Effect of Cr on mechanical properties and corrosion behaviors of Fe-Mn-C-Al-Cr-N TWIP steels

By using scanning electron microscopy (SEM) equipped with electron back-scattered diffraction (EBSD) system, transmission electron microscopy (TEM) and CorrTest4 electrochemical workstation, effects of chromium content (1.35wt% - 3.95 wt%) on the mechanical properties and anti-corrosion behaviours of high manganese Fe-Mn-C-Al-Cr-N twinning-induced plasticity (TWIP) steels were studied. The results show that Cr content has an obvious influence on the mechanical properties and fracture behaviors of the high manganese TWIP steels. The yield and ultimate tensile strengths of the steel sheets were improved with increasing Cr content while the elongation was reduced. In addition, with the increase of Cr content, the fracture mode changed from ductile fracture pattern with coarse dimples and tear ridges (Cr content ≤ 2.35%) to intergranular fracture (when Cr content is 3.95%). Furthermore, Cr content has a tremendous effect on anti-corrosion behaviors of the high manganese TWIP steels. The increase of Cr content enhanced the corrosion resistance of the annealed steel sheets by improving the proportion of low-angle boundary.