Analysis of a Turbine Blade Failure in a Military Turbojet Engine
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Benudhar Sahoo
Abstract
This paper deals with failure analysis of a low-pressure turbine blade of a straight flow turbojet engine. The blade is made of a wrought precipitation hardened Nickel base superalloy with oxidation-resistant diffusion aluminizing coating. The failure mode is found to be fatigue with multiple cracks inside the blade having crack origin at metal carbides. In addition to the damage in the coating, carbide banding has been observed in few blades. Carbide banding may be defined as inclusions in the form of highly elongated along deformation direction. The size, shape and banding of carbides and their location critically affect the failure of blades. Carbon content needs to be optimized to reduce interdendritic segregation and thereby provide improved fatigue and stress rupture life. Hence, optimization of size, shape and distribution of carbides in the billet and forging parameters during manufacturing of blade play a vital role to eliminate/reduce extent of banding. Reference micrographs as acceptance criteria are essential for evaluation of raw material and blade. There is a need to define the acceptance criteria for carbide bandings and introduce more sensitive ultrasonic check during billet and on finished blade inspection.
Acknowledgements
The authors acknowledge the support rendered by Director NAL for conducting the SEM study. Encouragement and permission to publish the work by the Chief Executive (A) and Group Director (P), CEMILAC, Bangalore is sincerely acknowledged.
Nomenclature
- LPTR
Low-pressure turbine rotor
- ECM
Electrochemical machining
- SRT
Stress rupture test
- LCF
Low-cycle fatigue
- HCF
High-cycle fatigue
- SEM
Scanning electron microscope
- EDAX
Energy dispersive X-ray analysis
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Articles in the same Issue
- Frontmatter
- Probabilistic Fatigue Life Prediction of Turbine Disc Considering Model Parameter Uncertainty
- Experimental Investigation of Reacting Flow Characteristics in a Dual-Mode Scramjet Combustor
- Adjoint Optimization of Multistage Axial Compressor Blades with Static Pressure Constraint at Blade Row Interface
- Wall Pressure Measurements in a Convergent–Divergent Nozzle with Varying Inlet Asymmetry
- Thermoelastic Simulations Based on Discontinuous Galerkin Methods: Formulation and Application in Gas Turbines
- Re-Educating Jet-Engine-Researchers to Stay Relevant
- Analysis of a Turbine Blade Failure in a Military Turbojet Engine
- Investigation of Positively Curved Blade in Compressor Cascade Based on Transition Model
- Design and Experimentation of Simulated Combustor Model for Aircraft Afterburner Applications
- Contact Stress Analysis and Fatigue Life Prediction of a Turbine Fan Disc
- Multidisciplinary Design Optimization on Conceptual Design of Aero-engine
Articles in the same Issue
- Frontmatter
- Probabilistic Fatigue Life Prediction of Turbine Disc Considering Model Parameter Uncertainty
- Experimental Investigation of Reacting Flow Characteristics in a Dual-Mode Scramjet Combustor
- Adjoint Optimization of Multistage Axial Compressor Blades with Static Pressure Constraint at Blade Row Interface
- Wall Pressure Measurements in a Convergent–Divergent Nozzle with Varying Inlet Asymmetry
- Thermoelastic Simulations Based on Discontinuous Galerkin Methods: Formulation and Application in Gas Turbines
- Re-Educating Jet-Engine-Researchers to Stay Relevant
- Analysis of a Turbine Blade Failure in a Military Turbojet Engine
- Investigation of Positively Curved Blade in Compressor Cascade Based on Transition Model
- Design and Experimentation of Simulated Combustor Model for Aircraft Afterburner Applications
- Contact Stress Analysis and Fatigue Life Prediction of a Turbine Fan Disc
- Multidisciplinary Design Optimization on Conceptual Design of Aero-engine
