Particularly in the production of shafts for turbomachines, for example turbo-compressors, steam turbines or gas turbines, shaft parts are often butt welded to one another end-on by bringing the two bar parts placed against one another into a melt in the region of the abutting ends by means of an electron beam passing into the join by means of an electron beam welding apparatus without further filler, which after cooling results in a joint. The main difficulty in relation to a radial seam welded by electron beam in the case of a shaft or any other bar material consists in the production of the flawless seam start and of the seam end. The seam start is to be understood as the region in which the electron beam is introduced and the seam end is to be understood as the region in which the electron beam is removed from the material. Further disturbances to the homogeneity of the material microstructure arise as a result of any instances of overwelding of the already welded weld seam in the event that regions of action of the electron beam overlap in the material during different welding operations. Additional difficulties arise given small shaft diameters or small bar thicknesses as a result of the accumulation of heat in the region of the center of the component, as a result of which flawless welding is not possible in the region of overlap and in the region of removal of the welded joint.
Even the most complicated modern electron beam control systems are unable to prevent the welding defects described completely.