CorroZone Podcast · 16 Jun 2026
Pitting Corrosion
- Free
- Lecture
- Beginner
- ~30 min
How passive films break down at chloride-attacked inclusion and defect sites, the autocatalytic acidified-chloride chemistry inside a growing pit, metastable versus stable pitting, the pitting and repassivation potentials read from a cyclic polarisation curve, ranking alloys by PREN and critical pitting temperature, and why pitting and crevice differ.
Show notes
What you'll learn
- Explain the mechanism of passive film breakdown by chloride ions at inclusion and defect sites
- Describe the autocatalytic chemistry inside a propagating pit (acidification, chloride enrichment, active dissolution)
- Distinguish metastable from stable pitting and explain the conditions for the transition
- Define the pitting potential (Epit) and repassivation potential (Erep) and interpret a cyclic polarisation curve
- Apply the PREN formula to rank stainless steel alloys by pitting resistance
- Use the critical pitting temperature (CPT) concept for alloy selection in chloride environments
- Compare initiation pathways of pitting versus crevice corrosion and explain why crevice requires higher PREN
Who this is for
Anyone beginning their study of corrosion — students, engineers, and technical staff who want a solid foundation in why metals corrode and what can be done about it. No prior background assumed.
What you'll learn
- Explain the mechanism of passive film breakdown by chloride ions at inclusion and defect sites
- Describe the autocatalytic chemistry inside a propagating pit (acidification, chloride enrichment, active dissolution)
- Distinguish metastable from stable pitting and explain the conditions for the transition
- Define the pitting potential (Epit) and repassivation potential (Erep) and interpret a cyclic polarisation curve
- Apply the PREN formula to rank stainless steel alloys by pitting resistance
- Use the critical pitting temperature (CPT) concept for alloy selection in chloride environments
- Compare initiation pathways of pitting versus crevice corrosion and explain why crevice requires higher PREN