Dalai, Ranes P. (Stratford, CT)
Walters, Jeremy J. (Trumbull, CT)
Ewing, Bruce A. (Shelton, CT)

05/243418

04/30/1974

04/12/1972

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Avco Corporation (Stratford, CT)

420/448

C22C19/05; C22C19/00

75/171,170 148/32,32.5

3677331	CASTING PROCESS FOR NICKEL BASE ALLOYS	July 1972	Lund et al.
3677747		July 1972	Lund et al.

Dean, Richard O.

Hogan, Charles Garfinkle Irwin M. P.

This application is a continuation-in-part of our U.S. Pat. application Ser. No. 189,733, filed Oct. 15, 1971, now abandoned.

1. A nickel base alloy exhibiting high strength, ductility, sulfidation and oxidation resistance and stability at elevated temperature and consisting essentially of the following in weight percent:

2. A nickel base alloy exhibiting high strength, ductility, sulfidation and oxidation resistance and stability at elevated temperature and consisting essentially of the following in weight percent:

3. A nickel base alloy exhibiting high strength, ductility, sulfidation and oxidation resistance and stability at elevated temperature and consisting essentially of the following in weight percent:

4. A nickel base alloy exhibiting, high strength, ductility, sulfidation and oxidation resistance and stability at elevated temperature and consisting essentially of the following in weight percent:

5. A nickel base alloy according to claim 1 which has been heat treated to

6. A vacuum cast article consisting of the alloy of claim 1.

This invention relates to nickel base alloys exhibiting high strength, stability, ductility and resistance to corrosion, sulfidation and oxidation at elevated temperatures and which are useful for blades, vanes and integrally cast turbine wheels.

The nickel base alloys of this invention contain relatively small, but nonetheless significant, amounts of tungsten and molybdenum for solid solution strengthening; chromium for oxidation and sulfidation resistance; tantalum for solid solution and carbide strengthening; aluminum and titanium to enhance the strength by precipitation of a fine dispersed phase, gamma prime Ni ₃ (Al, Ti), and hafnium for intermediate strength, ductility and improved oxidation resistance.

Compositions of the following analyses are contemplated as within the scope of the present invention the compositions being expressed in weight percent, the balance being Ni except for incidental impurities:

C 0.30 max. Hf 0.1-3 Cr 11-15 Ti 3.5-4.5 Co 8-12 Al 3-4 Mo 1-2.5 Ti + Al 7-8 W 3-10 B 0.005-0.025 Ta 3.5-10 Zr 0.05-0.4 balance Ni

A more preferred range of compositions is as follows:

C .25 max. Hf 0.4-3 Cr 11-13.5 Ti 3.5-4.5 Co 8-11 Al 3-4 Mo 1-2.5 Ti + Al 7-8 W 3-5 B 0.005-0.025 Ta 3.5-8 Zr 0.05-0.4 Balance Ni

A still more preferred range of compositions is as follows (in weight percent):

C 0.10-0.22 Hf 0.75-1.25 Cr 12.2-13.5 Ti 3.9-4.2 Co 8.5-9.5 Al 3.2-3.6 Mo 1.85-2.05 Ti + Al 7.25-7.70 W 3.65-8 B 0.01-0.02 Ta 3.65-8 Zr .08-.25 balance Ni

Exemplary alloys in accordance with the teachings of this invention had the compositions shown in Table I which follows:

