The advantages of galvanizing
Dipping clean steel in a molten zinc bath (450°C / 840°F) generates a metallurgical bonding of zinc alloys. These layers are subsequently coated with pure zinc.
The first steel alloy is harder than steel itself. This is what gives hot-dip galvanizing its high resistance to abrasion. While the smooth, pure zinc outer layer absorbs shocks, the other layers of alloys provide excellent protection to the base metal.
It is possible to determine the coating’s life by taking into account the weather conditions in which it will be used.
Research by the ASTM in different locations, where zinc layers were exposed to varied climate conditions, has been published.
Rust degrades scratched paint
The part of the steel exposed by scratched paint corrodes and a rust bubble appears. Having more volume than the steel, this bubble rises and raises the metal’s paint surface, causing puffiness. Over time, the corrosion increases.
The sacrificial protection of galvanizing
When a crack appears on galvanized steel, the galvanic protection ensures that the zinc coating is sacrificed to protect the steel it is bonded to. This protection will be maintained as long as there is zinc in the immediate vicinity of the crack..
In the case where the scratch appears on a hot galvanized coating, the steel is protected from corrosion by the surrounding zinc. This is the electrochemical property of the zinc, which is greater than that of the steel.
Corrosion is an electrochemical process. It attacks the zinc next to the steel, rather than the exposed part of the steel. Thus, unlike other corrosion prevention treatments, small cracks need not be touched up.