AU474792B2 - Nickel-base alloy - Google Patents

Description

-54,01 3/73

KUZMi/A IVANOVICH TEREKHOV, ALEXEI TIKHONOVICH TUMANOV, LJUDMILA SERGE EVNA AA-RINA, KLAVDIYA A LEEXE EVNA OKOLE LOVA, A LEXANDR FEDOROVICH BE LOV, NIKOLAI DMITRIEV ICH BOB VNIKOV, FEDOR VASILIEVIC I-I TULYANKIN, PETR ALEXEEVICH ZASETSKY. VLADIMIR NIKIFOROVICH ZHUCHIN, MIK(HAIL YAKOVLEVICH DZUGUTOV, MIKiAILl SEMENOVICH PODOLSKY and VALENTIN VASILIEVICH TOPILIN

KUZMA IVANOVICH TEREKHOV, ALEXEI TIKHONOVICH TUMANQV, LJUDMvILA SERGEEVNA AIARKINA, KLAVDIYA ALEXEEVNA OKOLELOVA, ALEXANDR FEDOROVICH BELOV, NIKOLAI DMITRIEVICH BOBOVNIKOV, FEDOR VASILIEVICH TULYANKIN, PETH ALEXEEVICH ZASETSKY, VLADIMIR NIKIFOROVICH ZHIUCHIN, MIKHAIL YAKOVLEVICH DZUGUTOV, MIXHAIL SEMENOVICH PODOLSKY and VALENTIN VASILIEVICH TOPILIN

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The present invention relates to non-ferrous metallurgy and more particularly to a high-temperature alloy which may

prove useful for the production of disks, baffles, nozzle

rings and other heavy-duty components of a turbine hot section

in turbojet or turboprop engines operating at high temperatu-

res ranging from 750 to 850 0 C; it may be also applicable to other fields of engineering and more specifically to the production of stationary turbines. As to the order of high-temperature strength, in the most critical for the turbine disks range of working temperatures (650-8000C) the alloy proposed herein is by 20-25% superior to serial disk alloys produced in the Soviet Union and to the best alloys developed abroad nimonic-105, astroloy, udimet-500) by which virtue the working temperature of the disks can be increased by 50-100°C and the weight of the tur- bine hot section components decreased by 10-12%. Hence, the weight of flying vehicle structures can be materially dimi- nished and their reliability enhanced during continuous ser- vice*

Known in the art is a nickel casting alloy (cf. British Patent No. 1029065, Cl. C7A) which has the following composi- tion, weight per cent: 0.1-0.2 carbon; 4-5*5 chromium; 2-7 titanium; 2-8 aluminum;

8-20 tungsten; 0-6 molybdenum; 5-15 cobalt; 0-3 tantalum; 0.01-Ool boron; OoO0-0.1 zirconium and the balance nickel. Howevero the composition of the above alloy incorporates high- priced and scarce elements, such as tantalum and tungsteno

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Moreover, the use of tungsten, whose contents in the prior-art alloy ranges from 8 to 20% by weight, increases the weight of fabricated parts owing to high specific gravity of

this element f= 19.2 g/cm3). In addition, tungsten contri. butes to the formation of a coarse heterogeneous liquation structure both in castings and stampings. Also known is a nickel-base alloy (cf. British Patent No. 1075216, Cl. C7A) comprising per cent by weights 0.02-0.1 carbon; 10-17 chromium; 11-16 cobalt; 5-9 molybdenuma 2.53-5.2 aluminum; 0-1.73 titanium; 1-3.5 niobium; 0-2.0

vanadium; 0.001-0.01 boron; 0.01-0.1 cerium and the balance-

nickel.

However the alloy given hereinbefore has low mechanical

properties: tensile strength 99-116 kg/m2 yield strength 79-104 2 kg/nm elongation 3-123. The object of the present invention eS to provide a nickel-base alloy which would feature the enhanced high-tempe- rature strength and high mechanical properties being in the meantime reasonably doped with cobalt and whose com- position would not incorporate scarce and high-priced ele- ments, such as tungsten and tantalum. Another important object of the invention is to provide a high-temperature alloy possessing high technological ducti- lity which would make possible the production of disk stamp- ings of intricate shape both on presses and hammers. The above objects are accomplished by the provision of a

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nickel-base alloy containing carbon, chromium, titanium, alu-

minum, niobium; cobaet, molybdenum, boron and cerium, the com-

position of said alloy, according to the invention, additio-

nally incorporating lanthanum, the weight percentage of the

components being:

0.04-0.08 carbon; 13-16 chromium; 2.3-3.0 titanium; 1.8-3.0

aluminum; 2.2-6.0 niobium; 6-12 cobalt; 4-8 molybdenum;

0.001-0.1 lanthanum; 0.001-0.01 boron; 0.001-0.03 cerium and

the balance-nickel.

