Seyyed Mehdi Mostashiri - University of Amirkabir Industrial Technology, Tehran, Iran
Heidar Abbasi - University of Applied Science and Technology of Khormuj, Chemical Engineering Department, Bushehr, Iran
Ali Haghighi Shad - University of Amirkabir Industrial Technology, Tehran, Iran
Abdolmajid Ramezani - University of Applied Science and Technology of Khormuj, Chemical Engineering Department, Bushehr, Iran

Pit corrosion of mild steel in seawater increased with Cr3+ concentration. SEM observations showed that increasing Cr3+ concentration caused microbes in biofilm on the steel surface to aggregate forming clusters. AFM images suggested that pit corrosion occurred largely on the mild steel surface between clusters, and only little corrosion on the surface covered by microbes

biofilm, chromium, corrosion, microbial clusters, sulphate-reducing bacteria