Extraordinary pitting resistance obtained by forming a partially recrystallized microstructure in a severely deformed 316LN stainless steel

Austenitic stainless steels with Cr-containing passive films are susceptible to pitting corrosion with the presence of aggressive anions. Repeated cold rolling and subsequent annealing were adopted to enhance the pitting resistance of a 316LN austenite stainless steel by balancing the deformed and the recrystallized microstructure. The highly ultra-fine grained structure formed during cold rolling gradually evolved to partially or fully recrystallized structures depending on the annealing parameters. Their microstructures were characterized by EBSD and the corrosion behaviors were evaluated through electrochemical techniques in a typical 3.5 wt% NaCl solution. The results show that the short-time annealed sample with a partially recrystallized structure exhibits extraordinary corrosion resistance compared with the cold rolled or the fully recrystallized one. This might be attributed to the elimination of the corrosion sensitive sites introduced during cold rolling by a proper extent of recrystallization without too many annealing twins, which are beneficial for pit nucleation.