ES2682362T3 - Super-alloy of rhenium-free nickel with low density - Google Patents

Abstract

Nickel-based alloy with high slip resistance, which is essentially free of rhenium or which comprises not more than 0.001% by weight of rhenium and has the following chemical composition: aluminum from 4.1 to 7.7% by weight, cobalt from 0 to 16.8% by weight, chromium from 6 to 11.8% by weight, molybdenum from 3.6 to 11.3% by weight, tantalum from 0 to 3.9% by weight, titanium from 0 to 3.6% by weight, tungsten from 0 to 11.3% by weight, carbon from 0 to 0.05% by weight, phosphorus from 0 to 0.015% by weight, copper from 0 to 0.05% by weight, zirconium 0 to 0.015% by weight, silicon from 0 to 0.01% by weight, sulfur from 0 to 0.001% by weight, iron from 0 to 0.15% by weight, manganese from 0 to 0.05% by weight, boron from 0 to 0.003% by weight, hafnium from 0 to 0.15% by weight, ytrium from 0 to 0.002% by weight, as well as nickel and unavoidable impurities.

Description

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DESCRIPTION

Super-alloy of rhenium-free nickel with low density

The present invention relates to a nickel-based alloy that is essentially free of rhenium, but which, at the same time, achieves the properties in relation to the slip resistance of nickel-based super alloys of the second generation and has a reduced density with respect to comparable alloys.

In gas turbines such as stationary gas turbines or turboprops, nickel-based superalloys are used, for example as blade materials, since these materials also have sufficient strength, even in the case of high working temperatures, for the high mechanical stresses. For example, turbine blades in the case of stationary gas turbines or jet engines in commercial aircraft are exposed to a stream of exhaust gases with temperatures up to 1500 ° C and, at the same time, are subjected to very high mechanical stresses. high by centrifugal forces. Under these conditions, it is, in particular, that the slip resistance of the material used satisfies the requirements. In order to continue increasing the slip resistance, turbine blades have also been manufactured in a monocrystalline manner for a few decades, in order to continue improving the slip resistance avoiding the grain boundary surfaces.

In the case of nickel-based superalloys currently employed, of the so-called second and third generation, alloys usually have the chemical element rhenium, namely, with a proportion of three or six percent by weight, given that rhenium continues to improve slip resistance.

However, due to the low availability of rhenium, the addition of rhenium is very expensive. Correspondingly, in the state of the art there are already efforts to reduce the proportion of rhenium or to completely renounce the addition by rhenium alloy, while maintaining mechanical properties, in particular in relation to resistance to glide. Investigations in this regard exist by A. Heckl, S. Neumeier, M. Goken, R.F. Singer, "The effect of Re and Ru on y / y 'microstructure, Y-solid solution strengthening and creep strength in nickel-base superalloys", in Material Science and Engineering A 528 (2011) 3435-3444 and Paul J. Fink, Joshua L. Miller, Douglas G. Konitzer, "Rhenium Reduction - Alloy Design Using an Economically Strategic Element", JOM, 62 (2010), 55-57. In addition, corresponding alloys are also subject to patent applications and patents such as, for example, EP 2 725 110 A1, DE 102010037046, US 2011/0076180 A1, EP 2 314 727 A1, EP 2 305 847 A1, EP 2 305 848 A1, US 2013/0129522 A1, WO 2013/083101 A1, EP 2 576 853 B1, WO 2009/032578 A1, WO 2009/032579 A1, EP 0 962 542 A1, US 6,054,096, US 2013/0230405 A1 and US 2010/0135846 A1.

For example, EP 2 725 110 A1 discloses a nickel-based alloy that is essentially free of rhenium and has a solidus temperature greater than 1320 ° C, where, at temperatures of 1050 ° C to 1100 ° C , there are segregations of a phase and 'in a matrix and with a proportion of 40 to 50% in vol., the mismatch and / and' at temperatures of 1050 ° C to 1100 ° C is in the range of - 0, 15% to - 0.25% and the tungsten content in the matrix and is greater than in the phases and 'segregated. The alloy has the following chemical composition: aluminum from 11 to 13% at., Cobalt from 4 to 14% at., Chromium from 6 to 12% at., Molybdenum from 0.1 to 2% at., Tantalize it from 0, 1 to 3.5% at., Titanium from 0.1 to 3.5% at., Tungsten from 0.1 to 3% at., As well as the remaining nickel and unavoidable impurities.

