EP2254725A1

EP2254725A1 - Device for welding using a process and welding method

Info

Publication number: EP2254725A1
Application number: EP09725353A
Authority: EP
Inventors: Bernd Burbaum; Selim Mokadem; Norbert Pirch
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Siemens AG
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Siemens AG
Priority date: 2008-03-27
Filing date: 2009-02-02
Publication date: 2010-12-01
Also published as: DE102008015913A1; US20110062120A1; WO2009118213A1

Abstract

Welding methods are often carried out using a protective gas but the effect of said gas is often insufficient. According to the invention, the component (4) to be welded is arranged in a process chamber (31).

Description

Apparatus for welding with a process chamber and a

welding processes

The invention relates to a device for welding with a process chamber and a welding method in a process chamber.

Welding techniques are used to join components together or to repair components by remelting cracks, with material (weld metal) added as needed to apply material.

In this case, an energy beam, for example a laser beam is guided over the surface of a component, which is surrounded by a process gas, in order to avoid oxidation of the hot (molten) welding material.

However, the protective effect of the process gas is not always sufficient.

It is therefore an object of the invention to overcome the above-mentioned problem.

The object is achieved by a device according to claim 1 and a method according to claim 10, wherein the component to be welded is arranged in a process chamber and is processed.

In the dependent claims further advantageous measures are listed, which can be combined with each other in order to achieve further advantages. Show it:

Figure 1, 2 devices of the invention, Figure 3 shows a gas turbine, Figure 4 is a perspective view of a turbine blade, Figure 5 is a perspective combustion chamber and Figure 6 is a list of superalloys. The figures and the description show only embodiments of the invention.

FIG. 1 shows a device 30 according to the invention. The device 30 has a process chamber 31, which preferably represents a vacuum chamber and / or which is flooded with a protective gas, such as argon (Ar) and / or nitrogen (N ₂ ) or a process gas or will.

Preferably, the process chamber 31 has a movement means 38, by means of which a component 4, 120, 130, 155, which is arranged on the movement means 38, tilted and / or can be rotated about the longitudinal axis. Preferably, the movement means 38 must be able to tilt the component 4 away from or away from at least one welding device 33. Tilting can occur during the laying of two welds, especially when the curvature of the welds to be laid changes. A welding process can be considered in the production of one or more welds.

Rotation preferably occurs about an axis perpendicular to the longitudinal axis 121 (FIG. 4) of the component 4. The longitudinal axis is most likely parallel to the beam direction of the welder 33 or the laser beams or the longitudinal direction of the process chamber 31.

A tilting of the component 4 can take place during processing by means of the welding apparatus 33 or only in advance of the irradiation by means of the welding apparatus 33. Thus, a curvature of the surface to be welded can be taken into account. Likewise, the component 4, 120, 130, 155 can be displaced by the movement means 38 in the height within the process chamber 31 by the movement means (38). Thus, the process chamber 31 can be adapted to different sizes of components, 120, 130, 155 and / or different high points of the component, 120, 130, 155, which are to be welded.

Preferably, the welding device 33 is a laser.

A heating loop 41 may preferably be present around the component 4, 120, 130, 155 in order to preheat the component 4, 120, 130, 155 to a specific temperature or to generate a temperature gradient for directional solidification of a melt pool generated by the welding apparatus 33 is going to produce. This generates a local temperature increase. Also preferably, the preheat temperature is measured and regulated.

The welder 33 may be located within (Fig. 1) the process chamber 31, but also outside, as e.g. is possible with a laser, which can radiate its laser beams into the process chamber 31 through a window 36 in the process chamber 31 (FIG. 2). In that case, the process chamber 31 with the component 120, 130 can be moved relative to the laser 33 in order to change the position or to guide the laser beam over the component 120, 130. Other welding methods using plasma do not allow this.

The closed system with the process chamber allows to more accurately determine the oxygen content and the temperature of the melt of the weldment, since external influences are minimized thereby and a vacuum generally reduces the heat seal during the preheating of the component.

The component preferably has a superalloy according to FIG. FIG. 3 shows by way of example a gas turbine 100 in a longitudinal partial section.

