Steel plate is a flat steel plate cast with molten steel and pressed after cooling. It is flat and rectangular, which can be directly rolled or cut by wide steel strip. Steel plates are divided according to thickness. Thin steel plates are less than 4mm (the thinnest is 0.2mm), medium thick steel plates are 4 ~ 60mm, and extra thick steel plates are 60 ~ 115mm. Steel plate is divided into hot rolling and cold rolling according to rolling. The width of the sheet is 500 ~ 1500 mm; The width of the thickness is 600 ~ 3000 mm. Thin plates are divided into ordinary steel, high-quality steel, alloy steel, spring steel, stainless steel, tool steel, heat-resistant steel, bearing steel, silicon steel and industrial pure iron thin plates; According to professional use, there are oil barrel plate, enamel plate, bulletproof plate, etc; According to the surface coating, there are galvanized sheet, tinned sheet, lead plated sheet, plastic composite steel plate, etc.