RU2353691C2 - Composition of heat-resistant nickel alloy (versions) - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field and can be used for manufacturing of rotor and nozzle blade monocrystalline of gas turbine engine, over a long period of time operating at temperatures higher than 1000°C. Alloy according to the first option contains, wt %: chrome1.0-4.0, aluminium 4.5-7.0, tungsten 10.0-14.0, tantalum 5.0-10,0, rhenium 4.0-7.0, cobalt 2.0-5.0, yttrium 0.003-0.1, lanthanum 0.001-0.1, cerium 0.003-0.1, nickel - the rest and is described with higher level of heat-resistance and less propensity for formation of topologically close-packed (TCP) phases, especially with continuous running. Alloy according to the second option contains, wt %: chrome1.0-4.0, aluminium 4.5-7.0, titanium ≤ 2.0, molybdenum ≤ 4.0, tungsten 8.0-14.0, tantalum 5.0-10.0, rhenium 4.0-7.0, cobalt 2.0-5.0, niobium ≤ 2.0, yttrium 0.003-0.1, lanthanum 0.001-0.1, cerium 0.003-0.1, carbon ≤ 0.1, nickel - the rest and defined with increased heat-resistance, improved casting characteristics, technological plasticity and increased corrosion resistance.

EFFECT: increasing of heat-resistance, improving of casting characteristics, technological plasticity and increasing of corrosion resistance.

2 cl, 2 tbl

Description

The invention relates to metallurgy of alloys, and in particular to the production of heat-resistant nickel alloys used for the production of parts of gas turbine engines, for example, turbine blades, operating for a long time at high temperatures of 1000-1100 ° C.

Known heat-resistant alloy CMSX-4, which is used as a material for single-crystal vanes and is a carbon-free single-crystal rhenium-containing alloy (US patent No. 4643782, IPC С22С 19/05, 1987.02.17) - analogue.

Known alloy has the following chemical composition (wt.%):

cobalt - 9.3-10.0

chromium - 6.4-6.8.

molybdenum - 0.5-0.7,

tungsten - 6.2-6.6,

tantalum - 6.3-6.7,

aluminum - 5.45-5.75,

titanium - 0.8-1.2,

hafnium - 0.02-0.12,

rhenium - 2.8-3.2,

nickel - the rest is up to 100%.

The known alloy has low heat resistance (hourly strength at 1000 ° C is 26 kgf / mm ² ) and, in addition, it exhibits phase instability associated with the release of topologically close packed phases (TPU) phases.

Known alloy CMSX-10, used to produce castings of blades with a single crystal structure of the following chemical composition (wt.%):

carbon - up to 0.04,

chrome - 1.8-2.5,

cobalt - 1.5-2.5,

titanium - 0.1-0.5,

aluminum - 5.5-6.1,

molybdenum - 0.25-0.6,

tungsten - 3.5-6.0,

tantalum - 8.0-9.0,

rhenium - 6.2-6.8,

niobium - 0.01-0.1,

hafnium - up to 0.04,

boron - up to 0.01,

yttrium - up to 0.01,

cerium - up to 0.01,

lanthanum - up to 0.01,

manganese - up to 0.04,

silicon - up to 0.05,

zirconium - up to 0.01,

sulfur - up to 0.001,

vanadium - up to 0.01

nickel - the rest is up to 100% (US patent No. 5540790, IPC: C22C 19/05, 1996.07.30) - prototype.

The long-term (hourly) strength of the known alloy at a temperature of 1000 ° C is 29-30 kgf / mm ² . At the same time, a relatively high dispersion of the durability of the samples during their creep test is noted, which indicates an insufficient balance of the chemical composition of the alloy adopted as a prototype.

The technical result to which the claimed invention is directed, according to the first embodiment, is the development of an alloy with a higher level of heat resistance and a lower tendency to form topologically close packed (TPU) phases, especially during long-term operation, i.e. increasing the long-term strength properties of the alloy.