The gas turbine 100 has inside a rotatably mounted about a rotation axis 102 rotor 103 with a shaft, which is also referred to as a turbine runner. Along the rotor 103 follow one another an intake housing 104, a compressor 105, for example, a toroidal combustion chamber 110, in particular annular combustion chamber, with a plurality of coaxially arranged burners 107, a turbine 108 and the exhaust housing 109th

The annular combustion chamber 110 communicates with an annular annular hot gas channel 111, for example. There, for example, four turbine stages 112 connected in series form the turbine 108.

Each turbine stage 112 is formed, for example, from two blade rings. As seen in the direction of flow of a working medium 113, in the hot gas channel 111 of a row of guide vanes 115, a series 125 formed of rotor blades 120 follows.

The guide vanes 130 are fastened to an inner housing 138 of a stator 143, whereas the moving blades 120 of a row 125 are attached to the rotor 103 by means of a turbine disk 133, for example.

Coupled to the rotor 103 is a generator or work machine (not shown).

During operation of the gas turbine 100, air 105 is sucked in and compressed by the compressor 105 through the intake housing 104. The compressed air provided at the turbine-side end of the compressor 105 is supplied to the burners 107 where it is mixed with a fuel. The mixture is then burned to form the working fluid 113 in the combustion chamber 110. From there it flows

Working fluid 113 along the hot gas channel 111 past the guide vanes 130 and the blades 120. On the blades 120, the working medium relaxes 113th impulse transmitting, so that the blades 120 drive the rotor 103 and this the driven machine coupled to it.

The components exposed to the hot working medium 113 are subject to thermal loads during operation of the gas turbine 100. The guide vanes 130 and rotor blades 120 of the first turbine stage 112, viewed in the flow direction of the working medium 113, are subjected to the greatest thermal stress in addition to the heat shield elements lining the annular combustion chamber 110.

To withstand the prevailing temperatures, they can be cooled by means of a coolant. Likewise, substrates of the components may have a directional structure, i. they are monocrystalline (SX structure) or have only longitudinal grains (DS structure). As the material for the components, in particular for the turbine blade 120, 130 and components of the combustion chamber 110, for example, iron-, nickel- or cobalt-based superalloys are used.

Such superalloys are known, for example, from EP 1 204 776 B1, EP 1 306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949; These documents are part of the disclosure regarding the chemical composition of the alloys.

The vane 130 has a guide vane foot (not shown here) facing the inner housing 138 of the turbine 108 and a vane head opposite the vane foot. The vane head faces the rotor 103 and fixed to a mounting ring 140 of the stator 143.

FIG. 3 shows a perspective view of a moving blade 120 or guide blade 130 of FIG

Turbomachine, which extends along a longitudinal axis 121. The turbomachine may be a gas turbine of an aircraft or a power plant for power generation, a steam turbine or a compressor.

The blade 120, 130 has along the longitudinal axis 121 consecutively a fastening region 400, a blade platform 403 adjacent thereto and an airfoil 406 and a blade tip 415.

As a guide blade 130, the blade 130 may have at its blade tip 415 another platform (not shown).

In the mounting region 400, a blade root 183 is formed, which serves for attachment of the blades 120, 130 to a shaft or a disc (not shown).

The blade root 183 is designed, for example, as a hammer head. Other designs as Christmas tree or Schwalbenschwanzfuß are possible. The blade 120, 130 has a leading edge 409 and a trailing edge 412 for a medium flowing past the blade 406.

In conventional blades 120, 130, in all regions 400, 403, 406 of the blade 120, 130, for example, massive metallic materials, in particular superalloys, are used.

Such superalloys are known, for example, from EP 1 204 776 B1, EP 1 306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949; These documents are part of the disclosure regarding the chemical composition of the alloy.

The blade 120, 130 can be made by a casting process, also by directional solidification, by a forging process, by a milling process or combinations thereof.

Workpieces with a single-crystal structure or structures are used as components for machines that are in operation high mechanical, thermal and / or chemical stresses are exposed.

