Different strain rate sensitivities between Fe-22Mn-0.6C and Fe-30Mn-3Si-3Al twinning-induced plasticity steels

The strain rate sensitivity (SRS) of Fe-22Mn-0.6C and Fe-30Mn-3Si-3Al twinning-induced plasticity (TWIP) steel was studied in the strain rate range from 10−4 to 10 °s−1. The Fe-22Mn-0.6C steel exhibited negative SRS, while the Fe-30Mn-3Si-3Al steel showed positive SRS. Dynamic strain aging (DSA) was detected in Fe-22Mn-0.6C steel but not in Fe-30Mn-3Si-3Al steel. Accordingly, the two typical TWIP steels can be classified as DSA-facilitated and DSA-free TWIP steels. Meanwhile, the density of twin boundary obviously decreased in Fe-22Mn-0.6C steel but had little change in Fe-30Mn-3Si-3Al steel with increasing the strain rate. The different SRS phenomena were discussed based on the twinning mechanism and DSA effect.