The Effect of Small Amounts of Elements on Shapes of Potentiodynamic and Potentiostatic Curves of Aisi 304l and Aisi 316l Stainless Steels in Chloride Media

Abstract

- Samples of high purity grade and commercial purity grade type AISI 304L and AISI 316L steels were studied by the potentiodynamic and potentiostatic techniques in a naturally aerated 3.5% NaCl aqueous solution at a controlled temperature of (23±2)°C. The anodic polarization curves of the potentiodynamic technique showed that not always is it possible to determine pitting potential: most of the curves of commercial purity grade steels displayed a smooth curvature in the region where the current density should increase sharply. The density current versus time potentiostatic curves also showed different shapes according to the purity grade steels: for the commercial purity grade steels, the current density showed large oscillations with time (related to unstable pits), whereas for the high purity grade steels, a regular behavior of current density as a function of time was found (related to stable pits

Modelling and analysis of pitting corrosion resistance of stainless steel overlays deposited by flux cored arc welding process

“…The fluctuations of current density that occurred in short periods of time were considered negligible. 11 During the test, a few metastable pits were observed for some specimens at around 200-300 mV (as indicated by current oscillations). In few cases, some oscillations of current near the pitting potential were also observed.…”

“…NaCl solution (3?5 wt-%, pH 6?9 -neutral chloride), representing sea water and other similar environments, was selected as the corrosion medium. [10][11][12][13][14] Specimen preparation Overlay specimens were prepared by depositing Type AISI 317L stainless steel on to the structural steel plate (IS: 2062). The chemical compositions of the materials used in the present study are given in Table 1.…”

“…NaCl solution (3?5 wt-%, pH 6?9 -neutral chloride), representing sea water and other similar environments, was selected as the corrosion medium. [10][11][12][13][14]…”

“…Hence, pitting potential (E p ), is taken as a parameter to evaluate and compare the pitting corrosion resistance (PCR) of the overlays deposited under different welding conditions. 11,19,20 In the present study, the potential at which the current monotonically increased after a passive region 11,[19][20][21] or where the current increased sharply 22 was considered as the critical pitting potential (E p ). The fluctuations of current density that occurred in short periods of time were considered negligible.…”