RU2769330C1 - Cast heat-resistant nickel alloy with monocrystalline structure - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy – to production of cast heat-resistant nickel alloys intended for casting blades and other critical parts of gas turbines having a single-crystal structure. Cast heat-resistant nickel alloy with monocrystalline structure contains carbon, chromium, cobalt, tungsten, molybdenum, aluminum, tantalum, rhenium, boron, cerium, lanthanum, yttrium, magnesium, it differs by the fact that it additionally contains hafnium, manganese, silicon, scandium, titanium, niobium, zirconium at the following ratio of components, wt%: carbon 0.002–0.1, chrome 2.8–6.0, cobalt 3.0–6.5, tungsten 2.0–5.0, molybdenum 1.5–3.5, aluminum 5.4–6.3, titanium 0.1–1.2, niobium 0.1–1.0, tantalum 7.2–9.0, hafnium 0.1–0.3; rhenium 4.3–7.0, boron 0.005–0.01, zirconium 0.005–0.03, cerium 0.001–0.1, lanthanum 0.001–0.1, yttrium 0.001–0.1, magnesium 0.01–0.03, manganese 0.01–0.2, silicon 0.01–0.2, scandium 0.005–0.03, nickel – the rest, subject to the following conditions: 44.2≥3.0C_Mo+1.6C_W+2.3C_Ta+1.3C_Re+10.0C_Hf, where C_Mo, C_W, C_Ta, C_Re, C_Hf – concentration of corresponding alloying elements in alloy, wt%, and C_Al/(C_Ti+C_Nb+C_Ta+C_Hf+0.57C_W+0.46C_Mo)≥1.0 (at.%/at.%), where C_Al, C_Ti, C_Nb, C_Ta, C_Hf, C_W, C_Mo – concentration of corresponding elements in γ'-phase, at.%.

EFFECT: reduced specific weight of alloy at maintaining high level of heat resistance.

1 cl, 2 tbl

Description

The invention relates to the field of metallurgy - to the production of cast heat-resistant nickel alloys intended for casting blades and other critical parts of gas turbines having a single-crystal structure.

Cast heat-resistant nickel alloy with a single-crystal structure, contains (wt.%): carbon 0.002-0.01; chromium 2.8-6.0; cobalt 3.0-6.5; tungsten 2.0-5.0; molybdenum 1.5-3.5; aluminum 5.4-6.3; niobium 0.1-1.0; tantalum 7.2-9.0; rhenium 4.3-7.0; boron 0.005-0.01; zirconium 0.005-0.03; cerium 0.001-0.1; lanthanum 0.001-0.1; yttrium 0.001-0.1; magnesium 0.01-0.03, and additionally titanium 0-1.2; hafnium 0.1-0.3; manganese 0.01-0.2; silicon 0.01-0.2; scandium 0.005-0.03; nickel - the rest.

The increase in the parameters of aircraft engines is directly related to the requirement to increase the heat resistance of nickel alloys used in the casting of single-crystal gas turbine blades.

порядка 300 МПа, однако при этом резко возросла их стоимость.At present, for the production of nickel alloys with a higher level of heat resistance in Russia and abroad, in addition to very expensive and scarce rhenium, the element of the platinum group ruthenium has also begun to be used. The implementation of this direction of development really made it possible to obtain alloys of the 5th generation with a level of properties

about 300 MPa, however, their cost has sharply increased.

, но при этом не имеющих в своем составе рутений.In this regard, one of the urgent tasks is the creation of alloys with the same high level of heat resistance, corresponding to metallic materials of the 4th-5th generations.

, but do not contain ruthenium.

Known heat-resistant nickel alloy (Pat. Wo2019/097163, Safran, France, publ. 11/14/2018), containing in its composition (wt.%):

rhenium 4.5-5.5 cobalt 3.5-12.5 molybdenum 0.3-1.5 chromium 3.5-5.5 tungsten 3.5-5.5 aluminum 4.5-6.0 titanium 0.35-1.5 tantalum 8.0-10.5 hafnium 0.15-0.3 silicon 0.05-0.15 nickel rest.

