Rotor of rotating machine and method of manufacturing the rotor

A rotor of a rotating machine to which steam or combustion gas is introduced as working fluid, the rotor being comprised of a plurality of members connected by welding such that material of each member is different in accordance with temperature of working fluid which flows in contact with the plurality of the members, the plurality of the members comprising:

• two first section members;
• and
• two second section members,
• wherein the two first section members are formed from Ni-based alloys having mean linear thermal expansion coefficient of 12.4×10−6/° C. to 14.5×10−6/° C. averaged within a temperature range from a room temperature to 700° C., and the two second section members are formed from high-chrome steels,
• wherein the rotor is composed such that the two first section members formed from Ni-based alloys are located in a working fluid inlet zone,
• and wherein the rotor is formed by joining together the two first section members formed from Ni-based alloys by welding, performing a first-stage aging treatment on a welded joint between the two first section members at 700 to 1000° C., then joining the two second section members to free ends of the two first section members, respectively, by welding, and then, simultaneously performing a second-stage aging treatment on the welded joint between the two first section members and a heat treatment on welded portions between the two first section members and the two second section members respectively, at a same temperature in a range of 600 to 800° C.