Abstract
A newly designed working electrode on which occurrence of crevice corrosion is prevented with the flushed port cell has been developed in order to measure the critical pitting temperature, CPT, and pitting potential, Epit, for stainless steels.
In the solution temperature range from 25°C to 100°C, the difference between the electrode surface temperature and bulk solution temperature could be maintained within 0.3°C in measuring CPT by using a pre-heating flushed water system. The measured values of CPT as well as Epit which were obtained from 12 trials of the measurement under the same condition, were found to obey the normal distribution. Epit at the constant temperature equivalent to CPT was found not to coincide with the setting potential for CPT due to the film formation in the CPT measurement. The mean value and deviation of Epit obtained by using the crevice corrosion preventing electrode were almost equal to those of Epit measured in the JIS method (JIS G 0577-1981). The newly developed method would be successfully applied to evaluate the difference in pitting corrosion resistance arising from the difference of surface finishing such as 2D, 2B, and BA, and the surface treatment of stainless steel.