The alloy proposed herein comprises an increased amodunt

of the main alloying elements aluminum, titanium and niobi-

um that enter the alloy base a solid solution, a feature

which has favoured the enhancement of durability, better

mechanical properties and ductility.

Higher aluminum and niobium contents resulted in an in- creased up to 30-35% amount of the reinforcing intermetallide

phase and accordingly in a substantial rise in the high-temperature strength.

At the same time a higher concentration of molybdenum

and niobium contributed to higher thermal stability of the alloy. In addition, niobium is responsible for a more compli- cated composition and structure of the main reinforcing inter- metallide phase Ni 3 (Al,Ti,Nb) instead of

Ni 3 (Al,Ti). To solve the above problem it was necessary to increase

the thermal stability of not only the intermnnetallide r-phase

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but of the alloy solid solution as well. This was attained by increasing the content of not only titanium, aluminum and nio- bium, but also of chromium and molybdenum and by the introduct- ion into the alloy composition of cobalt amounting to 6-125 by weight; this enhanced the technological ductility of the alloy which is of prime importance in the fabrication of stampings for turbine disks featuring an intricate geometric form and hardly liable to deformation* A higher chromium content made it possible to stabilize the solid solution and to increase the high-temperature strength of the alloy. Besides, introduced additionally into the alloy composit- ion are such important and efficient microalloying elements as lanthanum (0.001-0.1% by weight) and cerium (0.001-0.03% by weight). The use of the microalloying additions lanthanum and

cerium improve the state of grain boundaries, contribute to

the formation of fine-grain homogeneous structure and to im-

proved fracture quality, which has a marked effect on the enhancement of the order of mechanical properties of the

herein-proposed alloy. #anqe cfead Thus, the selection of the optimum percentageLof the

alloy components enabled an increase in both the mechanical

properties and high-temperature strength of the alloy retain-

ing its high ductility*

As compared with the known alloys in the same range, the

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incorporate composition of the herein-proposed alloy does not

high- e3 and scarce elements, such as tungsten and tantalum, the enhanced technological ductility of theL41ley being attain-

ed by doping it with reasonable amounts of cobalt (6-12% by weight) end the increased creep resistance by the introduct-

ion of molybdenum and niobium. The sum of the main alloying elements fetatm, alumi-

num and niobium forming the reinforcing r -phase is so chosen as to ensure adequate deformability of the alloy.

A well-balanced list of the alloying elements aluminum,

titanium, niobium, molybdenum and chromium-along with the reasonable doping with cobalt and lanthanum assure high meoha- nical properties and high-temperature strength of the alloy. The high-temperature strength of the proposed alloy in comparison with that of the known foreign-made nickel-base alloys is given in Table 1 which follows. Table 1

Alloy Cobalt Stress, kg/mm2 in 100 hr ontent 650° 700° 750° 800° 850° 870°

Proposed herein 10 85 68 55 40 30 22 Nimonic-105 (England) 20 79 62 49 38 29 23 Udimet-500 (USA) 20 77 60 46 32 28 22 Astroloy (USA) 15 79 62 49 38 29

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Illustrative examples of the embodiment of the present invention are given hereinbelow.

Example No.1

A nickel-base alloy of the following composition (in

woeight per cent) was taken; 0.05 carbon; 13 chromium; 2.3 ti-

tanium; 2.3 aluminum; 2.5 niobium; 8 cobalt; 4 molybdenum; 0.01 lanthanum; 0.001 boron; 0.001 cerium and the balance

nickel. The above alloy was subject to heat treatment which con-

sisted of hardening at a temperature of 1150°C for 8 hours and subsequent cooling in air. This was followed by the second hardening at a temperature of 1050°C for 4 hours after which

the alloy was cooled in air. Then the alloy was subject to ageing at a temperature of 850°C for 8 hours with subsequent

cooling in air. After that the second ageing operation was performed, the alloy being held for 32 hours at a temperature

of 730°C and cooled in air. After the above heat-treating operations the alloy pro-

posed herein had the following properties: 2 Tensile strength 66= 135-140 kg/ma 2 Yield strength 2= 85-90 kg/m

Ductility

It also possessed high order of high-temperature

strength: at 6500C 2 =83 kg/m at 700°C E=65 kg/mm2 at 750°C 6,,=52 kg/M 2 at 8000C ,=38 kg/mm2 and at a850°C 6=30 kg/mm2.

