WO2008108688A1

WO2008108688A1 - Composition of a heat-resisting nickel-based alloy used for single crystal casting (variants)

Info

Publication number: WO2008108688A1
Application number: PCT/RU2008/000129
Authority: WO
Inventors: Yrii Sergeevich Eliseev; Igor Mikhailovich Razumovskii; Valerii Aleksandrovich Poklad; Olga Gennadievna Ospennikova; Valentin Nikolaevich Larionov; Aleksandr Vyacheslavovich Logunov
Original assignee: Federalnoe Gosudarstvennoe Unitarnoe Predpriyatie 'moskovskoe Mashinostroitelnoe Proizvodstvennoe Predpriyatie 'salut'
Priority date: 2007-03-07
Filing date: 2008-03-06
Publication date: 2008-09-12
Also published as: RU2007108480A; RU2348724C2

Abstract

The invention relates tometallurgy, in particular to cast heat resisting nickel-based alloys used for producing rotor and nozzle blades of gas-turbine engines operating for a long time at temperatures greater than 1000°C. In the first variant the inventive alloy is chatracterised by the high heat resistance which does not affect the processing characteristics thereof such as coulability and processing plasticity and contains, in mass%: 0.5-4.0 chromium, 4.0-7.0 aluminium, 12.0-16.0 tungsten, 3.0-12.0 tantalum, 4.0-9.0 cobalt, 0.003-0.1 yttrium, 0.001-0.1 lanthanum, 0.003-0.1 cerium, the rest being nickel. In the second variant, in addition to the increased heat resistance and the improved coulability and processing plasticity, the inventive alloy exhibits the high corrosion resistance and contains, in mass%: 0.5-4.0 chromium, 4.0-7.0 aluminium, ≤ 2.0 titanium, ≤ 4.0 molybdenum, 12.0-16.0 tungsten, 3.0-12.0 tantalum, 4.0-9.0 cobalt, ≤ 2.0 niobium, 0.003-0.1 yttrium, 0.001-0.1 lanthanum, 0.003-0.1 cerium, ≤ 0.1 carbon, the rest being nickel.

Description

Composition of heat resistant nickel alloy for single crystal casting

(options).

The field of technology.

The invention relates to metallurgy of alloys, namely to the production of nickel-based alloys used for parts with a single crystal structure, for example, turbine blades operating at high temperatures.

The prior art.

Known nickel-resistant high-temperature alloy for single crystal casting CMSX-2 containing (wt.%): Chromium - 8.0, cobalt 5.0, aluminum 5.6, tungsten - 8.0, molybdenum - 0.6, tantalum - 6.0 , titanium - 1.0, nickel - the rest is up to 100%. (“Types of the international scientific and technical conference April 25-26, 2006, M.:BIAM, 2006, p. 43, table. L) - analogue.

The disadvantage of this solution is the low heat resistance, for example, the long-term strength of the alloy σY0 ^looo = 214 MPa (Collection “Foundry heat-resistant alloys” edited by Kablova EH, M. Nauka, 2006, p. 74, table 9).

Known nickel-resistant alloy ZhC-40, containing chromium - 6.0, aluminum 5.0-5.8, tungsten 6.0-7.8, tantalum - 6.0-7.8, molybdenum - 3.5-4 , 8, cobalt - 5.0, niobium - 0.05-0.50, nickel - the rest is up to 100% ("Cast blades of gas turbine engines)), Moscow, MISIS, 2001, p. 53, table 2.3.) - prototype.

SUBSTITUTE SHEET (RULE 26) A disadvantage of the known single crystal alloy with orientation [001] intended for the manufacture of highly loaded parts, for example, gas turbine blades operating at temperatures up to 1000 ⁰ C, is also insufficient heat resistance for the claimed field of application (σY0 ^looo ~ 240 MPa).

The technical result, to which the claimed invention is directed, is to increase the heat resistance of nickel alloys for single crystal casting, for example, gas turbine engine blades.

The claimed technical result is achieved in that the heat-resistant nickel alloy contains chromium, aluminum, tungsten, tantalum, cobalt, yttrium, cerium, lanthanum and nickel in the following ratio of components (wt.%): Chromium - 0.5-4.0 aluminum - 4 , 0-7.0 tungsten - 12.0-16.0 tantalum - 3.0-12.0 cobalt - 4.0-9.0 yttrium - 0.003-0.1 lanthanum - 0.001 - 0.1 cerium - 0.003 - 0.1 nickel - the rest is up to 100%.

Known nickel-resistant high-temperature alloy for single crystal casting CMSX-2 containing (wt.%): Chromium - 8.0, cobalt 5.0, aluminum 5.6, tungsten - 8.0, molybdenum - 0.6, tantalum - 6.0 , titanium - 1.0, nickel - the rest is up to 100%. (“Types of the international scientific and technical conference April 25-26, 2006, M.:BIAM, 2006, p. 43, table l.) - analogue.

