilled in the art will recognize that modifications and variations may be resorted to without departing from the spirit and scope of the invention. Such modifications and variations are considered to be Within the purview and scope of the invention.

I claim:

1. A nickel-base alloy useful at elevated temperatures under stress which consists essentially of in percent by weight about 8% chromium, about 10% cobalt, about 0.1% carbon, about 4% molybdenum, about 4.25% tantalum, about 6% aluminum, about 1% titanium, about 2% tungsten, about 1.5% hafnium, about 0.08% zirconium, about 0.015% boron with the balance being essentially nickel.

2.. An alloy casting made from the alloy of claim 1.

3. A cast nickel-base alloy useful at elevated temperatures under stress which consistsessentially of in percent by weight about 7.5% toabout 8.5% chromium, about 9.5% 'to about 10.5% cobalt, about;,0.08%" to about 0.13% carbon, about 3% to'about-'6.5% molybdenum, about 4% to about 4.5% tantalum, about 5.75% to about 6.25% aluminum, about 0 .8% to about..1.2%- titanium, about 0.75% to about 3% tungsten, provided that the sum of the percent molybdenum plus the percent tungsten is about 5% to' about 7.5 about 0.8% to 5% hafnium, about 0.05% to about 0.5% zirconium, about 0.01% to about 0.02% boron with the balance being' essentially nickel.

4. An alloy casting made from the" alloy-of. claim '3).

5. An alloy as in claim 3 which containsa'maximum of 3% hafnium and a total of percent aluminum plus percent titanium is about 7%; T

ReferenceslCite d UNITED STATES PA TS 7 3,479,151 11/1969 Richards et al 575-171 RICHARD o. DEAN, Primary'Examine'r