Effect of isochronal annealing on the microstructure, texture and mechanical properties of a cold-rolled high manganese steel

A Fe-17Mn-3Al-2Si-lNi-0.06C wt.% steel was subjected to cold-rolling to 42% thickness reduction and isochronally annealed for 300 s between 500 and 850 degrees C. The high Mn steel was characterised via electron back scattering diffraction, transmission electron microscopy and uniaxial tensile testing. The reversion of deformation-induced epsilon and alpha'-martensite to austenite (gamma) was witnessed with the formation of fine twins in reverted/recovered gamma grains after annealing to 650 degrees C. The nucleation of new gamma grains at the boundary of reverted/recovered gamma grains was also noted. Upon reversion, the gamma orientations originated from the epsilon and alpha'-martensite orientations by phase transformation via the Shoji-Nishiyama and Kurdjumov-Sachs orientation relationships, respectively. Upon segmenting the gamma grains, the recrystallised gamma grains were observed to nucleate with orientations similar to those of the reverted/recovered gamma grains. Uniaxial tension on a fully recrystallised gamma microstructure showed that the initial gamma grain size has a more significant effect on the yield strength than the epsilon and alpha'-martensite fractions. On the other hand, the initial epsilon and alpha'-martensite fractions affect the total elongation.