During recrystallization, as temperature increases, what happens to defect density, ductility, and strength?

• A. Defect density increases; ductility decreases
• B. Defect density decreases; ductility increases; strength decreases
• C. Defect density decreases; strength increases
• D. Defect density increases; ductility increases

Answer: (B)

During recrystallization, heating allows the deformed metal to form a new, defect-free set of grains and reduces the amount of stored dislocations and other defects. Fewer defects mean fewer barriers to dislocation motion, so the material can deform more easily under stress—ductility increases. At the same time, removing these defects and the associated internal stresses weakens the material, so its strength decreases. So, as temperature rises, defect density goes down, ductility goes up, and strength goes down. The other options either predict more defects, or predict increased strength, which doesn’t align with what happens during recrystallization.