Achieving Strength–Ductility Balance in TWIP Steel by Tailoring Cementite

TL;DR

This paper shows how adjusting cementite in TWIP steel can improve both strength and ductility, making the material more useful.

Contribution

A new method to balance strength and ductility in TWIP steel by tailoring cementite particles and recrystallized grains.

Findings

Annealing at 550–650 °C altered cementite particles and recrystallized grains.

Sample AN550 achieved a strength–ductility balance with 58.9 GPa% performance.

Secondary deformation twinning enhanced material properties alongside other mechanisms.

Abstract

High-Mn steels are widely used in various fields. However, the FCC structure is not conducive to improving strength, limiting their development and application. In this work, hot-rolled Fe-25Mn-1Al-3Si-1C (wt.%) steel was annealed at various temperatures to tailor the cementite particles and recrystallized grains, thus achieving a balance between strength and ductility. As the annealing temperature increased from 550 to 650 °C, the volume fraction of recrystallized grains slightly increased and the volume fraction of cementite particles initially increased and then decreased, which was explained and verified by the quantitative calculation. Especially, the high-density pre-dislocation and finely dispersed cementite particles in sample AN550 resulted in a relatively low volume fraction of recrystallized grains. Interestingly, secondary deformation twinning was activated during the subsequent tensile deformation in addition to the dislocations, stacking faults, and previous deformation twinning. This complex interaction among various deformation mechanisms indued a good balance between strength and ductility, achieving an outstanding result (58.9 GPa%) regarding tensile strength and total elongation. This work offers an effective route for developing a high-Mn TWIP steel with outstanding strength–ductility balance.

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