Development of High-Strength Low-Density Steel for Emerging Lightweight Electric Vehicle Technologies

In this present research, cost-effective methods for synthesizing structural materials have been adopted, focusing on low-cost Fe-Mn-Al-Si steel for an electric vehicle. The main procedure involves a two-step thermomechanical method that comprises hot forging (1100 °C) and hot rolling (800, 900, 1000 °C) followed by water quenching. In this design approach, both hard and soft phases of a microstructure were obtained to achieve a balance between strength and ductility properties. This microstructure comprises dislocation-enriched strain-induced twins and martensite along with both microsized and nanosized TiC precipitates. The synthesized material thus exhibits a unique combination of remarkable tensile strength (~2 GPa) together with low density (6.9 ± 0.05 gcm⁻³) and excellent ductility (~50% total elongation). This significant combination of properties is attributed to combined TWIP and TRIP effects along with the precipitation of TiC.