Which failure mode is most associated with overheating turbine blades?

Which failure mode is most associated with overheating turbine blades?

• A. Erosion
• B. Stress ruptures
• C. Thermal fatigue
• D. Corrosion

Answer: (B)

Overheating pushes the blade material into creep, a slow, time-dependent deformation that occurs under sustained high temperature and stress. When the load is kept up, this creep can concentrate until the material cannot carry the stress anymore and it ruptures. This creep rupture, or stress rupture, is the failure mode most closely tied to overheating because heat directly accelerates diffusion and grain-boundary sliding that drive deformation and eventual fracture. Erosion involves material loss from particle impacts, not heat. Thermal fatigue comes from repeated heating and cooling cycles that create cracks from thermal stresses, which is a different scenario than a steady high-temperature condition. Corrosion is chemical attack, which heat can influence but is not the primary mode caused by overheating alone.

Overheating pushes the blade material into creep, a slow, time-dependent deformation that occurs under sustained high temperature and stress. When the load is kept up, this creep can concentrate until the material cannot carry the stress anymore and it ruptures. This creep rupture, or stress rupture, is the failure mode most closely tied to overheating because heat directly accelerates diffusion and grain-boundary sliding that drive deformation and eventual fracture.

Erosion involves material loss from particle impacts, not heat. Thermal fatigue comes from repeated heating and cooling cycles that create cracks from thermal stresses, which is a different scenario than a steady high-temperature condition. Corrosion is chemical attack, which heat can influence but is not the primary mode caused by overheating alone.