The Relationship Between Phase Fraction and Pitting Corrosion Performance of a New Type of Fe-Cr-Mn-Al Duplex Stainless Steel

An economical Fe-Cr-Mn-Al duplex stainless steel not only has good thermos-plasticity, but also has excellent comprehensive mechanical properties. However, how to ensure that the prepared duplex stainless steel exhibits excellent corrosion resistance is crucial, therefore it becomes imperative to undertake a comprehensive study on the corrosion resistance of the duplex stainless steel and the underlying mechanisms that govern its behavior. This paper focuses on the influence of the phase fractions of ferrite and austenite on the pitting corrosion resistance of duplex stainless steel. The phase fraction is controlled by annealing treatment, and then the effect of phase ratio on the corrosion resistance of new Fe-Cr-Mn-Al duplex stainless steel and its related mechanism are revealed. The findings indicate that the alloying elements of ferrite and austenite in duplex stainless steel can be redistributed by adjusting the annealing temperature, and the difference of alloying elements distribution will inevitably change the pitting corrosion equivalent value of ferrite and austenite, thus affecting the pitting corrosion resistance of duplex stainless steel. It is found that the pitting corrosion resistance of new duplex stainless steel is determined by the galvanic corrosion rate between two phases.