Which option best describes the effects of annealing steel and aluminum alloys?

• A. Decrease in internal stress
• B. Softening of the metal
• C. Improved corrosion resistance
• D. Both 1 and 2

Answer: (D)

Annealing mainly relieves internal stresses and softens the metal. When steel and aluminum alloys are heated to appropriate temperatures and then cooled slowly, the atoms gain mobility, dislocations rearrange or annihilate, and new, strain-free grains form. This reduces hardness and makes the material more ductile, which is exactly what “softening” describes. Because both stress relief and softening occur as a direct result of the heat treatment, describing both effects fits best. While corrosion resistance can be influenced by composition and environment, annealing isn’t primarily done to improve corrosion resistance; its main outcomes are relieving residual stress and reducing hardness.