Heat treatment sequence: Arrange the metallurgical phenomena in correct chronological order for annealing of cold-worked steels. As temperature/time increases during a standard annealing heat cycle, the microstructural stages occur in a characteristic order (stress relief/recovery, recrystallisation, grain growth). Choose the correct sequence.
Mechanical Engineering
Engineering Materials
Difficulty: Easy
Choose an option
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AGrain growth → recrystallisation → stress relief
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BStress relief → grain growth → recrystallisation
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CStress relief → recrystallisation → grain growth
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DGrain growth → stress relief → recrystallisation
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ERecrystallisation → stress relief → grain growth
Answer
Correct Answer: Stress relief → recrystallisation → grain growth
Explanation
Concept/ApproachDuring annealing of cold-worked steels, three phenomena occur in order: (1) stress relief (recovery), (2) recrystallisation, (3) grain growth.
Why this order?• Stress relief / recovery: dislocation rearrangement lowers residual stresses without new grains forming.• Recrystallisation: new, strain-free grains nucleate and grow, replacing the deformed structure.• Grain growth: existing recrystallised grains coarsen when held longer/hotter.
Common pitfallsConfusing recovery with recrystallisation, or assuming grain growth can precede recrystallisation.
Final AnswerStress relief → recrystallisation → grain growth