The Influence of Plastic Deformation on the Corrosion Behavior of a Cast High-Alloy CrMnNi TRIP Steel

The influence of plastic deformation on the electrochemical corrosion behavior of a meta-stable high-alloy CrMnNi steel is investigated in a 5 wt% sodium chloride solution by cyclic voltammetry. Interrupted tensile tests are performed to attain two defined states of plastic deformation. The formation of straight slip bands and deformation-induced alpha'-martensite is observed in the austenite of the tensile samples which are deformed up to fracture. The deformation-induced alpha'-martensite fraction is evaluated by an in situ magnetic measurement method simultaneously to the tensile test. Microscopic observations after the potentiodynamic polarization revealed pitting corrosion at all surfaces. Furthermore, a strong dependency between applied anodic potential and degree of plastic deformation at forward polarization is found, whereas the reverse scan exhibits a significant influence of the pitting corrosion attack. Consequently, the forward polarization behavior is dictated by the previously applied mechanical stress, whereas the influence disappears when pits have been formed.