Possibilities of Confocal Laser Microscopy for Determining the Parameters of Local Corrosion

Abstract—The possibilities of confocal laser scanning microscopy (CLSM) methods for estimating the parameters of crevice and pitting corrosion of austenitic chromium–nickel AISI 316L steel after corrosion tests in aqueous media with various chlorine ion contents are estimated. Saturated and diluted artificial seawater with various chlorine ion contents in the range from ~100 to ~29 000 ppm is used as a corrosive medium, and the corrosion test time ranges from ~1000 to ~4200 h at temperatures of 25 and 70°C. Corrosion tests and CLSM studies have found that the foci of crevice corrosion form at a chlorine ion content of more than 7300 ppm in water at both test temperatures and all exposure times, and the formation of corrosion sites with metastable pittings is only detected after the maximum test time at 70°C and the maximum Cl^– content of ~29 000 ppm.