равно

МПа). При этом, однако, данного сплава

при максимально допустимом 0,9. Это означает, что в структуре сплава возможно появление охрупчивающих ТПУ-соединений. Кроме того, его удельный вес равен 9,02 г/см³, что также является нежелательным. Недавно в Китае был разработан сплав (патент Китая №106756249, опубл. 31.05.2017 г.), имеющий следующий состав (мас. %):The alloy has a high level of heat resistance (its

equals

MPa). However, this alloy

with a maximum allowable of 0.9. This means that embrittling TPU compounds may appear in the alloy structure. In addition, its specific gravity is 9.02 g/cm ³ , which is also undesirable. Recently, an alloy has been developed in China (China patent No. 106756249, published on May 31, 2017), which has the following composition (wt.%):

chromium 3-5 cobalt 6-13 tungsten 6-8 molybdenum 0.1-2.0 rhenium 4.5-6.0 ruthenium 2-4 aluminum 5.5-6.5 tantalum 6.0-10.0 hafnium 0.-0.2 nickel rest.

при удельном весе 8,96 г/см³.This alloy also has high heat resistance - its

with a specific gravity of 8.96 g/cm ³ .

(Re+Ru) и соответственно - высокая стоимость.Its main disadvantage, which limits its successful application, is the presence of

(Re+Ru) and, accordingly, high cost.

The closest analogue, taken as a prototype, is a cast nickel heat-resistant alloy with a single-crystal structure (RF patent No. 2402624, publ. 27.10.2010), having the following chemical composition (wt.%):

chromium 2.5-4.5 cobalt 5.0-6.0 aluminum 5.4-6.0 tungsten 3.5-4.5 molybdenum 2.8-3.8 tantalum 5.3-6.3 rhenium 5.8-6.8 ruthenium 4.6-6.4 cerium 0.001-0.02 lanthanum 0.002-0.1 neodymium 0.0005-0.01 yttrium 0.002-0.02 carbon 0.002-0.05 boron 0.0004-0.004 magnesium and/or calcium 0.001-0.009 nickel rest.

при достаточно большом удельном весе - 9,03 г/см³. Кроме того, в его составе находится

дорогих элементов (Re+Ru).The alloy is a representative of the 5th generation of single-crystal nickel superalloys. It has the heat resistance of it

with a sufficiently large specific gravity - 9.03 g/cm ³ . In addition, it contains

expensive elements (Re + Ru).

The technical result of the invention is a reduction in the total total content of extremely expensive alloying elements (Re + Ru) with the exclusion of ruthenium from the composition of the alloy, a decrease in its specific gravity while maintaining a high level of heat resistance.

The technical result is achieved by the fact that the casting heat-resistant nickel alloy with a single-crystal structure containing carbon, chromium, cobalt, tungsten, molybdenum, aluminum, tantalum, rhenium, boron, cerium, lanthanum, yttrium, magnesium, according to the present invention, additionally contains hafnium, manganese , silicon, scandium, titanium, niobium, zirconium in the following ratio of components (wt.%):

carbon 0.002-0.1 chromium 2.8-6.0 cobalt 3.0-6.5 tungsten 2.0-5.0 molybdenum 1.5-3.5 aluminum 5.4-6.3 titanium 0.1-1.2 niobium 0.1-1.0 tantalum 7.2-9.0 hafnium 0.1-0.3 rhenium 4.3-7.0 boron 0.005-0.01 zirconium 0.005-0.03 cerium 0.001-0.1 lanthanum 0.001-0.1 yttrium 0.001-0.1 magnesium 0.01-0.03 manganese 0.01-0.2 silicon 0.01-0.2 scandium 0.005-0.03 nickel rest.

In the claimed alloy, in order to reduce the specific gravity, the total content of refractory elements, which are characterized by a high specific gravity, is slightly reduced, however, in order to maintain the level of heat resistance, the concentration of tantalum is increased, which effectively increases the high-temperature performance of nickel alloys. For the same purpose, hafnium and scandium were added to the alloy. Hafnium is known to actively increase the heat resistance of nickel-based alloys. However, it has low solubility in γ-solid solution. Therefore, it is introduced in small amounts, avoiding the appearance of new phase precipitates and, accordingly, the appearance of grain boundaries that are undesirable for single crystals.

Scandium effectively increases the cohesive energy of nickel and thereby improves the high-temperature strength of the γ-matrix.

In addition, tantalum and scandium are primarily located in defective volumes, which leads to an increase in long-term strength.

