A component for a turbocharger can include a shaft made of a first material where the shaft includes a turbine wheel end and a shaft axis; a turbine wheel made of a second material where the turbine wheel includes a shaft end and a turbine wheel axis; a weld joint formed by solidification of at least a portion of a weld pool that includes the first material and the second material, where the weld joint joins the turbine wheel end of the shaft and the shaft end of the turbine wheel and where the weld joint includes an inner radial border and an outer radial border; a reservoir disposed radially inwardly of the inner radial border of the weld joint; and a solidified portion of the weld pool disposed in the reservoir. Various other examples of devices, assemblies, systems, methods, etc., are also disclosed.

A unit for a turbocharger can include a turbine wheel portion that includes a turbine wheel material and a turbine wheel axis; a shaft portion that includes a shaft material and a shaft axis; a first weld that includes a first average axial position over a first azimuthal span and first weld composition formed of a greater proportion of the turbine wheel material than the shaft material; and a second weld that includes a second average axial position over a second azimuthal span and second weld composition formed of a greater proportion of the turbine wheel material than the shaft material, where a sum of the first azimuthal span and the second azimuthal span is approximately 360 degrees, where the first average axial position differs from the second average axial position, and where the first weld composition differs from the second weld composition.

A unit for a turbocharger can include a turbine wheel portion that includes a turbine wheel material and a turbine wheel axis; a shaft portion that includes a shaft material and a shaft axis where the shaft material includes a molybdenum content less than 0.5 percent by weight; and a weld that includes a nail shape in cross-section where a head portion of the nail shape includes an axial dimension of approximately 1 mm or less and wherein a shank portion of the nail shape includes an axial dimension of approximately 0.4 mm or less.

A rotor disc having an enlarged radially outer rim defining a circumferentially-extending dovetail groove for housing the root portion of a rotor blade. The groove has a groove axis and the groove is unsymmetrical about the groove axis. For example, the dovetail groove may have a restricted radially outer opening extending to an enlarged radially inner bulb profile having a pair of axially opposed curved surfaces and the opposing curved surfaces may unsymmetrical about the groove axis.

A method of producing a rotor of a charging apparatus may include the steps of providing at least one compressor wheel and a turbine wheel. The compressor wheel and the turbine wheel may each include a bearing section having a radial bearing surface at a longitudinal end for mounting a bearing housing. At least one of the radial bearing surfaces may include a radial oversizing corresponding to a rotationally asymmetric geometry between at least the bearing section of the compressor wheel and the bearing section of the turbine wheel. The method may include the step of assembling the compressor wheel, the turbine wheel and each bearing section together to form a unitary structure, and machining the at least one of the radial bearing surfaces to reduce the respective radial oversizing until each of the radial bearing surfaces are rotationally symmetrical with respect to each other.

A shaft element of a turbomachine, in particular of a combined steam turbine, having at least two shaft subsegments integrally joined to each other by means of a weld, wherein different chemical and mechanical properties are inherent to the shaft subsegments, wherein the weld has a ratio of welding layer height to weld width of 1:14 to 1:2. A method produces a shaft element composed of two different materials having at least two shaft subsegments integrally joined to each other by means of a weld.

A method for assembling a section of a gas turbine engine is disclosed. The method involves aligning a vane ring with a first rotor hub such that a row of vanes on the vane ring is adjacent a first row of blades of the first rotor hub, and aligning a second rotor hub with the vane ring such that a second row of blades of the second rotor hub is adjacent the row of vanes and the row of vanes is axially between the first row of blades and the second row of blades. The first hub and the second hub are then non-mechanically bonded together.

A tool system for stress relieving a turbocharger turbine wheel longitudinally welded to a hardened rotor shaft. The shaft has a journal bearing region and a turbine-end body forming an A datum surface for receiving an axial bearing. The tool system includes an induction coil and an electronic oscillator, and a tool. The tool forms an opening configured to receive the rotor shaft such that the journal bearing region of the shaft extends into the tool housing while the A datum surface adjoins an end of the tool housing. The induction coil is positioned around the turbine-end body. The housing forms an annular cooling chamber surrounding the journal bearing region of the shaft. The housing forms an inlet passage to provide cooling fluid to the annular chamber, and an outlet passage to remove cooling fluid from the annular chamber.

A turbocharger wheel (4) and shaft (1) assembly exhibits a frustoconical geometry of welding zone contact surfaces extending to the outer circumference of the shaft (1). This frustoconical geometry not only allows continuous centering of the parts (1, 4) during joining, it also eliminates the problem of stress propagation along a plane. The location of the electron beam is shifted so that only the radially outer segment of the frustoconical contact surface is joined by welding, leaving a radially inner unmelted and unfused zone for maintaining firm contact of the oblique surfaces.

The present disclosure provides a rotary friction welding process including: providing an outer axisymmetric workpiece having a front first annular weld surface at a radially inward extent and a rear first annular weld surface at a radially inward extent; providing a front inner axisymmetric workpiece, the front inner workpiece having a front second annular weld surface at a radially outward extent of the front inner workpiece; providing a rear inner axisymmetric workpiece, the rear inner workpiece having a rear second annular weld surface at a radially outward extent of the rear inner workpiece; and rotary welding the workpieces together.