EP0574708B1 - Component for high temperatures, in particular turbine blade, and process for preparing this blade - Google Patents

Description

TECHNICAL AREA

The invention is based on a component for high Temperatures, especially a turbine blade, after the Preamble of claim 1. The invention also relates a method for producing such a component.

STATE OF THE ART

Such a component and a method for producing a such component are state of the art and for example in US-A-4 825 522. This patent document is a high-temperature resistant component made of a nickel-based alloy removable. Certain sections of this component are covered by Modification of the base material with different Alloy additions to different material-specific Adjusted requirements. Further relevant state of the art is also FR-A-2 317 502, US-A-4 787 821 and US-A-4 529 452 to remove.

Furthermore, a gas turbine blade is in FR-A1-2.136.170 described. This scoop has one of a eutectic Alloy cast, airfoil and airfoil containing blade body. The blade root is from one ductile cast body with non-directional structure formed. The The airfoil consists of a matrix and parallel aligned with each other and in the longitudinal direction of the blade, fibrous crystals, which are embedded in the matrix and which by directional solidification from an inductive heated melt are formed. Opposite the blade root the airfoil excels at significantly reduced Ductility from a much greater creep resistance. Especially when manufacturing a large airfoil however, it is difficult to find one for directional solidification sufficiently large temperature gradients and thus the desired Achieve high creep resistance in the airfoil.

PRESENTATION OF THE INVENTION

The invention as specified in claims 1 and 3 is based on the task of a component, in particular a Turbine blade, of the type mentioned at the beginning, which when used in a medium and high temperature operated device, such as in particular a turbine features a long service life, and at the same time a way to point, which enables such a component in simple and suitable for mass production.

The component according to the invention stands out comparable components according to the prior art by a long service life. This is due to the choice of gamma titanium aluminide as base material and of suitable Dopants, which in predetermined quantities the base material are added, determined. With the selected base material it is possible in a particularly simple manner to alloy define which sections have different stresses of the component are adjusted. Since these are local differently stressed component sections, such as Turbine blade or turbine base, adapted alloys contain a common base material occur in Border area of the sections none chemical reaction products. The sections therefore go without a sharp transition into each other, so that the component according to the invention when operating a thermal Machine, such as a gas turbine or one in particular Compressor, high thermal and graded can easily absorb mechanical loads. That for the production of the components according to the invention The method used is characterized by the fact that large components with high thermal and mechanical Resilience through common process steps, such as in particular by hot isostatic pressing or by Sintering, easier and for mass production can be produced in a suitable manner.

BRIEF DESCRIPTION OF THE DRAWING

Fig.1

eine Aufsicht auf einen in Längsrichtung geführten Schnitt durch eine erste Variante eines als Turbinenschaufel ausgeführten erfindungsgemässen Bauteils nach Beendigung eines beim Herstellverfahren ausgeführten heiss-isostatischen Pressvorganges,

Fig.2

eine Aufsicht auf einen in Längsrichtung geführten Schnitt durch eine zweite Variante eines als Turbinenschaufel ausgeführten erfindungsgemässen Bauteils nach Beendigung eines beim Herstellen ausgeführten heiss-isostatischen Pressvorganges, und

Fig.3

ein Schliffbild des umrandet angegebenen Bereichs der zweiten Variante des erfindungsgemässen Bauteils.

Preferred exemplary embodiments of the invention and the advantages which can be achieved thereby are explained in more detail below with reference to drawings. Here shows:

Fig. 1

1 shows a plan view of a longitudinal section through a first variant of a component according to the invention designed as a turbine blade after completion of a hot isostatic pressing process carried out during the manufacturing process,

Fig. 2

a top view of a longitudinal section through a second variant of a component according to the invention designed as a turbine blade after completion of a hot isostatic pressing process carried out during manufacture, and

Fig. 3

a micrograph of the outlined area of the second variant of the component according to the invention.

WAYS OF CARRYING OUT THE INVENTION

The shown in Figures 1 and 2 and each as Turbine blade 1 each contain components an elongated airfoil 2 and one at one end of the airfoil 2 molded blade root 3. With the Reference numeral 4 denotes a press can. This Press can encloses in the embodiment according to Fig. 1 the blade root 3 and has one from the airfoil 2 filled opening 5, which preferably through Welding or soldering the press jug 4 to the Blade 2 is sealed gas-tight. In the The embodiment according to FIG. 2 encloses the press can 4 the entire turbine blade 1.

The turbine blade 1 shown in FIG. 1 is produced as follows:
A cast body designed as an airfoil 2 is guided with its one end through the opening 5 into the press can 4. The press can 4, which is preferably made of steel, is soldered or welded to the cast body in a gas-tight manner in the region of the opening 5. Through a further opening of the press can 4, which is not shown, a cavity of the press can 4 receiving the blade root of the turbine blade 1 is filled with alloy powder. The press can 4 is then evacuated and sealed gas-tight.

