Turbine rotor for an exhaust gas turbine and method for producing the turbine rotor

A method of producing a turbine rotor, the method comprising the following method steps:

• providing workpieces, including a turbine rotor wheel of a highly heat-resistant metal alloy, a rotor shaft of steel, and a closure plug;
• forming a central recess into one or both of an end face of the rotor shaft and an end face of a rotor wheel hub of the turbine rotor wheel;
• inserting the closure plug into the central recess of the rotor shaft end or the rotor wheel hub to form a closed, hollow cavity between the closure plug and a bottom of the recess and to form a planar surface comprised of the closure plug and a respective end face of the rotor shaft or of the rotor wheel hub;
• applying a brazing material to one of the end faces of the rotor wheel hub or the rotor shaft;
• bringing together and centrally aligning the turbine rotor wheel and the rotor shaft by clamping the workpieces in a suitable device, with the end faces of the rotor wheel hub and the rotor shaft lying directly opposite one another and with the brazing material positioned in a brazing gap in between;
• heating up the brazing material and the end face region of the rotor wheel hub and the rotor shaft at the brazing gap with an electron beam, up to a predetermined brazing temperature lying above a melting temperature of the brazing material;
• maintaining the brazing temperature over a predetermined time, by way of a controlled supply of energy by the electron beam;
• cooling down the workpieces and creating the brazed connection between the turbine rotor wheel and the rotor shaft;
• and
• releasing the turbine rotor from the device.

A turbine rotor for an exhaust gas turbine, the turbine rotor comprising:

• a turbine rotor wheel consisting of a highly heat-resistant metal alloy, said rotor wheel having a rotor wheel hub with an end face;
• a rotor shaft consisting of steel, said rotor shaft having a rotor shaft end with an end face facing toward said rotor wheel hub;
• one or both of said rotor shaft end and said rotor wheel hub having a central recess formed therein configured to act as a thermal choke at a transition between said rotor wheel and said rotor shaft;
• a closure plug disposed in a respective said recess to form a closed cavity in said recess and closing off said recess toward the respective said end face and to form a planar surface with the respective said end face;
• and
• a brazed connection forming a metallurgical bond connecting said rotor wheel hub and said rotor shaft end to one another, said brazed connection being formed between said end face of said rotor wheel hub and said end face of said rotor shaft, between said closure plug and said rotor wheel hub, and between said closure plug and said rotor shaft.