Rolling steel production plate and strip product introduction
How to classify strip and strip products?
Sheets supplied in a single sheet and strips supplied in rolls are generally referred to as sheet strips. There are many varieties and specifications for strips and strips. According to the type of material, there are steel strips, copper strips and aluminum strips. Each type can be subdivided into a variety of sizes, materials and uses. For example, strip steel can be divided into three types according to product size specifications: thick plate (including medium plate and extra thick plate), thin plate and extremely thin strip (or foil). Generally, the thickness is 4mm or more, which is a medium-thick plate (including 4 to 20mm for the middle plate, 20 to 60mm for the thick plate, 60mm or more for the extra-thick plate), and 4 to 0.2mm for the thin plate, and 0.2mm. The following are very thin strips or foils.
What are the characteristics of the production process of strip steel?
(1) Heat heats the slab of the hot rolled strip, generally in the form of a continuous heating furnace. In order to meet the needs of increasing hot rolling production, modern continuous heating furnaces use hot-slide or step-type heating methods. On the one hand, multi-stage (6-8 sections) heating mode is adopted to extend the high temperature zone of the furnace to achieve intensive operation. Quickly burn steel to increase the unit area of the furnace bottom; on the other hand, increase the furnace width and furnace length as much as possible to expand the furnace capacity. To increase the length of the furnace, a stepping furnace can be used, which is the mainstream of modern hot rolling mill heating furnace. In order to save energy consumption, slab hot charging and direct rolling technology have been rapidly developed in recent years. The hot charging is to put the continuous casting billet or the preliminary rolling stock into the heating furnace under the hot state, and the higher the hot charging temperature, the more energy saving. The temperature requirements for hot slabs are not as strict as for direct rolling. For direct rolling, after the continuous casting or initial rolling, the slab is no longer heated in the heating furnace and only slightly compensated by the edge, that is, directly rolling.
(2) Rough rolling Tropical steel rolling is divided into several stages of descaling, rough rolling and finishing rolling. Unlike the rolling of the general strip, the width control of the hot strip rolling in the rough rolling stage is not limited to widening, but instead the width is used to reduce the slab width and improve the removal effect.
What is the strip shape?
The steel plate shape refers to the uniformity of the thickness distribution of the transverse section of the steel plate and the flatness of the plate surface. It is generally considered that the shape of the plate is caused by the uneven longitudinal extension of the dots in the width direction of the plate. Strictly speaking, the shape of the plate is caused by the residual stress in the strip after rolling. It is conceivable that the rolled piece just rolled out from the roll gap is relatively free due to its front end, so that uneven deformation in the width direction may be reflected in the shape of the front end, but when the length of the rolled piece is increased, continue The rolled rolled piece, the hindrance of the unevenly extending front end, is unlikely to continue to be reflected in the shape of the front end, thereby generating longitudinal tensile stress in the width direction. This tensile stress is the residual stress after deformation of the rolled piece. When the stress is large enough, the shape of the strip is characterized by waves, warpage and the like. Therefore, a good condition of the plate shape is that the rolled piece is rolled through the deformation zone, and the deformation due to the residual stress (generally referred to as “secondary deformation”) is equal to zero after leaving the roll gap. That is to say, when the sheet is rolled, the longitudinal distribution of the lateral distribution is completely uniform. The condition of this extension is that the elongation coefficient is the same along the transverse section.