Steam turbine rotor blade, steam turbine, and method for manufacturing steam turbine rotor blade

A steam turbine rotor blade comprising:

• a blade body which includes a pressure-side surface and a suction-side surface extending in a blade height direction and a leading edge portion which is formed by the pressure-side surface and the suction-side surface and extends in the blade height direction;
• a protrusion portion which is provided on a tip end portion of the blade body in the blade height direction and protrudes from the suction-side surface toward the leading edge portion side;
• and
• a transition-region seal member which is provided so as to cover at least a portion of a base end-side surface of the protrusion portion facing a base end side opposite to a tip end in the blade height direction, and a leading edge-side transition region, facing the leading edge portion side, of a connection portion between the protrusion portion and the suction-side surface, the transition-region seal member being formed of a material having a hardness higher than that of the blade body,
• wherein a first recessed portion which is recessed from the suction-side surface is formed in the leading edge-side transition region, and
• wherein the transition-region seal member includes
• a front-side seal portion which is disposed in the first recessed portion such that a surface of the front-side seal portion is flush with a surface of the blade body.

A method for manufacturing a steam turbine rotor blade, comprising:

• a blade body forming step of integrally forming a blade body which includes a pressure-side surface and a suction-side surface extending in a blade height direction and a leading edge portion which is formed by the pressure-side surface and the suction-side surface and extends in the blade height direction, and a protrusion portion which is provided on a tip end portion of the blade body in the blade height direction and protrudes from the suction-side surface toward the leading edge portion side;
• a seal member forming step of forming, by metal injection molding, a transition-region seal member which is shaped so as to cover at least a portion of a base end-side surface of the protrusion portion facing a base end side opposite to a tip end in the blade height direction, and a leading edge-side transition region, facing the leading edge portion side, of a connection portion between the protrusion portion and the suction-side surface, the transition-region seal member being formed of a material having a hardness higher than that of the blade body;
• and
• a joining step of joining the transition-region seal member to at least the leading edge-side transition region,
• wherein in the blade body forming step, a first recessed portion which is recessed from the suction-side surface is formed in the leading edge-side transition region, and
• wherein the transition-region seal member includes
• a front-side seal portion which is capable of being disposed in the first recessed portion such that a surface of the front-side seal portion is flush with a surface of the blade body.