Steel delivery status with hot rolling and cold drawn (rolled) delivery status.
Hot Rolled Delivery Status
Steel after hot-rolled or forged no longer special heat treatment, after cooling direct delivery, known as hot-rolled or hot-forging state, hot-rolled (forged) termination temperature is generally 800~900℃, then generally in the air naturally cooled, so the hot-rolled (forging) state equivalent to normalizing treatment. The difference is because the end temperature of hot rolling (forging) is high and low, unlike normalizing heating temperature control strict, so the steel structure and performance fluctuations than the positive fire. At present, many steel enterprises adopt control rolling, because the final rolling temperature control is very strict, and after the final rolling to take the forced cooling measures, so the grain refinement of steel, delivery of steel has a higher comprehensive mechanical properties. No twist-controlled hot-rolled wire rod performance is superior to the ordinary hot-rolled wire rods is the reason, hot-rolled (forged) state delivery of steel, due to the surface covered with a layer of oxidized tin, and thus have a certain corrosion resistance, storage and transportation requirements not like cold drawn (rolling) state delivery of steel as strict, large and medium-sized steel, Medium-thickness steel plate can be stored in the open yard or after thatch.
Cold drawn (rolled) delivery status
By cold drawn, cold-rolled cold processing molding steel, without any heat treatment and direct delivery of the state, known as cold drawn or cold-rolled state. Compared with the hot-rolling (forging) state, the cold drawn (rolling) state of steel, high dimensional accuracy, good surface quality, low surface roughness, and has a higher mechanical properties, due to cold drawn (rolling) state delivery of steel surface without oxide cover, and there is a large internal stress, very susceptible to corrosion or rust, thus cold drawn (rolling) state of Steel, Its packaging, storage and transportation are more stringent requirements, generally need to be kept in the warehouse, and should pay attention to the temperature and humidity in the warehouse control.