Based on specific requirements, there’ll be suitable steel types with different treatment of galvanizing. However, high quality galvanized steel still possess quite the same criteria such as followings:
- The product comes from factories with high production capacity and qualify the international standards that are widely applied for galvanized steel such as ASTM (American Society for Testing and Materials), JIS (Japanese Industrial Standards), or AS/NZ (Australian/New Zealand Standard)
- The finished product should be fully labeled so you will be able to check the origin of the product. This ensures that the steel you buy is from a prestigious supplier/manufacturer.
The surface should be smooth and bright, and there of course should not be any sign of corrosion.
Most steels can be satisfactorily hot-dip galvanized. However, reactive elements in the steel, in particular, silicon (Si) and phosphorus (P), have an effect on the result. An appropriate selection of composition can therefore give more consistent quality of coating with regard to appearance, thickness and smoothness. The prior history of the steel (e.g. whether hot rolled or cold rolled) can also affect its reaction with the zinc melt. Where aesthetics are important, or where particular coating thickness or surface smoothness criteria exist, specialist advice on steel selection should be sought prior to fabrication of the article.
The influence of silicon and phosphorus on steel reactivity
During steel production, silicon or aluminium is added to remove oxygen. These steels are known as “killed steels”. Steel may also be produced without these additions and are then called “rimming steels”. However, such steels are not so common today because of their lower quality.
Choice of steel
Since the type of steel, primarily the silicon content, has a large influence on the coating thickness in hot- dip galvanizing it is very important that the constructor or manufacturer are well aware of this in order to get the right result in every individual case.