Galvanized steel sheet
Galvanized sheet is a steel sheet whose surface is coated with a layer of zinc. Galvanizing is a cost-effective and effective rust-preventing method that is used in the world for about half of the world's zinc production.
Galvanized steel plate is to prevent the surface of the steel plate from corrosion to extend its service life, coated with a layer of metal zinc on the surface of the steel plate, zinc coated steel plate called galvanized plate.
According to the production and processing methods can be divided into the following categories:
hot dip galvanized steel sheet. The steel sheet is immersed in a molten zinc bath to adhere a zinc-plated steel sheet to the surface. At present, it is mainly produced by a continuous galvanizing process, that is, a coiled steel plate is continuously immersed in a plating tank in which zinc is melted to form a galvanized steel sheet;
alloyed galvanized steel sheet. This steel sheet is also produced by hot dip, but immediately after it is discharged, it is heated to about 500 ° C to form an alloy film of zinc and iron. This galvanized sheet has good adhesion and weldability of the coating;
electro-galvanized steel plate. The production of such a galvanized steel sheet by electroplating has good processability. However, the coating is thinner and the corrosion resistance is not as good as that of hot dip galvanized sheet;
single-sided plating and double-sided differential galvanized steel. Single-sided galvanized steel, that is, a product that is only galvanized on one side. It has better adaptability than double-sided galvanized sheet in welding, painting, anti-rust treatment and processing.
In order to overcome the shortcomings of uncoated zinc on one side, there is a galvanized sheet coated with a thin layer of zinc on the other side, that is, a double-sided differential galvanized sheet;
alloy, composite galvanized steel sheet. It is made of zinc and other metals such as aluminum, lead, zinc, etc., or even composite plated steel. This steel plate has excellent rust resistance and good coating properties;
In addition to the above five types, there are also colored galvanized steel sheets, printed galvanized steel sheets, and polyvinyl chloride laminated galvanized steel sheets. However, the most commonly used ones are still hot dip galvanized sheets.
The relevant product standards specify the standard thickness, length and width recommended for galvanized sheets and their tolerances. Generally speaking, the thicker the galvanized sheet is, the larger the tolerance is, instead of the fixed 0.02-0.04 mm, the thickness deviation also has different requirements according to the yield, the tensile coefficient, etc. The length and width deviation is generally 5 mm, the thickness of the sheet. Generally between 0.4-3.2.
(1) Surface state: The galvanized sheet has different surface treatment conditions due to different treatment methods in the coating process, such as ordinary zinc flower, fine zinc flower, flat zinc flower, zinc-free flower and phosphating surface. German standards also specify surface levels.
(2) The galvanized sheet should have a good appearance and must not have any harmful defects such as no plating, holes, cracks and scum, excessive plating thickness, scratches, chromic acid stains, white rust, etc. Foreign standards are not very clear about the specific appearance defects. Some specific defects should be listed on the contract when ordering.