This situation has been greatly improved after the current suspension of lead and the use of antimony to promote the formation of spangles. The blackened galvanized layer still has a protective effect on the steel base, but it has a certain impact on life. One is that after the galvanized sheet is used for a period of time, due to the influence of elements such as lead in the galvanized layer, the matte part of the spangle will turn black. In addition, there are two special corrosion conditions of the galvanized sheet called “blackening”. When the steel base starts to oxidize and corrode, the speed becomes very fast, “the galvanized sheet also ends its life. When the galvanized sheet is used for a long time, the corrosion of the galvanized layer is severe, and the steel base loses the “sacrificial anti-corrosion” effect of zinc, and begins to oxidize to form “red rust”. After a little longer time, the “white rust” on the surface will further react with impurity gases such as carbon dioxide in the moist gas to form “black spots”. It is more prone to corrosion if it is wetted by acid rain or there are chemical substances in the warehouse or there are chemical plants nearby.ĭuring the entire service life of the galvanized sheet, the first corrosion that occurs is the oxidation of the galvanized layer on the surface to form “white rust”.The zinc plate is not pure and contains impurities.When exposed to acid rain and other chemicals, it accelerates rusting.The zinc layer is too thin and the corrosion resistance is poor.The surface is damaged during transportation or installation, resulting in weakening of the anti-rust ability.
Galvanized steel sheets with uneven thickness are likely to rust first. The plating layer is not uniform, and there is a missing area.If the galvanized layer has poor local adhesion, even if the galvanized layer is thicker, it will start to rust from the poor adhesion. Under normal circumstances, the corrosion of galvanized sheet is not that the galvanized layer on the surface is uniformly corroded, but the coating is corroded first where the coating and the substrate are poorly bonded, resulting in severe local corrosion and loss of performance.įrom this point of view, the adhesion of the galvanized layer, especially the overall adhesion, is more important than the thickness of the galvanized layer. Generally, cold-dip galvanized steel sheet is easier to rust, while hot-dip galvanized steel sheet is not easy to rust. Galvanized steel sheet is also divided into cold-dip galvanized steel sheet and hot-dip galvanized steel sheet. It can generally be used permanently without rust and corrosion. If galvanized sheet is placed indoors and kept dry and don’t let the galvanized sheet get water stains and corrosive liquid, so the rust time of the galvanized sheet will be prolonged. If the galvanized steel sheet is left outdoors for a long time, the galvanized steel sheet will rust, the service life is about seventy years. The rust time of galvanized steel is determined by the environment in which it is used.
4 How do you keep galvanized steel from rusting? How long will it take for galvanized steel to rust?
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