Simultaneously enhancing the strength and ductility of Fe-Mn-C twinning-induced plasticity steel via Cr/N alloying

The effect of Cr/N alloying on the tensile deformation behavior of Fe-Mn-C twinning-induced plasticity steel was investigated through monotonic tensile tests, X-ray diffraction, electron back-scattered diffraction, transmission electron microscopy, and digital image correlation technique. The results demonstrate that the addition of Cr/N significantly enhances both the strength and ductility of Fe-18Mn-0.6C steel while dynamic strain aging (DSA) behavior weakens or even disappears. Compared with that in the Fe-18Mn-0.6C steel, more densely-spaced, thinner deformation twins were formed in the Cr/N-alloyed steel. Moreover, the Cr/N additions promote deformation twins to form over a wider strain range. This unique twinning behavior leads to a sustained high strain-hardening rate at higher strains, thereby delaying plastic instability and concurrently enhancing strength and ductility.