Abstract: An Fe—Ni—Cr alloy formulated to contain a strengthening phase that is able to maintain a fine grain structure during forging and high temperature processing of the alloy. The alloy contains a sufficient amount of titanium, zirconium, carbon and nitrogen so that fine titanium and zirconium carbonitride precipitates formed thereby are near their solubility limit in the alloy when molten. In the production of an article from such an alloy by thermomechanical processing, a dispersion of the fine titanium and zirconium carbonitride precipitates form during solidification of the melt and remain present during subsequent elevated processing steps to prohibit austenitic grain growth.

Abstract: A method and system for determining the fiber volume fraction of a composite structure. The system includes a unit for ultrasonically determining the porosity volume fraction in the article, and a unit for calculating the volume fraction of the fibrous reinforcement material in the article based on the porosity volume fraction in the article and the mass densities of the article and the fiber and matrix materials within the article. The method entails determining the mass density of the article, obtaining the mass densities of the fiber material and the matrix material, ultrasonically determining the porosity volume fraction in the article, and then calculating the volume fraction of the fibrous reinforcement material in the article based on the porosity volume fraction in the article, the mass density of the article, the mass density of the matrix material, and the mass density of the fiber material.

Abstract: A method for metallurgically bonding a stator bar to a coupling to reduce the incidence of leak paths resulting from corrosion. The stator bar comprises strands through which a liquid coolant can flow. Adjacent ends of the strands are received in an interior cavity of the coupling through an opening in the coupling. A joining material is provided on a first portion of the stator bar within the coupling opening and adjacent the ends of the strands. The first portion is heated to melt the joining material. At essentially the same time, a second portion of the stator bar outside the coupling is also heated. Once the joining material is suitably molten, the first portion is allowed to cool while the second portion remains heated, thereby causing the joining material nearest the ends of the strands to solidify first.

Abstract: A method of processing a rotor. The rotor is formed by casting an ingot to have first and second regions formed of different alloys that intermix during casting to define a transition zone therebetween. The ingot is forged to yield a rotor forging that contains axially-aligned first and second alloy regions and a transition zone therebetween. A three-dimensional approximation of the transition zone is generated, which can be used to predict the effects of the transition zone on the dynamic performance of a rotor machined from the forging.

Abstract: An apparatus and process for depositing an overlay weld on a boiler tube panel comprising a plurality of tubes with adjacent tubes joined together with membranes therebetween, and then straightening the panel in response to bowing that occurs as a result of depositing the overlay weld. The apparatus generally comprises an overlay welding apparatus that deposits an overlay weld on a surface of a boiler tube panel, and a straightening apparatus for straightening the panel following deposition of the overlay weld. The straightening process entails placing the boiler tube panel between two members, and the pressing a portion of the panel therebetween.

Abstract: An insulated stator bar and method of applying an outer insulation to a bare stator bar to form the insulated stator bar. The outer insulation surrounds a perimeter of the bare bar and extends along a longitudinal length of the bar. The outer insulation comprises at least one extruded member, e.g., a single extruded member, two individual extruded members, etc., containing an electrical insulation material. The at least one extruded member comprises an opposing pair of edges parallel to the longitudinal length of the bar. The edges are attached together so that the perimeter of the bar is entirely enclosed by the at least one extruded member.

Abstract: A method and system for ultrasonically inspecting turbine wheels and other disk-shaped articles having a central opening and multiple secondary openings radially spaced outward from the central opening. At least one ultrasonic transducer is placed in at least one of the secondary openings of the wheel. The transducer is configured and oriented to perform a pulse-echo diagnostic technique on the wheel by emitting ultrasonic signals that intersect radials of the wheel at angles of approximately ninety degrees to the radials. The ultrasonic signals intersect the radials at points so that a plurality of points are located on a plurality of radials. The points define a locus of points through the volume of the wheel between the central opening and the secondary opening, such that the volume is inspected for defects. The transducer receives ultrasonic signals that are reflected from one or more points when a defect is encountered.

