Galvanized steels; a surface treatment against corrosion

Hot-dip galvanizing of steel is a widespread industrial process with many applications all around us. However, there is still a lack of knowledge about the technique and properties of this metallic surface treatment.

This article has been written to help fill this gap. It is aimed at all users and specifiers who have to resolve issues of steel durability and combat corrosion phenomena, particularly atmospheric corrosion. In a context where the longevity of structures and the preservation of our natural resources are paramount, galvanized steel is the preferred choice, and a thorough understanding of its characteristics is essential.

The first section describes the metallic structure of the coating obtained by hot-dip galvanizing and the conventional industrial process used to control it. The interaction and reactivity between molten zinc and steel are highlighted, and research results are presented to point the way to solutions currently under development.

Long-lasting performance, durability and service life are the main characteristics of this surface treatment. It gives steel parts a service life compatible with the new requirements of building owners (who demand at least 30 years of maintenance-free operation). We'll see how hot-dip galvanizing meets these new requirements for sustainable construction.

Over and above the characteristics of the metal coating, the industrial process complies with strict rules to ensure consistent quality of galvanized parts, whatever the nature of the parts treated. Efforts to protect the environment have been considerable in recent years, necessitating rigorous effluent management and total recycling.

The impact of zinc on the natural environment has been the subject of numerous studies. This aspect will be discussed in order to clear up any misunderstandings on the subject, and to recall the new concepts established by the international scientific community.