As a widely used structural component in both industrial and civilian fields, the corrosion resistance of hot-dip galvanized steel grating is the core indicator for measuring product quality. The zinc layer formed by hot-dip galvanizing process can provide long-term protection for steel grating, but its corrosion resistance is affected by various factors and exhibits significant differences in different environments.
The protective mechanism of hot-dip galvanized layer is mainly reflected in two aspects. On the one hand, zinc, as a more reactive metal than iron, will preferentially undergo oxidation reactions in corrosive environments by sacrificing itself to protect the steel substrate, known as the “sacrificial anode protection method”; On the other hand, products such as zinc oxide and zinc hydroxide formed after the oxidation of the zinc layer will form a dense passivation film on the surface, effectively blocking corrosive media such as water and oxygen from contacting the steel. The zinc layer of high-quality hot-dip galvanized steel grating needs to reach a certain thickness, which can be maintained for a long time without significant corrosion in a dry indoor environment.
The corrosion resistance of hot-dip galvanized steel grating faces multiple tests in outdoor natural environments. The humidity, sulfur dioxide, salt and other substances in the atmosphere will accelerate the consumption of zinc layer. In rural areas, due to high air cleanliness, the annual corrosion rate of zinc layer is slower and its service life is longer; In industrial or coastal areas, due to the presence of a large amount of pollutants or chloride ions in the air, the corrosion rate of the zinc layer will significantly accelerate, and its service life may be shortened. Especially in the high salt spray environment of coastal areas, chloride ions can penetrate the passivation film, causing pitting corrosion of the zinc layer and subsequently leading to steel corrosion.
In special working conditions, the corrosion resistance limitations of hot-dip galvanized steel grating will gradually become apparent. In chemical workshops with high acid and alkali concentrations, the zinc layer will react chemically with the acid and alkali to produce soluble zinc salts, leading to rapid failure of the protective layer; In high temperature and high humidity environments, the zinc layer is prone to “white rust” phenomenon, that is, loose zinc hydroxide is generated on the surface. Although it has a certain protective effect on the bottom zinc layer, it will affect the appearance quality and protective performance. In addition, if the zinc layer on the welding points, cuts, and other parts of the steel grating is not fully covered, it will become a breakthrough point for corrosion, causing local rusting and gradually spreading.
Multiple measures need to be taken to improve the corrosion resistance of hot-dip galvanized steel grating. The production process should strictly control the parameters of the galvanizing process to ensure that the zinc layer is uniform and continuous, and perform secondary plating treatment on the welded parts; Regularly clean the accumulated dust and debris on the surface during use to avoid the accumulation of corrosive media; In highly corrosive environments, specialized zinc based coatings can be applied to the surface of the zinc layer to form a composite protective layer. Regularly detecting the thickness and corrosion condition of the zinc layer and taking timely repair measures can effectively extend the service life of hot-dip galvanized steel grating.
Hot dip galvanized steel grating has excellent corrosion resistance in general environments and can meet the needs of most industrial and civilian scenarios, but auxiliary protective measures need to be combined in extreme corrosive environments.
