Cold Drawing
Pulling hot rolled bar through a hardened die at room temperature to reduce its diameter, remove scale and raise strength by work hardening.
What it changes
Drawing takes the bar down by typically 1-3 mm, strips the rolling scale and leaves a bright, smooth surface. The cold work raises tensile strength by 15-25% and yield strength considerably more, while cutting elongation — an EN1A bar at 430 MPa hot rolled comes out of the die nearer 550 MPa.
What it costs
Residual stress. A drawn bar that is then machined asymmetrically — a keyway down one side, a flat milled off — will bow as the stress redistributes. Where that matters, specify stress relieved bar or a turned and ground finish instead.
Related terms
Where this applies
Free Cutting Bright Bars, Carbon Steel Bright Bars
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