Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
  • B23K35/24—Selection of soldering or welding materials proper
  • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
  • B23K35/3033—Ni as the principal constituent
  • B23K35/304—Ni as the principal constituent with Cr as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/056—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 10% but less than 20%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/057—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being less 10%

Definitions

• Gas turbines as for example aircraft engines or stationary gas turbines, in operation are subject to high mechanical and thermal stress.
• blades e.g., turbine blades
• thermal stress and material removal This results in thermal fatigue cracks and eroded surfaces, which must be completely and reliable repaired when servicing or repairing the aircraft engine.
• soldering methods are used in addition to welding methods.
• the solder alloy is a nickel-based alloy and includes at least the following elements: chromium (Cr), cobalt (Co), molybdenum (Mo) and nickel (Ni).
• the molybdenum (Mo) replaces the tungsten (W) using in conventional solder alloy.
• molybdenum (Mo) increases the strength of the ⁇ -nickel matrix, without, however, disadvantageously increasing the melting point of the solder alloy to the same extent as tungsten (W).
• the solder alloy may additionally include tantalum (Ta), niobium (Nb) and aluminum (Al). This may achieve an additional strength by particle hardening effects. Tantalum (Ta), niobium (Nb) and aluminum (Al) are ⁇ ′-forming elements.
• the solder alloy may additionally include palladium (Pd) in a proportion of 0.5 to 5 wt. % and boron (B) in a proportion of 0.5 to 2.5 wt. %.
• Palladium (Pd) lowers the melting point of the solder alloy and increases the strength of the ⁇ -nickel matrix by mixed crystal hardening. Furthermore, it may be provided that palladium (Pd) improves the wetting behavior and the fluidity of the molten solder alloy or of the molten multi-component soldering system.
• the solder alloy may additionally include yttrium (Y) in a proportion of 0.1 to 1 wt. % and hafnium (Hf) in a proportion of 1 to 5 wt. %.
• Y yttrium
• Hf hafnium
• Palladium (Pd) hafnium
• hafnium (Hf) may improve the wetting behavior and the fluidity of the molten solder alloy or of the molten multi-component soldering system and increases at the same time the oxidation-resistance of the soldered regions.
• the hafnium portion is limited to 5 wt. %.
• yttrium may lower the melting point or the melting range of the solder alloy such that soldering temperatures may be set specifically in the range of 1200° C. to 1260° C. by the combination of elements Pd—B—Y.
• the melting range is defined as the temperature interval between the melting of the first alloy components (solidus point) and the completely liquid state (liquidus point) of the particular alloy.
• the melting point of the solder alloy may be lowered further in combination with the palladium, boron and yttrium.
• Example embodiments of the present invention relate to the use of a soldering method for repairing thermodynamically stressed components of a gas turbine, for example of guide blades of an aircraft engine or also of a stationary gas turbine.
• Example embodiments of the present invention relate not only to the soldering method itself, but rather also to the provision of a solder alloy or a multi-component soldering system as well as to a use of the solder alloy and the multi-component soldering system.
• the solder alloy and the multi-component soldering system are suitable both for repairing turbine components, which are manufactured from a polycrystalline alloy, as well as for turbine components that are manufactured from a directedly solidified or monocrystalline alloy.
• soldering method or solder alloy or multi-component soldering system makes it possible to achieve sufficiently high mechanical properties in the soldered regions of the gas turbine components such as, e.g., the fatigue-resistances such that the structural integrity of the relevant component of a gas turbine is maintained. Furthermore, improved oxidation and corrosion properties may be achieved in the soldered regions as compared to those regions that are repaired using conventional soldering methods.
• the solder alloy is a nickel-based alloy and in addition to nickel (Ni) includes at least also chromium (Cr), cobalt (Co) and molybdenum (Mo).
• Cr chromium
• Co cobalt
• Mo molybdenum
• the tungsten (W) used in conventional solder alloys is largely replaced by molybdenum (Mo). This may increase the strength of the repaired region by mixed crystal hardening of the ⁇ -nickel matrix without raising the melting point of the solder alloy.
• the solder alloy includes palladium (Pd) as well as yttrium (Y). Both palladium (Pd) as well as yttrium (Y) may lower the melting range of the solder alloy into a range of 1050° C. to 1200° C. and simultaneously may improve the oxidation properties of the solder alloy or of the soldered region. Palladium (Pd) may be limited to a maximum portion of 5 wt. % since it may make the solder material much more expensive if it is alloyed in excessively high concentrations.