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54.013 /73- E: In Ex~arples Nos. 1 and 2, the spnbols used have the meanings given below:

LB means the static tensile strength (kg/mm2);

S0, 2 means the yield strength (k-g/ra);

6100 means the extended tensile strength for 100 hours at a given temperature (Zg/UMm 2).

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Example No*2

A nickel-base alloy of the following composition (weight per cert) was taken: 0.07 carbon; 15 chromium; 3.0 titanium; aluminum; 4.0 niobium; 12 cobalt; 6 molybdenum; 0,1 lant-

hanum; 0.01 boron; 0.01 cerium and the balance nickel.

The above alloy was subject to heat treatment which

involved hardening at a temperature of 115000 for 8 hours with subsequent cooling in still air. This was followed by the second hardening at a temperature of 105000 for 4 hours and cooling in air. After that ageing was effected by hold- ing the alloy at a temperature of 8500C for 8 hours with subsequent cooling in air* On completion of the said heat treatment the alloy pro- posed herein had the following propertiess 2 Tensile strength 160 kg/n Yield strength 6qz= 100 kg/mm2 I

Ductility 2C% and the high level of the high-temperature strength:

at 650°C 61= 85 kg/mm2; at 7000 C -c 68 kg/mmn2; at 750°0 2 55 k/inm at 8000C 42 kg/rn 2

30-32 kg/m 2 8500 The nickel-base alloy of the composition proposed herein-

before has a high order of the high-temperature strength and technological ductilityp adequate deformability and high mechanical properties by which virtue it can find wide appli- cation for the production of turbine disks and other component?

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operating at a temperature of 800 0 C and over, the stresses

ranging from 40 to 42 kg/mm2 and with the service life of 100 hr. An important merit of the alloy is its full insensitivity to the effect of stress concentrator owing to its high ducti- lity, thermal stability and relaxation resistance. The proposed alloy is superior in the level of the high- temperature strength to the now- existing alloys, bothlppe- Auehe4 in the Soviet Union and abroad. The contents of high- priced and scarce elements in the alloy proposed herein is decreased by 1.5-2 times, and it does not contain such a scarce alloying element as tungsten is. The proposed nickel-base alloy is adaptable for the manufacture of turbine and compressor disks for turbojet and turboprop engines operating at higher temperatures and stres- see than nilia yl -gvehiole.

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Claims (1)

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   The cl~iwa lofining the ir~ention are as followas

   1. A nicKel-base ailoy comprisinG the following components

   in wei_;ht per cent: 0.O4-O.U8 carbon; 13-16 chromium;

   2.3-3.0 titanium; 1.8-3.0 aluminun; 2.2-6.0 niobium; 6-12 cobalt; -8 molybdenum; 0.UO1-U.l lanthanum; 0.001-0.01 boron; 0.001-0.03 cerium and the balance nicKel.

   2. An alloy, as claimed in Claim 1, substantially as

   hereinbefore described with reference toA( I~4I.

   DATED this TWENTY-SEVENTH day of MARCH, 1973 KUZMA IVANOVICH TEREKHOV ALEXEI TIKHONOVICHI TUMANOV LJUDMILA SERGEEVNA MARKLNA KLAVDIYA ALEXEEVNA OKOLELOVA ALEXANDR FEDOROVICH BELOV NIKLAI DMITRIEVICH BOBOVNIKOV FEDOR VASILIEVICH TULYANKIN PETR ALEXEEVICH ZASETSKY VLADIMIR NIKIFOROVICH ZHUCHIN MIKHAIL YAKOVLEVICH DZUGUTOV MIKHAIL SEMENOVICH PODOLSKY VALENTIN VASILIEVICH TOPILNb

   Patent Attorneys for the Applicants SPRUSON FERGUSON

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