Cold-rolled steel rusts. Cold rolled steel refers to the steel produced by cold rolling. Oxygen in the air oxidizes the iron in the cold-rolled steel into iron oxide (rust), so the cold-rolled steel rusts. In fact, all steel will oxidize, but the degree of oxidation is different, such as stainless steel in the common environment is oxidized for a long time. In addition, the surface of cold rolled steel plate can be galvanized, oiled, painted and so on to prevent rust.
Cold rolling is to further thin No.1 steel plate to the target thickness at room temperature. Compared with hot rolled steel plate, cold rolled steel plate thickness is more accurate, and the surface is smooth, beautiful, but also has a variety of superior mechanical properties, especially machining performance. Because the cold rolled original coil is brittle and hard, it is not suitable for processing, so the cold rolled steel plate is usually handed to the customer after annealing, pickling and surface leveling.