Question

What will happen at the accelerating or tertiary creep stage?

• A. Work hardening is less than recovery
• B. Work hardening is greater than recovery
• C. Work hardening is equal to recovery
• D. None of the above

Hint:

Tertiary creep leads to \textbf{microstructural damage}, including void formation and grain boundary separation, ultimately resulting in material failure.

Answer 1

The Correct Option is A

Creep is the time-dependent deformation of materials under a constant load, typically at elevated temperatures. Creep deformation generally occurs in three stages: primary, secondary, and tertiary (accelerating) creep. Step 1: Understanding Creep Stages 1. Primary Creep: The strain rate decreases over time due to work hardening, where the material strengthens as it deforms. 2. Secondary Creep (Steady-State Creep): The strain rate remains constant as work hardening and recovery (softening) balance each other. 3. Tertiary Creep: The strain rate accelerates due to a dominance of recovery and damage processes, eventually leading to failure.


Step 2: Evaluating the Options - Option (A) - Correct: During tertiary creep, work hardening is less than recovery, which leads to material weakening and increased deformation. - Option (B) - Incorrect: In the tertiary stage, work hardening becomes less significant than recovery, so the strain rate increases. - Option (C) - Incorrect: Work hardening and recovery are equal in the secondary creep stage, not tertiary. - Option (D) - Incorrect: Since option (A) is correct, this option is invalid.


Step 3: Conclusion In the tertiary creep stage, work hardening is less than recovery, which results in material degradation and increased deformation, making option (A) the correct answer.