| 摘要 |
PROBLEM TO BE SOLVED: To provide a high and low pressure integrated turbine rotor excellent in high temperature strength characteristic in a high pressure part not to cause creep embrittlement and excellent in toughness in a low pressure part. SOLUTION: In CrMoV heat resisting steel and CrMoV heat resisting steel containing tungsten, very small amount impurities such as phosphorus, sulfur, copper, aluminum, arsenic, tin, and antimony are decreased to a specified level or lower. Further, slight amount impurities such as cobalt, niobium, tantalum, nitrogen, boron and the like are added to use and alloy steel increased in smooth creep strength. In this manufacturing method, the high pressure part of turbine rotor raw material of the above specified composition is held at a high temperature as much as 980 to 1100 deg.C and the low pressure part is held at a high temperature as much as 850 to 980 deg.C. The high pressure part is cooled at a speed higher than air blast cooling, and the high pressure part is subjected to quenching for cooling at a speed higher than oil hardening. The creep rupture time of notch creep rupture test is 10,000 hours or more.
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