Hot rolling utilizes continuously cast slabs or primary-rolled slabs as raw materials. These are meticulously heated in a walking-beam furnace, descaled using high-pressure water jets, and then fed into a roughing mill for initial rolling. Following rough rolling, the material undergoes head and tail cropping before entering the finishing mill, where the rolling process is executed under precise computer control. Upon completion of the final rolling pass, the material is cooled using a laminar flow system-with the cooling rate strictly regulated by computer-and subsequently coiled by a downcoiler to produce a finished hot-rolled coil.
Cold rolling employs hot-rolled steel coils as its feedstock. These coils undergo pickling to remove surface scale before being processed through a continuous cold rolling mill train. The resulting "full-hard" coils exhibit enhanced strength and hardness due to work hardening induced by continuous cold deformation; however, their toughness and ductility are correspondingly reduced. Consequently, their stamping performance is somewhat compromised, making them primarily suitable for parts requiring only simple deformation.