Abstract: Castable and weldable nickel-base alloys that exhibit a desirable balance of strength and resistance to corrosion and oxidation suitable for gas turbine engine applications. The alloy contains, by weight, about 10% to about 25% cobalt, about 20% to about 28% chromium, about 1% to about 3% tungsten, about 1.6% to about 3.8% aluminum, about 0.4% to about 1.5% titanium, where the sum of aluminum and titanium is about 1.8% to about 5.0%, about 0.5% to about 1.5% columbium, 0.5% to about 1.5% tantalum, about 0.001% to about 0.025% boron, about 0.05% maximum zirconium, about 0.02% to about 0.15% carbon, with the balance essentially nickel and incidental impurities. The alloy may more preferably contain about 2.8% to about 3.8% aluminum where the sum of aluminum and titanium is about 3.0% to about 5.0%, or about 1.6% to about 2.8% aluminum, where the sum of aluminum and titanium is about 1.8% to about 4.3%.

Abstract: A monolithic rotor comprising first and second rotor regions axially aligned within the monolithic rotor and a transition zone therebetween. The first and second rotor regions are formed of different alloys and the transition zone having a composition that differs from and varies between the first and second rotor regions. The first rotor region is located within a high pressure region of the monolithic rotor and is formed from an alloy chosen from the group consisting of CrMoV low alloy steels, martensitic stainless steels containing about 11 to about 14 weight percent chromium, Fe—Ni alloys, and nickel-base alloys. The second rotor region is located within a low pressure region of the monolithic rotor and is formed from an alloy chosen from the group consisting of NiCrMoV low alloy steels and martensitic stainless steels containing about 11 to about 14 weight percent chromium.

Abstract: A process of selectively removing layers of a thermal barrier coating system from a surface of a component. A thermal barrier coating system of interest comprises an inner metallic bond coat layer, an outer metallic bond coat layer that is less dense than the inner metallic bond coat layer, and a ceramic topcoat having vertical cracks therethrough. The process involves directing a jet of liquid at the component to simultaneously remove the topcoat and the outer metallic bond coat layer without removing the inner metallic bond coat layer.

Abstract: A method and system for inspecting a turbine wheel having axial slots along a perimeter thereof that are configured for mating with and securing airfoil members to the perimeter of the wheel, and an annular slot that intersects the axial slots. The method and system make use of one or more eddy current probes that are placed in the annular slot to electromagnetically inspect the annular slot and at least one of the axial slots for cracks in surfaces thereof. The probe is part of a probe assembly that includes a mounting member for engaging at least one of the annular and axial slots. The probe assembly is operable to maintain the probe at a fixed distance from surfaces of the annular slot as the probe travels through the annular slot.

Abstract: A power generation plant comprising a power generating unit that includes at least one first generator, such as an induction generator, coupled to at least one synchronous generator having a rotor with a superconducting (SC) coil. The induction generator and the SC synchronous generator are coupled so that the SC synchronous generator supplies the induction generator with reactive power. Sufficient reactive power is preferably generated by the SC synchronous generator to meet the demand of the induction generator for VARs, as well as permit the induction generator to have a relatively large airgap.

Abstract: A method of repairing a thermal barrier coating (16) on a component (10) designed for use in a hostile thermal environment, such as turbine, combustor and augmentor components of a gas turbine engine. The method more particularly involves repairing a thermal barrier coating (16) on a component (10) that has suffered localized spallation (20) of the thermal barrier coating (16). After cleaning the surface area (22) of the component (10) exposed by the localized spallation (20), a ceramic paste (24) comprising a ceramic powder in a binder is applied to the surface area (22) of the component (10). The binder is then reacted to yield a ceramic-containing repair coating (26) that covers the surface area of the component and comprises the ceramic powder in a matrix of a material formed when the binder was reacted.

