Electrochemical study of Type 304 and 316L stainless steels in simulated body fluids and cell cultures.

The electrochemical corrosion behaviour of Type 304 and 316L stainless steels was studied in Hanks' solution, Eagle's minimum essential medium (MEM), serum containing medium (MEM with 10% of fetal bovine serum) without cells, and serum containing medium with cells over a 1-week period. Polarization resistance measurements indicated that the stainless steels were resistant to Hanks' and MEM solutions. Type 304 was more susceptible to pitting corrosion than Type 316L in Hanks' and MEM solutions. The uniform corrosion resistance of stainless steels, determined by R(p), was lower in culturing medium than in Hanks' and MEM. The low corrosion resistance was due to surface passive film with less protective to reveal high anodic dissolution rate. When cells were present, the initial corrosion resistance was low, but gradually increased after 3 days, consistent with the trend of cell coverage. The presence of cells was found to suppress the cathodic reaction, that is, oxygen reduction, and increase the uniform corrosion resistance as a consequence. On the other hand, both Type 304 and 316L stainless steels became more susceptible to pitting corrosion when they were covered with cells.