In metals processing, what term describes deformation of metal by rolling, hammering, or bending that increases strength?

• A. Cold worked or work hardened
• B. Annealed
• C. Solution treated
• D. Stress relieved

Answer: (A)

Cold work, or work hardening, is deformation of metal by rolling, hammering, or bending performed at temperatures below the material’s recrystallization temperature. As the metal is shaped, dislocations multiply and tangle, creating obstacles to further motion of other dislocations. This increases the material’s strength and hardness, but at the expense of ductility. Since no new grains form during this process, the metal becomes stronger without changing its overall composition. If you want to restore ductility after cold work, the metal can be annealed to recrystallize and relieve the strain.

The other options describe different heat-treating concepts: annealing softens and increases ductility; solution treatment dissolves alloying elements to form a uniform solid solution; and stress relief reduces residual stresses without increasing strength.