Plastic deformation regimes — definition of cold working Cold working of metals is carried out at what temperature range relative to the recrystallisation temperature of the metal?

Introduction / Context:
Metalworking processes are classified as cold, warm, or hot depending on temperature relative to the metal's recrystallisation temperature. This classification dictates flow stress, work hardening, surface finish, and dimensional accuracy of the finished product.

Given Data / Assumptions:

• Recrystallisation temperature T_r is material dependent, often ≈ 0.3–0.5 of absolute melting temperature.
• Cold working retains significant work hardening and high dimensional control.
• Examples include cold rolling, drawing, bending, and pressing of sheet/rod at room temperature.

Concept / Approach:
Cold working is defined as plastic deformation performed below T_r so that no significant recrystallisation occurs during deformation. Dislocation density increases, raising strength (strain hardening) but reducing ductility. Subsequent annealing may be used to restore ductility by recrystallisation and grain growth if needed.

Step-by-Step Solution:
Identify definition: cold work occurs below T_r.Relate to properties: increased strength/hardness, decreased ductility, improved surface finish and tolerances.Contrast with hot working (above T_r): dynamic recovery/recrystallisation prevents strain hardening.Therefore, select “below the recrystallisation temperature”.

Verification / Alternative check:
Manufacturing texts consistently place cold work below T_r, warm work around 0.3–0.5 T_m (in absolute units), and hot work above T_r where recrystallisation is active.

Why Other Options Are Wrong:
At or above T_r implies hot working conditions; “any temperature” is too broad; “well above melting” is non-sensical for deformation processing.

Common Pitfalls:
Forgetting that T_r is alloy-specific; what is cold for aluminum may be warm for steel in absolute temperature terms.

Final Answer:
below the recrystallisation temperature