High-manganese austenitic TWIP steels exhibit very high strength and elongation before necking. The
peculiarity of these steels is that mechanical twins form during straining due to their low stacking fault
energy (SFE). These twins are usually thought to have a huge impact on the outstanding properties of
the materials, either by bringing about a dynamic Hall & Petch effect and/or a composite effect. In this
study, the appearance of mechanical twins during tensile straining is investigated for a Fe–20%Mn–1.2%C
TWIP steel. The twinning rate was estimated by means of point counting analysis on EBSD micrographs
at different strain levels. The reliability of this method is first thoroughly discussed. It is then shown that
there exists a first order relationship between this twinning rate and the work hardening rate.
The studied Fe–20%Mn–1.2%C TWIP steel achieves very high
stress and elongation without necking due to a large work hardening
rate specific to Fe–Mn–C TWIP steels. A first initial decrease
of the work hardening rate is followed by a large enhancement
and a second final decrease. The twin volume fraction evolution
was seen to evolve following a S-shape, with specific points corresponding
to the transitions on the work hardening curve. This
twinning rate was established by point counting analysis based on
EBSD micrographs. The reliability of this method was evaluated.