DE202018002644U1 - Apparatus for connecting a gas turbine blade with a gas turbine blade root - Google Patents

Abstract

Apparatus configured to carry out a method for connecting a gas turbine blade (100), hereinafter referred to as blade (100), with a gas turbine blade root (200), hereinafter referred to as blade root (200), wherein the blade (100) and the blade root (100) 200) are made of non-fusion-weldable materials, comprising the following steps: - providing a blade (100) and a blade root (200), - arranging for connecting the blade (100) and the blade root (200) in a joining zone (5) a gas turbine blade (300), preheating the airfoil (100) and the blade root (200) at least in the joining zone (5), wherein the preheating temperature is greater than the temperature for the brittle-ductile phase transition of the materials of the airfoil (100) and the Blade root (200), - connecting the blade (100) to the blade root (200) to form a circumferential in the joint zone (5) n gas-tight weld (1) by fusion welding, and diffusion welding by hot isostatic pressing of the composite of the airfoil (100) with the blade root (200).

Description

The present invention relates to a device configured to carry out a method for connecting a gas turbine blade, hereinafter referred to as a blade, with a gas turbine blade root, hereinafter referred to as blade root, wherein the blade and the blade root are made of non-meltable materials, according to the preamble of Claim 1.

Gas turbines may include gas turbine blades and adjacent components made of different materials. For example, the blade, the blade root, the rotor body and / or other components can be made of different materials. This may be due to the fact that, for example, an airfoil is exposed to very high temperatures, a blade root and a rotor base body, however, is designed at relatively lower temperatures for certain high mechanical loads. Different materials are available for the different materials, which include titanium alloys, nickel alloys and other alloys. Here, in particular, the investment casting and forging from the prior art are known. Many highly stressed gas turbine components, such as the blades for a compressor, are often forgings. Blades and vanes of the turbine, however, can be executed as precision castings.

A gas turbine blade having an airfoil and a blade root made of different materials may be referred to as a hybrid blade. The production of this hybrid blade, for example, from different titanium alloys, is usually possible only by joining technology. As a possible method of joining the blade root of a first titanium alloy with a blade of a second titanium alloy, a linear or an orbital friction welding, or alternatively an additive manufacturing method may be used. For example, the electron beam melting (EBM), the Selective Laser Melting (abbreviated SLM) or the Laser Metal Deposition (abbreviated LMD) can be counted among the additive manufacturing processes , However, these joining technologies may require elaborate preheating in the friction welding, or cause potential bonding defects in the component made by additive manufacturing. Such binding errors are difficult to detect by a final non-destructive material testing. Despite these disadvantages, it may be necessary for structural mechanical reasons to use certain combinations of materials for a gas turbine blade.

An object of the present invention is to propose a device configured to carry out a method of joining a blade with a blade root, wherein the blade and blade root are made of non-fusion weldable materials.

The object of the invention is achieved by a device having the features of claim 1.

• T _{v, Min} - Mindest-Vorwärmtemperatur
• T _{Spröd-Duktil, Werkstoff Schaufelblatt} - Temperatur für den Spröd-Duktil-Phasenübergang des Schaufelblatt-Werkstoffs
• T _{Spröd-Duktil, Werkstoff Schaufelfuß} - Temperatur für den Spröd-Duktil-Phasenübergang des Schaufelfuß-Werkstoffs

According to the invention, a device is claimed which is configured to carry out a method for connecting a blade with a blade root, wherein the blade and the blade root are made of non-fusion-weldable materials. The method comprises, as a first step, providing an airfoil and a blade root. The second step of the method includes arranging to connect the airfoil and the blade root in a joining zone to a gas turbine blade. The joining zone can be referred to as contact area. The third step of the method includes preheating the airfoil and the blade root at least in the joint zone, wherein the preheat temperature is greater than the brittle-to-ductile phase transition temperature of the blade and blade root materials. The temperature for the brittle-ductile phase transition can be referred to as the phase transition temperature. This preheat temperature condition can be represented by the following equation: $${\text{T}}_{\text{V}\text{, min}}>\text{Max}\left({\text{T}}_{\text{Brittle-ductile}\text{, Material airfoil}}.{\text{T}}_{\text{Brittle-ductile}\text{, Material blade root}}\right)$$

• T _{v, Min} - minimum preheat temperature
• T _{brittle ductile, material airfoil} - temperature for the brittle-ductile phase transition of the airfoil material
• T _{brittle ductile, material blade} root - temperature for the brittle-ductile phase transition of the blade root material

The fourth step of the method comprises bonding the airfoil to the blade root to form a gas-tight weld seam circulating in the joint zone by fusion welding. The joining can be called joining. The fifth step of the method comprises a diffusion welding by hot isostatic pressing (abbreviated HIP) of the composite of the airfoil with the blade root.

