Advantages Of Galvanized Steel Sheet

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1. Galvanized Steel Sheet

1.1 Definition It describes the base metal coating with thin layer of zinc in order to be protected from corrosion, caused by the surrounding environment such as moisture, oxygen and other elements in the air. There are 2 ways which the zinc coating can prevent the rusting or corrosion. Firstly, it prevents oxygen and moisture from reaching the steel surface. Secondly, it acts as cathodic protection in the form of process called “galvanic corrosion”. [1] When the metal contacting with zinc in an electrolyte such as salty water has been scratched, the difference in electrochemical causes zinc to be corroded first since it has more electropositive (more easily to be oxidized, higher in reactivity) than iron,
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• Outstanding resistance to mechanical damage.
• Protection to small areas of steel exposed through damage.

1.6 The Different between Galvannealed from Galvanized steel sheet
1.6.1 In term of process The mainly different of these two steel sheets is in the heating even they were both made from hot-dip coating process. For the galvanized coating, there is only zinc on a galvanized coating with roughly 0.20 to 0.30% aluminum in the coating. The adding aluminum purpose is to increase the adhesion between the coating and the steel substrate during forming operations. On the other hand, the coating surface of final product on galvannealed steel sheet is an alloy composed of 90% zinc and 10% iron. Its process is started by heating up to approximately 538 to 565°C by passing through a furnace directly above the coating bath and holding strip at this temperature for a specific period of time. The diffusion of molten zinc and iron from the steel strip. The total amount of diffusion depends on time and heating cycle which affects to the final iron concentration.
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