Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
  • F01D25/005—Selecting particular materials
• • 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°C
  • B23K35/3033—Ni as the principal constituent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
  • B23P6/00—Restoring or reconditioning objects
  • B23P6/002—Repairing turbine components, e.g. moving or stationary blades, rotors
  • B23P6/007—Repairing turbine components, e.g. moving or stationary blades, rotors using only additive methods, e.g. build-up welding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/013—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C37/00—Cast-iron alloys
  • C22C37/04—Cast-iron alloys containing spheroidal graphite
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
  • F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
  • F01D25/24—Casings; Casing parts, e.g. diaphragms, casing fastenings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/005—Repairing methods or devices
• • 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
  • B23K2101/00—Articles made by soldering, welding or cutting
  • B23K2101/001—Turbines
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2251/00—Treating composite or clad material
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/20—Manufacture essentially without removing material
  • F05D2230/23—Manufacture essentially without removing material by permanently joining parts together
  • F05D2230/232—Manufacture essentially without removing material by permanently joining parts together by welding
  • F05D2230/233—Electron beam welding
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/30—Manufacture with deposition of material
  • F05D2230/31—Layer deposition
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/80—Repairing, retrofitting or upgrading methods
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/11—Iron
  • F05D2300/111—Cast iron
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/17—Alloys
  • F05D2300/171—Steel alloys

