RU2765297C1 - Nickel granular heat-resistant alloy for gas turbine disks - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely, to heat-resistant nickel alloys for gas turbine disks produced by the method of granule metallurgy and intended for operation in the conditions of active impact of high temperatures and stresses. The granular heat-resistant nickel alloy comprises, wt.%: carbon - 0.06 to 0.15, chromium - 4.0 to 8.0, cobalt - 14.0 to 20.0, tungsten - 1.5 to 4.0, molybdenum - 2.0 to 5.0, titanium - 2.0 to 5.0, aluminium - 3.0 to 5.0, niobium - 1.5 to 3.5, tantalum - 4.0 to 7.0, rhenium - 0.5 to 2.5, hafnium - 0.05 to 0.3, iron - 0 to 0.01, boron - 0.01 to 0.03, vanadium - 0.1 to 0.5, zirconium - 0.01 to 0.03, cerium - 0.01 to 0.05, lanthanum - 0.01 to 0.05, yttrium - 0.01 to 0.05, scandium - 0.01 to 0.05, magnesium - 0.01 to 0.06, nickel the rest.

EFFECT: high level of short-term and long-term strength of the heat-resistant nickel alloy produced by the method of granule metallurgy is provided in the range of working temperatures from 20 to 850°C.

4 cl, 2 tbl, 1 dwg

Description

The invention relates to the field of metallurgy, in particular to heat-resistant nickel alloys obtained by granular metallurgy and intended for gas turbine disks and other critical parts of gas turbine engines and gas turbines operating under conditions of elevated temperatures, power loads and thermal stresses. The alloy is distinguished by high values of long-term, short-term strength and ductility in a wide temperature range from 20 to 850°C.

Known high-temperature nickel alloys for the production of disks of gas turbines. In particular, RF patent No. 2590792 (publ. bull. No. 19, 2016) proposes a heat-resistant nickel alloy for disks of gas turbine engines and installations, obtained by the method of granule metallurgy and intended for operation at high temperatures. The alloy contains carbon, chromium, cobalt, tungsten, molybdenum, titanium, aluminum, niobium, hafnium, boron, zirconium, magnesium, cerium and nickel in its composition in the following ratio of components (wt.%):

carbon - 0.03-0.08

chromium - 9.0-11.0

cobalt - 14.0-16.0

tungsten - 5.5-6.5

molybdenum - 3.2-3.8

titanium - 3.8-4.2

aluminum - 3.4-4.2

niobium - 1.5-2.2

hafnium - 0.2-0.4

boron - 0.005-0.055

zirconium-0.001-0.055

magnesium - 0.01-0.06

cerium - 0.001-0.055

nickel - the rest.

этого сплава равна (1540-1620) МПа, а

составляет величину (1108-1120) МПа, что не всегда отвечает современным требованиям к дисковым материалам этого класса.The alloy is characterized by a high operating temperature (750°C), but the level of its properties at room and operating temperatures is not sufficient. In particular

this alloy is equal to (1540-1620) MPa, and

is (1108-1120) MPa, which does not always meet modern requirements for disk materials of this class.

Known high-temperature granular heat-resistant nickel alloy for disks of gas turbines of the following chemical composition (wt.%), published in the patent of the Russian Federation No.

carbon - 0.08-0.15

chromium - 10.5-15.5

cobalt - 14.0-16.0

tungsten - 4.0-6.0

molybdenum - 2.6-3.6

titanium - 2.5-3.5

aluminum - 3.6-4.6

niobium - 3.0-4.0

tantalum - 0.1-1.3

hafnium - 0.05-0.2

vanadium - 0.1-0.5

boron - 0.005-0.05

zirconium - 0.001-0.05

cerium - 0.001-0.05

scandium - 0.01-0.1

magnesium - 0.001-0.05

nickel - the rest.

в мас. %.An additional requirement for the composition of this alloy is the condition

in wt. %.

остается на уровне (1590-1620) МПа.The alloy has high strength, heat resistance and fatigue resistance. In particular, the time of its destruction at 650°C and a load of 1118 MPa is (152-265) hours. However, short-term strength at room temperature

remains at the level of (1590-1620) MPa.

