Crevice Corrosion of 304 L Stainless Steel in Chloride Environments

Electrochemical techniques have been applied to study the crevice corrosion resistance of 304 L stainless steel in sodium chloride solution at 25 and 80 degree C. Two types of specimens were used in this investigation. Cylindrical type specimens were used for the determination of passive currents and critical crevice solution (CCS) characteristics which are the pH and the chloride ion concentration. The other type, a metal to non metal assembly, is used for the evaluation of the crevice corrosion susceptibility. The potentiodynamic results showed that the critical pH of the crevice solution for 304 L stainless steel (as defined by old field (1) and sutton) lies between 2.1 and 2.5 in I M NaCl. on the other hand, the critical PH of the crevice solution as defined by crolet (2) is about 2.5 in 1 M NaCl. increasing the chloride ion concentration resulted in increasing the pH of the crevice solution. Cyclic potentiodynamic polarization scans conducted in 1 M NaCl at 25 degree C and 80 degree C showed that 304 L stainless steel sulfur from sever crevice corrosion in the test solution with the increase in severity of the attack with temperature. The cyclic polarization scans were further supplemented by Sem investigation. 10 figs