Abstract
Alloy 33 has been introduced as a highly ductile austenitic alloy specifically suited for application in chloride containing aqueous environments due to its resistance against crevice and pitting corrosion. In the present work limiting crevice corrosion conditions respective to chloride contents and pH in artificial seawater as well as temperature have been quantitatively evaluated for alloy 33 in the as delivered condition by measuring corrosion currents in a Remote Crevice Assembly (RCA) with various NaCl contents. As a result, at a sodium chloride content of 75 g/l a pH level below 1,65 at RT leads to a significant increase in crevice corrosion rates. At 150 g/l of sodium chloride a pH level of below 2,00 initiates crevice corrosion respectively. Increasing the temperature from RT up to 50°C increases the corrosion rates by a factor of about 10, taking the results for 75 g/l sodium chloride and and pH = 1,9 as a reference at RT. At the same time the crevice corrosion initiation times are significantly reduced by increasing temperatures, decreasing pH and increasing chloride contents. The results are compared to the literature describing standard testing.
