EBSD Observations of Recrystallisation and Tensile Deformation in Twinning Induced Plasticity Steel

The microstructure evolution of cold-rolled and isochronally annealed Fe-24Mn-3Al-2Si-1Ni-0.06C twinning induced plasticity steel was investigated by electron back-scattering diffraction (EBSD). Deformation behaviour of a fully recrystallised sample was tracked in a selected area as a function of the true strain using a combination of interrupted tensile testing and EBSD. The results show that the cold rolled microstructure contained a large fraction of primary and secondary twins as well as remnants of annealing twins carried over from the prior hot rolling stage. A novel deconstruction technique was applied to a partially recrystallised sample in order to separate the microstructure into deformed, recovered, newly nucleated and growing recrystallised grains. The interrupted tensile tests revealed the formation of fine striations in grains with and orientations just after yielding. While the striations could be attributed to either stacking faults or the formation of fine twin packets, some of them manifested as twin boundaries as the true strain was increased up to 0.209.