Considering that the alloy is intended for operation at very high temperatures (1000°C and more) under conditions of active corrosion, manganese and silicon are additionally introduced into the alloy in amounts at which they provide effective protection against high-temperature corrosion, but at the same time do not reduce strength properties. characteristics.

Since, to increase the heat resistance, it is important to use the minimum possible hardening mechanisms, titanium is additionally introduced into the alloy, which reduces the coagulation rate of particles and raft plates of the γ'-phase during high-temperature loading of alloys, thereby improving their performance.

When alloying an alloy, it is also necessary to introduce requirements that ensure the absence of conditions for the decay of the γ-matrix and the separation of embrittling TPU phases from it. This condition is based on a widely used dependency in the New Phacomp method, namely:

суммарная энергия валентных электронов элементов, входящих в состав сплава, С_i - атомные концентрации элементов, образующих γ-фазу.Here

the total energy of the valence electrons of the elements that make up the alloy, C _i are the atomic concentrations of the elements that form the γ-phase.

For the alloying area of the proposed alloy, dependence (1) is transformed into the following:

where C _i - the concentration of the corresponding alloying elements (wt.%) in the alloy.

, которое в методе New Phacomp равно 0,93, зависит от атомной массы γ-фазы сплава и для уровня сложности предлагаемой области легирования оно равно 0,9.We point out that, in accordance with our research

, which in the New Phacomp method is equal to 0.93, depends on the atomic mass of the γ-phase of the alloy and for the level of complexity of the proposed alloying area it is equal to 0.9.

To limit the process of decomposition of the strengthening γ'-phase of the proposed alloy, which leads to a decrease in its performance, the following dependence is presented:

here C _i is the concentration (at %) of the corresponding elements in the γ'-phase.

Thus, in addition to the specified alloying area, conditions (2) and (3) are introduced to ensure the required performance of the proposed alloy.

A comparative assessment of the level of heat resistance of the proposed alloy (3 experimental compositions) and the known alloy (RF patent No. 2530932), selected as a prototype, are presented in Tables 1 and 2.

более 300 МПа отличается от прототипа:Comparison of the results shown in Table 2 shows that the proposed alloy at the level of long-term strength

more than 300 MPa differs from the prototype:

- lower specific gravity (which is very important to ensure a lower specific gravity of the gas turbine);

- higher performance, since the temperature of complete dissolution of the γ'-phase in the proposed alloy (equal to or higher than 1320°C) significantly exceeds T _prγ' prototype having 1308°C;

тыс руб.;- the most important thing is that the new alloy is significantly (more than 35%) more economical than the prototype, the cost of 1 kg of its charge is (22.8-23.4) thousand rubles, while the specific price of the charge of the alloy with (Re + Ru) amounts to

thousand roubles.;

- when using this material, there is no need to use elements of the precious platinum group.

Claims (7)

Cast high-temperature nickel alloy with a single-crystal structure containing carbon, chromium, cobalt, tungsten, molybdenum, aluminum, tantalum, rhenium, boron, cerium, lanthanum, yttrium, magnesium, characterized in that it additionally contains hafnium, manganese, silicon, scandium, titanium, niobium, zirconium in the following ratio of components, wt.%: carbon 0.002-0.1 chromium 2.8-6.0 cobalt 3.0-6.5 tungsten 2.0-5.0 molybdenum 1.5-3.5 aluminum 5.4-6.3 titanium 0.1-1.2 niobium 0.1-1.0 tantalum 7.2-9.0 hafnium 0.1-0.3 rhenium 4.3-7.0 boron 0.005-0.01 zirconium 0.005-0.03 cerium 0.001-0.1 lanthanum 0.001-0.1 yttrium 0.001-0.1 magnesium 0.01-0.03 manganese 0.01-0.2 silicon 0.01-0.2 scandium 0.005-0.03 nickel rest, subject to the following conditions: 44.2≥3.0C _Mo +1.6C _W +2.3C _Ta +1.3C _Re +10.0C _Hf , where C _Mo , C _W , C _Ta , C _Re , C _Hf are the concentrations of the corresponding alloying elements in the alloy, wt.%, and

where C _Al , C _Ti , C _Nb , C _Ta , C _Hf , C _W , C _Mo are the concentrations of the corresponding elements in the γ'-phase, at.%.