Micro-structural study of high-Mn TWIP steels using diffraction profile analysis

We have investigated micro-structural parameters, twin and stacking fault probabilities and dislocation density, of twinning induced plasticity (TWIP) steels by using neutron diffraction profile analysis. It is observed that the addition of 1.4 wt.% Al in Fe–18Mn–0.6C steel leads to lower tensile strength and higher elongation, reducing twin formation rate. In other words, Al addition weakens the tendency of twin and stacking faults evolution under applied strain in the range of ɛ = 0.0–0.4, while the screw component of dislocations is increased. It is also confirmed that enlarged austenite grain size in TWIP steels disfavors twin and stacking fault formation.

► Line profile analysis of TOF neutron scattering data is desired to analyze the quantitative micro-structural parameters of TWIP steels.
► The exhaustion of staking faults in TWIP steel was found after specific strain, ɛ ≅ 0.3.
► Dislocation correlation is alleviated by Al addition.
► Al addition in TWIP steel weakens the tendency of twin/stacking faults evolution and dislocation accumulation.
► Al addition increases the screw fraction of dislocations, which enhances cross-slip.