Method for repairing worn surfaces of first-stage working blades of gas turbine engines made of heat-resistant alloys using laser powder cladding

Abstract

FIELD: gas turbines.SUBSTANCE: invention relates to the repair of uncooled working blades of the first stage of a gas turbine unit turbine, in particular to the restoration of the feather, sealing combs and ends of the locking section of the working blade. The blade feather is restored by laser surfacing in continuous mode with a laser beam, the diameter of which is 0.8-1.5 mm with the simultaneous supply of a gas-powder jet of surfacing material with a flow rate of 2-8 g / min, whereas the laser radiation power is 250-500 W, the speed of the laser surfacing process is 3-10 mm / s, and the flow rate of the shielding gas is 10 l / min, then the working blade is tilted by 45 degrees and the sealing ridges and the end locking part are restored in continuous mode with a laser beam of 1.1-1.4 mm with the simultaneous supply of a gas-powder jet of surfacing material with a flow rate of 3-10 g / min, a laser radiation power of 300-700 W, the speed of the laser surfacing process is 8-10 mm / s, and the flow rate of the shielding gas is 10 l / min. The working tool is then tilted 30 degrees to ensure optimal access to the processing area and the ends of the lock are restored in a continuous mode, after which mechanical processing is carried out and a thermal barrier layer is applied. To control the final geometry, laser 3D scanning of the turbine blade is performed.EFFECT: increasing the productivity during the repair of working blades using a heat-resistant cobalt alloy, as well as in the possibility of repairing the feather, sealing combs and ends of the locking section of the turbine working blades while eliminating the formation of cracks in it.3 cl, 4 dwg

Description

[0001] The invention relates to a technology for repairing uncooled working blades of the first stage of a gas turbine plant turbine, in particular, to restoring the feather, sealing combs and ends of the locking part of the working blade.

[0002] It is known that during the operation of gas turbine units, the rotor sections, consisting essentially of disks with blades, bear the heaviest loads. Various loads, namely centrifugal and gas forces, causing tensile and bending stresses, combined with uneven thermal stresses, lead to wear on the rotor blade surfaces, cracks, nicks, and geometric distortions. These types of defects lead to deviations in the calculated values ​​of all turbine gas-dynamic parameters, disrupting engine operation or even causing its failure.

[0003] The implementation of this method allows for the restoration of the feather, sealing combs and ends of the locking section of the working blades of gas turbine units using the laser powder cladding method.

[0004] A known method for repairing blades is high-temperature brazing in a vacuum (Advanced Developments in High-Temperature Brazing of Heat-Resistant Alloys, authors O.G. Ospennikova, V.I. Lukin, A.N. Afanasyev-Khodykin, I.A. Galushka, O.V. Shevchenko, 2017, Aviation Materials and Technologies). This processing method is used to restore blades on blisk-type structures. Powder with a fractional composition from 10 to 200 μm is used as a filler material. This method makes it possible to bring the structure of the filler material closer to the structure of the base metal due to activated diffusion interaction. The disadvantages of this method are the high energy intensity of the technological process (> 4 hours), which affects the productivity of the process; high process temperatures, which can result in irreversible structural changes, and may also limit the use of heat-resistant alloys based on other materials.

[0005] A known method for restoring the surfaces of a single-crystal part or a part obtained by directional solidification (RU patent 2409708, published January 20, 2011). Laser radiation is directed at the surface to be treated while simultaneously feeding filler material. The surfacing process takes place in a protective device filled with an inert gas to create a neutral environment. A disadvantage of this method is the use of an additional device to protect the surfacing zone and cool the blade to a temperature below 600 degrees Celsius before the next layer, which leads to a decrease in process productivity. The presence of a protective device also limits the movement of the working tool, and therefore the surfacing zone of the working blades.

[0006] The closest analogue in technical essence and chosen as a prototype is the method of restoring the end face of the working blade of the first stage of a high-pressure turbine by the method of laser gas-powder surfacing on the TruLaser Cell 7020 laser complex (Study of the technology of restoring the end face of the working blade of the first stage of a high-pressure turbine (HPT) made of ZhS32-VI alloy by the method of laser gas-powder surfacing using metal powder of ZhS32-VI alloy produced by the atomization method, authors Nerush S.V., Ermolaev A.S., Rogalev A.M., Vasilenko S.A., Proceedings of VIAM, 2016). Using this processing method, the geometry of the end face of the working blade feather made of the ZhS32-VI alloy was restored using metal powder of the same alloy grade, the fraction of which was 40-80 µm; however, microanalysis of transverse sections confirmed the presence of hot cracks, the length of which ranged from 0.3 to 1 mm.To address this issue, degassing annealing of the ZhS32-VI metal powder was performed, the blade airfoil was preheated to 500°C, and post-heat treated in a vacuum furnace. As a result, the airfoil tip geometry of the first-stage turboprop rotor blades was completely restored, the deposition height was 1.8 mm, and the deposited material was free of defects (cracks or lack of fusion).

