Failure Assessment of the First Stage Blade of a Gas Turbine Engine

• Published in: Transactions of the Indian Institute of Metals 2017-10, Vol.70 (8), p.2103-2110
• Main Authors: Salehnasab, B., Hajjari, E., Mortazavi, S. A.
• Format: Article
• Language: English
• Subjects: Breaking down; Brittle fracture; Chemistry and Materials Science; Corrosion and Coatings; Gas turbine engines; Impact damage; Materials Science; Metallic Materials; Metallurgy; Nickel base alloys; Superalloys; Technical Paper; Tribology; Turbine blades
• ISSN: 0972-2815; 0975-1645
• DOI: 10.1007/s12666-016-1031-4

The gas turbine engine under investigation in this paper was in service after major overhaul for about 2 h at 9:47 A.M. on 18 October, 2014. The 60 MW gas turbine engine experienced a forced break down because of extremely high vibrations and subsequent output power reduction. The blade was made of Inconel 738LC nickel-based super-alloy. Evaluation of the microstructures of the root and tip of the damaged blade, showed no significant change in the microstructure. In closer observation of the fractured blade, some points affected by impact of the remaining airfoil were observed. Metallurgical investigations of the damaged zones of the fractured blade showed many iron rich zones near the fractured surface. The morphology of the fractured surface showed a semi-brittle fracture due to the impact. Finally, it was concluded that the main reason for the gas turbine failure was domestic object damage due to the impact of the liberated components of the turbine engine on the blades.