The specified technical result is achieved in that the composition of the heat-resistant nickel alloy contains nickel, chromium, cobalt, tungsten, rhenium, tantalum, yttrium, lanthanum and cerium in the following ratio of components (wt.%):

chrome - 1.0-4.0,

aluminum - 4.5-7.0,

tungsten - 10.0-14.0,

tantalum - 5.0-10.0,

rhenium - 4.0-7.0,

cobalt - 2.0-5.0,

yttrium - 0.003-0.1.

lanthanum - 0.001-0.1,

cerium - 0.003-0.1

nickel - the rest is up to 100%.

Known heat-resistant alloy ZhS-32-VI the chemical composition of which includes (wt.%):

chrome 4.3-5.6,

cobalt - 8.0-10.0,

tungsten - 7.7-9.5,

aluminum - 5.6-6.3,

rhenium - 3.5-4.5,

tantalum 3.5-4.5,

niobium 0 1.4-1.8,

carbon - 0.12-0.18,

molybdenum - 0.8-1.4,

boron - 0.02,

cerium - 0,025,

nickel - the rest is up to 100%.

A disadvantage of the known alloy is the low limit of long-term strength, as well as the possibility of phase transformations with the formation of TPU phases (σ, μ) or Me6C carbides.

Known alloy CMSX-10 used to produce castings of blades with a single crystal structure of the following chemical composition (wt.%):

carbon - up to 0.04,

chrome - 1.8-2.5,

cobalt - 1.5.2.5,

titanium - 0.1-0.5,

aluminum - 5.5-6.1,

molybdenum - 0.25-0.6,

tungsten - 3.5-6.0,

tantalum - 8.0-9.0,

rhenium - 6.2-6.8,

niobium - 0.01-0.1,

hafnium - up to 0.04,

boron - up to 0.01,

yttrium - up to 0.01,

cerium - up to 0.01,

lanthanum - up to 0.01,

manganese - up to 0.04,

silicon - up to 0.05,

zirconium - up to 0.01,

sulfur - up to 0.001,

vanadium - up to 0.01

nickel - the rest is up to 100%, (US patent No. 5540790, IPC: C22C 19/05, 1996.07.30) - prototype.

The long-term (hourly) strength of the known alloy at a temperature of 1000 ° C is 29-30 kgf / mm ² . At the same time, a relatively high dispersion of the durability of the samples during their creep test is noted, which indicates an insufficient balance of the chemical composition of the alloy adopted as a prototype.

The technical result to which the claimed invention is directed according to the second embodiment is to increase the heat resistance of nickel alloys for single crystal casting, for example, gas turbine engine blades, improve the casting properties of the alloy, its technological plasticity and increase the corrosion resistance of the claimed alloy.

The specified technical result is achieved in that the composition of the heat-resistant nickel alloy containing nickel, chromium, cobalt, tungsten, aluminum, tantalum, rhenium, molybdenum, yttrium, lanthanum and cerium additionally contains titanium and niobium in the following ratio of components (wt.%):

chrome - 1.0-4.0,

aluminum 4,5-7,0,

titanium ≤ 2.0,

molybdenum ≤ 4.0,

tungsten - 8.0-14.0,

tantalum - 5.0-10.0,

rhenium - 4.0-7.0,

cobalt - 2.0-5.0,

niobium ≤ 2.0,

yttrium - 0.003-0.1,

lanthanum - 0.001-0.1,

cerium - 0.003-0.1

carbon ≤ 0.1

nickel - the rest is up to 100%.

The development of modern heat-resistant nickel alloys (ZhS) of the latest generations is mainly associated with the application of two main approaches in the field of materials science and technology:

- introduction of new refractory metals, for example, tantalum and rhenium, into the alloying system;

- using directional crystallization technology to produce single crystals.