Currently, active research is being carried out in the world to create heat-resistant nickel alloys for gas turbine disks, which have high (more than 1650 MPa) strength at room temperatures and, at the same time, are capable of operating reliably at temperatures up to (830-850) ° C, which corresponds to the criterion

и

а в US Pat. №6974508 (2005 г.) фирма GE сообщает о создании перспективного сплава LSHR, обладающего

МПа и

для работы при температурах до 815°С. При этой температуре и нагрузке 345 МПа его удлинение 0,2% достигается за 50…300 час.In particular, US Pat. No. 6,468,368 (2002) indicates the development of a ME3 (Rene 104) powder disk alloy having

and

and in US Pat. No. 6974508 (2005), GE announces the creation of a promising LSHR alloy with

MPa and

for operation at temperatures up to 815°С. At this temperature and a load of 345 MPa, its elongation of 0.2% is achieved in 50 ... 300 hours.

оцененный по среднему составу и характеризующий по принятому в мировой практике методу оптимизации химического состава сплавов New Phacomp суммарный уровень энергии валентных электронов в γ-фазе, который с целью обеспечения в их структуре условий отсутствия ТПУ-фаз должен быть менее 0,93, на самом деле имеет величину, близкую к 0,942. Это означает, что в данном сплаве возможным является образование охрупчивающих σ-, μ-, η- и других ТПУ-соединений. Кроме того, сплав имеет не очень высокую (исходя из современных представлений) температуру сольвус - его

равна 1170°С.The LSHR alloy indeed provides a high complex of strength characteristics, however, its parameter

estimated by the average composition and characterizing the total energy level of valence electrons in the γ-phase, which should be less than 0.93 in order to ensure the conditions for the absence of TPU-phases in their structure, in fact has a value close to 0.942. This means that the formation of embrittling σ-, μ-, η- and other TPU compounds is possible in this alloy. In addition, the alloy has a not very high (according to modern concepts) solvus temperature - its

equal to 1170°C.

Subsequently, GE, improving this alloy, received a patent for a new material (US Pat. No. 2010/0303666, published on December 2, 2010) of the following composition (wt.%):

cobalt - 18.0-30.0

chromium - 11.4-16.0

tantalum - up to 6.0

aluminum - 2.5-3.5

titanium - 2.5-4.0

molybdenum - 5.5-7.0

niobium - up to 2.0

hafnium - up to 2.0

carbon - 0.04-0.2

boron - 0.01-0.05

zirconium - 0.03-0.09

nickel - the rest.

и

Для сплавов, показавших наиболее высокие результаты:

In this case, the following condition is met:

and

For alloys that have shown the highest results:

МПа), но заметно улучшены прочностные характеристики при высоких температурах. В частности

достигла значений ≈ 693 МПа (средний состав) вместо 679 МПа (для сплава LSHR).A feature of this alloy is that it retains a high level of strength at room temperatures (its

MPa), but the strength characteristics at high temperatures are noticeably improved. In particular

reached values of ≈ 693 MPa (medium composition) instead of 679 MPa (for the LSHR alloy).

находится на уровне (0,927-0,932). Отметим: современные исследования показывают, что гарантированное отсутствие явления образования ТПУ-фаз для сплавов указанного сложного состава обеспечивается при

However, the composition of this alloy does not guarantee the complete absence of embrittling TPU precipitates, since. his

is at the level (0.927-0.932). It should be noted that modern studies show that the guaranteed absence of the phenomenon of the formation of TPU phases for alloys of the indicated complex composition is ensured at

Known powder heat-resistant nickel alloy for gas turbine disks (Pat. USA No. 02014/0205449, publ. 07/24/2017, GE) of the following composition (wt.%):

cobalt - 16.0-30.0

chromium - 9.5-12.5

tantalum - 4.5-6.0

aluminum - 2.0-4.0

titanium - 2.0-3.4

tungsten - 3.0-6.0

molybdenum - 1.0-4.0

niobium - 1.5-3.5

hafnium - up to 1.0

carbon - 0.02-0.2

boron - 0.01-0.05

zirconium - 0.02-0.1

nickel - the rest.

In this case, the sum (W + Nb-Cr) should be less than - 6. The alloy has a duration until reaching an elongation of 0.2% at 705 ° C and a load of 690 MPa of the order of 1000 hours.

а высокотемпературная длительная прочность

выросла до (730-750) МПа.It features a high level of strength at 20°C

and high temperature long-term strength

increased to (730-750) MPa.

равный (0,924-0,929), что не гарантирует отсутствие в структуре охрупчивающих ТПУ-выделений. Последний фактор является особо важным именно для дисков, работающих на весьма высоких оборотах, с большими нагрузками и при этом конструктивно имеющих заметное количество концентраторов напряжений. Кроме того для перспективных ГТД желательно иметь более высокий уровень прочностных характеристик при (750-850)°С.The disadvantage of the alloy is a large specific gravity (≈8.55 g/cm ³ ), as well as a high coefficient

equal to (0.924-0.929), which does not guarantee the absence of embrittling TPU precipitates in the structure. The last factor is especially important for disks operating at very high speeds, with heavy loads and, at the same time, structurally having a noticeable number of stress concentrators. In addition, for advanced gas turbine engines, it is desirable to have a higher level of strength characteristics at (750-850)°C.

