Corrosion mechanism and protection methods of A588 weathering steel

Corrosion of A588 weathering steel

A588 weathering steel is the first choice for many projects because of its excellent corrosion resistance compared to other steel alloys. The main constituent of A588 steel is iron, which is an electrolyte in most aqueous media and is therefore capable of forming galvanic couples with more noble metals in the presence of electrolytes. During corrosion, oxidizing species such as oxygen or chloride ions are reduced, while more electronegative metals or alloys are oxidized. Moisture or humidity in the atmosphere can also reduce the repassivation potential of the surface, which can lead to corrosion.

In the presence of oxygen or moisture, A588 weathering steel is susceptible to corrosion of its metal surface, a process called Atmospheric corrosion. This occurs when the metal becomes oxidized and corrodes through contact with humid air enriched with oxygen and other gases like nitrogen and carbon dioxide. The result is a slow but steady formation of rust on the metal. In addition to Atmospheric corrosion, A588 weathering steel is also susceptible to chloride ion-enriched corrosion which is much more aggressive compared to atmospheric corrosion. Chloride ion-enriched corrosion occurs when the metal’s protective oxide layer is compromised or broken and it comes in contact with solutions high in chloride ions such as seawater, brine or in industrial applications, cleaning solutions that have not been fully rinsed after use.

Protection methods for A588 weathering steel

To protect A588 weathering steel from corrosion, it is important to apply protective coatings such as paints, primers and other finishes. A coat of paint or primer provides a near-impermeable seal against oxygen, preventing oxidation and therefore atmospheric corrosion. Priming A588 weathering steel with a suitable sealer prior to painting will also provide improved protection. Other coatings such as aluminium or zinc can also be used to protect A588 weathering steel from further corrosion.

Galvanizing is another method for protecting A588 steel from corrosion. This process involves the application of a layer of zinc coating to the steel which acts as sacrificial anode, guarding against secondary corrosion and forming a barrier of protection. This sacrificial zinc coating can be applied either by hot-dipping or by electroplating.

In addition to the protection methods above, it is also important to keep A588 weathering steel in good condition by carrying out regular maintenance and repairs. This involves replacing parts that are beginning to show signs of wear and tear, cleaning and painting surfaces regularly and keeping the surrounding environment clean and dry.

A588 weathering steel can be protected from the effects of corrosion by applying a protective coating, galvanizing, and undergoing regular maintenance inspections. Regular maintenance of A588 weathering steel is important to ensure it continues to be protected from the effects of corrosion for as long as possible.