The applicant and the authors conducted theoretical and experimental studies regarding the effect of rhenium on the structure and properties of modern single-crystal heat-resistant alloys, characterized by a high level of structural stability. Based on the results, it was concluded that the rhenium content should be limited from above and that the maximum rhenium content should not exceed 7.0% of the mass composition. The specified limitation is associated with the following features of the physicochemical properties of rhenium:

- rhenium, unlike tantalum, tungsten and some other refractory metals, practically does not dissolve in the γ'-phase, the amount of which in modern alloys reaches 60-70 vol.%. This means that even in the complete absence of segregation, the rhenium content in the matrix is more than double its nominal value in the alloy, which increases the tendency of the alloy matrix to separate rhenium containing phases from it;

- rhenium is not among the strong carbide-forming elements, but can actively seek the formation of intermediate TPU phases;

- Rhenium is one of the most highly liquified elements of heat-resistant alloys. Moreover, the alignment of its concentration occurs very slowly;

- in the alloy, even with a small amount of rhenium (depending on the presence in the composition and the amount of other alloy components), it is possible to isolate the brittle plates of the σ phase from the matrix.

In the inventive alloys according to the first and second embodiments, the amount of rhenium and the alloying system are balanced in such a way as to minimize the possibility of formation of TPU phases and, consequently, embrittlement of the alloys.

A feature of the inventive alloy according to the first embodiment (KS-3) is the high tungsten content within the stated limits. The upper limit of the tungsten content limits the concentration range, beyond which increases the likelihood of tungsten precipitating from the solid solution in the form of the α phase, which is not such an effective hardener as the γ'phase based on Ni3Al, and when the tungsten content is below the lower limit, it stabilizes the effect on the structure is weakened.

The claimed amount of tantalum is introduced into the composition of the heat-resistant nickel alloy against the background of a high tungsten content. The alloying system of the inventive alloy (KS-3) is balanced in such a way that α-phase precipitation does not occur in the alloy despite the fact that tantalum, like tungsten, has a bcc lattice.

The effect of tantalum on the properties of the claimed alloy is largely similar to the effect of tungsten, tantalum is also characterized by high cohesive strength, which is also characteristic of the alloy, claimed in a given ratio of components. Tantalum is distributed between the γ matrix and the strengthening γ'-phase, stabilizing and strengthening both main phases of the heat-resistant alloy. When the content of tantalum is more than 10.0 wt.%, The likelihood of it falling out of the solid solution in the form of Ni-Ta intermetallic compounds increases, and when the content is less than 5.0 wt.% Its effect on the properties is practically absent.

The introduction of the claimed composition of a heat-resistant alloy of the specified amount of chromium is due to the need to increase its heat resistance. With an increase in the chromium content above 4.0 wt.%, The probability of the formation of a topologically close-packed (TPU) chromium-based phase increases, which embrittle the alloy, in addition, in alloys with a rather high rhenium content, the chromium content can be reduced to 4.0 wt. %, since rhenium refers to elements that increase the resistance of the alloy to gas corrosion.

The alloying of the alloy with cobalt in the claimed amounts is due to the need to improve the technological characteristics of the alloy - technological plasticity and casting properties, as well as corrosion resistance.

The system of microalloying additives, namely the combined use of lanthanum, yttrium and cerium in the claimed amounts ensures the stabilization of structural defects in the single crystals of the inventive alloy, and together with other components of the alloy composition provides increased heat resistance compared to the prototype.

A feature of the inventive alloy in the second embodiment is the similarity of the effects of rhenium, tungsten, tantalum, cobalt and a system of microalloying additives (yttrium, lanthanum and cerium), but in addition, the properties of the inventive alloy in the second embodiment are affected by the presence of titanium, molybdenum, niobium and possibly carbon.

Titanium is one of the main γ 'forming elements, the amount of which, on the one hand, ensures the formation of the necessary content of the strengthening γ'-phase, and on the other hand, limits the volume of excess eutectic (γ' + γ).

Niobium and molybdenum - provide increased durability of the material in the temperature range ≈1000 ° С. Molybdenum is a hardener of a solid solution, however, its contribution is most significant in changing the parameter γ of a solid solution and, as a consequence, the morphology of the hardening secondary γ'-phase, making it cubic and thereby providing high creep resistance of heat-resistant alloys.

Carbon may be introduced into the alloy to form the second hardening phase of heat-resistant alloys — carbides. The total content in the inventive alloy of carbon and carbide-forming elements ensures the absence of embrittlement TPU phases.

The inventive composition of heat-resistant nickel alloy according to the second variant in quantitative and qualitative composition provides, along with increased heat resistance, improved casting properties of the alloy and its technological ductility, increased corrosion resistance.

