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Toshiba Corp
Original Assignee
Toshiba Corp
Tokyo Shibaura Electric Co Ltd
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Filing date
Publication date
Application filed by Toshiba Corp, Tokyo Shibaura Electric Co LtdfiledCriticalToshiba Corp
Priority to JP13131579ApriorityCriticalpatent/JPS5655552A/en
Publication of JPS5655552ApublicationCriticalpatent/JPS5655552A/en
Publication of JPS62993B2publicationCriticalpatent/JPS62993B2/ja
PURPOSE: To enhance the tensile strength and toughness of a 12Cr-Ni steel for the rotor of a steam turbine of large capacity by adding a specifically minute amount of Nb or Ta to the steel.
CONSTITUTION: This alloy steel contains 0.05W0.30% C, 0.2W1.5% Mn,<0.2% Si, 8W13% Cr, 0.2W1.5% Mo, 0.05W0.3% V, 3.0W4.0% Ni and 0.01W0.05% Nb and/or Ta. The Ni content of a 12Cr-Ni steel is adjusted to 3W4% to improve the tensile strength and toughness, and by adding Nb and/or Ta, the crystal grains are refined to further enhance the toughness. A rotor made of this steel is heat treated while adjusting the cooling rate of hardening to 2°C/min and that of tempering to 20°C/hr. This alloy steel is remarkably superior to a conventional 12Cr-Ni alloy steel in tensile strength and toughness.
Cr-mo steel material with plate thickness of 75mm or more for use in retroleum refining apparatus, coal gasifying apparatus and other pressure container