Galvanized steel coils are metallic materials with a zinc layer adhered to the surface of thin steel sheets through a continuous galvanizing process. The main materials are steel and zinc alloys, and they are divided into two types: ordinary galvanized steel sheets and alloyed galvanized steel sheets. China is the world's largest producer of hot-dip galvanized steel coils, with an output maintained at around 90 million tons. Galvanized sheets are mainly used in the construction industry, home appliance industry, automobile manufacturing, and light industry. With the increasing market penetration of new energy vehicles, the demand for galvanized sheets has increased significantly.
Products are classified into seven grades based on performance, including general purpose, mechanical interlocking, and stamping. The substrate is made of cold-rolled coils or hot-rolled pickled coils. The coating is classified into four categories based on the zinc spangle structure: normal zinc spangle, small zinc spangle, no zinc spangle, and zinc-iron alloy, and further designated by codes from Z60 to Z600 based on the weight of the double-sided coating. Surface treatments include passivation, oiling, paint sealing, and phosphating. Defects mainly include coating peeling, white rust, black spots, and mechanical damage.