Examples of specific performance.

To test the results, alloys were cast according to the first and second variants. Casting of alloys was carried out in a vacuum-induction furnace "Crystal" with a capacity of 5-10 kg. The order of introduction of the components of the claimed alloy compositions is standard: nickel, chromium, cobalt, tungsten, molybdenum, tantalum, carbon, melting, carbon deoxidation, the subsequent introduction of titanium, aluminum and microalloying additives (elements with high oxygen activity) and casting.

To test the alloy according to the first embodiment, two alloy compositions were smelted (one claimed and one prototype alloy - CMSX-10) containing the components (in wt.%) Shown in Table 1.

Table 1
Monocrystal structure, orientation of the growth axis [100]. No. p / p Alloy Composition Components Cr Al W That With Re Y La Xie Ni The inventive alloy 2.0 5.5 10.1 8.3 2.0 6.0 0.02 0.02 0.02 Ost. CMSX-10 2.0 6.0 5.5 8.5 2.0 6.5 0.01 0.01 0.01 Ost.

After that, the cast samples were subjected to high-temperature gas-static sealing (the inventive alloy), heat treatment and were tested.

Test Results:

Alloy CMSX-10 (prototype):

T = 1000 ° C, σ100 = 290 MPa,

The inventive alloy.

T = 1000 ° C, σ100 = 330 MPa,

To test the alloy according to the second embodiment, two alloy compositions were smelted (one claimed and one prototype alloy - CMSX-10) containing the components (in wt.%) Shown in Table 2.

No. p / p Alloy Composition Components Cr Al W That With Y La FROM Xie Ti MO Nb Re Ni KS-3 1.9 5.2 10.1 7.5 2.2 0.015 0.015 0.004 0.015 0.3 0.1 0.3 5.5 Ost. CMSX-10 2.0 5,6 4,5 8.5 2.0 0.01 0.01 0.02 0.01 0.4 0.4 0.05 5.5 Ost.

After that, cast samples without subsequent mechanical processing were tested.

Test Results:

Alloy CMSX-10 (prototype):

T = 1000 ° C, σ100 = 300 MPa,

The inventive alloy.

At a temperature of T = 1000 ° C and σ = 300 MPa, the durability is τ = 174.2 hours.

At a temperature of T = 1000 ° C and σ = 250 MPa, the durability is τ = 648 hours.

At a temperature of T = 800 ° C and σ = 750 MPa, the durability τ = more than 680 hours.

The introduction of additional alloying elements in the inventive alloy according to the second embodiment leads to an improvement in the foundry dendritic structure - the number of foundry micropores is reduced by 20-30%, which can have a positive effect on the fatigue characteristics of the alloy and durability over long resources.

The test results show that, compared with the prototype of the inventive alloys according to the first and second options ensure the achievement of a technical result.

Claims (2)

1. The composition of the heat-resistant nickel alloy for single crystal casting containing chromium, aluminum, tungsten, tantalum, rhenium, cobalt, yttrium, lanthanum and cerium, characterized in that it contains components in the following ratio, wt.%:
chromium 1.0-4.0 aluminum 4,5-7,0 tungsten 10.0-14.0 tantalum 5.0-10.0 rhenium 4.0-7.0 cobalt 2.0-5.0 yttrium 0.003-0.1 lanthanum 0.001-0.1 cerium 0.003-0.1 nickel rest 2. The composition of the heat-resistant nickel alloy for single crystal casting containing chromium, aluminum, titanium, molybdenum, tungsten, tantalum, rhenium, cobalt, niobium, yttrium, lanthanum, cerium and carbon, characterized in that it contains components in the following ratio, wt. %:
chromium 1.0-4.0 aluminum 4,5-7,0 titanium ≤2.0 molybdenum ≤ 4.0 tungsten 8.0-14.0 tantalum 5.0-10.0 rhenium 4.0-7.0 cobalt 2.0-5.0 niobium ≤2.0 yttrium 0.003-0.1 lanthanum 0.001-0.1 cerium 0.003-0.1 carbon ≤0.1 nickel rest