Method of making a high temperature - low temperature rotor for turbines

A method of forming a turbine rotor from separate rotor segments comprised of different alloy materials comprising:

• providing a first rotor segment, of an alloy material, having a longitudinal axial center line, an outer surface, and a first end face, with a cavity in said first end face, extending radially from the axial center line of said first rotor segment to a location spaced from the outer surface thereof, forming a first axially extending annular flange having an axially facing surface;
• providing a second rotor segment, of another alloy material, having a longitudinal axial center line, an outer surface, and a second end face, with a cavity in said second end face, extending radially from the axial center line of said second rotor segment to a location spaced from the outer surface thereof forming a second axially extending annular flange having an axially facing surface;
• welding a clad layer of filler material onto the axially facing surface of the annular flange of the first end face, with a portion thereof extending beyond the outer surface of said first rotor segment;
• machining the clad layer so applied to provide a smooth surface thereon;
• heat treating said applied layer and contiguous section of the annular flange of said first rotor segment;
• aligning said first and second rotor segments with said end faces confronting each other and said annular flanges in spaced adjacent relationship to provide a welding root opening therebetween;
• welding said first and second rotor segments together across said welding root opening to form a juncture weld, with a portion of said weld extending beyond the outer surfaces thereof;
• heat treating said juncture weld;
• and
• machining said juncture weld to form a smooth surface thereof complementary with the outer surface of said first and second rotor segments.