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Difference Between the Production Process and Performance of Sainless Steel Cold Rolling and Hot Rolling.

Mar. 30, 2020

There are two main types of stainless steel plates: hot-rolled and cold-rolled. From the appearance to the application performance, the difference between the two is very obvious. The supplier of Cold Rolled Steel Sheet Supplier will explain it in detail.

Hot-Dipped Galvanized Steel Angle and cold-rolled coil are two different rolling technologies. As the name implies, cold-rolling is the rolling of steel at normal temperature, which has a high hardness. Hot rolling is when the steel is tied at high temperatures.

The first is hot rolling. The temperature of stainless steel rolled products is high, the deformation resistance is small, and it can show a large amount of deformation. And because the stainless steel plate has a small width-to-thickness ratio, the requirement for dimensional accuracy is relatively low, and it is not easy to cause plate shape problems, mainly for controlling convexity. If there is a requirement for the metal structure, the microstructure and mechanical properties of the stainless steel plate is usually controlled by controlling the rolling temperature, finish rolling temperature and coiling the temperature of the finish rolling.

Using continuous casting slabs or preliminary rolled slabs as raw materials, heated by a step-type heating furnace, descaled by high-pressure water, and then enters the roughing mill. The rough rolling material is cut into the head, tail, and then into the finishing mill. Computer-controlled rolling is implemented. After the final rolling, it is coiled by laminar cooling (computer-controlled cooling rate) and coiler to become a straight hair coil. Straight hair curls tend to be tongue-shaped and fish-tail-shaped, with poor thickness and width accuracy, and often have wavy, folded, and tower-shaped defects on the sides. Its coil weight is heavy and the inner diameter of the steel coil is 760mm. (Commonly used in the tube industry.) After straight hair is processed through cutting, tailing, trimming and multiple straightening and levelling lines, and then cut or re-rolled, it becomes: hot rolling Steel plate, flat hot rolled steel coil, slitting tape and other products. If the hot-rolled finishing coil is pickled to remove scale and oil, it will become a hot-rolled pickled coil. This product has the tendency to partially replace the cold-rolled sheet and the price is moderate, and it is loved by customers.

1.2mm Standard Hot Rolled Steel Coils for Building Construction

1.2mm Standard Hot Rolled Steel Coils for Building Construction

However, the Coating Galvanized Steel Strip is usually without heating before rolling. However, because the thickness of the board is small, the problem of board shape is more likely to occur. In addition, most products are cold-rolled after being rolled. Therefore, in order to control the dimensional accuracy and surface quality of stainless steel plates, a complicated production process is used. The cold rolling production line is long, the equipment is many and the process is very complicated.

It uses hot-rolled steel coils as raw materials and performs cold continuous rolling after pickling to remove oxide scale. The finished product is rolled hard coils. The cold work hardening caused by continuous cold deformation increases the strength, hardness and toughness of rolled hard coils The index decreases, so the stamping performance will deteriorate, and it can only be used for parts that are simply deformed. Hard-rolled coils can be used as raw materials for hot-dip galvanizing plants because hot-dip galvanizing units are equipped with annealing lines. The weight of rolled hard coil is generally 6 ~ 13.5 tons and the inner diameter of the steel coil is 610mm.

Generally, the continuous cold-rolled plates and coils should be subjected to continuous annealing (CAPL unit) or bell furnace annealing to eliminate cold hardening and rolling stress and meet the mechanical performance indicators specified by the corresponding standards. The surface quality, appearance, and dimensional accuracy of cold-rolled steel are better than those of hot-rolled steel and the thickness of the product are right-rolled to about 0.18mm, so it is favoured by customers. The cold-rolled steel coil is used as the substrate for deep processing of the product, which becomes a high value-added product. Such as electro-galvanized, hot-dip galvanized, fingerprint-resistant electro-galvanized, colour-coated steel plate coil and vibration-damping composite steel plate, PVC coated steel plate.

The difference in appearance is also obvious, and the surface of the cold-rolled stainless steel plate has better gloss. If the hot-rolled stainless steel plate is not pickled, it is almost the same as the surface of many ordinary steel plates on the market. The surface with rust is red, and the surface without rust is purple-black.

The performance advantages of cold-rolled stainless steel plates compared with hot-rolled stainless steel plates are mainly higher accuracy, and the thickness difference of cold-rolled stainless steel does not exceed 0.01 ~ 0.03mm. And its size is thinner, the thinnest cold-rolled can be rolled 0.001mm steel strip; hot rolling now the thinnest can reach 0.78mm. Its surface quality is even better. Cold-rolled stainless steel plates can even produce mirror surfaces, but the surface of hot-rolled stainless steel plates will have defects such as scale and pits. Cold rolled stainless steel plate can adjust its mechanical properties according to user requirements.

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