[0007] The disadvantages of this method are the presence of several technological processes, which lead to an increase in the labor intensity of the process and a decrease in the productivity of the part repair, as well as the inability to process the worn surfaces of the working blades in other areas.

[0008] The technical problem, the solution of which is provided by the implementation of the proposed invention and cannot be realized using the prototype, is the calculation of the technological window of laser cladding parameters, which does not require additional heating, as well as the repair of the feather, sealing combs and ends of the locking part of the turbine blades.

[0009] The technical result of the claimed invention is an increase in productivity during the repair of working blades made of a heat-resistant nickel alloy using a heat-resistant cobalt alloy, as well as the possibility of repairing the feather, sealing combs and ends of the locking part of the turbine working blades while eliminating the formation of cracks in it.

[0010] According to the invention, the heat-resistant nickel alloy can be the alloy ХН58КВТЮМБЛ-ВИ.

[0011] According to the invention, the surfacing material for surfacing the feather, sealing combs and ends of the locking part can be cobalt alloy PR-K60Kh30VS.

[0012] The specified technical result is achieved due to the fact that in the method of repairing the worn surfaces of the first stage working blades of gas turbine engines made of heat-resistant alloys by the laser powder cladding method, an incoming inspection is first carried out.

[0013] When conducting incoming inspection, defective areas of the working blade are identified by measuring the main geometric dimensions.

[0014] The essence of the invention is explained by figures, where

[0015] Fig. 1 - shows a working blade;

[0016] Fig. 2 - shows the strategy for surfacing the blade feather;

[0017] in fig. 3 - shows a diagram of fillet surfacing;

[0018] Fig. 4 shows a diagram of the weld on the end of the lock.

[0019] The following elements are indicated by numbers on the figures:

[0020] 1 - sealing comb 11 mm long;

[0021] 2 - sealing comb 7mm long;

[0022] 3 - end of the lock;

[0023] 4 - feather;

[0024] 5 - fillet;

[0025] 6 - technological tool;

[0026] 7-9 - the order of forming rollers from the first to the third.

[0027] According to the design documentation (Fig. 1), the height of the working blade airfoil should be 109 mm. The distances from the blade root to sealing ridges 1 and 2 should be 28.9 and 30 mm, respectively. The distance between the ends of root 3 should be 47 mm. Measurements were taken using a measuring ruler and a ШЦ-1 caliper. The measured working blades were in the range of 105-108 mm for the airfoil, 28.2-28.7 mm and 29.3-29.8 mm for sealing ridges 1 and 2, respectively. The measured sealing ridges were in the range of 46.2-46.7 mm.

[0028] Removal of thermal barrier coatings is performed to provide full access to the base metal of the working blade in order to avoid the ingress of coating impurities during surfacing.

[0029] The thermal barrier coating was removed mechanically using an angle grinder and burrs in the area of ​​the feather, sealing combs and ends of the locking part of the working blade.

[0030] The working blade is placed vertically on the positioning table in the laser cladding setup. Next, multi-pass bead cladding is performed along the blade's trajectory, layer by layer forming the missing portion of the blade's blade (Fig. 2).

[0031] Clad mode:

[0032] • Spot diameter 1 mm;

[0033] • Laser power: 250W;

[0034] • Laser radiation type: continuous;

[0035] • Consumption of welding powder: 2.0 g / min;

[0036] • Welding speed: 3 mm / s;

[0037] • Shielding gas consumption (argon): 10 l / min.

[0038] Then the working blade is placed in the laser cladding machine on a positioning table at a 45-degree angle to ensure optimal access of the working tool to the machining area. Beads are deposited on the fillet along the trajectory of the defective area, layer by layer forming supports for the subsequent cladding of the sealing ridges and the ends of the working blade lock (Fig. 3).

[0039] Clad mode:

[0040] • Spot diameter 1mm;

[0041] • Laser power: 250W;

[0042] • Laser radiation type: continuous;

[0043] • Consumption of surfacing powder: 2.0 g / min;

[0044] • Welding speed: 3 mm / s;

[0045] • Shielding gas consumption (argon): 10 l / min.

[0046] Next, the working blade is placed vertically on the laser cladding table. The working tool is then tilted 30 degrees to ensure optimal access to the processing area, and the lock ends are continuously restored (Fig. 4). The sealing ridges are restored in a similar manner, except that the working blade is placed horizontally on the positioning table.

[0047] Clad mode:

[0048] • Spot diameter 1mm;

[0049] • Laser power: 250W;

[0050] • Laser radiation type: continuous;

[0051] • Consumption of welding powder: 2.0 g / min;

[0052] • Welding speed: 3 mm / s;

[0053] • Shielding gas consumption (argon): 10 l / min.

[0054] Then the restored surfaces are mechanically processed to ensure the rotor blades meet the specified geometric dimensions. This is accomplished mechanically using an angle grinder and burrs.

[0055] To inspect the final geometry of the rotor blades, 3D laser scanning is performed using a Scantech TrackScan P42 3D scanning system in conjunction with TViewer software.

