**2.2 Effect of deformation**

Results of corrosion tests described above concern steels in the annealed or supersaturated state. The influence of cold plastic deformation on corrosion behaviour in 3.5wt% NaCl was studied in Fe-0.5C-29Mn-3.5Al-0.5Si steel (Ghayad et al., 2006). It was found on the basis of potentiodynamic tests, that the steel shows no tendency to passivation, independently on the steel structure after heat treatment (supersaturated, aged or strain-aged). Higher corrosion rate of deformed specimens than that of specimens in supersaturated state, was a result of faster steel dissolution caused by annealing twins, which show a different potential than the matrix. The highest corrosion rate was observed in strain-aged samples, as a result of ferrite formation, which creates a corrosive galvanic cell with the austenitic matrix. The enhanced corrosion attack at the boundaries of deformation twins was also observed in Fe-22Mn-0.5C steels (Mazancova et al., 2010).