Advantageous developments of the present invention are the subject of subclaims and embodiments.

Exemplary embodiments according to the invention may have one or more of the following features in any combination, provided that one or the concrete combination is not apparent to the person skilled in the art as obviously technically impossible. The subject matters of the dependent claims in each case according to the invention, exemplary embodiments.

In all of the statements made above and below, the use of the term "may be" or "may have" etc. is synonymous with "preferably" or "preferably", etc., and is intended to illustrate exemplary embodiments of the invention.

Whenever alternatives are introduced herein with "and / or", those skilled in the art will understand the "or" contained therein as preferably "either or" and preferably not "and".

Embodiments referred to herein are to be understood as being purely exemplary embodiments of the present invention, which are not to be considered as limiting.

The term fusion welding may include various welding methods for joining components which are carried out under the action of heat or heat. In contrast to the pressure welding process, in the fusion welding process usually no large forces are necessary to perform the compound structurally stable. Fusion welding methods include fire welding, resistance melt welding, gas fusion welding (eg, autogenous welding), and beam fusion welding. In beam fusion welding, the beam, in particular a laser beam or an electron beam, is generally used in order to liquefy the material or component to be connected locally in a very small range of, for example, a few tenths of a millimeter. The intensity of the laser beam can be adjusted to the melting point of the material.

In some embodiments of the invention, the airfoil is an airfoil blank and the blade root is a blade root stock. The blade root blank may be cuboid, oval with rounded corner areas for better heat distribution, or other shape. The front-side mating surface of the blade bladed blank may have the corresponding mating surface of the blade root blank mold to allow a stepless weld.

In some embodiments of the invention, the apparatus configured to perform a method comprises the further step of using a jet fusion process as a fusion welding process, wherein the jet fusion process may be a laser beam fusion welding process or an electron beam fusion welding process.

In some embodiments according to the invention, the energy per unit area during fusion welding amounts to a maximum of 15 kJ / m. The path energy can continue to be at most 10 kJ / m, in particular about 6 kJ / m. The energy per unit length can be described and defined as the ratio of on the one hand the power of the laser beam or the electron beam and on the other hand the feed speed of the laser beam or electron beam.

In some embodiments of the invention, the apparatus configured to perform a method includes the further step of using electron beams and / or laser beams and / or an inductive preheating method.

In particular, in laser beam welding, the preheating can be performed inductively.

If the heater is heated, the beam can be set in a defocused position so that the beam focus is not set directly on the surface to be heated. This can advantageously a point warming or at least a locally very limited heating, which can lead to local overheating, avoided become. This defocused beam can increasingly heat the preheating area to a desired setpoint temperature by, for example, heating the surface several times or sweeping over the joining zone. The setpoint temperature can be referred to as the preheat temperature. The heat measurement for checking that the preheating temperature has been reached can be effected by non-contact measuring methods, for example by a thermal imaging camera.

In some embodiments of the invention, the apparatus configured to perform a method includes the further step of using a shield gas chamber to connect the airfoil to the blade root to form a weld by fusion welding. In particular, in laser beam welding, a closed protective gas chamber, which can be referred to as a so-called glove box, are used. As protective gas, for example, argon or helium can be used. The electron beam fusion welding is usually carried out in a high vacuum pressure range, so that a separate protective gas chamber is not necessary. The high vacuum is advantageously used to avoid embrittlement of the materials to be joined or excluded.

In some embodiments of the invention, the apparatus configured to perform a method includes the further step of monitoring the preheat temperature using a thermal imaging camera. A thermal imaging camera may be referred to as an imaging device that receives infrared radiation for temperature measurement.

• T_V - Vorwärmtemperatur
• T_{V, Min} - Mindest-Vorwärmtemperatur
• ΔT - Temperaturdifferenz zwischen der Beendigung der Vorwärmung und dem Beginn des Schmelzschweißens

In some embodiments of the invention, the apparatus configured to perform a method includes the further step of using a preheat temperature that is greater than the sum of the brittle-to-ductile phase transition temperature of the airfoil and blade root materials and a temperature span Delta T (ΔT), which corresponds to a cooling after the completion of preheating and before the start of fusion welding. The temperature span delta T (ΔT) may be referred to as the temperature difference between the completion of preheating and the start of fusion welding. This condition for the preheat temperature can be represented by the following equation: $${\text{T}}_{\text{V}}>{\text{T}}_{\text{V}\text{, min}}+\mathrm{\Delta }\text{T}$$

