On the low-cycle fatigue response of pre-strained austenitic Fe61Mn24Ni6.5Cr8.5 alloy showing TWIP effect

The low-cycle fatigue behavior of a high manganese austenitic alloy showing TWIP (Twinning-Induced Plasticity) in its homogenized as-received (AsRec) and in pre-strained conditions was determined. Pre-strains were applied both in tension and compression. The fatigue experiments, conducted in total strain control under fully reversed push–pull loading, were accompanied by thorough microstructural investigations utilizing electron backscatter diffraction and transmission electron microscopy. The results clearly lay out the different microstructural evolutions during cyclic loading of the AsRec and the pre-deformed conditions. Cyclic hardening prevails for the AsRec condition due to the increase in dislocation density and the subsequent rearrangement of dislocations into labyrinth and cell structures upon further cycling, whereas pronounced softening accompanied by a decrease in absolute value of mean stress dominated the cyclic deformation response of the pre-deformed conditions.