• boron (B) Another element that may be included in the solder alloy is boron (B). Like palladium (Pd) and yttrium (Y), boron (B) may lower the melting range of the solder alloy into a range of 1050° C. to 1200° C. and may be limited to a maximum portion of 2.5 wt. %. By limiting boron (B) to a maximum of 2.5 wt. %, it is possible effectively to limit the boride phase portion in the soldered regions, which has an embrittling effect.
• the solder alloy may include a suitable proportion of aluminum (Al), tantalum (Ta) and niobium (Nb) in addition to the above-mentioned elements.
• the portion of aluminum (Al) may be between 2 and 8 wt. %.
• tantalum (Ta) is included in a proportion of 1 to 8 wt. %
• niobium (Nb) is included in a proportion of 0.1 to 2 wt. %.
• the solder alloy may include hafnium (Hf) in a proportion of 1 to 5 wt. %.
• hafnium may have a positive effect on the wetting and flow properties of the molten solder alloy and the oxidation-resistance of the repaired regions of the respective component.
• the portion of hafnium (Hf) is limited to the specified maximum value of 5 wt. % in order to limit the portion of the hafnium-containing hard phases in the soldered regions, which have an embrittling effect.
• the solder alloy may include silicon (Si) in a proportion of 0.1 to 1 wt. %.
• silicon (Si) is able to support and strengthen the melting point-reducing effect of the palladium (Pd), yttrium (Y) and boron (B), without increasing the boride phase portion in the repaired regions of the component.
• the solder alloy may have the following composition:
• the solder alloy may be particularly suitable for use in repairing guide blades of an aircraft engine, the guide blades being made either from a polycrystalline or a directedly solidified or monocrystalline alloy. Following the repair of the relevant regions of the gas turbine using the solder alloy, the soldered regions may have mechanical properties that correspond as much as possible to the material of the undamaged guide blade.
• the solder alloy is adapted specifically for the purpose of repairing engine components.
• the solder alloy may have optimized melting properties, flow properties and wetting properties as well an optimized ability to fill cracks.
• solder alloys A2, A3, A5 and A10 are compared.
• Table 1 Compositions of the solder alloys, concentrations in percentages by weight.
• Solder alloy Ni Cr Co Mo Al Ta Nb Y Hf Pd B A2 Bal. 10 10 4 4 2 1 0.5 4 4 1.8 A3 Bal. 10 10 4 4 2 1 0 0 4 1.8 A5 Bal. 10 10 4 4 2 1 0.5 0 0 1.8 A10 Bal. 10 10 4 4 2 1 0 4 0 1.8
• Table 2 shows the solidus and liquidus points of the examined solder alloys A2, A3, A5 and A10 determined by the DSC analysis. TABLE 2 Melting Ranges of the Solder Alloys Solder alloy T solidus/° C. T liquidus/° C. A2 1059 1196 A3 1010 1254 A5 1039 1249 A10 1068 1244
• the solidus and liquidus point listed in Table 2 illustrate the effect of the melting point-lowering elements Y and Pd used in addition to the element boron.
• Solder alloy A5 includes 0.5 wt. % of Y, but no Pd. Compared to A10, A5 has a reduced solidus temperature of 1039° C., although at 1249° C. its liquidus temperature is even somewhat higher than A10.
• a similar effect occurs in A3, which includes Pd at 4 wt. %, but no Y.
• both the solidus temperature (1059° C.) as well as the liquidus temperature (1196° C.) are reduced as compared to A10.
• the combination of the two alloy elements yttrium and palladium and their use, in addition to boron, as melting point-reducers in the solder alloy may be particularly advantageous.
• soldering temperature of the solder alloy described here is adjusted to the different solution annealing temperatures of the polycrystalline or directedly solidified or monocrystalline alloys.
• the multi-component soldering system includes the solder alloy, as already described above, and additionally of at least one additive material.
• the multi-component soldering system is obtained by mixing the solder alloy and the additive material, the mixing not having to be limited to the powdery components.
• additive materials namely, a metal powder, which in addition to nickel (Ni) also include one or more of the following elements:
• the additive material may have the following composition:
• the mechanical properties of the multi-component soldering systems made up of the solder alloy and the additive material may ensure that the solder structures in the repaired regions have, on the basis of their static and cyclical strength, a sufficiently high resistance with respect to the thermal and mechanical stresses in the gas turbines.
• solder alloy A2 is mixed with an additive material M1 at a mixture ratio of 1:1 (percentage by weight), M1 having the following composition:
• the hot tensile tests are conducted at a temperature of 871° C. ⁇ 3° C. Using a radiation furnace, the specimens are heated such that a homogeneous temperature distribution may be ensured across the entire sample. The tests are conducted in a servohydraulic machine. The extension rate may be 0.93 mm/min such that the tests must be classified as displacement-controlled.