• T _V - preheating temperature
• T _{V, Min} - minimum preheat temperature
• ΔT - temperature difference between the completion of preheating and the beginning of fusion welding

In some embodiments of the invention, the apparatus configured to perform a method includes the further step of using a thermal conduction welding process for fusion welding. The welding depth can be between 0.05 mm and 2 mm, in particular between 0.1 mm and 1 mm. A thermal conduction welding process may be described as a welding process in which the fusion welding beam, such as a laser beam, melts the components to be joined along the joint. The melts can flow into one another and solidify into a weld. The energy can pass through the heat conduction welding in the workpiece only by heat conduction. The penetration depth can be less than a tenth of a millimeter up to about 1 to 2 mm. The thermal conductivity of the material can limit the maximum penetration depth, which can be called the seam depth.

The step of using a heat conduction welding process for fusion welding advantageously allows a crack-free weld. The weld can be called weld-in. The avoidance of surface cracks can be an important prerequisite for a gas tightness of the weld seam and thus of the subsequent diffusion welding process by hot isostatic pressing HIP. Surface cracks can be detected, for example, by a dye penetration test.

In some embodiments of the invention, the apparatus configured to perform a method comprises the further step of widening the weld perpendicular to the feed direction of the weld and parallel to the surface of the airfoil and the blade root by means of periodic beam deflection.

In some embodiments of the invention, the apparatus configured to carry out a method comprises the further step of using a temperature between 900 ° C and 1200 ° C and a pressure between 1000 bar and 5000 bar for a period of between 30 minutes and 600 minutes Process step of hot isostatic pressing of the composite from the blade with the blade root.

In some embodiments of the invention, the material for the airfoil and / or for the blade root is a titanium-aluminum alloy or comprises such a material.

In some embodiments of the invention, the apparatus configured to carry out a method comprises the further step of finishing a gas turbine blade made by means of an airfoil blank and / or a blade root blank by means of a metal cutting process and / or an electrochemical machining process ,

In some embodiments of the invention, the gas turbine blade is configured as a blade of a gas turbine.

Some or all embodiments according to the invention may have one, several or all of the advantages mentioned above and / or below.

By means of the device according to the invention can be advantageously used a fusion welding method as a joining method for connecting a gas turbine blade with a gas turbine blade root, wherein the blade and the blade root are made of non-meltable materials. With the device according to the invention, the disadvantages of previously used methods, in particular a costly preheating in a linear or an orbital friction welding, or possible binding errors in the material in an additive manufacturing process can be avoided.

The inventive step of diffusion welding by hot isostatic pressing (HIP) of the composite of the blade with the blade root in a HIP system advantageously allows to load the HIP system simultaneously with a plurality of components, ie a plurality of gas turbine blades. Depending on the size of the HIP system, more than 100 gas turbine blades can be loaded simultaneously. Furthermore, the HIP plant advantageously allows to carry out an optional and often necessary, downstream heat treatment of the gas turbine blades in the HIP plant without a renewed loading or reloading.

The quality of the diffusion welding produced by the hot isostatic pressing can advantageously be checked simply by, for example, a contactless ultrasonic testing of the gas turbine blades. Optionally, airfoil blanks are joined together with blade root blanks to form a gas turbine bladed blade that can be inspected in the same manner by non-contact ultrasonic testing.

By means of the device according to the invention can be kept low by a small welding depth during the beam welding process a required allowance in the frontal foot region of the gas turbine blade.

• 1 zeigt ein Gasturbinenschaufelblatt-Rohteil, ein Gasturbinenschaufelfuß-Rohteil, eine Schweißnaht und einen vorgewärmten Bereich an einer Fügezone des Schaufelblatt-Rohteils und des Schaufelfuß-Rohteils; und
• 2 zeigt die erfindungsgemäßen Schritte eines Verfahrens zum Verbinden des Schaufelblatts mit dem Schaufelfuß in einer Fügezone zu einer Gasturbinenschaufel.

The present invention will be explained in the following with reference to the accompanying drawings, in which identical reference numerals designate identical or similar components, by way of example. In the highly simplified schematic figures:

• 1 shows a gas turbine blade blank, a gas turbine blade root, a weld and a preheated area at a joining zone of the airfoil blank and the blade root blank; and
• 2 shows the inventive steps of a method for connecting the airfoil with the blade root in a joining zone to a gas turbine blade.

