Rotor, a steam turbine and a method for producing a rotor

A steam turbine, comprising:

• a rotor, comprising:
• a shaft high pressure section having a first end and a second end;
• and
• a shaft intermediate pressure section joined to the second end of the shaft high pressure section;
• wherein the shaft high pressure section comprises:
• a first high pressure section;
• a second high pressure section, the second high pressure section joined to the first high pressure section at a first weld;
• and
• a third high pressure section, the third high pressure section joined to the second high pressure section at a second weld;
• and
• wherein the shaft intermediate pressure section comprises:
• a first intermediate pressure section;
• and
• a second intermediate pressure section, the second intermediate pressure section joined to the first intermediate pressure section;
• and
• wherein at least a portion of the second high pressure section is formed of a high-chromium alloy steel comprising 0.1-1.2 wt % of Mn, up to 1.5 wt % of Ni, 8.0- 15.0 wt % of Cr, up to 4.0 wt % of Co, 0.5-3.0 wt % of Mo, 0.05-1.0 wt % of V, 0.02- 0.5 wt % of Nb, 0.005-0.15 wt % of N, up to 0.04 wt % of B, up to 3.0 wt % of W, and balance Fe and incidental impurities, and the first weld is along a main steam flow path and the shaft intermediate pressure section is joined to the third high pressure section of the shaft high pressure section by bolting, the third high pressure section being formed of a low-chromium alloy steel.

A method of manufacturing a rotor, comprising:

• providing a first, second and third high pressure sections;
• and
• joining the first, second and third high pressure sections to form a shaft high pressure section, wherein the second high pressure section is joined to the first high pressure section at a first weld and the third high pressure section is joined to the second pressure section at a second weld;
• providing a first and second intermediate pressure sections;
• joining the first and second intermediate pressure sections to form a shaft intermediate pressure section;
• and
• joining the shaft high pressure rotor section and the shaft intermediate pressure sections to form a rotor;
• wherein at least a portion of the second high pressure section is formed of a high-chromium alloy steel comprising 0.1-1.2 wt % of Mn, up to 1.5 wt % of Ni, 8.0-15.0 wt % of Cr, up to 4.0 wt % of Co, 0.5-3.0 wt % of Mo, 0.05-1.0 wt % of V, 0.02-0.5 wt % of Nb, 0.005-0.15 wt % of N, up to 0.04 wt % of B, up to 3.0 wt % of W, and balance Fe and incidental impurities, and the first weld is along a main steam flow path and the shaft intermediate pressure section is joined to the third high pressure section of the shaft high pressure section by bolting, the third high pressure section being formed of a low-chromium alloy steel.