*2.3. Crevice Corrosion*

The crevice corrosion test was carried out according to ASTM F746-87 [35]. The samples, of cylindrical shape—6.35 mm diameter, 5 cm long—obtained by machining of 10-mm-diameter steel profiles, "mirror" polished, were embedded in a polytetrafluoroethylene (PTFE) collar at one of the extremities (Figure 1). Both transverse and longitudinal surfaces were subjected to the corrosion test.

**Figure 1.** Specific assembly for the crevice corrosion test. Crevice corrosion aspect of the test sample.

The sample was mounted in the rotating electrode of the measuring cell (Figure 2). The test consisted of two stages:


**Figure 2.** The electrochemical assembly and the electrochemical measuring cell.

If the current recorded stayed within the cathodic domain (negative values), a fresh measurement cycle was started: excitation for 10 s at 800 mV and current measurement for a potential set at Eabandon +25 mV (ASTM recommends +50 mV). The cycles were repeated, each time at a higher potential, until the current measured moved into the anodic domain (positive values). As a result, the crevice potential was determined, which corresponded to the last-but-one measurement for which the current

was positive. Once the Teflon ring was removed, a groove of crevice corrosion was noted on the surface of the metal sample.