• Table 3 shows the averages of hot tensile strengths (UTS) as well as the UTS values of the nickel-based alloys René-80 (polycrystalline) and DS René-142 (directedly solidified) as basic material data.
• UTS hot tensile strengths
• Table 3 shows that multi-component soldering system A2/M1 has remarkably good hot tensile properties.
• the hot tensile strength (UTS) of A2/M1 corresponds to the value of the base material René-80, which corresponds to a UTS value of 75% of DSR142. Even at a gap width of 0.5 mm and 1.0 mm, 80% (with respect to René-80) or 60% (with respect to René-142) of the hot tensile strength (UTS) are still achieved.
• the hot tensile tests provide guide values for the strength properties of the solder structures.
• the results of the LCF tests are more meaningful since they more closely reflect the actual thermomechanical alternating stress of the gas turbine components.
• the test temperature of the LCF tests is 982° C.+/ ⁇ 10° C., the flat specimens made of the DS alloy René-142 heated inductively.
• the flat tensile specimens have a cross section of 9.53 ⁇ 1.55 mm and a measuring path of 12.7 mm.
• the test is conducted as an axial, force-controlled tensile threshold test having a sinusoidal stress characteristic. For this purpose, 20 cycles/min at a ratio of stress amplitude/average stress of 0.95 are applied to the specimen.
• Average values are in Table 4. TABLE 4 LCF data (average values) of the multi-component soldering system A2/M1 for different gap widths and maximum voltages.
• Soldering system Gap width/mm Max. voltage/MPa Load changes A2/M1 0.25 152 50244 173 6729 207 4626 241 702 A2/M1 0.5 152 9146 173 11785 241 949 A2/M1 1.0 152 9679 173 4406 207 842 241 454 René - 142 DS 311 13243 345 7369 380 2793 414 1283 René - 80 283 5000 276 7000 262 10000 255 30000
• Table 4 shows that multi-component soldering system A2/M1 has remarkably good fatigue properties.
• the LCF tests show a dependency of the fatigue or tensile threshold strength on the gap width of the solder structures.
• the fatigue strength of the A2/M1 solder structures for gap widths of 0.26 mm and 0.5 mm amounts to 65-70% of the value of the René-80 base material or 50-55% of the value of the René-142 base material.
• a gap width of 1.0 mm only a low decline to 60% (with respect to René-80) or 48% of the fatigue strength of the base material (with respect to René-142) is ascertained.
• solder alloy hereof or the multi-component soldering system hereof, a method may be provided for processing, e.g., repairing, workpieces, that is, for processing guide blades of an aircraft engine.
• the workpieces may be manufactured from a polycrystalline or directedly solidified or monocrystalline alloy.
• the method is based on high-temperature diffusion soldering using the solder alloy hereof or using the multi-component soldering system hereof. This is a repair method.
• the high-temperature diffusion soldering occurs under the following conditions:
• the high-temperature diffusion soldering may be followed by the following heat treatment: Heating under vacuum or protective gas to a temperature of 1065-1093° C. with a subsequent holding time of approximately 240 min, this, e.g., occurring in the context of a coating process.
• the high-temperature diffusion soldering may be followed by the following heat treatment: heating under vacuum or protective gas or ambient atmosphere to a temperature of 871-927° C. with a subsequent holding time of 60-960 min, this, e.g., occurring in the context of an aging process.
• solder alloy and of the multi-component soldering system is not limited to pure repair methods. Rather, the solder alloy and the multi-component soldering system are generally also applicable for joining processes. Due to the mixing ratio of the solder alloy and possibly additive materials optimized for repair purposes, however, the use in the repair of guide blades of an aircraft engine may be particularly advantageous.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Chemically Coating (AREA)

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• 2003
  • 2003-12-04 DE DE10356562A patent/DE10356562A1/de not_active Withdrawn
• 2004
  • 2004-11-13 EP EP04819576A patent/EP1702081B1/de not_active Not-in-force
  • 2004-11-13 WO PCT/DE2004/002516 patent/WO2005054528A1/de active IP Right Grant
  • 2004-11-13 DE DE502004006362T patent/DE502004006362D1/de active Active
  • 2004-11-13 JP JP2006541792A patent/JP4842140B2/ja not_active Expired - Fee Related
  • 2004-11-13 US US10/581,778 patent/US20070175546A1/en not_active Abandoned
  • 2004-11-13 AT AT04819576T patent/ATE387513T1/de not_active IP Right Cessation

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