Abstract
Stainless steel is a common material in reactors, tanks, pipes, mixers, filters and valves in process industry. The selection of a suitable stainless steel grade for a specific industrial application is conducted based on the characteristics of the environment, but often limited by the foreseen lifecycle costs. For applications in raw material sector, the main challenge is that corrosion performance data for several stainless steel grades for, e.g., hydrometallurgical processes is lacking. Corrosion rate of the materials may remain low when general corrosion is the primary corrosion form, but material losses across wall thickness may become high if localized corrosion is present. Therefore, in order to make material choices that enable a continuous and safe operation of the process, it is important to define such operation conditions that cause the corrosion mechanism change.
In this research, altogether six austenitic and duplex stainless steel grades with a varying Pitting Resistance Equivalent Number (PREN) were studied in test environments which varied with respect to their H2SO4 and chloride concentrations, while temperature ranged from room temperature up to 90 °C. The results from potentiodynamic polarization measurements are presented and discussed. The electrochemical measurements are complemented with immersion tests conducted in environments with chlorides.