[0056] Using the laser cladding method in continuous mode with a laser beam and the simultaneous supply of a gas-powder jet of surfacing material with specified process parameters for restoring the feather, sealing ridges and ends of the locking part of the working blade allows for surfacing of worn surfaces in one technological operation, as well as eliminating the need for additional heating of the restored surface, which collectively increases the productivity of the laser cladding technological operation, and therefore increases the speed of the repair cycle of the turbine working blades.

[0057] Unlike the prototype, the heat-resistant nickel alloy is, for example, the alloy KhN58KVTYuMBL-VI from the alloying system Ni-CO-Cr-W- -Fe-Mo-Ti-Fe-Al.

[0058] Unlike the prototype, the surfacing material for restoring the feather, sealing combs and ends of the locking part of the working blade is a cobalt alloy powder, for example, PR-K60Kh30VS from the CO-Cr-W-Ni-Fe alloying system.

[0059] The method is as follows: the turbine blade is cleaned of contaminants. The cleaned blade undergoes incoming inspection, which includes visual and dimensional inspection of the rotor blade's main dimensions, as well as non-destructive liquid penetrant inspection for defects. To further restore the turbine blades, the thermal barrier layer, traces of oxidation, and corrosion are removed. Next, defects are removed and the area of ​​the airfoil 4, sealing ridges 3, and the ends of the rotor blade locking section 1 and 2 are cleaned.

[0060] After this, the blade 4 is installed and fixed in a vertical position for surfacing. A control program is developed based on the defective surface area. The blade 4 is then restored using continuous laser surfacing with a laser beam with a diameter of 0.8-1.5 mm and a simultaneous supply of a gas-powder jet of surfacing material at a flow rate of 2-8 g / min. The laser power is 250-500 W, the laser surfacing speed is 3-10 mm / s, and the shielding gas flow rate is 10 l / min. The working tool is then tilted 45 degrees to provide access to the ends of the locking part 3 and the sealing ridges of the blades 1 and 2, and a control program is developed that corresponds to the defective area.After this, the ends of the locking part 3 and the sealing ridges of the working blade 1 and 2 are restored in continuous mode with a 1.1-1.4 mm laser beam with the simultaneous supply of a gas-powder jet of surfacing material at a flow rate of 3-10 g / min, a laser radiation power of 300-700 W, the speed of the laser surfacing process is 8-10 mm / s, and the flow rate of the shielding gas is 10 l / min. Using the technological tool 6, surfacing is performed on the fillet 5 according to the strategy in Fig. 3: first, bead 7 is surfacing, then beads 8, 9 are surfacing by shifting the technological tool.

[0061] After laser cladding of the airfoil 4, the ends of the locking section 3, and the sealing ridges of the rotor blades 1 and 2, the turbine rotor blade is machined to achieve the required geometry. To ensure protection against oxidation and corrosion, a thermal barrier layer is applied. The final step is 3D laser scanning of the turbine rotor blade to verify the final geometry.

[0062] The method for restoring the feather, sealing combs and ends of the locking section of the first-stage working blades of gas turbine engines made of heat-resistant alloys using the laser powder cladding method has passed experimental tests in the pilot production of the enterprise and is currently being implemented in the repair production of gas turbine engine blades.

[0063] Thus, the proposed invention with the above-mentioned distinctive features in combination with known features makes it possible to increase the productivity of the process of repairing turbine blades, as well as the possibility of repairing the feather, sealing combs and ends of the locking part of the turbine working blades while eliminating the formation of cracks in it.

Claims

1. A method for repairing worn surfaces of uncooled working blades of the first stage of a gas turbine engine turbine made of heat-resistant alloys using laser powder cladding, which consists in first carrying out an incoming inspection, removing the thermal barrier coating, selecting defects in the area of ​​the feather, sealing combs and ends of the locking part of the working blade and installing and fixing the working blade in a vertical position, after which the blade feather is restored using laser cladding in continuous mode with a laser beam with a diameter of 0.8-1.5 mm with the simultaneous supply of a gas-powder jet of surfacing material with a flow rate of 2-8 g / min, while the laser radiation power is 250-500 W, the speed of the laser cladding process is 3-10 mm / s, and the flow rate of the protective gas is 10 l / min, then the working blade is tilted by 45 ° and the sealing combs and end are restored the locking part in continuous mode with a laser beam of diameter 1.1-1,4 mm with the simultaneous supply of a gas-powder jet of surfacing material with a flow rate of 3-10 g / min, a laser radiation power of 300-700 W, the speed of the laser surfacing process is 8-10 mm / s, and the flow rate of the shielding gas is 10 l / min, then the working tool is tilted by 30° and the ends of the lock are restored in a continuous mode, after which mechanical processing is carried out, a thermal barrier layer is applied and laser 3D scanning of the turbine working blade is carried out.

2. The method according to paragraph 1, characterized in that the heat-resistant alloy may be the KhN58KVTYuMBL-VI alloy.

3. The method according to paragraph 1, characterized in that the surfacing material for restoring the feather, sealing combs and ends of the locking part of the working blade may be cobalt alloy powder, for example PR-K60Kh30VS.

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