engleski

Stainless steel crevice corrosion testing in natural and synthetic seawater

Susceptibility of stainless steel to crevice corrosion in natural and synthetic seawater was investigated by a new test method, developed by a research group, CrevCorr, of the Marine Working Party of the European Federation of Corrosion. The method was defined on the basis of the Round Robin test performed by twenty laboratories over the world(1, 2). Among them was our Institute at the Adriatic coast. Geometry of the crevice model, gasket materials, finishing of metal surface and the electrochemical potential increase rate were strictly defined. The monitoring of the free corrosion potential of two austenitic steels and a duplex steel, in the constant flowing conditions, as well as the redox potential, temperature, chloride and oxygn content, have been carried out during six months in the natural seawater from the Adriatic Sea at the location in Dubrovnik, Croatia. Sharp drop of the corrosion potential was used as an indication of the crevice corrosion initiation. After exposure to the seawater eventual crevice damage on a steel specimen was detected by visual and microscopic inspection. In the synthetic seawaer the organic component was simulated by glucose and glucose oxidaze (3, 4). The monitoring of the free corrosion potential and the redox potential was performed at 20, 30 and 40C degrees during five days, and results compared with those obtained in the atural seawater at the same temperature.

stainless steel; crevice corrosion; natural seawater; synthetic seawater

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