Investigation of Bowing of Steam Turbine Rotor during Long Term Service

• Published in: Transactions of the Iron and Steel Institute of Japan Vol. 24; no. 2; pp. 107 - 112
• Main Authors: KIRIHARA, Seishin, SHIGA, Masao, KURIYAMA, Mitsuo, SASAKI, Ryoichi, HISANO, Katsukuni
• Format: Journal Article
• Language: English
• Published: Tokyo The Iron and Steel Institute of Japan 1984; Iron and steel institute of Japan
• Subjects: Applications; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Creep; Cross-disciplinary physics: materials science; rheology; Engineering techniques in metallurgy. Applications. Other aspects; Exact sciences and technology; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals, semimetals and alloys; Metals. Metallurgy; Physics; Specific materials; Steam turbine; Reduction in area; Temperature; Creep test; Creep strength; Time; High temperature; Hardness; Creep resistant steel; Quenching; Heterogeneity; Elongation at fracture; Tempering; Bending; Microstructure; Creep deformation; Quenching and tempering
• ISSN: 0021-1583; 1881-1183
• DOI: 10.2355/isijinternational1966.24.107

Rotor bowing is a problem encountered in high pressure (HP) and intermediate pressure (IP) turbine rotors during a long term service. The problem occurred in the solid block of HP and IP turbine rotors where the main steam temperature was 566°C. In this paper, it is indicated that such rotor bowing is caused by the metallurgical heterogeneity of materials in rotor, and that the rotor materials should be manufactured under a precisely controlled heat treatment. The experimental results are summarized as follows: (1) Bowing of the rotor shaft during a long term service is caused by the scatter of creep strain rate in rotor material. (2) Difference of creep strain rate in the rotor section is caused by the non uniform temperature distribution during heat treatment. (3) The asymmetric distribution of sulphur segregation in a rotor section has no effect on the ratio of creep strain rate. (4) Temperature difference during heat treatment should be controlled within 6°C. In this case, the ratio of the maximum to the minimum creep strain rate in rotor shafts may be less than 1.20, and this prevents the rotor shafts from bowing during a long term service. (5) Rotating heat treatment is effective for the prevention of rotor bowing.