Patent ID: 7771166

Claim:
A turbine rotor shaft, comprising: a middle region consisting of a middle bloc, having a middle region material and a longitudinal axis and having a first end face oriented perpendicular to the longitudinal axis and arranged at a first end of the middle region and a second end face arranged at a second end of the middle region opposite the first end face; a first outer region consisting of a first bloc, having a first material and arranged coaxially with the longitudinal axis abutting the first end face of the middle region, comprising a first bearing surface configured to receive a first bearing which mounts the first outer region to the turbine, wherein when disposed in a steam turbine the first outer region abuts the first end face of the middle region upstream of a last row of blades and downstream of a first row of blades within a high pressure part of the steam turbine; and a second outer region consisting of a second bloc, having a second material and arranged coaxially with the longitudinal axis and abutting the second end face of the middle region, comprising a second bearing surface configured to receive a second bearing which mounts the second outer region to the turbine, wherein the middle region material has a higher heat resistance than the first and second materials.