Study of stainless steels corrosion in a strong acid mixture. Part 2: anodic selective dissolution, weight loss and electrochemical impedance spectroscopy tests

The corrosion resistance of austenitic stainless steels AISI 316L, AISI 904L and Sanicro 28 and duplex stainless steels SAF 2205, SAF 2507 and SAF 2707, was studied at 40 and 60 degrees C in a strong acid mixture containing tartaric acid saturated solution, H2SO4 and HCl. Anodic selective dissolution, weight loss and electrochemical impedance tests were performed. The results show that all stainless steels corrode actively and the micro-galvanic coupling, present on duplex stainless steels and 316L, determines severe selective corrosion and impairs their tendency to passivate. 904L and Sanicro 28 showed this tendency and the lowest corrosion rates.