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.