Abstract: A nickel-base alloy consists of, by weight, about 15.0 to about 17.0% chromium, about 7.0 to about 10.0% cobalt, about 1.0 to about 2.5% molybdenum, about 2.0 to about 3.2% tungsten, about 0.6 to about 2.5% columbium, less than 1.5% tantalum, about 3.0 to about 3.9% aluminum, about 3.0 to about 3.9% titanium, about 0.005 to about 0.060% zirconium, about 0.005 to about 0.030% boron, about 0.07 to about 0.15% carbon, the balance nickel and impurities. Preferably, columbium is present in an amount greater than tantalum. Tantalum can be essentially absent from the alloy, i.e., only at impurity levels.

Abstract: A method of forming a welded component by electron beam welding, and the resulting welded assembly. The method is particularly directed to the welding of a component whose subcomponents are formed of dissimilar metals, with the result that an electron beam used to weld the subcomponents is prone to being deflected away from the contact surface interface between the subcomponents and into one of the subcomponents as it passes through the interface. The method is also suitable for welding applications in which the interface between the subcomponents has an arcuate shape. The method involves magnetically steering the electron beam so that the beam is caused to follow the desired path through the interface.

Abstract: The method of repairing a metal alloy component, and the resulting repaired component. The method involves machining the component surface to remove a defect, and then placing in the resulting surface cavity a filler insert whose size and shape are predetermined so that the welding operation can be carried out to completely melt the insert while minimizing the melting of the component immediately surrounding the insert. As such, minimum mixing occurs between the materials of the insert and the component, thereby reducing the risk of cracking following the welding operation.

Abstract: A retaining system for field winding end turns of a rotor, such as for a dynamoelectric machine. The rotor has an outer peripheral surface, radial end surfaces, axially-extending slots in the peripheral surface, and field windings in the slots. The field windings axially project from the end surfaces of the rotor and are connected outside of the slots by field winding end turns. The end turns are surrounded by the retaining system, which includes a shield member surrounding the end turns and a retainer member surrounding to the shield member. The shield member has flanges received in the slots along with the field windings. Fastening features engage the flanges to inhibit axial movement of the retaining system.

Abstract: An assembly that includes a CMC article, and a method of forming the assembly, so as to reduce the likelihood during a transient thermal condition of the CMC article becoming interlocked with the worn shank of a fastener used to secure the article to its support structure. The CMC article has oppositely-disposed first and second surfaces, a hole through the article and intersecting the first and second surfaces so as to define oppositely-disposed first and second openings at the first and second surfaces, respectively, and continuous chamfers along the entirety of the first and second openings. The assembly further includes a support structure adjacent the article, and a fastener received in the hole of the CMC article and securing the CMC article to the support structure. The location of the chamfers at the perimeter of each opening eliminates a relatively sharp edge that could interlock with the worn shank of the fastener during a thermal excursion.

Abstract: A seal assembly and method for a turbomachine having a rotary member and a stationary member circumscribing the rotary member. The seal assembly comprises an annular-shaped platform on the rotary member so as to be disposed at an outer circumferential region thereof. The platform is supported radially outward from the rotary member so as to project beyond axially-adjacent regions of the rotary member. The platform has a contact region radially separated from the rotary member by a cavity. A sealing member is disposed at a radially inward region of the stationary member, with a portion of the sealing member in rubbing contact with the contact region.

Abstract: An electrical machine stator core and method for reducing electromagnetic losses and the consequent heating of the core. The stator core makes use of laminations made from an iron-aluminum alloy at the core-ends of the core, while laminations between the core-ends are formed of a ferromagnetic alloy different from the iron-aluminum alloy. Use of iron-aluminum alloy laminations at the core-ends makes possible a relatively simple technique for generator uprate, by removing laminations located at the core-ends of the stator core, and then installing replacement laminations formed of the iron-aluminum alloy at the core-end, again with the result that the laminations located at the core-ends are formed of an Fe—Al alloy that is different from the alloy of the laminations between the core ends.