| Corrosion Resistance |
Electrochemical Protective Action |
Zn with stronger ionization tendency than iron becomes compound of Zn carbonate and protects the surface of iron. Even though the surface of zinc is destroyed, Zn melts because of its stronger ionization tendency and iron gets long life by Zn sacrificial anode. |
| Physical Protective Action |
If Zn is exposed to the air as a reactive metal, it becomes zinc oxide by sharply reacting with oxygen and also forms a thin film of basic zinc carbonate by reacting with carbon dioxide. This thin film prevents rust from corrosive environment with good dense adhesion. |
| Corrosion Resistance in the air |
The life of Hot Dip Galvanized Iron & Steel is proportional to the coating weight of Zn. For same coating weight, however, the life may be largely changed by the usage environment. The corrosion resistance of hot dip galvanized iron and steel in a city or industrial area is just 25~40% compared to an unpolluted rural area. The interior life at the same area is longer 5-10 times than the exterior life. |
| Formability |
Due to excellent adhesion of Zn and ultra thin alloyed layer of Fe-Zn, flaking hardly does not occur even after drawing work. Its formability is very excellent as much as cold rolled steel plates and it is available for diverse works. |
| Paintability |
Hot Dip Galvanized Iron & Steel is mostly used after final coating, and the corrosion resistance of painting products depends on the disk, pre-treatment before painting and a kind of paint and varnish. |
| Weldability |
For it has better electric conductivity than iron, such good conductivity makes electric resistance on the contact surface of the steel plate small and heating value is also small. |
| It has the lower meting point than iron. So, Zn attaches to electrode when welding and such attachment causes low continuous weldability. |
| Its current density falls a little bit due to comparatively wide contact areas by welding force(electrode force). |
| Corrosion Resistance |
For alloyed galvanized steels, its plating layer is Fe-Zn alloy coating. So, its corrosion device is different from one of hot dip galvanized Iron & Steel. Rust is remarkably generated in the severe accelerated corrosion test like a salt spray test by the iron in the alloy layer much than hot dip galvanized Iron & Steel, but its white rust resistance is stable under constant temperature and humidity. |
| Weldability |
For the surface of alloyed galvanized steel is made of Fe-Zn alloy, its weldability is good with good hardness and high melting point compared to pure Zinc. |
| Flare Groove Weld |
It is good as much as cold rolled steel. |
| Others |
Paintability is improved because there is no spangle on the surface, corrosion resistance is excellent because of low electromotive force, and ark and seam weldability is outstanding. |
