Service-like TMF tests for the life assessment of an SX GT blade

Abstract

Thermo-mechanical fatigue (TMF) is the main source of failure of gas turbine (GT) components, owing to thermal gradients and complex geometry. A GT-component life assessment procedure has to consider TMF and the effect of metallic coatings. A single crystal (SX) blade is analysed by FE simulation to identify the critical locations and their thermo-mechanical conditions during a ‘cold’ startup/shutdown transient. The defined TMF cycle is applied to SX superalloy specimens with two different coatings. The results highlight a significant life reduction for specimens with the coating having the highest Re content due to its microstructure. The experimental results are confirmed by field feedback from operated blades.

This paper is part of a thematic issue on the 9th International Charles Parsons Turbine and Generator Conference. All papers have been revised and extended before publication in Materials Science and Technology.

Keywords:

• TMF
• NiCoCrAlY coating
• GT blade
• SX superalloy
• FE simulation

Acknowledgements

Tullio Ranucci and Dr Maurizio Maldini from CNR Ieni Milan are acknowledged for the TMF test execution and their useful support in testing set-up and results understanding.

ORCID

E. Vacchieri http://orcid.org/0000-0003-2726-6194