Evaluation of corrosion fatigue crack propagation life at low-pressure steam turbine rotor groove

• Published in: Engineering fracture mechanics Vol. 73; no. 12; pp. 1615 - 1628
• Main Authors: Morita, Akira, Kagawa, Hiroyuki, Sugawara, Manabu, Kondo, Yoshiyuki, Kubo, Shiro
• Format: Journal Article
• Language: English
• Published: Tarrytown, NY Elsevier Ltd 01.08.2006; Oxford Elsevier
• Subjects: Corrosion fatigue; Crack propagation; Exact sciences and technology; Finite element method; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Hot water; Life consumption rate; Life prediction; Physics; Rotor groove; Solid mechanics; Structural and continuum mechanics; Turbine rotor; Life prediction; Finite element method; Life consumption rate; Turbine rotor; Corrosion fatigue; Hot water; Crack propagation; Rotor groove; Steam turbine; Fatigue life; Crack depth; Durability; Life test; Fatigue fracture; Wedge; Modeling; Fatigue crack; Low pressure; Crack initiation
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2006.02.008

The corrosion fatigue crack propagation life of Christmas-tree type rotor groove with three hooks is studied. Each corner of the hook can be a candidate for crack initiation site therefore the condition where cracks initiate and propagate simultaneously at several hook corners must be considered. When a blade is inserted in the rotor groove, narrow gap is introduced unavoidably between the rotor groove and the blade root. The effect of this narrow gap on the crack behavior must also be considered. A procedure was presented to assess the crack initiation and propagation behavior under such a condition. Using the procedure, crack initiation and propagation behavior was evaluated for several gap conditions. It was revealed that the gap condition had little effect on the relation between crack depth at the third hook corner and life consumption ratio (ratio of loading cycle to final failure life). A corrosion fatigue test was performed using a rotor groove model specimen, and the results were compared with the evaluation results.