Although there are already some proposed solutions for a reduction of rhenium either for nickel-based superalloys free of rhenium, there is still a need to develop nickel-based superalloys reduced in rhenium or rhenium-free, whose mechanical properties, in Particularly high-temperature properties, such as slip resistance, are in the range of nickel-based superalloys with rhenium content and currently free of rhenium and present, with respect to these alloys, additionally improved properties such as, by example, lower density.

Therefore, it is the mission of the present invention to indicate a nickel-based super alloy that exhibits comparable mechanical properties, in particular high temperature properties, such as slip resistance, such as those of the second and third nickel-based super alloys. generation, currently employed, but not essentially containing rhenium. In addition, the alloy must have a density as low as possible and a good incandescent capacity in solution, can be manufactured in a cost-effective and efficient way and consolidates in a monocrystalline way or in an oriented and present way, with respect to the base alloy of rhenium-free nickel disclosed in EP 2 725 110 A1, in the case of a comparable slip resistance, improved properties, in particular a lower density, a lower proportion of residual eutectic mixing and an improved solution incandescence.

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TECHNICAL SOLUTION

This problem is solved by an alloy with the characteristics of claim 1 and a corresponding object, in particular, a component of a stationary gas turbine or aviation gas turbine with the characteristics of claim 12. Advantageous embodiments are subject to dependent claims.

The present invention relates to a nickel-based superalloy containing at least the elements Al, Cr, Mo and Ta, which was optimized with the following objectives:

- Isss weighted mixed glass hardness index in the matrix as high as possible

- morphology and optimal:

or mismatch y / y 'at 1100 ° C from - 0.1 to - 0.5% or proportion of y' at 1100 ° C from 44 to 48% by mole

- solidus temperature> 1320 ° C.

In this case, Isss 2.44 xYRe + 1.22 xYw + xYMo (xYi = concentration in% at. Of the respective element in the matrix) and the mismatch y / y 'is defined as the normalized difference of the network constants of the two phases Y and Y ':

1/2 * (ay ’+ ay)

According to the above optimization, a nickel-based alloy can have the following chemical composition: aluminum from 4.1 to 7.7% by weight, cobalt from 0 to 16.8% by weight, chromium from 6 to 11.8 % by weight, molybdenum of

3.6 to 11.3% by weight, tantalum from 0 to 3.9% by weight, titanium from 0 to 3.6% by weight, tungsten from 0 to 11.3% by weight, carbon from 0 to 0.05% by weight, phosphorus from 0 to 0.015% by weight, copper from 0 to 0.05% by weight, zirconium from 0 to 0.015% by weight, silicon from 0 to 0.01% by weight, sulfur from 0 to 0.001% in weight, iron from 0 to 0.15% by weight, manganese from 0 to 0.05% by weight, boron from 0 to 0.003% by weight, hafnium from 0 to 0.15% by weight, andtrium from 0 to 0.002% in weight, as well as the rest nickel and inevitable impurities. As can be seen, the alloy is essentially free of rhenium, that is, it contains rhenium in any case only in a range of trace amounts (eg, not more than 0.001% by weight). The alloy can also be essentially free of tantalum.

In a preferred embodiment, a nickel-based alloy according to the present invention may have the following chemical composition: aluminum 4.7 to 5.7% by weight, cobalt 2.6 to 13.6% by weight, chromium 6.3 to 7.3% by weight, molybdenum 3.7 to 4.7% by weight, tantalum 0 to 0.5% by weight, titanium 2.8 to 3.6% by weight, tungsten from 7.4 to 8.4% by weight, carbon from 0 to 0.05% by weight, phosphorus from 0 to 0.015% by weight, copper from 0 to 0.05% by weight, zirconium from 0 to 0.015% by weight, silicon from 0 to 0.01% by weight, sulfur from 0 to 0.001% by weight, iron from 0 to 0.15% by weight, manganese from 0 to 0.05% by weight, boron from 0 to 0.003 % by weight, hafnium from 0 to 0.15% by weight, andtrium from 0 to 0.002% by weight, as well as the remaining nickel and unavoidable impurities.

