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Hot And Cold Rolled Steel Metallurgy Process
Sep 29, 2017

From the steel mill out of the billet is only semi-finished products, must go to the rolling mill to be rolled before they can become qualified products. From the steel mill sent over the continuous casting billet, first into the heating furnace, and then after repeated rolling mill, into the finishing mill. Rolling steel is a metal pressure processing, that simple point, rolling steel plate like noodles, rolling pin by rolling several times with the push, the surface of the more rolling thin. In the hot-rolled production line, the heat becomes soft, the roller is fed into the rolling mill, and finally rolled into the size required by the user. Rolling is a continuous uninterrupted operation, the steel belt in the roller workers running fast, highly automated equipment, high efficiency. General continuous casting slab thickness of 150 ~ 250mm, first through the descaling to the beginning of rolling, through the roller into the finish rolling mill, finishing mill generally consists of seven 4-roll mill, the machine before the tamping roller and flying shear, Board head. The speed of the finishing mill can reach 23m / s. Hot-rolled products are divided into two kinds of coil and ingot plate, after hot-rolled rail thickness is generally a few millimeters, if the user requirements thinner steel, but also through Cold Rolled Steel.

Compared with the hot-rolled, cold-rolled; processing lines are more dispersed, cold-rolled products are mainly cold-rolled plate, coated plate is tin plate, galvanized sheet and color coated plate. After the hot rolling mill sent to the coil, first after three consecutive technical treatment, and use hydrochloric acid to remove the oxide film, and then sent to the Cold Rolled Steel mill. In the cold rolling mill, the uncoiler opened the coil and then the steel strip was introduced into a five-stand mill to roll into a thin coil. From the rack out there are different specifications of ordinary steel coil, it is based on a variety of user requirements to process. After the Cold Rolled Steel of the strip in the warehouse directly to the hot-dip galvanizing unit feed section, the coil in the unit open-book, welding, after the hatch into the unit after the process section. The strip is preheated in the non-tantalum furnace and subjected to surface oiling, then heat-treated in the furnace of reduced oxygen, and the appropriate surface for the next step of galvanizing the strip, pulled directly from the furnace into the zinc pot, The surface of the zinc coating, and then use the air knife to blow, control the thickness of zinc and zinc flower controller to control the zinc layer when the crystallization of zinc flower size, after cooling, but also according to the need for galvanized strip after finishing , Stretching straightening, surface chemical treatment and other processes. In the discharge section, after printing, oil and rolled into galvanized steel coil. If the flute is delivered in the state of the steel plate, the steel roll is cut to the crosscutting unit for cutting and packing.