Microstructural Evolution and Tensile Performance of a Commercial Fe-Mn-Al-C High-Manganese Steel

High-manganese austenitic steels are one kind of superior materials applied in automotive lightweight industry because of their high strength and large plasticity. Herein, transmission electron microscopy and electron channeling contrast imaging combined with electron backscatter diffraction, etc. are used to analyze the microstructural evolution and dominant deformation mechanisms of a Fe-13.6Mn-1.2Al-0.6C (wt%) steel during tensile deformation. Due to the multiple-stage strain hardening effect, this alloy exhibits excellent combination of strength and plasticity. The yield strength, ultimate tensile strength, and elongation reach 540 (+/- 30) MPa, 1120 (+/- 70) MPa, and 74 (+/- 3)%, respectively. The early hardening stage is fully determined by dislocation accumulation and planar slip. With the strain increasing, the plastic deformation of the steel is dominated by twinning and microbanding, which lead to the synergetic effect of twinning-induced plasticity and microband-induced plasticity.

Automated summary

In this study, transmission electron microscopy and electron channeling contrast imaging combined with electron backscatter diffraction were used to analyze the microstructural evolution and dominant deformation mechanisms of a Fe-13.6Mn-1.2Al-0.6C (wt%) steel during tensile deformation. Due to the multiple-stage strain hardening effect, this alloy exhibits excellent combination of strength and plasticity, with a yield strength, ultimate tensile strength, and elongation of 540 (+/- 30) MPa, 1120 (+/- 70) MPa, and 74 (+/- 3)%, respectively. The early hardening stage is determined by dislocation accumulation and planar slip, while twinning and microbanding dominate the plastic deformation of the steel, resulting in the synergetic effect of twinning-induced plasticity and microband-induced plasticity.