In another preferred embodiment, a nickel-based alloy according to the present invention may have the following chemical composition: aluminum of 5.0 to 5.4% by weight, cobalt of 2.9 to 13.3% by weight, chromium from 6.6 to 7% by weight, molybdenum from 4 to 4.4% by weight, tantalum from 0 to 0.2% by weight, titanium from 3.1 to 3.5% by weight, tungsten from

7.7 to 8.1% by weight, carbon from 0 to 0.05% by weight, phosphorus from 0 to 0.015% by weight, copper from 0 to 0.05% by weight, zirconium from 0 to 0.015% by weight, silicon 0 to 0.01% by weight, sulfur from 0 to 0.001% by weight, iron from 0 to 0.15% by weight, manganese from 0 to 0.05% by weight, boron from 0 to 0.003% by weight, hafnium from 0 to 0.15% by weight, andtrium from 0 to 0.002% by weight, as well as the rest nickel and inevitable impurities.

In another preferred embodiment, a nickel-based alloy according to the present invention may have a cobalt content of less than 5% by weight, preferably less than 4% by weight. Since cobalt has a lower molar mass than nickel, a relatively low cobalt content has an advantageous effect on the total density of the nickel-based alloy and, therefore, also on the total weight of the target component part manufactured from of this alloy.

Alternatively, the nickel-based alloy according to the present invention may, however, also have a cobalt content greater than 11% by weight, preferably greater than 13% by weight. A correspondingly high cobalt content has a positive impact on segregations in the case of consolidation and stability of the microstructure against the unwanted formation of TCP phases.

It is further preferred that the nickel-based alloy according to the present invention contain at least 67% at., In particular at least 68% at. of nickel.

It is further preferred that the nickel-based alloy according to the present invention have one or more (and preferably all) of the following properties:

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- density not greater than 8.5 g / cm3, preferably not greater than 8.4 g / cm3;

- solidus temperature greater than 1320 ° C;

- 44 to 48% in vol. of secretions of a phase and 'in a matrix and at a temperature of 1100 ° C;

- mismatch and / and 'in the range of - 0.1% to - 0.5% at a temperature of 1100 ° C;

- residual eutectic mixture not greater than 4%, preferably not greater than 3%.

By "unavoidable impurities" in the alloy, elements are to be understood, the addition of which is not foreseen, but which, for technical reasons, cannot be prevented or can only be done with extremely high complexity. For example, in the alloy according to the invention the following elements may be present in the form of trace elements, the content of which is limited, however, at the following intervals: bismuth from 0 to 0.00003% by weight, selenium from 0 at 0.0001% by weight, thallium from 0 to 0.00005% by weight, lead from 0 to 0.0005% by weight and tellurium from 0 to 0.0001% by weight.

With the alloy according to the present invention, in particular, objects such as gas turbine components, preferably turbine blades, and the like, which can be configured in monocrystalline mode or consolidated in an oriented manner can be manufactured.

The attached figure shows a Larson-Miller plot to explain the slip stability of the alloy according to the present invention compared to known alloys.

An alloy was prepared in accordance with the present invention, the composition of which can be deduced from the following Table (alloy 1). Alloys 2 and 3 were chosen as comparative alloys, the alloy 3 in the chemical composition essentially corresponding to that of the RMSX-4 ruthenium-containing material and the alloy 2 being the nickel-free nickel-based superalloy disclosed in the EP 2 725 110 A1. The components of the alloys are indicated in percentage by weight in the Table (nickel residue and unavoidable impurities).

 Alloy No.

 Al Co Cr Mo Re Ta Ti W

 one

 5.2 3.1 6.8 4.2 - - 3.3 7.9

 2

 4.8 8.6 5.0 1.4 - 10.1 1.3 8.8

 3

 5.6 9.0 6.5 0.6 3.0 6.5 1.0 6.0

Alloy 1 according to the present invention was prepared in a Bridgman laboratory casting facility in a geometry of three columnar crystalline shaped rods. The rods had a diameter of 12 mm in each case and a length of 180 mm in each case and showed a typical dendritic microstructure with a distance between dendrites of approximately 230 pm. The proportion of residual eutectic mixture is 2.8%, very low (alloys 2 and 3 have a residual eutectic mixture of 6.5% or 9.0%). In the case of a suitable heat treatment (see below), the alloy 1 has a typical phase morphology and 'totally cubic'.