The production of such monocrystalline workpieces takes place e.g. by directed solidification from the melt. These are casting processes in which the liquid metallic alloy is transformed into a monocrystalline structure, i. to the single-crystal workpiece, or directionally solidified. Here, dendritic crystals are aligned along the heat flow and form either a columnar grain structure (columnar, i.e., grains that run the full length of the workpiece and here, in common usage, are referred to as directionally solidified) or a monocrystalline structure, i. the whole workpiece consists of a single crystal. In these processes, it is necessary to avoid the transition to globulitic (polycrystalline) solidification, since non-directional growth necessarily produces transverse and longitudinal grain boundaries which negate the good properties of the directionally solidified or monocrystalline component. If the term generally refers to directionally solidified structures, it means both single crystals that have no grain boundaries or at most small-angle grain boundaries, and stem crystal structures that have grain boundaries that are probably longitudinal but no transverse grain boundaries. In these second-mentioned crystalline

Structures are also called directionally solidified structures.

Such methods are known from US Pat. No. 6,024,792 and EP 0 892 090 A1; these writings are part of the revelation regarding the solidification process.

Likewise, the blades 120, 130 may have coatings against corrosion or oxidation, e.g. M is at least one element of the group iron (Fe), cobalt (Co), nickel (Ni), X is an active element and stands for yttrium (Y) and / or silicon and / or at least one element of the rare ones Earth, or hafnium (Hf)). Such alloys are known from EP 0 486 489 B1, EP 0 786 017 Bl, EP 0 412 397 B1 or EP 1 306 454 A1, which should be part of this disclosure with regard to the chemical composition of the alloy. The density is preferably 95% of the theoretical density. A protective aluminum oxide layer (TGO = thermal grown oxide layer) is formed on the MCrAlX layer (as an intermediate layer or as the outermost layer).

Preferably, the layer composition comprises Co-30Ni-28Cr-8A1-0, 6Y-0, 7Si or Co-28Ni-24Cr-10Al-0, 6Y. In addition to these cobalt-based protective coatings, nickel-based protective layers such as Ni-10Cr-12Al-0.6Y-3Re or Ni-12Co-21Cr-IIAl-O, 4Y-2Re or Ni-25Co-17Cr-10Al-0.4Y-1 are also preferably used , 5RE.

On the MCrAlX may still be present a heat-insulating layer, which is preferably the outermost layer, and consists for example of Zrθ2, Y2θ3-Zrθ2, i. it is not, partially or completely stabilized by yttrium oxide and / or calcium oxide and / or magnesium oxide.

The thermal barrier coating covers the entire MCrAlX layer. By suitable coating methods, e.g. Electron beam evaporation (EB-PVD) produces stalk-shaped grains in the thermal barrier coating. Other coating methods are conceivable, e.g. atmospheric plasma spraying (APS), LPPS, VPS or CVD. The thermal barrier coating may have porous, micro- or macro-cracked grains for better thermal shock resistance. The thermal barrier coating is therefore preferably more porous than the MCrAlX layer.

The blade 120, 130 may be hollow or solid. If the blade 120, 130 is to be cooled, it is hollow and may still have film cooling holes 418 (indicated by dashed lines). FIG. 4 shows a combustion chamber 110 of the gas turbine 100. The combustion chamber 110 is designed, for example, as a so-called annular combustion chamber, in which a multiplicity of burners 107 arranged around a rotation axis 102 in the circumferential direction open into a common combustion chamber space 154, which generate flames 156. For this purpose, the combustion chamber 110 is configured in its entirety as an annular structure, which is positioned around the axis of rotation 102 around.

To achieve a comparatively high efficiency, the combustion chamber 110 is designed for a comparatively high temperature of the working medium M of about 1000 ^° C. to 1600 ^° C. In order to lend a comparatively long service life to these operating parameters, which are unfavorable for the materials, the combustion chamber wall 153 is provided on its side facing the working medium M with an inner lining formed of heat shield elements 155.

Due to the high temperatures inside the combustion chamber 110 may also be provided for the heat shield elements 155 and for their holding elements, a cooling system. The heat shield elements 155 are then, for example, hollow and possibly still have cooling holes (not shown) which open into the combustion chamber space 154.

