Hot Working (Crystallization) occurs when deformation is performed at temperatures which are:

• A. Below the recrystallization temperature
• B. At room temperature
• C. At temperatures below the recrystallization temperature
• D. Above the recrystallization temperature

Answer: (D)

Hot working means shaping a metal while it is hot enough for new, strain-free grains to form during deformation. This requires being above the recrystallization temperature, so dynamic recrystallization can occur as the material deforms. As dislocations are generated, they’re continually reorganized into new grains, keeping the material soft and able to deform easily with relatively low resistance.

If deformation happens below that temperature, the metal cannot recrystallize during shaping, so dislocations accumulate and the material work-hardens, making it harder to deform and more prone to cracking—this is characteristic of cold working. Room temperature is well below the recrystallization temperature, so it isn’t hot working.

Thus, hot working occurs when deformation is performed above the recrystallization temperature.