Estimation and extension of the life of hot gas turbine components
Product introduction
The turbine blades, when placed in service conditions, are prone to microstructural degradation and surface cracks, which limit the lifespan of the component. Microstructural degradation includes the coarsening of primary gamma prime particles, carbide decomposition, the formation of creep cavities, and the development of TCP phase. Additionally, the surfaces of the blades are damaged due to fatigue cracks and defects resulting from being in service conditions. As a result, the mechanical properties of the components are reduced to a level that does not meet the minimum requirements for safe operation. The process of life estimation and extension (LTE) evaluates the condition of the received blade through analytical and experimental methods, reconstructs the service-induced damage, and restores the microstructure of the component to its pre-service condition.
benefits
- Predict the impact of service conditions on component life
Significantly reduce repair and maintenance costs
Improve reliability and availability by modifying repair and maintenance intervals
Increase lifespan through rejuvenation
How it works
A conventional LTE process includes visual inspection, cutting, and metallographic examinations, microstructural analysis to estimate the extent of exposure to high temperatures, mechanical testing of components before and after exposure, and the processes of reconstruction and rejuvenation. In visual inspection, a complete assessment and measurement of the geometry after service is conducted, which typically serves as a guide for subsequent destructive tests. Cutting locations for destructive examinations are selected based on the results of finite element analysis (FEA), such that the worst combination of stress and surface temperature of the airfoil is usually considered for more detailed examination. Specific reconstruction processes, such as welding or brazing, can be employed to address surface defects. On the other hand, rejuvenation heat treatments are performed on the component after service to recover the degraded microstructure, thereby extending its useful life.
Successful experiences
- Estimation and extension of the life of more than 120 sets of fixed blades and gas turbine combustors
Tracing the failure of hot section parts of gas turbines
Development of technical knowledge and development of advanced overhaul instructions
Estimation and extension of the life of moving blades
- Estimation and extension of the life of more than 120 sets of fixed blades and gas turbine combustors
