Tinplate (commonly known as tinplate) refers to a steel plate with a thin layer of metal tin on the surface. Tinplate is made by rolling low carbon steel into a steel plate about 2mm thick, pickling, cold rolling, electrolytic cleaning annealing, flattening, trimming, and then cleaning, electroplating, soft melting, passivation, oiling, and shearing into a finished tinplate plate. The tin used for tinplate is high-purity tin (Sn>99.8%). The tin layer can also be applied by hot dip plating. The tin layer of the tinplate obtained by this method is thicker, the amount of tin is large, and no purification treatment is required after tin plating.
Tinplate consists of five parts, from the inside to the outside, the steel substrate, the tin-iron alloy layer, the tin layer, the oxide film and the oil film.
The production process of tinplate mainly includes electroplating tin, soft melting, cathode passivation and oiling. The electroplating tinning process deposits a layer of metallic tin on the cold-rolled sheet. The reflow process forms a very thin tin-iron alloy layer between the cold-rolled substrate and the pure tin layer. The cathode passivation treatment and oiling process form a passivation film and an oil film respectively.
Tinplate has the advantages of being odorless, non-toxic, light in weight, and easy to process and shape. Printing different patterns can also beautify the product, so it has been widely used in the food canning industry, electronic devices, chemical paint and other industries. In the production process of tinplate, after the strip steel is reflowed by tin plating, in order to prevent the tin layer from oxidizing and yellowing during storage or paint baking, and to improve the tinplate's anti-sulfur properties, the tinplate must be passivated.