In addition, pressure sliding tests were carried out on cylinders manufactured from heat treated finished alloys 1 to 3 (diameter 4.0 mm, height 6.4 mm). The front surfaces were rotated in order to guarantee their parallelism in the plane. All slip tests were carried out at constant voltages and with the following parameters: 1100 ° C / 137 MPa, 1050 ° C / 200 MPa, 950 ° C / 300 MPa, 950 ° C / 400 MPa. The corresponding sliding curves are represented in the Figure (1% plastic expansion, material DB, A = 220 pm).

As it turns out from the Figure, the alloy 1 (L1) according to the invention exhibits a slip resistance that is essentially equal to that of the rhenium-free alloy 2 (L2), the slip resistance of these alloys being similar to the slip resistance of alloy 3 (L3), which corresponds to a nickel-based super alloy of the second generation. In comparison with alloys 2 and 3, alloy 1 has, however, in particular, a lower density. Analysis of the microstructure of alloy 1 according to the present invention after slippage did not provide any TCP phase formation.

It is clear from this that by teaching according to the invention nickel-based superalloys can be provided that can give up the hard-available rhenium element, but which, at the same time, can provide high temperature mechanical properties such as, for example, a corresponding sliding stability as alloys with rhenium content can provide

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known and, in addition, may have a lower density than alloys with rhenium content and known rhenium-free.

In the following Table some properties of alloys 1-3 are confronted with each other.

 Property

 Alloy 1 Alloy 1 Alloy 2 Alloy 3

 calculated measured measured calculated

 Density, g / cm3

 8.3 8.4 9.0 8.7

 Temp. of liquidus, ° C

 1373 1371 1371 1381

 Temp. of solidus, ° C

 1348 1302 * 1318 * 1338

 Temp. of solvent and ', ° C

 1232 1255 1242 1257

 Mismatch and / and ',

 - 0.5 - 0.45 ** - 0.02 ** - 0.17

 1110 ° C,%

 Proportion of y ', 1100 ° C,

 44.0 - - 44.9

 mol%

 * gaseous state ** room temperature

In particular, the relatively lower density of alloy 1 according to the invention should be noted. The mismatch and / and 'could only be measured at room temperature; usually, the values are higher at higher temperatures.

The solution incandescence of the alloy 1 can be carried out, for example, in two stages, as follows:

• alloy heating around 4 K / min up to 1285 ° C,

• keep for 2 h at 1285 ° C,

• alloy heating around 1 K / min up to 1300 ° C,

• maintain for 6.5 h at 1300 ° C,

• subsequent rapid cooling.

In addition, alloy 1 may undergo, after solution incandescence, one or both of the following segregation heat treatments:

Segregation heat treatment 1:

 Temperature

 Heating Rate Maintenance Time

 1000 ° C

 4K / min

 1050 ° C

 1 K / min

 1050 ° C

   1 hour

 20 ° C

 fast cooling

Segregation heat treatment 2:

 Temperature

 Heating Rate Maintenance Time

 840 ° C

 4K / min

 870 ° C

 1 K / min

 870 ° C

   24 h

 20 ° C

 fast cooling

Incandescent times greater than 2 hours at 1050 ° C or higher temperatures lead to excessive aging of the microstructure.

In summary, it can be established that the alloy according to the invention described above has, in particular, the following properties:

• slip resistance close to that of CSMX-4

• low density of 8.4 g / cm3 (comparison: CSMX-4: 8.7 g / cm3)

• 2.8% low residual eutectic mixture (comparison: CSMX-4: 9.0%)

10 • good incandescent capacity in solution (maintenance for 8.5 hours at 1285 ° C / 1300 ° C)

• poor tendency to TCP phases.

Although the present invention has been described in detail with the aid of an example of embodiment, it is natural for the person skilled in the art that the invention is not limited to this embodiment, but rather, modifications in the sense are possible. that individual characteristics may be omitted or characteristics otherwise combined, provided that the scope of protection of the appended claims is not abandoned. The present disclosure discloses all combinations of all the individual characteristics presented.