Known is a heat-resistant nickel alloy for GTE disks, obtained by technology (casting + deformation), having the following chemical composition (wt.%) in accordance with the patent of the Russian Federation No.

carbon - 0.03-0.12

chromium - 7.0-10.0

cobalt - 16.0-28.0

tungsten - 2.5-6.0

molybdenum - 2.8-4.8

titanium - 2.5-5.4

aluminum - 3.2-4.6

niobium - 0.5-3.0

tantalum - 2.6-4.6

hafnium - 0.05-0.2

rhenium - 1.0-3.0

boron - 0.005-0.015

zirconium - 0.005-0.03

cerium - 0.01-0.05

lanthanum - 0.01-0.05

yttrium - 0.01-0.05

magnesium - 0.01-0.06

nickel - the rest.

In this case, the following conditions must be met:

Сплав отвечает современным требованиям для материала дисков газовых турбин. Однако желательным является дальнейшее улучшение его прочностных характеристик как при комнатной, так и при высоких (750°С) температурах.In this case, the alloy has

The alloy meets modern requirements for the material of gas turbine disks. However, it is desirable to further improve its strength characteristics both at room and high (750°C) temperatures.

In addition, to ensure the guaranteed absence of embrittling TPU precipitates, it is necessary to introduce an additional condition to prevent the decay of the γ-matrix and the release of σ-, μ-, η- and other harmful electronic compounds from it.

The closest to the proposed invention in composition and purpose (prototype) is a granulated high-temperature nickel alloy intended for the manufacture of disks and other highly loaded parts of turbine rotors (RF patent No. 2697674, publ. 08.16.2019, bull. No. 23), having the following (wt.%) chemical composition:

carbon - 0.03-0.12

chromium - 7.0-9.0

cobalt - 17.0-22.0

tungsten - 1.0-2.4

molybdenum - 2.8-4.8

titanium - 2.5-4.5

aluminum - 3.2-4.6

niobium - 0.5-2.9

tantalum - 4.7-6.0

hafnium - 0.3-0.5

rhenium - 1.0-3.0

boron - 0.005-0.015

zirconium - 0.005-0.03

cerium - 0.01-0.05

lanthanum - 0.01-0.05

yttrium - 0.01-0.05

magnesium - 0.01-0.06

manganese - 0.05-0.5

silicon - 0.05-0.5

nickel - the rest.

Вместе с тем достигнутый уровень свойств не является достаточным. Необходимо дальнейшее улучшение прочностных показателей как при комнатной, так и повышенных температурах. Кроме того, актуальной остается задача введения условий, обеспечивающих отсутствие распада как основной упрочняющей γ'-фазы и выделения из нее охрупчивающих δ-, β- и других фаз, а также γ-матрицы и образования электронных σ-, μ-, η- и т.д. соединений.An alloy with a specific weight of (8.47-8.48) g / cm ³ has high strength characteristics

However, the achieved level of properties is not sufficient. It is necessary to further improve the strength characteristics both at room and elevated temperatures. In addition, the problem of introducing conditions that ensure the absence of decomposition as the main strengthening γ'-phase and the separation of embrittling δ-, β- and other phases from it, as well as the γ-matrix and the formation of electronic σ-, μ-, η- and etc. connections.

The technical result to which the present invention is directed is to provide a high level of short-term and long-term strength of a heat-resistant nickel alloy obtained by granule metallurgy in the operating temperature range from 20°C to 850°C.

This technical result is achieved in that the well-known heat-resistant nickel alloy containing carbon, chromium, cobalt, tungsten, molybdenum, titanium, aluminum, niobium, tantalum, hafnium, rhenium, boron, zirconium, cerium, magnesium, lanthanum, yttrium, iron additionally contains vanadium and scandium. In this case, manganese and silicon are excluded from the composition of the alloy. The total content of (La+Ce+Sc) should be at the level of (0.06-0.1) wt. %, and the total concentration (Zr+Hf) is equal to (0.25-0.33) wt. %.