Each heat shield element 155 made of an alloy is equipped on the working medium side with a particularly heat-resistant protective layer (MCrAlX layer and / or ceramic coating) or is made of highly temperature-resistant material (solid ceramic blocks).

These protective layers can be similar to the turbine blades, so for example MCrAlX means: M is at least one element of the group iron (Fe), cobalt (Co), nickel (Ni), X is an active element and stands for yttrium (Y) and / or

Silicon and / or at least one element of the rare earths, or hafnium (Hf). Such alloys are known from EP 0 486 489 B1, EP 0 786 017 Bl, EP 0 412 397 B1 or EP 1 306 454 Al, which should be part of this disclosure with respect to the chemical composition of the alloy.

On the MCrAlX may still be present, for example, a ceramic thermal barrier coating and consists for example of Zrθ2, Y2Ü3-Zrθ2, i. it is not, partially or completely stabilized by yttria and / or

Calcium oxide and / or magnesium oxide.

By suitable coating methods, e.g. Electron beam evaporation (EB-PVD) are stalk-shaped grains in the

Thermal insulation layer generated.

Other coating methods are conceivable, e.g. atmospheric plasma spraying (APS), LPPS, VPS or CVD. The

Thermal barrier coating may have porous, micro- or macro-cracked grains for better thermal shock resistance.

Refurbishment means that turbine blades 120, 130, heat shield elements 155 may need to be deprotected (e.g., by sandblasting) after use. This is followed by removal of the corrosion and / or oxidation layers or products. Optionally, cracks in the turbine blade 120, 130 or the heat shield element 155 are also repaired. Thereafter, a re-coating of

Turbine blades 120, 130, heat shield elements 155 and a re-use of the turbine blades 120, 130 or the heat shield elements 155th

Claims

claims

A device (30) for welding a component (4, 120, 130, 155), comprising: a process chamber (31) in which the component (4, 120, 130, 155) can be arranged and is weldable and a Welding machine (33).

2. Device according to claim 1, in the process chamber (31) comprises a movement means (38) for the component (4, 120, 130, 155), the (38) the component (4, 120, 130, 155) of the Welding device (33) can tilt or tilt and / or (38) the component (4, 120, 130, 155) can rotate and / or the (38) the component (4, 120, 130) in the height within the Can adjust process chamber (31).

3. Apparatus according to claim 1 or 2, comprising a heating loop (41), which (41) is guided around the component (4, 120, 130, 155).

4. Apparatus according to claim 1 or 2, wherein the welding device (33) within the process chamber (31) is arranged.

5. Apparatus according to claim 1 or 2, wherein the welding device (33) outside the process chamber (31) is arranged.

6. Apparatus according to claim 1, 2, 4 or 5, wherein the welding device (33) is a laser.

7. Apparatus according to claim 1, 2, 4 or 5, wherein the process chamber (31) is a vacuum chamber

8. Apparatus according to claim 1, 2, 5 or 7, wherein in the process chamber (31), a protective gas can be used.

9. Apparatus according to claim 1, wherein the moving means (38) is only a pivoting apparatus that can only tilt the component (1, 120, 130, 155).

10. A method for welding a component (4, 120, 130, 155), wherein the component (4, 120, 130, 155) in a process chamber (31), in particular according to one of claims 1 to 9, is arranged and there is welded.

11. The method of claim 10, wherein during welding with a welding device (33), the component (4, 120, 130, 155) is tilted.

12. The method of claim 10, wherein the component (4, 120, 130, 155) is preheated by a heating loop (41).

13. The method of claim 10 or 11, wherein a laser is used as a welding device (33).

14. The method of claim 10, wherein in the process chamber (31) a vacuum is generated.

15. The method of claim 10, 13 or 14, wherein a laser (33) outside the process chamber (31) is used.

16. The method of claim 15, wherein the process chamber (31) with the component (4, 120, 130, 155) relative to the laser (33) is moved.

17. The method of claim 10, 14, 15 or 16, wherein in the process chamber (31) a protective gas is used.

18. The method of claim 10 or 12, wherein the preheating temperature of the component (4, 120, 130, 155) is measured and controlled.