Claims (11)

5 10 fifteen twenty 25 30 35 1. Nickel-based alloy with high slip resistance, which is essentially free of rhenium or which comprises no more than 0.001% by weight of rhenium and has the following chemical composition: aluminum from 4.1 to 7.7% by weight, cobalt from 0 to 16.8% by weight, chromium from 6 to 11.8% by weight, molybdenum 3.6 to 11.3% by weight, Tantalize from 0 to 3.9% by weight, titanium from 0 to 3.6% by weight, tungsten from 0 to 11.3% by weight, carbon from 0 to 0.05% by weight, phosphorus from 0 to 0.015% by weight, copper from 0 to 0.05% by weight, Zirconium from 0 to 0.015% by weight, silicon from 0 to 0.01% by weight, sulfur from 0 to 0.001% by weight, iron from 0 to 0.15% by weight, manganese from 0 to 0.05% by weight, boron from 0 to 0.003% by weight, hafnium from 0 to 0.15% by weight, ytrium from 0 to 0.002% by weight, as well as the rest nickel and inevitable impurities. 2. Nickel-based alloy according to claim 1, characterized in that the alloy has the following chemical composition: aluminum 4.7 to 5.7% by weight, Cobalt from 2.6 to 13.6% by weight, chromium 6.3 to 7.3% by weight, molybdenum 3.7 to 4.7% by weight, tantalum from 0 to 0.5% by weight, titanium from 2.8 to 3.6% by weight, tungsten from 7.4 to 8.4% by weight, carbon from 0 to 0.05% by weight, phosphorus from 0 to 0.015% by weight, copper from 0 to 0.05% by weight, Zirconium from 0 to 0.015% by weight, silicon from 0 to 0.01% by weight, 5 10 fifteen twenty 25 30 35 sulfur from 0 to 0.001% by weight, iron from 0 to 0.15% by weight, manganese from 0 to 0.05% by weight, boron from 0 to 0.003% by weight, hafnium from 0 to 0.15% by weight, ytrium from 0 to 0.002% by weight, as well as the rest nickel and inevitable impurities. 3. Nickel-based alloy according to claim 2, characterized in that the alloy has the following chemical composition: aluminum from 5.0 to 5.4% by weight, Cobalt from 2.9 to 13.3% by weight, chromium 6.6 to 7% by weight, molybdenum from 4 to 4.4% by weight, tantalum from 0 to 0.2% by weight, titanium from 3.1 to 3.5% by weight, tungsten 7.7 to 8.1% by weight, carbon from 0 to 0.05% by weight, phosphorus from 0 to 0.015% by weight, copper from 0 to 0.05% by weight, Zirconium from 0 to 0.015% by weight, silicon from 0 to 0.01% by weight, sulfur from 0 to 0.001% by weight, iron from 0 to 0.15% by weight, manganese from 0 to 0.05% by weight, boron from 0 to 0.003% by weight, hafnium from 0 to 0.15% by weight, ytrium from 0 to 0.002% by weight, as well as the rest nickel and inevitable impurities. 4. Nickel-based alloy according to any one of the preceding claims, characterized in that the alloy has a cobalt content of less than 5% by weight, preferably less than 4% by weight. 5. Nickel-based alloy according to any one of claims 1-3, characterized in that the alloy has a cobalt content greater than 11% by weight, preferably greater than 13% by weight. 6. Nickel-based alloy according to any one of the preceding claims, characterized in that it has a density not greater than 8.5 g / cm3, preferably not greater than 8.4 g / cm3. 7. Nickel-based alloy according to any one of the preceding claims, characterized in that it has a solidus temperature greater than 1320 ° C. 8. Nickel-based alloy according to any one of the preceding claims, characterized in that it has a residual eutectic mixture not greater than 4%, preferably not greater than 3%. 9. Object, produced from a nickel-based alloy according to any one of the preceding claims. 10. Object according to claim 9, characterized in that the object is monocrystalline or consolidated in an oriented manner. 5. Object according to one of claims 9 and 10, characterized in that the object is a gas turbine stationary or aviation gas turbine, in particular a turbine blade. 12. Process for the production of a nickel-based alloy, characterized in that the process comprises the gathering and casting of metals in quantitative ratios resulting in an alloy according to any one of claims 1 to 8.