Types and uses of low carbon steel plates

The type of steel plate is usually divided into three kinds according to its thickness: thick plate (above 6mm), medium thick plate (3-6mm) and thin plate (below 3mm). In terms of plate making process, low carbon steel plate can be divided into cold rolling and hot rolling two kinds. Low carbon steel plates of about 1.2mm and stainless steel plates of about 2mm can be made by hot rolling alone, and thinner plates can be made by cold rolling and annealing and tempered rolling.

Cold rolled steel plate

Cold rolled steel plate for parts forming requires the plastic deformation of the material, the surface should not have wrinkles, cracks and other parts. For different parts, different grades of steel plate are used. For example, the standard of Japanese automobile steel plate is divided into three categories, the first class (SPCC) is the ordinary cold rolled steel plate, usually the boiling steel rolled, the second class (SPCD) is the rolling steel plate, the third class (SPCE or SPCEN) is the deep drawing cold rolled steel plate.

In the past, due to the large segregation of boiling steel components, unstable performance, sensitive aging, limited to unimportant stamping parts. The cost of non - time - effective aluminum steel is 10-20% higher than that of ordinary boiling steel. In the past, finishing cold rolling was used to suppress the aging effect of boiling steel plates, which in fact only delayed the occurrence of aging. Countries are studying new ways to improve. The loose coil annealed steel plate (O.C.A) developed by the United States is a special annealing of boiling steel plate in the atmosphere containing water steam and hydrogen, because annealing in this atmosphere can remove the solid solution of steel and carbides in the combined carbon, inhibit the aging sensitivity, and further soften the steel plate. At the same time, due to the growth of recrystallized grains, the {111} aggregate crystalline arrangement parallel to the surface of the steel plate increases. According to the research of Armco Steel Company in the United States, this is related to the improvement of the plastic deformation anisotropic of steel plate, resulting in the improvement of the stamping formability of steel plate 84. In recent years, based on the loose coiled-annealed steel plate, the United Annealed steel plate (U.A.D) is developed, in which several coiled-rolled steel plates are welded into one coil and placed in a special annealing furnace for decarburization. Its advantages are lower than the cost of loose coiling annealing, and the steel plate treated in this way has been widely used in cold rolled steel plate for drawing.

Hot rolled steel plate

Compared with cold rolled steel plate manufacturing process is simple, the cost is cheaper, but foreign experience that hot rolling method is only suitable for the manufacture of thick steel plate more than 1.6 mm, for thinner steel plate is uneconomic, hot rolled steel surface quality and dimensional accuracy are not as good as cold rolled steel plate, hot rolled steel plate on the car, in addition to the frame rail, beam and various supports, Also stamping requires a certain strength of the wheel rim, wheel, etc., as well as the force is not big, surface requirements are not too high shell cover plate. The former is 3-5 mm thick steel plate, the latter medium plate, sheet are used, the use of hot rolled plate on the automobile, to thick plate. In the standard of hot SLSN plate for automobiles formulated by Japan Automobile Association, SAPH type is used as car beam and wheel, while SPH type is hot-rolled soft steel plate for making non-stressed shell.

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Recently, more and more hot rolled steel plate is rolled by continuous cast steel slab, and the surface quality of steel plate is constantly improved and stable. Rolls of hot rolled steel are also commonly used.