Metals treated by which process become soft?

• A. Annealing
• B. Hardening
• C. Tempering
• D. Quenching

Answer: (A)

Softening metals through heat treatment is achieved by annealing. In annealing, metal is heated to a high enough temperature to allow recrystallization, then held there and cooled slowly. This process lets new, strain-free grains form and lets dislocations rearrange, which reduces hardness and increases ductility. Other common treatments tend to increase hardness or alter brittleness—quenching cools rapidly to create a harder structure, hardening amps up hardness through processes like quenching and alloying, and tempering follows hardening to reduce brittleness but still leaves the metal harder than in the annealed state. So, the process that softens metal is annealing.