SUBSTITUTE SHEET (RULE 26) The disadvantage of this solution is low heat resistance, for example, the long-term strength of the alloy σl00 ^looo = 214 MPa (Collection “Foundry heat-resistant alloys” edited by Kablova EH, M. Nauka, 2006, p. 74, table 9).

Known nickel-resistant alloy ZhC-40, containing chromium - 6.0, aluminum 5.0-5.8, tungsten 6.0-7.8, tantalum - 6.0-7.8, molybdenum - 3.5-4 , 8, cobalt - 5.0, niobium - 0.05-0.50, nickel - the rest is up to 100% (“Cast blades of gas turbine engines)), Moscow, MISIS, 2001, p.53, table 2.3.) - prototype.

A disadvantage of the known single crystal alloy with orientation [001] intended for the manufacture of highly loaded parts, for example, gas turbine blades operating at temperatures up to 1000 ⁰ C, is insufficient corrosion resistance, technological plasticity, and also insufficient heat resistance for the claimed field of application (σl00 ^looo ~ 240 MPa).

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 heat-resistant nickel alloy containing chromium, aluminum, titanium, molybdenum, tungsten, tantalum, cobalt, niobium, yttrium, lanthanum, cerium and nickel, additionally contains carbon, in the following ratio (wt.%): Chromium - 0.5-4.0

SUBSTITUTE SHEET (RULE 26) aluminum - 4.0-7.0 titanium <2.0 molybdenum ≤ 4.0 tungsten - 12.0-16.0 tantalum - 3.0-12.0 cobalt 4.0-9.0 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%.

Disclosure of the invention.

As you know, successes in the development of high-temperature nickel alloys of the latest generations are largely associated with alloying alloys with a large amount of rhenium, for example, 9.3 wt.% In ZhC-47 alloy, and / or ruthenium, for example, 6 wt.% In TMS - 162 (E.N. Kablov, N.V. Petrushin “Modern alloyed nickel heat-resistant alloys”, Proceedings of the International Technical Conference, M., BHAM, 2006, p. 43). However, due to the fact that rhenium and especially ruthenium are very expensive and scarce metals, the question arises as to whether the possibilities of improving heat-resistant alloys, including nickel, by alloying them with traditional, less expensive and more affordable elements are completely exhausted, for example, such as tungsten, tantalum and others.

SUBSTITUTE SHEET (RULE 26) The authors analyzed the alloying system of heat-resistant nickel alloys in terms of the binding energy (cohesion energy) of the alloying elements. Considering the binding energy of elements as a fundamental parameter that determines the level of mechanical properties and operational characteristics of the material, the distribution of alloying elements of heat-resistant alloys by the values of binding energy for a generalized alloying system of nickel heat-resistant alloys: Ni, Co, Cr, V, Ti, Al, Ru, Mo, Nb, Zr, Hf, Ta, W, Re, Os, Ir.

The resulting distribution diagram of alloying elements according to the values of the binding energy (cohesion energy) is shown in Fig 1.

When analyzing the data presented in the diagram, we will assume that the contribution to the binding energy of the alloy of a particular alloying element, for example, tantalum, is directly proportional to the value of its own binding energy and the content of this element in the alloy in atomic percent. In this case, the presence of the main γ ′ -forming element, aluminum, is mandatory in the alloy, and its content allows the formation of the necessary amount of the strengthening γ′-phase released during the decomposition of the supersaturated solid solution.

In view of the foregoing, we will consider Ni-Al with the possibility of replacing a certain amount of aluminum with titanium as the basic system of nickel refractory alloys.

The results presented in the diagram show that tungsten should be considered the first element contributing to the greatest increase in nickel binding energy. Therefore, the basic system of heat-resistant nickel alloys should primarily contain tungsten, and its amount should be kept at

SUBSTITUTE SHEET (RULE 26) the highest possible level when its maximum content is limited by the solubility of tungsten in the nickel alloy. It should be borne in mind that tungsten or rhenium substitution with tungsten is impractical, since the cohesive strength of the alloy will not increase with such a replacement.

The next element for alloying nickel heat-resistant alloys is tantalum. It is advisable to introduce tantalum into heat-resistant alloys against the background of a high tungsten content, controlling the possibility of the release of Ta-containing intermediate phases in the alloy.

The use of the principle of multicomponent alloying in this case is advisable because it allows to increase the total content of alloying elements with high cohesive strength in heat-resistant alloys, providing maximum hardening of the entire alloy.

When analyzing the diagram presented in Fig. L, the following is noteworthy: the obligatory component of the latest modifications of heat-resistant alloys - ruthenium, is almost similar to molybdenum. Among the γ '-forming elements, which can increase the cohesive strength of heat-resistant alloys, in addition to the tantalum already considered, titanium and niobium should be noted.

Based on the foregoing, the authors have developed the inventive alloys.

