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

1. 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 a 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, and

a base end-side seal portion which is integrally formed with the front-side seal portion and is disposed on the base end-side surface such that a surface of the base end-side seal portion protrudes from the base end-side surface and the base end-side seal portion forms a step with the base end-side surface.

2. The steam turbine rotor blade according to claim 1 ,

wherein the transition-region seal member covers a boundary line at which a leading edge-side surface of the protrusion portion facing a leading edge side and the base end-side surface of the protrusion portion are connected to each other, over a predetermined length from a connection point between the boundary line and the suction-side surface, and

wherein in a case where a length of the boundary line from the connection point to a tip end portion of the protrusion portion is defined as L, the predetermined length is a length of 0.9 L or less from the connection point.

3. The steam turbine rotor blade according to claim 1 , further comprising a leading-edge seal member which is provided so as to cover the leading edge portion and is formed of a material having a hardness higher than that of the blade body,

wherein the blade body includes a second recessed portion which is recessed from the surface of the blade body at the leading edge portion, and

wherein the leading-edge seal member is disposed in the second recessed portion such that a surface of the leading-edge seal member is flush with the surface of the blade body.

4. The steam turbine rotor blade according to claim 3 ,

wherein the transition-region seal member and the leading-edge seal member are integrally formed with each other, and

wherein the first recessed portion and the second recessed portion are formed to be connected to each other and to have the same depth.

5. A steam turbine comprising:

a rotor which includes the steam turbine rotor blade according to claim 1 ; and

a casing which covers the rotor.

6. 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 a 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,

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, and

a base end-side seal portion which is integrally formed with the front-side seal portion and is capable of being disposed on the base end-side surface and the base end-side seal portion forms a step with the base end-side surface such that a surface of the base end-side seal portion protrudes from the base end-side surface, and

wherein in the joining step, the transition-region seal member is joined to at least a portion of the base end-side surface and the leading edge-side transition region.

7. The method for manufacturing a steam turbine rotor blade according to claim 6 ,

wherein in the joining step, the transition-region seal member is brazed to the blade body and the protrusion portion.