METHOD FOR WELDING ROTORS FOR POWER GENERATION

The invention relates to a method for welding rotors for power generation (gas turbines, steam turbines, generators), which comprise a plurality of rotor discs arranged along a rotor axis, said method comprising the steps of: providing forged and NDT tested rotor discs (26); machining said discs (26) for weld seam preparation, said weld seam preparation comprising an inner narrow TIG welding gap and an adjoining outer SAW welding gap; stapling the discs (26) on top of each other; checking the run-out of the stapled discs (26) relative to each other and as a whole and, if necessary, adjusting the staple; melting the root of the weld without weld filler using TIG welding; increasing the weld height by narrow gap TIG welding with parent metal weld filler to allow tilting of the rotor in horizontal position. tilting the rotor in horizontal position; finalizing the welding by filling the outer SAW welding gap using SAW welding; and checking the welds of the rotor by NDT using ultrasonic testing. A costly and time-consuming additional machining step is avoided by said weld seam preparation machining step comprising preparing an optimized transition geometry of TIG welding gap to SAW welding gap transition with a first opening (28) having a first opening angle and a second opening (29) having a second opening angle greater than said first opening angle.