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 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 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.