Hot rolled and cold rolled steel

Hot rolled uses the slab continuous casting slabs as raw material, the reheating furnace heating, high-pressure water in addition to the scales into the roughing mill, roughing material by cutting heads, tails, and then into the finishing mill, the implementation of computer-controlled rolling system, after the final rolling through laminar cooling (computer-controlled cooling rate) and the take-up reel, become straight hair volume. Straight hair volume of head, tail often showed poor tongue and tail shape, thickness, width, precision, often there is wave-shaped edges, folding, pyramid and other defects. Its volume weight heavier, coil inner diameter of 760mm. (generally prefer to use the pipe industry.). After the straight hair volume is by cutting head, cut tail, trimming and multi-pass straightening, leveling and other finishing line treatment, and then cutting board or heavy volume, it becomes: hot steel, hot-rolled steel coil leveling, sitting with other products. Hot rolling finishing after acid pickling to remove scale and greased and becomes the hot-rolled pickling plate volumes.

Cold rolled use the hot rolled coil as raw materials for cold rolling pickling after descaling, the finished product is rolling hard volumes, due to the continuous work hardening caused by cold deformation rolling hard volumes of the strength, hardness rise, tough plastic index declined deterioration stamping performance, only for simple deformation of parts. Rolling hard volumes can serve as raw material for hot-dip galvanizing plant, because hot dip galvanizing line is provided with annealing line. Rolling hard roll weight is usually 6 to 13.5 tons, coil inner diameter of 610mm. Conventional cold rolling plate, roll through continuous annealing should (CAPL unit) or hood-type annealing furnace to eliminate the stress of work hardening and rolling, to the mechanical properties of standard indicators. Cold-rolled steel sheet surface quality, appearance and dimensional precision are higher than hot-rolled sheet.