Metallurgical evaluation of keyway cracking in low-pressure turbine disks. Final report

Technical Report · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5228120

Burghard, Jr, H C

A metallurgical evaluation of keyway cracking in the rotor discs of large LP steam turbines was performed. Three particular cases of the development of major keyway cracks in LP turbine discs at two nuclear steam electric generating stations were investigated. The overall objectives of the investigation were to characterize the disc material, establish the nature and extent of the keyway cracks and identify the cracking mechanism. Metallographic and fractographic examinations established that the cracking was predominantly intergranular and that significant corrosive attack had occurred within the keyways. It was also determined that the composition, mechanical properties and microstructure were normal for quenched and tempered NiCrMoV alloy steels and that the cracking was not associated with any inherent materials defect or abnormality. The identified the cracking mechanism as intergranular stress corrosion cracking (IGSCC). It is concluded that the keyway cracks developed as the result of the combined effects of the inherent IGSCC susceptibility of NiCrMoV alloy steels, the operating stresses, and environmental conditions encountered within large LP steam turbines.

• Research Organization: Southwest Research Inst., San Antonio, TX (USA)
• OSTI ID: 5228120
• Report Number(s): EPRI-NP-3341; ON: DE84920241
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
200100* -- Fossil-Fueled Power Plants-- Power Plants & Power Generation
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210200 -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
ALLOYS
CHEMICAL REACTIONS
CORROSION
CRACK PROPAGATION
CRACKS
FRACTOGRAPHY
INSPECTION
INTERGRANULAR CORROSION
IRON ALLOYS
IRON BASE ALLOYS
MACHINERY
METALLOGRAPHY
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
POWER PLANTS
ROTORS
STEAM TURBINES
STEELS
STRESS CORROSION
THERMAL POWER PLANTS
TURBINES
TURBOMACHINERY