Definitions

• the present disclosure relates generally to turbine or turbomachine casing components and more specifically to the material composition, construction and repair methods therefor.
• Nodular cast iron such as ductile cast iron grade GGG40 (DIN)
• DIN ductile cast iron grade GGG40
• Casings are usually large and cast in non-serial production. This often leads to casting defects, as the process is not fully optimized. Furthermore, the casting can be damaged during machining due to damaged cutting tools or incorrect process settings.
• Turbine casings are exposed to high mechanical loads during operation. Vibrations can lead to material fatigue and thus to the formation of cracks. Thermal stresses occur during start and stop sequences of the gas turbine. These temperature fluctuations and the concomitant expansion and contraction of the housing/casing can contribute to the formation of cracks and promotes the spread of existing cracks. If the cracks exceed design limits, the casings may be scrapped and new casings are required, which leads to high cost not only due to the manufacturing cost but also due to the delay in starting operation of the turbine. If possible, the defective castings are repaired mechanically and less often by welding due to the difficulty in the process. The welds often crack during the welding process, upon cooling or shortly during service time.
• Hot welding comprises of depositing nodular cast iron material in the defective area. This process requires high preheat, 594°C (1,100°F) or higher, that may lead to deformation of the casing. For that reason, hot welding cannot be performed on finish machined parts.
• Cold welding involves using welding wire or electrode made of Ni, Ni-Fe or Ni-Fe-Mn alloy. The Ni alloy usually have lower strength than nodular cast iron. Ni-Fe and Ni-Fe-Mn alloys match the strength of nodular cast iron but those alloys have very low coefficient of thermal expansion (CTE). It makes the welding easier, however in large repairs will likely lead to failure during thermal cycling of the casing due to the increased stresses from the CTE mismatch.
• CTE coefficient of thermal expansion
• a casing component is part of a gas or steam turbine.
• the casing component includes a base made of nodular cast iron, and a repaired region in the base.
• the repaired region includes a butter layer applied on the base and a filling layer applied on the butter layer.
• a method for repairing a casing component that is part of a gas or steam turbine includes a step for applying a butter layer on a base material.
• the butter layer is applied with a first interpass temperature.
• a second step applies a fill layer on the butter layer, and the fill layer is applied with a second interpass temperature.
• the first interpass temperature is lower than the second interpass temperature.
• FIG. 1 illustrates a sectional view of a portion of a steam turbine to which an exemplary aspect of the disclosure may be applied;
• FIG. 2 illustrates an expanded view of a section of FIG. 1 showing a repaired region of an exemplary aspect
• FIG. 3 illustrates a sectional view of a repaired region that includes one or more butter layers and a fill layer, according to an exemplary aspect
• FIG. 4 illustrates a flowchart for a method for repairing a casing component that forms part of a flow path in a steam or gas turbine.
• FIG. 1 illustrates a section of an axial flow steam turbine to which exemplary embodiments may be applied. Shown is a casing component 10, a steam flow path 22 and a last stage 20 comprising a stationary vane row 16 and a downstream rotating blade row 18.
• the casing component 10 forms a radial outer limit of the axial steam flow path 22, thereby in part defining the axial steam flow path 22.
• the casing component 10 may additionally provide a carrier means for carrying one or more stationary vane rows 16.
• the casing component 10 may form only a portion of the casing of the steam turbine. That is, the casing component 10 is one component of several components. Alternatively, the casing component 10 may define the casing of the steam turbine.
• stationary vane rows 16 that are each followed downstream, that is an axial direction corresponding to the nominal flow direction or working fluid through the flow path 22, by rotating blade rows 18.
• the last vane row 16 / blade row 18 combination contained within the flow path 22 defines the last stage 20 of the turbine.
• the casing component 10 comprises a base 12 made of nodular cast iron (or ductile iron) and a repaired region 14 that is located the base 12 in a region exposed to the steam flow path 22.
• the repaired region 14 consists of a butter layer underlying a filler or fill layer.
• the repaired region 14 is located in a region radially between the rotating blade row 18 and the base 12, wherein the radial direction is defined at the direction perpendicular to the rotational axis of the rotating blade row 18.
• the repaired region 14 may be located anywhere in or on casing 10.
• FIG. 3 illustrates a sectional view of a repaired region 14 that includes one or more butter layers 32 and a fill layer 34, according to an aspect of the present disclosure.
• the substrate or base 12 is comprised of nodular cast iron, which may also be referred to as ductile iron, ductile cast iron, spheroidal graphite iron, or spheroidal graphite cast iron.
• nodular cast iron which may also be referred to as ductile iron, ductile cast iron, spheroidal graphite iron, or spheroidal graphite cast iron.
• graphite In ductile or nodule cast irons, graphite is in the form of spheres or nodules rather than flakes as in grey iron. In grey iron, sharp graphite flakes create stress concentration points within the metal matrix.
• region 14 may take the form of a cavity or recess, and this recess may be further excavated to provide a stable base on which to build the repair.
• the substrate or component may then be subjected to an optional pre-heating step, where the substrate is heated to a maximum of 204°C (400°F). This optional heating step is to facilitate the removal of undesired moisture levels.
• each butter layer 32 may be comprised of nickel, a nickel alloy, a nickel iron alloy or a nickel iron manganese alloy.
• the butter layers 32 are relatively soft and do not form a brittle microstructure due to the large carbon pickup from the cast iron base 14.
• the butter layers 32 are preferably applied with low heat input, an interpass temperature less than 204°C (400°F) and low to no preheat.
• Interpass temperature is the temperature of the weld site at which subsequent weld runs are deposited, and a specific maximum interpass temperature is selected to control weld metal microstructural development and to minimize the risk of solidification or liquation cracking for austenitic nickel and nickel alloys.
• a welder must wait for the weld site to cool before making another pass, if the local temperature is above the desired interpass temperature.
• a fill layer 34 is applied on the butter layers 32.
• the fill layer 34 may be comprised of
• a low carbon steel material or welding electrode is one in which the carbon content does not exceed about 0.25% and the manganese content does not exceed about 1.65%.
• the carbon steel material has a similar mean coefficient of thermal expansion as the nodular cast iron ensuring that the welded region will expand and contract at the approximately same rate as base material during thermal cycles of the casing.
• the fill layer 34 may be applied in one or multiple passes until a desired profile is obtained. An advantage to using the fill layer 34 is that it may deposited with a higher rate than the butter layers 32 and with higher interpass temperature, up to 400°C (750°F).
• the butter layers 32 may be deposited by using a welding electrode or welding wire.
• a material composition (by weight) for a welding/buttering electrode is iron (Fe) balance, nickel (Ni) about 56.8%, carbon (C) about 1.18%, silicon (Si) about 0.49% and manganese (Mn) about 0.49%.
• Mechanical properties of a resulting weld metal are a tensile strength of about 480 N/mm 2 or 70 ksi, elongation of about 18% and a hardness of about 170 to 190 HV or 85-90 HRB.
• welding/buttering electrode material compositions are: Ni balance, Fe 0.80% to 5.3%, C 0.43% to 1.2%, manganese 0.25% to 2.5%, Si 0.32% to 0.70%.
• a nickel or nickel alloy welding/buttering electrode may also be employed in specific applications for the butter layers 32.
• a suitable Ni alloy has a composition of at least 85% Ni, a Ni-Fe alloy has 45% - 75% Ni with the balance Fe, and a Ni-Fe-Mn alloy has a minimum of 35% Ni, 10% to 15% Mn, and the balance Fe.
• the nickel alloys may have trace or small amounts of C, Si, Mn, Cu, A1 and up to 3% strong carbide forming elements.
• FIG. 4 illustrates a flowchart for a method 40 for repairing a casing component that forms part of a flow path in a turbine.
• the turbine may be a gas turbine or a steam turbine.
• the method includes a preparing step 42 that prepares the base material.
• the base material 10 is ductile cast iron or nodular cast iron.
• the preparing step 42 may include identifying a region needing to be repaired or serviced, excavating this region and cleaning the region. Excavating may entail removing loose base material or profiling the shape of the region to a desired shape for subsequent repair/service.
• an applying step 44 applies one or more butter layers 32 to the base material 10.
• the butter layer(s) 32 are applied on the base material 10 with a first preheat temperature and a first interpass temperature.
• the first preheat temperature may be from about room or ambient temperature up to 204°C (400°F).
• the interpass temperature ranges from ambient to 204°C (400°F).
• a second applying step 46 applies one or more fill layers 34 on the butter layer 32.
• the fill layer 34 is applied with a second interpass temperature that ranges between ambient to 400°C (750°F).
• the first heat input level may be lower than the second heat input level.
• the fill layer 34 may also be applied at a second deposition rate which is higher than the first deposition rate.
• a finishing step 48 may be used to machine or polish the surface of the repaired area to a desired shape profile or surface roughness.
• Coupled to another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being“directly on,”“directly engaged to”,“directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present.
• Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g.,“between” versus“directly between,”“adjacent” versus“directly adjacent,” etc.).
• the term“and/or” includes any and all combinations of one or more of the associated listed items.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Butt Welding And Welding Of Specific Article (AREA)
• Laminated Bodies (AREA)

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• 2019
  • 2019-04-17 EP EP19461528.2A patent/EP3725457B1/en active Active
  • 2019-04-17 PL PL19461528.2T patent/PL3725457T3/pl unknown
• 2020
  • 2020-04-13 KR KR1020217034835A patent/KR102845172B1/ko active Active
  • 2020-04-13 JP JP2021560674A patent/JP7520878B2/ja active Active
  • 2020-04-13 CN CN202080029001.2A patent/CN113692331A/zh active Pending
  • 2020-04-13 WO PCT/US2020/027893 patent/WO2020214514A1/en not_active Ceased
  • 2020-04-13 US US17/594,369 patent/US11708770B2/en active Active

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