TABLE I ____________________________________________________________ ______________ Heat No. C Cr Co Mo W Ta Hf Ti Al Ti+Al B Zr Ni ____________________________________________________________ ______________ I .15 12.50 9.35 1.94 3.99 3.86 1.10 3.96 3.57 7.53 .015 .17 Bal II .15 12.50 9.35 1.94 3.99 3.86 2.28 3.96 3.57 7.53 .015 .21 Bal III .23 12.80 8.68 1.97 4.00 3.77 0.49 4.32 3.28 7.60 .016 .13 Bal IV .23 12.38 8.68 1.97 4.00 3.77 1.07 4.32 3.28 7.60 .016 .16 Bal V .23 12.38 8.68 1.97 4.00 3.77 1.55 4.32 3.28 7.60 .016 .14 Bal VI .23 12.38 8.68 1.97 4.00 3.77 1.80 4.32 3.28 7.60 .016 .20 Bal VII .23 12.38 8.68 1.97 4.00 3.77 0.44 4.32 3.28 7.60 .016 .14 Bal VIII .20 12.31 9.18 1.94 3.72 4.05 1.06 4.08 3.38 7.46 .014 .15 Bal TX .20 12.31 9.18 1.94 3.72 4.05 2.26 4.08 3.38 7.46 .014 .22 Bal X .20 12.31 9.18 1.94 3.72 4.05 2.16 4.08 3.38 7.46 .014 .21 Bal XI .20 12.31 9.18 1.94 3.72 4.05 1.16 4.08 3.38 7.46 .014 .16 Bal XII .19 12.66 9.42 1.92 3.75 3.86 2.40 4.01 3.27 7.28 .015 .22 Bal XIII .15 12.50 8.88 2.04 3.95 5.0 1.13 3.96 3.22 7.18 .013 .10 Bal XIV .15 12.50 8.88 2.04 3.95 6.0 1.13 3.96 3.22 7.18 .013 .10 Bal XV .20 13.35 8.88 1.91 3.87 8.0 1.20 4.18 3.21 7.39 .012 .11 Bal XVI .20 13.35 10.88 1.91 3.87 6.0 1.20 4.18 3.21 7.39 .012 .11 Bal XVII .20 13.35 10.88 1.91 3.87 7.0 1.20 4.18 3.21 7.39 .012 .11 Bal XVIII .20 13.35 10.88 1.91 3.87 8.0 1.20 4.18 3.21 7.39 .012 .11 Bal XIX .15 12.87 9.49 2.01 4.01 4.0 1.05 4.10 3.23 7.33 .013 .11 Bal XX .15 12.87 9.49 2.01 5.01 7.50 1.05 4.10 3.23 7.33 .013 .11 Bal XXI .15 12.87 9.49 2.01 7.50 5.0 1.05 4.10 3.23 7.33 .013 .11 Bal XXII .15 12.87 9.49 2.01 10.0 5.0 1.05 4.10 3.23 7.33 .013 .11 Bal XXIII .16 12.60 9.40 2.0 3.97 3.85 0.50 4.0 3.55 7.55 .020 .10 Bal XXIV .21 12.80 9.40 2.19 4.0 4.08 1.95 4.05 3.25 7.30 .014 .10 Bal XXV .21 12.80 9.40 2.19 4.0 4.08 1.95 4.05 3.25 7.30 0.14 .15 Bal XXVI .21 12.80 9.40 2.19 4.0 4.08 1.95 4.05 3.25 7.30 .014 .20 Bal XXVII .09 12.30 9.10 1.87 7.40 4.94 1.25 4.18 3.35 7.53 .012 .12 Bal XXVIII .09 12.30 9.10 1.87 4.90 4.94 1.25 4.18 3.35 7.53 .012 .12 Bal XXIX .27 12.40 9.00 1.87 7.40 4.90 1.15 4.06 3.20 7.26 .013 .11 Bal ____________________________________________________________ ______________

After vacuum melting, the alloys noted above were vacuum cast into test bars and subjected to stress rupture testing according to ASTM Standard E139. The test bars were heat treated before testing as follows: heated to 2,050° F, held at that temperature for 2 hours then air cooled, then reheated to 1,550° F and held at 1,550° F for 4 hours, then air cooled, then reheated to 1,400° F and held at that temperature for 16 hours then air cooled.

After the heat treatment described above, stress rupture tests were conducted on cast test bars representative of each of the heats in the heat treated condition at 1,400° F/90Ksi, 1,400° F/100Ksi, 1,700° F/39Ksi and 1,800° F/29Ksi. The results are given in Table II, it being noted that thickwall data refers to 0.250 inch diameter solid test bar results. Thinwall data refers to tubular test bar results in which wall thickness is 0.040 inch. Thickwall or solid test bar data reflects mechanical property capability of heavy sections such as might be represented by turbine blade roots. Thin wall or tubular test bar properties reflect the mechanical property capabilities of thin walled sections such as might be represented by cored or hollow turbine blade airfoils. Thinwall data are for tests at 1,700° F/35Ksi.

