Hot-Rolled Steel Angles and Channels

Angles, channels and beams are made in a merchant or bar mill by hot rolling a steel billet through shaped rolls. The steel is kept above its recrystallisation temperature, so the grains re-form as it is squeezed and the metal does not work-harden. A billet, typically 100–140 mm across, passes through roughing, intermediate and finishing stands, each changing its cross-section a step closer to the final L or U. The finished section comes out covered in mill scale, an oxide formed at the high temperature, within about 2–5% of its nominal size.