Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method can include co-axially locating a turbine wheel and a shaft where a force applicator applies an axially directed force to the turbine wheel, where the turbine wheel transfers at least a portion of the force to shaft and where a rotatable shaft collet supports the shaft; rotating the rotatable shaft collet; energizing at least one laser beam; and, via the at least one laser beam, forming a weld between the turbine wheel and the shaft.

Abstract: A system can include a controller; a force applicator; a rotatable shaft centering collet; a drive mechanism that rotates the rotatable shaft centering collect; and a laser beam unit.

Abstract: 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.

Abstract: A system can include a controller; a force applicator; a rotatable shaft centering collet; a drive mechanism that rotates the rotatable shaft centering collect; and a laser beam unit.

Abstract: A method can include co-axially locating a turbine wheel and a shaft where a force applicator applies an axially directed force to the turbine wheel, where the turbine wheel transfers at least a portion of the force to shaft and where a rotatable shaft collet supports the shaft; rotating the rotatable shaft collet; energizing at least one laser beam; and, via the at least one laser beam, forming a weld between the turbine wheel and the shaft.

Abstract: 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.

Abstract: 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.

Abstract: A variable geometry turbocharger includes vanes disposed therein having an inner airfoil surface oriented adjacent a turbine wheel, and an outer airfoil surface oriented opposite and parallel to the inner airfoil surface. The vane includes first and second axial surfaces that are each positioned perpendicular to and interposed between the inner and outer airfoil surfaces. A vane leading edge is positioned along a first inner and outer airfoil surface junction, and a trailing edge is positioned along a second inner and outer airfoil surface junction. One or more of the first and second axial surfaces have a composite construction comprising a solid section that extends a distance from the leading edge towards the trailing edge, and a cored-out section that extends a distance from the trailing edge towards the leading edge.