Pitting Corrosion
Pitting corrosion is local destruction of passive metal surfaces by aggressive anions like chloride, forming pinpoint pits. It is caused by breakdown of the protective layer.
Physicochemical Mechanism of Action
Aggressive anions like chloride react with the metal and breach the passive protective layer, leading to localized corrosion sites. These reactions occur near holes or under the influence of moisture.
Metallurgical Relevance & Welding Risks
Pitting corrosion can cause cracks and destruction of the metal structure, especially at locations with pre-existing holes or under the influence of chloride. This increases the risk of hot cracking and reduces the component's service life.
Workshop Practice & Instructions
Avoid chloride-containing media near metal parts. When welding steels with pre-existing holes, thorough cleaning and application of a passive corrosion protection agent are essential. Monitor ambient temperature and humidity to prevent chloride formation.