Flash Rust
Flash rust is a fine, superficial iron oxide formation that occurs shortly after mechanical descaling or blasting of steel parts when exposed to moisture. It must be removed before coating.
Physical-Chemical Mechanism of Action
Flash rust forms on the surface of steel parts when they are exposed to moisture after mechanical descaling or blasting. It is a fine layer of oxidized iron molecules that can form quickly.
Metallurgical Relevance & Welding Risks
Flash rust can cause coating problems because it impairs the adhesion of coatings. It can also alter welding behavior and lead to porosity or uneven weld bead cooling. Furthermore, it can increase corrosion susceptibility.
Workshop Practice & Action Instructions
Before applying coatings, flash rust must be thoroughly removed. This can be done by additional cleaning with a fine descaler or a chemical cleaning liquid. Make sure to keep the steel parts dry and clean to avoid flash rust formation.