The pitting resistance of pickled, ground and electropolished surfaces of EN 1.4404 (AISI 316L) tubes has been tested using cyclic polarization and ASTM G150 for determination of the pitting potential and CPT, respectively. The materials were tested in chloride-containing solutions with 0.05 to 5.0% Cl-. Crevice corrosion was avoided using a flushed port cell with a specially cast gasket. Ground finish having low surface roughness shows no improvement over the coarse pickled finish, while electropolished finish provides considerably higher resistance but at the same time scattered results. The two testing techniques give almost identical CPTs that show only little dependence on chloride concentration. The variation in pitting resistance has been correlated to the surface morphology of the different surface conditions.

Subject
Surface finishing, Pits, Test methods, Materials, Cyclic polarization, Tubes, Roughness, Surfaces, Pitting, Surface profile, Corrosion resistance, Polarization, Chlorides
Keywords:
EN 1.4404, tubes, surface condition, pitting potential, critical pitting temperature, ASTM G150
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2006
Association for Materials Protection and Performance (AMPP)
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