TABLE II ____________________________________________________________ ______________ C103 STRESS RUPTURE TEST results ____________________________________________________________ ______________ THICKWALL THINWALL Heat 1400°F/90Ksi 1400°F/95Ksi 1400°F/100Ksi 1700°F/29Ksi 1800°F/29Ksi 1700°F/35Ksi No. Life El Life El Life El Life El Life El Life El (Hrs.) (%) (Hrs.) (%) (Hrs.) (%) (Hrs.) (%) (Hrs.) (%) (Hrs.) (%) ____________________________________________________________ ______________ ____________________________________________________________ ______________ I 462 4 163 3 72 5 483 5 99 5 II 382 7 79 9 III 225 5 99 10 87 10 106 10 IV 211 5 106 10 180 5 V 73 3 119 5 48 8 VI 208 4 77 9 VII 277 4 65 7 419 5 121 3 VIII 286 5.5 50 8 408 6 37 6 IX 530 3 45 10 38 6 36 7 X 505.7 7.5 71 8 50 6 56 7 XI 273 4 60 7.5 97 8.0 XII 160 8 153 6 XIII 97 5 88 6 44 5 61 6 XIV 159 5 129 9 61 8 58 5 XV 70 4 53 4 48 6 46 3 56 4 49 6 49 3 XVI 104 8 62 7 22 8 63 8 27 10 XVII 130 8 93 7 38 10 45 9 XVIII 35 9 37 8 XIX 130 9 72 9 53 6 103 8 58 6 XX 149 4 50 6 64.4 6.0 174 4 28 9 70.6 5.0 178.0 5.0 XXI 142 4 43 10 129 5 224 5 79 5 189 5 81 7 254 5 XXII 224 5 45 5 101 N/A 51 8 137 6 XXIII 113 4 39 4 116 3 67 4 XXIV 144 9 109 10 167 6 88 10 99 10 XXV 181 15 65 N/A 71 8 XXVI 172 6 79 10 168 8 83 8 80 9 XXVII 163 5 59 8 60 3 157 7 58 5 68 4 XXVIII 130 4 119 8 60 10 111 5 212 6 75 9 61 9 125 5 125 9 XXIX 110 4 81 5 122 4 133 5 61 8 184 4 212 5 INCO 713 16 6 5 4 20 12 MARM 421 50 3 20 3 15 15 IN792 255 7.5 75 7 75 9 ____________________________________________________________ ______________

Corresponding values for three presently known commercial alloys are appended to Table II for comparison.

INCO 713C is reported to be an alloy with a nominal composition of

C Cr Mo W Cb Ti Al Zr B Ni ____________________________________________________________ ______________ 0.14 13.0 4.5 0.20 2.0 0.75 5.75 0.05 0.012 Balance ____________________________________________________________ ______________

MAR-M-421 is reported to be an alloy with a nominal composition of

C Cr Co Mo W Cb Ti Al Zr B Ni ____________________________________________________________ ______________ 0.15 15.8 9.5 2.0 3.8 2.0 1.8 4.3 0.05 0.015 Balance ____________________________________________________________ ______________

INCO IN792 is reported to be the alloy described in U.S. Pat. No. 3,619,182.

Table III presents the room temperature tensile properties of the alloy of this invention, heat treated as before, after casting into test bars.

TABLE III ____________________________________________________________ ______________ C103 ROOM TEMPERATURE TENSILE TEST RESULTS ____________________________________________________________ ______________ Heat No. Uts. (Ksi) 0.2% Y.S.(Ksi) El (%) R.A. (%) ____________________________________________________________ ______________ VIII 181.4 169.2 3.5 3.2 172.5 163.9 3.5 3.2 INCO-713C 123 106 7.9 11.6 MAR-M-421 150 130 3.5 5 ____________________________________________________________ ______________

Comparable values for the same commercial alloys are appended to the table for comparison.

In the Tables IV and V respectively, data is presented on cyclic oxidation test results conducted at 1,750° F and hot corrosion test conducted at 1,650° F.

TABLE IV ______________________________________ COMPARATIVE C103 CYCLIC OXIDATION TEST RESULTS ______________________________________ Material Weight Change (Mg/Cm ² ) After 240 Hours at 1750°F Heat VIII 1.15 Heat IX 0.95 INCO 713C -4.40 MAR-M-421 -2.20 ______________________________________

TABLE V ______________________________________ COMPARATIVE C103 HOT CORROSION TEST RESULTS ______________________________________ Material Depth of Attack (Mils) After 150 Hours at 1650°F with 6 ppm Salt Heat VIII 4.2 INCO 713C 26.0 MAR-M-421 15.0 ______________________________________

It is not intended that the invention sought to be patented be limited by the foregoing description, but merely by the scope of the appended claims.