The materials for the cast body and the powder included one of two each on a common base material based alloys of different chemical Compositions which differ from one another by the Presence and / or the amount of at least one of them Distinguish the base material of the alloyed dopant. An intermetallic is preferably used as the base material Phase, such as in particular a gamma titanium aluminide, is used. At least one of the two containing gamma titanium aluminide Alloys have a share of at least 0.2 and at most 8 atomic percent of dopant, such as one or more of the elements B, C, Co, Cr, Ge, Hf, Mn, Mo, Nb, Pd, Si, Ta, V, Y, W and Zr.

In Atom%: 48 Al - 3 Cr - Rest Ti und Verunreinigungen;

In Gew.%: 33,2 Al - 3,9 Cr - Verunreinigungen kleiner 0,5 - Rest Ti.

Die Grösse der Pulverteilchen ist typischerweise kleiner 500µm.
Eine weitere typische Legierung für das Schaufelblatt weist folgende Zusammemsetzung in Atom% auf:
48 Al - 2 Cr - 2 Ta - Rest Ti und Verunreinigungen.A typical alloy for the airfoil 2 has, for example, the following composition:

In atom%: 48 Al - 3 Cr - remainder Ti and impurities;

In% by weight: 33.2 Al - 3.9 Cr - impurities less than 0.5 - balance Ti.

The size of the powder particles is typically less than 500 µm.
Another typical alloy for the airfoil has the following composition in atomic%:
48 Al - 2 Cr - 2 Ta - balance Ti and impurities.

In Atom%: 48 Al - 2 Cr - 2 Nb - Rest Ti und Verunreinigungen;

In Gew.%: 32,5 Al - 2,9 Cr - 5 Nb - Verunreinigungen kleiner 0,5 - Rest Ti.

Die Grösse der Pulverteilchen ist typischerweise kleiner 200µm, vorzugsweise kleiner 100µm.
Eine weitere typische Legierung für den Schaufelfuss weist folgende Zusammensetzung in Atom% auf:
48 Al - 2 Cr - 2 Ta - 0,5 Si - Rest Ti und Verunreinigungen.A typical alloy for the blade root 3 has, for example, the following composition:

In atomic%: 48 Al - 2 Cr - 2 Nb - balance Ti and impurities;

In% by weight: 32.5 Al - 2.9 Cr - 5 Nb - impurities less than 0.5 - balance Ti.

The size of the powder particles is typically less than 200 μm, preferably less than 100 μm.
Another typical alloy for the blade root has the following composition in atomic%:
48 Al - 2 Cr - 2 Ta - 0.5 Si - balance Ti and impurities.

The gas-tight closing of the press jug 4 Completed sample is placed in a press device and hot isostatic at temperatures between 900 and 1200 ° C condensed. A typical pressing process at approx. 1070 ° C took about 3 at a pressure of about 250 MPa Hours. Here, the two alloys, without the Borderline chemical reaction products were formed non-porous with a gradual transition from the airfoil 2 compressed to the blade root 3.

This already has the shape of the turbine blade Composite material was deformed after removing the press can 4 then at temperatures above 700 ° C typically heat treated for about 4 hours. Subsequent was due to slight material lifting Processing, such as grinding, polishing and / or electrochemical treatment, the turbine blade after the Invention completed.

In the manufacture of those shown in Fig.2 Turbine blade 1 was extended in the longitudinal direction and the entire turbine blade 1 receiving press can 4 used. In this press jug 4 was the first Shovel blade 2 entered and cast below according to the previously described Embodiment filled the alloy powder. The Press can 4 was then evacuated and gas-tight locked. The test specimen thus produced was according to the previously described embodiment treated. The alloys used were the same Composition on as described above Embodiment.

Instead of a cast body forming the airfoil 2 can also be a body from a hot isostatic in the press jug 4 compacted powder are introduced. In a another alternative embodiment of the invention that used to form the airfoil Alloy powder with 48 atomic percent Al, 3 atomic percent Cr, Balance Ti and small amounts of impurities in a Temperature of approx. 1070 ° C and a pressure of approx. 250 MPa hot isostatically compressed for approx. 3 hours. Of the resulting body was then in the in Fig.2 brought press can 4 and at the there described conditions together with the blade root 3 forming alloy powder with 48 atomic percent Al, 2 Atomic percent Cr, 2 atomic percent Nb, balance Ti and minor Amounts of impurities are hot isostatically compressed. Of the then the compacted body became the same as before described embodiment heat treated and reworked.

