A transmission kikuchi diffraction study of a cold-rolled and annealed Fe-17Mn-2Si-3Al-1Ni-0.06C wt% Steel
This study applies the recently developed transmission Kikuchi diffraction technique to investigate the microstructures and micro-textures of a multi-phase Fe-17Mn-3Al-2Si-1Ni-0.08C wt% steel that concurrently exhibits twinning- and transformation-induced plasticity effects. The steel was cold rolled to 66% thickness reduction and subsequently annealed at 625 °C for 300 s. The cold-rolled microstructure mainly consisted of α′ martensite interspersed with blocky Ïμ martensite and remanent nanometer-sized grains of γ. Annealing at 625 °C led to the partial transformation of α′ → γ and the reversion of Ïμ → γ such that the microstructure comprised predominant nanometer-sized γ grains interspersed with a smaller α′ phase and a trace fraction of nanometer-sized Ïμ along γ grain boundaries. During deformation via cold rolling and reverse transformation during annealing, micro-texture analysis indicated the operation of the Shoji-Nishiyama, Kurdjumov-Sachs, and Burgers ORs between γ 虠 Ïμ , γ 虠 α′, and Ïμ 虠 α′, respectively. Transmission Kikuchi Diffraction (TKD) band contrast (top) and phase distribution (bottom) maps of Fe-17Mn-2Si-3Al-1Ni-0.06C TRIP-TWIP steel after 66% cold rolling (LHS) and 625 °C annealing for 300 s (RHS). After cold rolling (left), long aspect ratio α′ subgrains (blue) are interspersed with blocky Ïμ (yellow) and remanent γ (red) subgrains. Annealing at 625 °C (right) results in γ grains ringed by minor α′ and trace μ phases.