Influence of Pseudomonas on corrosion and mechanical properties of carbon steel in sea water

Abstract

In order to separate the effects of a specific microbial species (Pseudomonas) in sea water on carbon steel, a comparative study of the corrosion and mechanical properties of AISI 1045 carbon steel in natural sea water, sterile sea water and Pseudomonas inoculated sea water was carried out using tensile testing, mass loss experiments and microscopy. The results of mass loss showed that the corrosion rate of the specimens in the single Pseudomonas system was faster than that in sterile sea water but slower than in natural sea water. Microscopy revealed that a loose corrosion product layer formed on the surface of carbon steel, and micropitting corrosion occurred underneath the corrosion product. Energy dispersive X-ray analysis of this deposit indicated that iron and oxygen were the main components, and a large amount of carbon, which most likely originated from the bacteria and its exopolymer, could also be detected. The tensile strength of carbon steel was reduced by the action of Pseudomonas, but hydrogen embrittlement was not found.