Abstract
In the present paper, a new technique of measurements using wire beam electrodes (WBE) has been introduced and the data ranges from WBE measurements were chosen as the parameters for estimating the pitting sensitivity of metals in various environments. Comparisons of this technique and traditional cyclic potentiodynamic polarization were made for stainless steel in NaCl solutions of different concentrations. The potential range of the WBE changes with materials, solutions and exposure time. According to the range - time curves, the transition between the unstable pitting stage and the stable pits growth stage could be determined and acceleration factors could be studied. The potential ranges of the WBE increased linearly as the NaCl concentration increased logarithmically. WBE measurements for carbon steels, two common pipe steels were also conducted. The results show that carbon steels in NaCl solutions have less pitting sensitivity than stainless steel, although they have a much higher general corrosion rate than stainless steel. On the other hand, one of pipeline steels, API 5L grade X70 has a higher sensitivity for suffering from pitting corrosion than another pipeline steel, 16Mn which is commonly used in China, although 16Mn steel has a much higher general corrosion rate than X70 steel.