The alloy according to the present invention has a composition with the following ratio of alloying components (wt.%).

carbon - 0.06-0.15

chromium - 4.0-8.0

cobalt - 14.0-20.0

tungsten - 1.5-4.0

molybdenum - 2.0-5.0

titanium - 2.0-5.0

aluminum - 3.0-5.0

niobium - 1.5-3.5

tantalum - 4.0-7.0

rhenium - 0.5-2.5

hafnium - 0.05-0.3

boron - 0.01-0.03

vanadium - 0.1-0.5

zirconium - 0.01-0.03

cerium - 0.01-0.05

lanthanum - 0.01-0.05

yttrium - 0.01-0.05

scandium - 0.01-0.05

iron - 0-0.01

magnesium - 0.01-0.06

nickel - the rest

In this case, the following conditions must be met:

Since it is necessary, to the maximum extent possible, to implement the criteria that ensure an increase in strength characteristics in the temperature range from room temperature to (800-850) ° C by optimal alloying and at the same time obtain a thermally stable (without decomposition of the main strengthening γ'-phase, as well as a γ-matrix with separation of embrittling TPU- and other harmful phases) structure, the authors implemented the following approaches.

The composition of the proposed alloy ensures the release of a larger amount of the strengthening γ'-phase, since it is known that an increase in its volume content to (65-68)% increases the high-temperature heat resistance. It should be noted that the volume content of the strengthening γ'-phase (υ _γ'-phase ) in disk heat-resistant nickel alloys is noticeably lower than in cast bladed ones. This feature is due to the fact that the complication of alloying and, accordingly, an increase in υ _γ'-phase , firstly, sharply reduces manufacturability (including deformability), and secondly, the resistance to destruction caused by the presence of stress concentrators, which in the disk due to its design features, there are quite a lot.

However, materials obtained by granular metallurgy are much more technologically advanced. This circumstance allowed the authors to realize the compositions of disk alloys with a higher content of the strengthening γ'-phase (that is, with an increased total concentration of γ'-forming elements). At the same time, it is important to develop criteria that determine the upper and lower levels of the limiting content of the sum (Al + Ti + Ta + Nb + Hf), as well as guarantee the absence of a possible decomposition of the strengthening γ'-phase and the release of harmful compounds from it.

и

(Рис. 1а, б).For this purpose, dependencies were built

and

(Fig. 1a, b).

It can be seen that the optimal values of this sum are within:

14.7≤(Al+Ti+Ta+Nb)≤16.0 wt% (3)

In this case: 0.8≤Al/Ti≤1.25 wt.% (4).

Thus, the conditions [equations (3), (4)] are determined, which provide a high content of the strengthening γ'-phase, but at the same time there is no possibility of its decomposition and the release of harmful compounds from it.

On the other hand, high-temperature hardening of the γ-solid solution is important in order to ensure that no precipitation of embrittling TPU phases from it is guaranteed.

(патент РФ №2695797) или 25≤(Cr+Со)≤27 мас. % и

(патент РФ №2623540), или (Cr+Со)≤22,8 мас. % и (Mo+W)≥9,5 мас. % (патент РФ №2590792), или 7,2≤(Cr+Мо)≤10,5 мас. % (патент РФ №2571674).As a criterion for ensuring the absence of TPU compounds in the structure, many patents indicate different ratios, in particular:

(RF patent No. 2695797) or 25≤(Cr+Co)≤27 wt. % and

(RF patent No. 2623540), or (Cr + Co) ≤ 22.8 wt. % and (Mo+W)≥9.5 wt. % (RF patent No. 2590792), or 7.2≤(Cr+Mo)≤10.5 wt. % (RF patent No. 2571674).

The authors propose to establish a similar criterion on the basis of modern generally recognized models that describe the state of the structure of nickel heat-resistant alloys, namely, on the basis of the New Phacomp method.

In accordance with this method, the condition for the absence of embrittling TPU compounds in the alloy structure is as follows:

- суммарная энергия валентных d-электронов.where C _Ni …C _Hf are the concentrations of the corresponding elements (at. %) in the γ-phase, and

- total energy of valence d-electrons.

For the doping area lying inside the compositions we offer, we can take: C _Ni =0.56; C _Al = 0.086; C _Ta =0.018; C _Co = 0.177; C _Nb =0.013; C _Ti =0.043; C _Hf =0.001; C _Re ≤0.003 (atomic content).

In this case:

where С _Cr …C _Re is the concentration of elements (wt %) in the alloy.

Thus, dependence (6) is a 4-component dependence that determines the phase boundary of alloys with and without TPU phases formed.

