Cold rolling and hot rolling are two ways of rolling steel. Cold rolling and hot rolling are two different steel rolling technologies. As the name suggests, cold rolling is done in steel at normal temperature. The hardness of this steel is large. Hot rolling is the steel that is made at high temperatures. So what is the difference between them? Cold Rolled Steel Sheet Supplier Will come to tell everyone.
1. Hot rolling
Continuous casting slab or slab slab is used as raw material, heated by step heating furnace, dewatered by high pressure water and then into rough rolling mill. The rough rolling material passes through the cutting head and tail and then enters the finishing mill to carry out computer controlled rolling. After the final rolling, it is subjected to laminar cooling (computer controlled cooling rate) and coiler winding, which becomes a straight hair roll. The head and tail of the straight hair roll are often in the shape of a tongue and a fishtail. The thickness and width are poorly accurate, and the side has frequent defects such as a wave shape, a folded edge, and a tower shape. The weight of the coil is heavier and the inner diameter of the coil is 760 mm. (Generally, the tube industry likes to use it.) After the straight hair is wound through the cutting, cutting, trimming and multi-pass straightening, leveling and other finishing lines, then cutting or rewinding, it becomes: hot rolling Steel plates, flat hot rolled steel coils, slitting belts and other products. If the hot-rolled finishing roll is pickled to remove the scale and oiled, the hot-rolled pickled sheet roll is formed. This product has a tendency to partially replace cold-rolled sheets, and the price is moderate, which is very popular among users.
Cold Rolled Steel Coil
2. Cold rolling
The hot-rolled steel coil is used as raw material, and the scale is removed by pickling, and then cold-rolled, and the finished product is Cold Rolled Steel Coil. The cold work hardening caused by continuous cold deformation causes the strength and hardness of the rolled hard roll to rise and the toughness index The drop, so the stamping performance will deteriorate, can only be used for parts that are simply deformed. Rolled hard rolls can be used as raw materials for hot-dip galvanizing plants because the hot-dip galvanizing units are equipped with an annealing line. The hard roll weight is generally 6~13.5 tons, and the inner diameter of the coil is 610mm.
Generally, cold-rolled rolled sheets and coils should be subjected to continuous annealing (CAPL unit) or hood furnace annealing to eliminate cold work hardening and rolling stress, and achieve the mechanical properties specified in the corresponding standards.
The surface quality, appearance and dimensional accuracy of the Cold Rolled Steel Sheet are superior to those of the hot-rolled sheet, and the thickness of the product is thinly rolled to about 0.18 mm, which is favored by the majority of users. Deep processing of products with cold-rolled steel coils as a substrate has become a high value-added product. Such as electro-galvanizing, hot-dip galvanizing, fingerprint-resistant electro-galvanizing, color-coated steel coils and vibration-damping composite steel sheets, PVC laminated steel sheets.
Specifically embodied on the steel plate is:
1. The surface of the cold-rolled sheet has a certain degree of gloss. It is smooth to the touch and is similar to the very common steel cup used to drink water.
2. If the hot-rolled sheet is not pickled, it is similar to the surface of many ordinary steel sheets on the market. The surface with rust is red, and the surface without rust is purple-black (iron oxide scale).
The final performance advantages of the cold-rolled sheet and the hot-rolled sheet
1. The precision is higher, and the difference in thickness of cold-rolled strip steel does not exceed 0.01~0.03mm.
2, the size is thinner, cold rolled to thin can be rolled 0.001mm steel strip; hot rolling can now reach 0.78mm thin.
3, the surface quality is more superior, cold-rolled steel plate can even produce a mirror surface; and the surface of the hot-rolled plate has defects such as iron oxide scale and pitting.
4, cold-rolled sheet can be adjusted according to user requirements, such as tensile strength and process properties such as stamping properties.
The above is the difference between cold rolling and hot rolling steel, and I hope to help everyone.