A feature of the inventive alloy according to the first embodiment (KC-I) is a high tungsten content in the range from 12.0 to 16.0 wt.%. The upper limit of the tungsten content limits the concentration range, beyond which increases the likelihood of tungsten precipitation from the solid solution in the form of an α-phase, which is not

SUBSTITUTE SHEET (RULE 26) by such an effective hardener as the γ'-phase based on NiЗl, and when the tungsten content is below 12 wt.%, its stabilizing effect on the structure and a favorable effect on heat resistance are 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 (KC-I) is balanced in such a way that the α-phase is not released 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 hardening γ'-phase, stabilizing and strengthening both main phases of the heat-resistant alloy. When the content of tantalum is more than 10 wt.%, The probability of its precipitation from the solid solution in the form of Ni-Ta intermetallic compounds increases, and when the content is less than 5 wt.%, Its effect on the properties decreases markedly.

The introduction of the inventive composition of the heat-resistant alloy of the claimed amount of chromium is due to the need to increase its heat resistance. With an increase in the chromium content above 4 wt.%, The probability of the formation of a topologically close packed (TPU) phase based on chromium increases, which embrittle the alloy.

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.

SUBSTITUTE SHEET (RULE 26) The system of microalloying additives, namely the combined use of lanthanum, yttrium and cerium in the claimed amounts provides 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 tungsten, tantalum, cobalt and a system of microalloying additives (yttrium, lanthanum and cerium), but besides this, the properties of the inventive alloy in the second embodiment are affected by the presence of titanium, molybdenum, niobium and carbon in its composition.

Aluminum and titanium are 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) and contributes to an increase in the corrosion resistance of the alloy.

Niobium and molybdenum - provide increased material durability in the temperature range of ~ 1000 ⁰ C. Carbon is 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 option in quantitative and qualitative composition provides, along with increased heat resistance, improved casting properties of the alloy and its technological ductility and increased corrosion resistance.

Embodiments of the invention. SUBSTITUTE SHEET (RULE 26) To test the results, alloys were cast according to the first and second variants. Alloy casting was carried out in a Kristall vacuum induction furnace 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 melted (one of the claimed and one prototype alloy - ZhS-40) containing the components (in wt.%) Shown in Table 1.

Monocrystal structure, orientation of the growth axis [001].

Table 1.

After that, cast samples subjected to high-temperature gas-static treatment (the inventive alloy) and heat treatment were tested. Test results: ZhS-40 alloy (prototype): T = 900 ° C, σyo = 440 MPa, σ500 = 350MPa,

SUBSTITUTE SHEET (RULE 26) T = IOOO ⁰ C, σyuo = 240 MPa, σ500 = 190 MPa (Collection “Foundry heat-resistant alloys” edited by Kablov EH, M. Nauka, 2006, p. 54, table 2.4).

The inventive alloy.

T = 900 ° C, σyo = 467 MPa, σ500 = 371 MPa,

T-IOOO ⁰ C, σioo = 255 MPa, σsoo = 2OlMpa

To test the alloy according to the second embodiment, two alloy compositions were melted (one of the claimed and one prototype alloy - ZhS-40) containing the components (in wt.%) Shown in Table 2.

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

Test Results:

ZhS-40 alloy (prototype):

T = 900 ° C, σyo = 440 MPa, σsoo = 35OMPa,

T = 1000 ° C, σyo = 240 MPa, σ5θo = 19OMpa

The inventive alloy.

T = 900 ° C, σyo = 471 MPa, σ5θo = 379 MPa,

SUBSTITUTE SHEET (RULE 26) T = IOOO ⁰ C, σуo = 252 MPa, σ500 = 200 MPa.

The introduction of additional alloying elements in the inventive alloy according to the second embodiment leads to a decrease in casting porosity in the interdendritic regions of the alloy: the volume fraction of pores is reduced by 20-30% compared with the prototype. It is known that the formation of microcracks can occur on foundry pores, which can turn into main cracks during the destruction of parts.

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

SUBSTITUTE SHEET (RULE 26)

Claims

The formula of the invention "Cocoa heat-resistant Nickel alloy for single crystal casting (options))).

1. The composition of the heat-resistant nickel alloy for single crystal casting containing nickel, chromium, cobalt, tungsten, aluminum and tantalum is characterized in that it additionally contains yttrium, lanthanum and cerium in the following ratio of components (wt.%): Chromium - 0.5-4 , 0 aluminum 4.0-7.0 tungsten - 12.0-16.0 tantalum - 3.0-12.0 cobalt 4.0-9.0 yttrium - 0.003-0.1 lanthanum - 0.001-0.1 cerium - 0.003-0.1 nickel - the rest is up to 100%.

2. The composition of the heat-resistant nickel alloy for single crystal casting containing nickel, chromium, cobalt, tungsten, aluminum, tantalum, niobium and molybdenum characterized in that it additionally contains yttrium, lanthanum, cerium and titanium in the following ratio of components (wt.%): chrome - 0.5-4.0 aluminum 4.0-7.0 titanium <2.0 molybdenum <4.0 tungsten - 12.0-16.0 tantalum - 3.0-12.0

SUBSTITUTE SHEET (RULE 26) cobalt 4.0-9.0 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%.

SUBSTITUTE SHEET (RULE 26)