Question

Stage II creep is characterized by:

• A. Accelerating strain rate
• B. Constant strain rate
• C. Decelerating strain rate
• D. No strain

Hint:

Remember: Stage II (secondary creep) shows a constant strain rate — this is the most stable and useful region for designing high-temperature components.

Answer 1

The Correct Option is B

Creep is the time-dependent plastic deformation of materials when subjected to a constant load at high temperatures. The creep curve generally consists of three distinct stages:
- Stage I (Primary creep): Decelerating strain rate due to work hardening.
- Stage II (Secondary or steady-state creep): Constant strain rate, representing a balance between work hardening and recovery processes.
- Stage III (Tertiary creep): Accelerating strain rate due to microstructural damage and eventual failure.
Stage II is the longest and most predictable phase, where the material deforms at a steady pace. It is crucial in engineering design for predicting long-term behavior of components under sustained high temperatures.