In further variants of the invention, instead of Cast body or that formed from hot compressed powder Body each forming the airfoil 2 Alloy powder of the chemical specified above Composition filled into the press jug 4. After that was an alloy powder forming the blade root 3 with the in the previously described embodiments specified composition backfilled. The press can 4 was then filled without shaking and without the Mix powder together, evacuated and gas-tight locked. By hot isostatic pressing for approx. 3 hours at approx. 1070 ° C and a pressure of approx. 250 MPa a non-porous material was made, from which Remove the press jug 4 after two hours Heat treatment at approx. 1350 ° C and material removing Post-processing a turbine blade according to the invention was produced. One designed in this way Turbine blade is according to the ones mentioned before Design variants also shown in Fig.2.

The structure and the are from the micrograph according to FIG Microstructure of a part indicated by a border in Fig. 2 one - as described above - exclusively Alloy powders produced turbine blade after the Invention to see. It can be seen from this that the the airfoil 2 forming alloy a coarse and the alloy forming the blade root 3 is a fine-grained one Has microstructure, and that at the transition zone no undesirable reaction zone between the two alloys with chemical reaction products or with excretions occurs. Both alloys go coarser with the teeth and fine crystallite gradually overlap.

Material tests have been carried out for that of the invention Turbine blade 1 underlying material following Properties result:

The alloy forming the airfoil 2 has Room temperature to a ductility of about 0.5%, which the Alloy forming blade root 3 is one of 2.1%. At a temperature of approx. 700 ° C Blade 2 has a creep resistance, which corrected considerably above the creep resistance of the usually used in this temperature range Nickel-based superalloys. The whole Turbine blade 1 shows the material of the Blade 2 corresponding ductility of 0.5%. Your mechanical and thermal properties are due to the No transition zone between the two alloys impaired. The turbine blade 1 according to the invention is characterized by a blade root 3 with high Ductility and a brittle one at room temperature high temperatures, however, a high creep resistance having blade 2. The strength in Transitional area is because of the two alloys common base material and the lack of brittle Reaction products large enough to be safe Operation of the turbine blade 1 at high temperatures guarantee.

In a further variant of the invention, it is possible to Place a press can 4 as a form for receiving the Alloys use a sintered mold, and compacting to achieve the turbine blade in a sintering process.

The invention is not limited to turbine blades. It also applies to others at high temperatures mechanically heavily loaded components, such as in one piece trained turbine wheels of turbochargers.

LIST OF DESIGNATIONS

1

Turbine blade

2nd

Airfoil

3rd

Blade root

4th

Press jug

5

opening

Claims (8)

1. High-temperature component, especially a turbine blade (1), having a component body containing at least one first section (blade root 3) and a second section (blade leaf 2), in which component body the first section (3) is formed by a ductile material and the second section (2) has a material which is brittle as compared with the ductile material, in which each of the two materials contains in each case one of two alloys, derived from a common base material, of different chemical compositions which differ from one another by the presence and/or the quantity of at least one doping material alloyed with the base material, characterized in that the base material is gamma-titanium aluminide, in that the proportion of doping material in at least one of the two alloys is at least 0.2 and at most 8 atom per cent, and in that the component contains at least one or more of the elements B, C, Co, Cr, Ge, Hf, Mn, Mo, Nb, Pd, Si, Ta, V, Y, W and Zr as doping material.
2. Component according to Claim 1, characterized in that a first alloy, forming the first section (3), of the two alloys contains a doping material which promotes the establishment of a fine-crystalline microstructure, such as, in particular, one or more of the elements Cr, Mn, V and Si, and a second alloy, forming the second section (2), of the two alloys contains a doping material which promotes the establishment of a coarse-crystalline microstructure and increases the creep strength, such as, in particular, one or more of the elements Nb, Ta and W.
3. Process for producing the component according to Patent Claim 1, which comprises hot-compacting the two alloys to give the component body and filling a first alloy, forming the first section (3), of the two alloys as powder into a mould before the hot compaction.
4. Process according to Patent Claim 3, characterized in that a second alloy is used, forming the second section (2), of the two alloys in the form of a casting or of a body formed from hot-compacted powder, and transferring this casting or the body formed from the hot-compacted powder with at least one end into the mould formed as a press can (4) and contacting it in the press can (4) with the powder.
5. Process according to Patent Claim 4, characterized in that the press can (4) has an opening (5) which is filled by the introduced body and is sealed preferably by welding or soldering the press can (4) to the body.
6. Process according to Patent Claim 5, characterized in that a second alloy, forming the second section (2), of the two alloys is filled as powder into the mould before the hot compaction.
7. Process according to any of Claims 3 to 6, characterized in that the hot compaction is carried out at temperatures between 900 and 1200°C.
8. Process according to any of Claims 4 to 7, characterized in that the material formed by hot compaction is heat-treated at temperatures higher than 700°C.

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