Abstract: A damper pin for a turbine bucket includes an elongated main body portion of substantially uniform cross-sectional shape having opposite ends, one only of said opposite ends coated with a corrosion and oxidation-resistant coating.

Abstract: A weld process cuitable for repairing precipitation-strengthened superalloys, and particularly gamma prime-strengthened nickel-based superalloys. The process entails forming a weldment in a cavity present in a surface of an article formed of a precipitation-strengthened superalloy. The cavity has a root region and a cap region between the root region and the surface of the article. A solid body formed of a superalloy composition is placed in the root region of the cavity so as to occupy a first portion but not a second portion of the root region. A first filler material formed of a solid solution-strengthened superalloy is then weld-deposited in the second portion of the root region. Subsequently, a second filler material formed of a precipitation-strengthened superalloy is weld-deposited in the cap region of the cavity.

Abstract: Methods and apparatus for cooling rotor blades of a gas turbine are provided. The turbine blade has an airfoil connected to the platform and a dovetail extending from the platform. A main cooling circuit extends through the dovetail and into the airfoil. The main cooling circuit includes an exit for main cooling flow from the airfoil to exit out through the dovetail. In one aspect, the method includes the steps of extracting a portion of the coolant flowing through the main cooling circuit into a platform cooling circuit. After cooling a portion of the platform, the platform cooling flow splits with one portion of the flow rejoining the main cooling circuit and is used to cool the airfoil. The rest of the platform cooling flow continues to cool the platform and then returns to the main cooling circuit to flow through the exit.

Abstract: A damper pin for a turbine bucket includes an elongated main body portion of substantially uniform cross-sectional shape having opposite ends, one only of said opposite ends coated with a corrosion and oxidation-resistant coating.

Abstract: The welding process includes in a single pass heating and melting a filler wire of gamma-prime strengthened nickel-based superalloy along a major portion of the weld followed by a weld using a solid solution strengthened nickel-based superalloy for the remaining portion of the weld pass. Both filler materials are particularly useful for welding a single crystal gamma-prime strengthened nickel-based superalloy based metals.

Abstract: An open cooling circuit for a gas turbine bucket wherein the bucket has an airfoil portion, and a tip shroud, the cooling circuit including a plurality of radial cooling holes extending through the airfoil portion and communicating with an enlarged internal area within the tip shroud before exiting the tip shroud such that a cooling medium used to cool the airfoil portion is subsequently used to cool the tip shroud.

Abstract: A core for use in casting a turbine bucket including serpentine cooling passages is divided into two pieces including a leading edge core section and a trailing edge core section. Wall thicknesses at the leading edge and the trailing edge of the turbine bucket can be controlled independent of each other by separately positioning the leading edge core section and the trailing edge core section in the casting die. The controlled leading and trailing edge thicknesses can thus be optimized for efficient cooling, resulting in more efficient turbine operation.

Abstract: A turbine bucket includes an airfoil portion having leading and trailing edges; at least one radially extending cooling passage within the airfoil portion, the airfoil portion joined to a platform at a radially inner end of the airfoil portion; a dovetail mounting portion enclosing a cooling medium supply passage; and, a crossover passage in fluid communication with the cooling medium supply passage and with at least one radially extending cooling passage, the crossover passage having a portion extending along and substantially parallel to an underside surface of the platform.

Abstract: A core for use in casting a turbine bucket including serpentine cooling passages is divided into two pieces including a leading edge core section and a trailing edge core section. Wall thicknesses at the leading edge and the trailing edge of the turbine bucket can be controlled independent of each other by separately positioning the leading edge core section and the trailing edge core section in the casting die. The controlled leading and trailing edge thicknesses can thus be optimized for efficient cooling, resulting in more efficient turbine operation.

Abstract: An open cooling circuit for a gas turbine bucket wherein the bucket has an airfoil portion, and a tip shroud, the cooling circuit including a plurality of radial cooling holes extending through the airfoil portion and communicating with an enlarged internal area within the tip shroud before exiting the tip shroud such that a cooling medium used to cool the airfoil portion is subsequently used to cool the tip shroud.