Low carbon steel plate is a kind of material that is used a lot, which is divided into ordinary low carbon steel plate and special steel plate, including low alloy high strength steel and corrosion and heat resistant laminated steel plate. Ordinary low carbon steel plate is divided into cold rolled and hot rolled two, cold rolled steel plate surface quality is good, thickness and size is accurate, and it is used for manufacturing body and so on. Hot-rolled plates are often used to make car frames.

    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. Hot rolling alone can produce about 1.2mm of low carbon steel plate and about 2mm of stainless steel plate, and thinner plates are made by cold rolling and annealing and tempered rolling.

Cold-rolled steel plate

    The cold-rolled steel plate is used for parts forming parts that require large plastic deformation of the material and no wrinkles or cracks on the surface. For different parts, different grades of steel plates are used. For example, the standard of Japanese automobile steel plate is divided into three categories, the first class (SPCC) is an ordinary cold-rolled steel plate, usually rolled by boiling steel, the second class (SPCD) is a rolling steel plate, and the third class (SPCE or SPCEN) is a deep-drawn cold-rolled steel plate.

    In the past, due to the large segregation of the components of the boiling steel, the performance is unstable and the aging is sensitive, and it is limited to unimportant stamping parts. If the time-free aluminum killed steel is used, the cost is 10-20% higher than that of ordinary boiling steel. Finishing cold rolling has previously been used to suppress the aging of boiling steel plates, in fact only delaying the occurrence of aging. Countries are researching new ways to improve. The loose coil annealed steel plate (O.C.A) developed by the United States is a special annealing of the boiling steel plate in an atmosphere containing water steam and hydrogen, because the annealing in this atmosphere can remove the solid solution in the steel and the combined carbon in the carbide, 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 the Armco Steel Company in the United States, this is related to the improvement of the plastic deformation anisotropy of the steel plate, so that the stamping formability of the steel plate is improved. In recent years, on the basis of the loosely rolled annealing steel plate, the combined annealing steel plate (U.A.D) has been developed, which is to weld several rolls of steel plates into one roll and put them in a special annealing furnace for decarbonization. Its advantages are less than the cost of loose coil annealing, and the steel plate treated in this way has been widely promoted in the cold-rolled steel plate for drawing.

Hot rolled steel plate

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

    Recently, more and more foreign hot rolled steel plate is used to roll continuous casting steel slab, and the surface quality of steel plate is constantly improved and stable. Hot rolled steel sheets in rolls are also commonly used.