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Hot Rolled SteelHot rolling is a process involving large pieces of steel, which are heated above their recrystallization temperature and pushed between a set of rollers to form thin sheets which exhibit heavy thickness, high strength levels and good formability. This type of steel is not as hard as cold rolled, but is often used for high strength and structural applications within the automotive, appliance, railroad and ship building industries. Hot rolled steel is used for a wide variety of products, such as frame components for cars, wheels, tubing, agricultural equipment parts and machinery parts. It is usually a blue-grey color, and is only painted if it has been pickled with zinc or iron phosphates. This type of steel is available in yield strengths up to 60 ksi. To produce hot rolled steel, steel service centers heat semi-finished slabs of steel nearly to their melting point in a furnace, where they become easily moldable. The slab is pushed through a set of rollers, a process comparable to cookie dough beneath a rolling pin. Its thickness is cut down from 8 or 9 inches to 1 to 1.5 inches. The steel is then cropped into different shapes by a pair of steel drums with large shearing blades and left to return to room temperature. As it cools, a metallurgical transformation in the crystal structure takes places, which hardens the steel considerably. Outside processing, such as pickling, temper rolling, re-squaring, slitting and cutting-to-length is done as a last step.
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