1 schematically shows a gas turbine blade bladed greatly simplified 100 , a gas turbine blade-blank 200 , a weld 1 and a preheated area 3 at a joining zone 5 of the airfoil blank 100 and the blade root blank 200 , The Airfoil blank 100 and the blade root stock 200 are made of non-melt-weldable materials, such as titanium-aluminum alloys, in particular of different titanium-aluminum alloys for the blade blank 100 and the blade root stock 200 , In order to avoid the disadvantages of the known joining method of friction welding and of additive manufacturing methods, a fusion welding method is used according to the invention. In order that the two materials that are not suitable for fusion welding can nevertheless be joined by means of the fusion welding process, the 2 performed in detail process steps.

The blade root blank 200 is designed cuboid. The corresponding mating surface of the blade blank 100 has a rectangular shape, so that the two components by means of the weld 3 be joined or joined together without having to bridge a step or a paragraph. Optionally, the corners of the rectangle shape may be rounded. The corners of the rectangular shape may have radii.

To finish the two interconnected blanks 100 . 200 further processed, for example by means of a machining process or an electrochemical machining process. Thereafter, the gas turbine blade 300, for example, as a gas turbine blade segment, connected to a rotor body and assembled or assembled to a gas turbine blade ring.

2 shows the inventive steps of a method for connecting a gas turbine blade 100 , hereinafter referred to as a blade 100 designated, with a gas turbine blade foot 200 , hereinafter referred to as blade root 200 designated, wherein the airfoil 100 and the blade foot 200 made of non-fusion-weldable materials. The blade 100 and the blade foot 200 can be present as blanks and processed as blanks in steps S1 to S5. The blade 100 can then be used as an airfoil blank 100 and the blade foot 200 as a blade footer blank 200 be designated.

In step S1, an airfoil 100 and a shovel foot 200 provided.

In step S2, the airfoil 100 and the blade foot 200 for connecting to a gas turbine blade 300 in the joining zone 5 arranged. The joining zone 5 may be referred to as contact area 5. The arrangement is in particular such that the surfaces to be joined lie as accurately as possible against each other, so that at an outer peripheral edge in the region of the joining zone 5 the weld 1 can be applied.

In the subsequent step S3, the airfoil 100 and the blade foot 200 preheated. The preheating takes place at least in the joining zone 5 , however, may be beyond the localized joining zone 5 extend beyond. The preheating can be done by means of a radiation heating, by means of inductive heating or in another way. In the case of spot heating, the beam can be set in a defocused position so that there is no point heating or at least locally very limited heating, which can lead to local overheating. This defocused jet can control the preheat area 3 for example, by repeated surface heating or sweeping the joining zone 5 increasingly heat up to a desired setpoint temperature.

The rays for a radiation heating may be electron beams, laser beams or other rays.

In a fusion welding of two non-fusion weldable materials or components made of these materials, as here present in the form of the two components airfoil 100 and shovel foot 200 the case is, the temperature should be in the joint area of the weld 1 be sufficiently high to avoid cracking of the components. A sufficiently high temperature according to the invention is a temperature above the so-called brittle-ductile phase transition of the respective material. This temperature can be referred to as the phase transition temperature. The phase transition from a brittle material behavior to a ductile material behavior is a temperature-dependent material parameter, whereby simplifying here is assumed or assumed constant ambient pressure. The phase transitions may be referred to as phase transitions.

To take into account a cooling of the preheating area 3 in a period between the completion of the preheat and the start of the fusion welding operation, the preheat temperature may be increased by a temperature span delta T (ΔT).

To avoid heat accumulation at the corners of the components to be heated, for example, in rectangular blanks of the airfoil 100 and the blade foot 200 can occur, it may be advantageous to round off these corner areas for better heat distribution. The corner regions of the rectangular blanks can therefore have, for example, radii.

In the following step S4, the airfoil becomes 100 with the blade foot 200 forming one in the joining zone 5 circumferential gas-tight weld 1 connected by fusion welding. This joining can be referred to as joining. Preferably, a beam melting method is used, for example a laser beam fusion welding method or an electron beam fusion welding method.

The fusion welding is preferably carried out with a maximum energy of 15 kJ / m, in particular of at most 10 kJ / m, for example of about 6 kJ / m.

The weld can be widened by means of a periodic beam deflection perpendicular to the feed direction of the weld and parallel to the surface of the blade and the blade root in order to achieve a secure gap bridging between the components to be joined.

The method step S4 can be carried out in a protective gas chamber.

The beam welding process is preferably carried out as a heat conduction welding process. The penetration depth of the heat conduction into the component to be connected in the region of the joining zone 5 can be a few tenths of a millimeter up to about 1 mm.

