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

Abstract

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 α′‐martensite is observed in the austenite of the tensile samples which are deformed up to fracture. The deformation‐induced α′‐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.

Influence of Cold Deformation and Phase Transformation on the Electrochemical Corrosion Behavior of Nitrogen‐Alloyed Stainless Steel in Chloride Solution

“…A further increase in plastic deformation resulted in a distinct decrease in film resistance due to film rupture and the formation of both deformation bands and anodic α’ ‐martensite at the surface. When considering the microstructural observations (Figure ) and comparing them to the literature, it may be concluded that due to plastic deformation accompanied by martensitic transformation and the formation of deformation bands, the passivation behavior and, therefore, the corrosion resistance of the alloy deteriorated strongly . The electrochemical behavior of the double layer was also affected by the plastic deformation.…”

“…However, cold deformation and phase transformation has a significant influence on the corrosion behavior of metastable austenitic steels. This is due to the formation of α’ ‐martensite, residual stresses, and the presence of deformation bands with lower corrosion resistance than the initial state . Different methods may be applied to increase the corrosion resistance of stainless steels further.…”