Effects of Multi-Scale Microstructure on Pitting Corrosion and Mechanical Properties of High-Mn-N Low-Ni Superduplex Stainless Steel

A high-Mn-N low-Ni superduplex stainless steel 25Cr-2Ni-3Mo-10Mn-0.5N with multi-scale microstructures has been prepared through severe cold rolling and annealing, and the effects of multi-scale grains on the pitting corrosion and mechanical properties have been investigated. The results show that the multi-scale microstructures have a strong relation with the annealing time, that is, the average grain sizes of austenite and ferrite increase with prolonging of the annealing time at 1050 °C, they have the minimum values of 1.5 and 7.18 μm, respectively, when the alloy is annealed for 1 min. The tensile strength, yield strength and reduction in area of the sample decrease with the growth of multi-scale grains, whereas the pitting corrosion resistance of the specimen is enhanced. The multi-scale microstructures play an important role on the pitting corrosion and the mechanical properties of superduplex stainless steel 25Cr-2Ni-3Mo-10Mn-0.5N.