Effects of Mn and W addition on the microstructure, mechanical properties, and corrosion resistance of Fe-Cr-Mn type stainless steels

The effect of annealing and Mn/W additions on the microstructure, mechanical properties, and corrosion resistance of Fe-Cr-Mn type stainless steels were studied. The volume fraction of austenite phase was increased with Mn content and ε-martensite showed the maximum in 21% Mn content. This seems to be related to the low stacking fault energy in martensite transformation. Annealing temperature didn't affect greatly on the change of a microstructure in Fe-Cr-Mn steels. W addition to Fe-12Cr-17Mn steel induced the formation of ferrite and its content was increased with increasing annealing temperature. Increasing Mn content of the alloy, the elongation and impact energy were increased, but the yield strength and tensile strength were decreased. This behavior is due to the increment of the volume fraction of austenite phase. Mn content had not influenced on the anodic polarization behavior in chloride solution. In sulfuric acid, the secondary passivation occurred at high potential region by the formation of MnO2. Especially. W addition decreased the passive current density in chloride solution, but increased the passive current density in sulfuric acid solution. This seems to be related to the interaction between SO12- ion and WO12- ion in passive film