Cold rolling is the process of deforming metal by rollers at a temperature below the recrystallization temperature. Because the metal is at room temperature, it is less ductile than metal above the recrystallization temperature. This makes cold rolling a more labor-intensive and costly process than hot rolling.
The process increases the yield strength and hardness of the metal, which is done by introducing defects into the metal’s crystal structure, creating a strengthened microstructure that prevents further slippage.
Cold rolling can also reduce the grain size of the material, causing Hall-Petch strengthening.