Medium Mn Dual-Phase Nanotwinned Steel

The nanotwinned alloys produced during the previous decades are generally single-phased. Here we propose a nanotwinned steel with dual-phase microstructure. Such dual-phase nanotwinned steel can be fabricated by a deformation and annealing process. A medium Mn steel with both transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) effects during deformation is used as a starting material. The yield strength of the dual-phase nanotwinned steel is 1.2 GPa, with a total tensile elongation of 15 pct. However, it is found that the recovery annealing process reduces the tensile ductility, which could be due to the formation of the coarse cementite precipitates during annealing at 400 degrees C. The design of dual-phase nanotwinned structure can also be applied to other alloy systems such as high entropy alloy with both TRIP and TWIP effects.

Automated summary

In this study, a dual-phase nanotwinned steel is proposed, which is fabricated through a deformation and annealing process. The steel exhibits high yield strength and total tensile elongation, but the annealing process reduces its ductility, possibly due to the formation of precipitates.