In the subsequent step S5, the process step of diffusion welding is carried out by hot isostatic pressing of the composite from the airfoil 100 with the blade foot 200 , In this case, following the formation of the gas-tight welds between the airfoil 100 and the blade foot 200 the thus formed composite subjected to diffusion welding by hot isostatic pressing (abbreviated HIP). Hot isostatic pressing can be described as a process in the field of manufacturing technology in which powders and solids, for example metals, are simultaneously hot-pressed and sintered. Due to the diffusion processes in the metal structure forming during hot isostatic pressing, a compact, flat connection between the blade leaf 100 and the blade root can then be achieved 200 arise. Possible fissures created during fusion welding can thus be closed. This can be referred to as so-called annealing of the material or of the component. In particular, a post-processing can advantageously no longer be necessary or at least only to a very limited extent. The hot isostatic pressing is preferably carried out at a temperature between 900 degrees Celsius (° C) and 1200 degrees Celsius (° C), at a pressure between 1000 bar and 5000 bar, preferably in a protective gas environment, for example with argon or helium as protective gas, and a period of time between about 30 min and 600 min performed.

LIST OF REFERENCE NUMBERS

100

Gas turbine airfoil blank; Blade-blank; airfoil

200

Gasturbinenschaufelfuß-blank; Blade-blank; blade

300

Gas turbine blade

1

Weld

3

preheated area

5

Joining zone; contact area

S1 - S5

steps

Claims (14)

Device configured to carry out a method for connecting a gas turbine blade (100), hereinafter referred to as blade (100), with a gas turbine blade root (200), hereinafter referred to as blade root (200), wherein the blade (100) and the blade root (100) 200) are made of non-fusion-weldable materials, comprising the following steps: - providing an airfoil (100) and a blade root (200), - Arranging for connecting the airfoil (100) and the blade root (200) in a joining zone (5) to a gas turbine blade (300), preheating the airfoil (100) and the blade root (200) at least in the joining zone (5) Preheating temperature is greater than the temperature for the brittle-ductile phase transition of the materials of the airfoil (100) and the blade root (200), - connecting the airfoil (100) to the blade root (200) to form one in the joint zone (5) gas-tight weld (1) by fusion welding, and - diffusion bonding by hot isostatic pressing of the composite from the airfoil (100) with the blade root (200). Device after Claim 1 wherein the airfoil (100) is an airfoil blank (100) and the blade root (200) is a blade root blank (200). Device after Claim 1 or 2 with the further step of: - using a jet melting process as a fusion welding process, wherein the jet melting process is a laser beam fusion welding process or an electron beam fusion welding process. Device according to one of the preceding claims, wherein a path energy during fusion welding is a maximum of 15 kJ / m. Device according to one of the preceding claims, with the further step: - Using electron beams and / or laser beams and / or an inductive method for preheating. Device according to one of the preceding claims, with the further step: - Using a protective gas chamber for connecting the airfoil (100) with the blade root (200) to form a weld (1) by fusion welding. Device according to one of the preceding claims, with the further step: - Monitoring the preheating temperature by means of a thermal imaging camera. Device according to one of the preceding claims, with the further step: - Using a preheating temperature, which is greater than the sum of the temperature for the brittle-ductile phase transition of the materials of the airfoil (100) and the blade root (200) and a temperature span Delta T, the cooling after the completion of preheating and before corresponds to the beginning of fusion welding. Device according to one of the preceding claims, with the further step: - Using a heat conduction welding process for fusion welding, wherein the welding depth between 0.05 mm and 2 mm, in particular between 0.1 mm and 1 mm. Device according to one of the preceding claims, with the further step: - Widening of the weld (1) perpendicular to the feed direction of the weld (1) and parallel to the surface of the blade (100) and the blade root (200) by means of a periodic beam deflection. Device according to one of the preceding claims, with the further step: - Using a temperature between 900 ° C and 1200 ° C and a pressure between 1000 bar and 5000 bar for a period of time between 30 min and 600 min in the process step of hot isostatic pressing the composite of the airfoil (100) with the blade root (200) , Device according to one of the preceding claims, wherein the material for the airfoil (100) and / or for the blade root (200) is a titanium-aluminum alloy or comprises such a material. Device according to one of Claims 2 to 12 with the further step of: - finishing a gas turbine blade (300) produced by means of an airfoil blank (100) and / or a blade root blank (200) by means of a machining method and / or an electrochemical machining method. Apparatus according to any one of the preceding claims, wherein the gas turbine blade (300) is a gas turbine blade.

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