What is hot rolling? What is cold rolling? What is the difference?

1, different raw materials hot rolling mainly to slab as raw material, after heating, by the roughing mill unit as well as finishing mill unit to make steel. Hot rolled strip from the finishing * mill through the laminar flow cooling to a set temperature, from the coiler to the strip rolls, after cooling to the strip rolls, according to user requirements after different finishing line processing, to become steel plate, flat rolls and longitudinal strip products.  Cold rolling to hot rolled steel coils as raw materials, pickling and removal of oxide skin after cold rolling pressure, the finished product is rolled hard coil. As a result of continuous cold deformation caused by cold hardening, rolled strength, hardness rise, toughness indicators decline, stamping performance deterioration, can only be used for simple deformation of the parts. Rolled hard rolls are usually used to make products that do not need to be bent or stretched, and the thickness is below 1.0 for products bent on two or four sides.

2, the process is different cold rolled and hot rolled for comparison, hot rolled is above the crystallization temperature for rolling; and cold rolled is below the crystallization temperature for rolling.
3, the appearance and surface quality is different Because the cold plate is obtained from the hot plate in the cold rolling process, and in the cold rolling at the same time will carry out some surface finishing, so the cold plate in the surface quality, such as surface roughness is better than the hot plate. Therefore, if there is a high demand for the coating quality of the product, such as later painting, cold plate is generally chosen.  In addition, hot plate is divided into pickled plate and non-acid-washed plate. The surface of pickled plate becomes normal metal color due to pickling, but the surface is not as high as cold plate because it is not cold rolled. The surface of non-acid-washed plate usually has an oxidized or ooze layer of iron tetraoxide. Generally speaking, this is like baking on fire, if the storage environment is not good, usually with a little rust.
4, specification thickness is different Ordinary cold rolled coil is usually thinner than hot rolled coil, the thickness range of cold rolled coil is 0.3 ~ 3.5 mm, while hot rolled coil 1.2 ~ 25.4 mm.

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