Polarisation austenitic steel

Suzuki, Yamake and Kitamura determined the pHs, chloride ion concentrations, metal ion concentrations and the potentials of artificial pits in Fe, Cr, Ni and Mo, and in three austenitic stainless steels during anodic polarisation in 0-5 N NaCl at 70°C. In the case of the pure metals the pH values were found to be lower than those calculated from the metal ion concentrations (Table 1.17), and the experimentally determined pHs were as follows ... 

The electrochemical examination of fusion joints between nine pairs of dissimilar metal couples in seawater showed that in most cases the HAZ was anodic to the weld metals" . Prasad Rao and Prasanna Kumarundertook electrochemical studies of austenitic stainless steel claddings to find that heat input and 5Fe content significantly affected the anodic polarisation behaviour under active corrosion conditions whilst Herbsleb and Stoffelo found that two-phased weld claddings of the 24Cr-13Ni type were susceptible to inter-granular attack (IGA) as a result of sensitisation after heat treatment at 600°C /pa was unaffected by heat input. 

Fig. 11.10 Anodic polarisation of 5-ferrite and Y-austenite showing potential ranges for etching and eleciropolishing. Stainless-type steels in S tio sulphuric acid (after Cihal and...

The polarisation resistance can be related to the rate of general corrosion for metals at or near their corrosion potential, corr. Polarisation resistance measurements are an accurate and rapid way to measure the general corrosion rate (CR) of bioinert Ti alloys, biotolerant austenitic surgical steels or biodegradable magnesium alloys. 

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