Water-turbine runner and process for manufacturing the same
AssigneeHitachi, Ltd.
InventorsMasami Yada, Takao Funamoto, Michio Kitamura, Junzo Komatsu, Masakazu Midorikawa, Tsugio Yoshikawa
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Abstract
A water turbine runner has a plurality of vanes, each made of a rolled steel plates which contains, by weight, 0.01 to 0.10% of C, 0.10 to 1.0% of Si, 0.10 to 2% of Mn, 2 to 7% of Ni, 10 to 15% of Cr and 0.10 to 4% of Mo, 71.9 to 87.7% of Fe, and which has a metallic structure mixture containing, by volume, martensite and 10 to 35% of residual austenite. Each of the vanes is made of a plurality of plate pieces, cut out from the rolled steel plate, press-formed in a shape of a part of the vane and joined by welding into the complete vane.
Claims14
A water-turbine runner comprising a rotary member with a central portion for connecting a drive shaft, and a plurality of vanes each provided on said rotary member, each of said vanes is made of a rolled steel plate comprising, by weight, 0.01 to 0.10% of C, 0.10 to 1.0% of Si, 0.10 to 2% of Mn, 4 to 6% of Ni, 10 to 15% of Cr and 0.10 to 3% of Mo, and 71.9 to 87.7% of Fe, and has a metallic mixture containing, by volume, martensite and 10 to 35% of residual austenite, and wherein weld means are provided for mounting said vanes on said rotary member.
A water-turbine runner comprising a crown ring and a plurality of vanes each mounted on said crown ring, each of said vanes comprising a plurality of plate pieces cut off from a rolled steel plate consisting essentially of, by weight, 0.01 to 0.10% C, 0.10 to 1.0% of Si, 0.10 to 2% of Mn, 4 to 6% of Ni, 10 to 15% of Cr and 0.10 to 3% of Mo, and the balance of Fe, and which has a metallic mixture containing, by volume, martensite and 10 to 35% of residual austenite, wherein each of said plate pieces has a shape of a portion of the respective vanes, and weld means are provided for integrating said plate pieces into the respective vanes.
A water-turbine runner comprising:
- a crown ring with a shaft receiving portion at a central portion thereof, a band and a plurality of vanes interposed between said crown ring and said band,
- wherein each of said plurality of vanes comprise plate pieces consisting essentially of, by weight, 0.02 to 0.05% of C, 0.2 to 0.5% of Si, 0.5 to 1% of Mn, 4.5 to 5.8% of Ni, 12 to 14% of Cr and 0.2 to 2% of Mo, and the balance of Fe, a maximum oxygen and a maximum nitrogen contained in said rolled steel plate being 60 ppm and 150 ppm, respectively, and which has a metallic mixture containing, by volume, martensite and 10 to 35% of residual austenite.
A process for manufacturing a water-turbine runner, comprising the steps of:
- forming into a three-dimensional shape a rolled steel plate which contains, by weight, 0.01 to 0.10% of C, 0.10 to 1.0% of Si, 0.10 to 2% of Mn, 4 to 6% of Ni, 10 to 15% of Cr and 0.10 to 3% of Mo, 71.9 to 87.7% of Fe, the oxygen content being no greater than 60 ppm, and the nitrogen being no greater than 150 ppm, and which has a metallic structure mixture containing martensite and residual austenite and which is regulated such that the residual austenite is 10 to 35% by volume;
- electron beam welding the formed steel plate;
- and
- subjecting the steel plate to a heat treatment so that welded portions contain 10 to 35% of residual austenite by volume.
Dependencies are inferred from the claim text.