Taking into account that in order to ensure the highest level of short-term and long-term strength, it is important to use all available possibilities, it is necessary to improve alloying in order to additionally strengthen both the alloy matrix and interfacial and grain boundaries.

For this purpose, vanadium and a scandium microalloying element were added to the alloy.

Vanadium is an effective hardener for nickel alloys. Its effect on the cohesive energy of nickel (characterizing the strength of interatomic bonds) is higher than that of aluminum and titanium. The disadvantage is that when its concentration in the alloy is above 0.5%, it begins to have a negative effect on corrosion resistance. However, given that the operating temperatures of disk alloys are much lower than those for working and nozzle blades, and the need to increase high-temperature strength is great, this element is introduced into the alloy in an amount not exceeding 0.5 wt. %.

In addition, the composition of the alloy contains a microalloying element, scandium, which very effectively strengthens the interphase and grain boundaries. The specified metal together with lanthanum, scandium and cerium with complex alloying have an active synergistic effect on strength properties at all temperatures. At the same time, studies have shown that the optimal total content (La + Ce + Sc) should be at the level of 0.06-0.1 wt. %.

For nickel heat-resistant alloys obtained by the method of granular metallurgy, it is very important to introduce hafnium into their composition. This element significantly improves the morphology of the resulting carbides, which varies from "Chinese characters" to rounded inclusions, which simultaneously increases not only strength, but also ductility.

However, this element has a very low solubility in the nickel γ-matrix, so it is advisable to introduce it in amounts necessary for the formation of carbides with improved morphology (that is, up to 0.3 wt.%). A further increase in its concentration does not lead to noticeable positive effects.

Given that silicon and manganese, while increasing corrosion resistance, have a noticeable negative effect on thermodynamic parameters and strength characteristics, both of these elements are excluded from the composition of the alloy. Since the temperatures of its operation are noticeably lower than those of alloys for GTE blades (hence, corrosion processes proceed much (several orders of magnitude) slower.

The results of a comparative evaluation of the claimed alloy and the prototype (RF patent No. 2697674, 2019) are shown in tables 1 and 2.

As can be seen, the proposed alloy surpasses the prototype alloy in its strength characteristics both at room and at high temperatures.

At the same time, it is thermodynamically more stable, since its temperatures of the beginning and end of the dissolution of the strengthening γ'-phase are noticeably higher. Therefore, compared with the prototype, it is able to operate at higher temperatures.

предлагаемого сплава ниже, чем у прототипа, это означает, что он более устойчив против образования охрупчивающих ТПУ-фаз. Указанная особенность важна для сплавов, предназначенных для работы в качестве дисков турбин.In addition, since

of the proposed alloy is lower than that of the prototype, which means that it is more resistant to the formation of embrittling TPU phases. This feature is important for alloys designed to work as turbine discs.

Claims (31)

1. Granular heat-resistant nickel alloy containing carbon, chromium, cobalt, tungsten, molybdenum, titanium, aluminum, niobium, tantalum, rhenium, hafnium, iron, boron, zirconium, cerium, lanthanum, yttrium, magnesium, characterized in that it is additionally contains vanadium and scandium with the following ratio of alloying components, wt.%: carbon - 0.06-0.15 chromium - 4.0-8.0 cobalt - 14.0-20.0 tungsten - 1.5-4.0 molybdenum - 2.0-5.0 titanium - 2.0-5.0 aluminum - 3.0-5.0 niobium - 1.5-3.5 tantalum - 4.0-7.0 rhenium - 0.5-2.5 hafnium - 0.05-0.3 iron - 0-0.01 boron - 0.01-0.03 vanadium - 0.1-0.5 zirconium - 0.01-0.03 cerium - 0.01-0.05 lanthanum - 0.01-0.05 yttrium - 0.01-0.05 scandium - 0.01-0.05 magnesium - 0.01-0.06 nickel - the rest. 2. An alloy according to claim 1, characterized in that it contains components for which: 0.06≤(La+Ce+Sc)≤0.1 wt% (1) 0.25≤(Zr+Hf)≤0.33 wt% (2). 3. Alloy according to claim 1, characterized in that it contains components for which: 14.7≤ (Al+Ti+Ta+Nb+Hf)≤16.0 wt% (3) 0.8≤Al/Ti≤1.25. 4. Alloy according to claim 1, characterized in that it contains components for which: C _Cr + 0.54C _Mo + 0.41C _W + 0.39C _Re ≤ 0.13 wt% (5), where C _Cr , C _Mo , C _W and C _Re are the concentrations of the corresponding elements in wt.% in the γ-phase.

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