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<p>Fe–Mn–Al–C low-density high-strength (LDHS) steels possess significant application potential in the automotive industry. However, the failure to achieve a higher synergy of strength and ductility remains one of the key bottlenecks hindering the further development of such steels. This study designed an Fe–30Mn–10Al–2Ni–1.5C–0.5Ti–xCr (wt.%, x = 1/3/5) LDHS steel to investigate the influence mechanism of Cr addition on its microstructure and properties. The results indicate that after solution treatment, the alloy's microstructure consists of single-phase austenite and two types of precipitates: TiC and κ-carbides ((Fe, Mn)<sub>3</sub>AlC<sub>x</sub>). Increasing the Cr content from 1 wt.% to 5 wt.% raised the critical nucleation energy of κ-carbides, resulting in a reduction of their average size and volume fraction. The alloy with 5 wt.% Cr exhibited optimal comprehensive performance: a 15–20% reduction in density (<i>ρ</i> = 6.57&#xa0;g/cm<sup>3</sup>), a tensile strength of 936.8&#xa0;MPa, an elongation of 64.1%, and an outstanding strength–ductility product (60.1 GPa·%). This study provides a potential alloy design and processing route for automotive applications requiring ultra-high strength and lightweight characteristics.</p> Graphical abstract <p></p>

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Effect of Cr content on microstructure and mechanical properties of Fe–30Mn–10Al–2Ni–1.5C–0.5Ti–xCr low-density steels

  • 期刊论文

  • 发表日期：

    2026年3月4日

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  • Yan Yang,
  • Xueqian Gao,
  • Hongjun Li,
  • Zhentao Gong,
  • Ming Huang,
  • Sen Yang

摘要

Fe–Mn–Al–C low-density high-strength (LDHS) steels possess significant application potential in the automotive industry. However, the failure to achieve a higher synergy of strength and ductility remains one of the key bottlenecks hindering the further development of such steels. This study designed an Fe–30Mn–10Al–2Ni–1.5C–0.5Ti–xCr (wt.%, x = 1/3/5) LDHS steel to investigate the influence mechanism of Cr addition on its microstructure and properties. The results indicate that after solution treatment, the alloy's microstructure consists of single-phase austenite and two types of precipitates: TiC and κ-carbides ((Fe, Mn)3AlCx). Increasing the Cr content from 1 wt.% to 5 wt.% raised the critical nucleation energy of κ-carbides, resulting in a reduction of their average size and volume fraction. The alloy with 5 wt.% Cr exhibited optimal comprehensive performance: a 15–20% reduction in density (ρ = 6.57 g/cm3), a tensile strength of 936.8 MPa, an elongation of 64.1%, and an outstanding strength–ductility product (60.1 GPa·%). This study provides a potential alloy design and processing route for automotive applications requiring ultra-high strength and lightweight characteristics.

Graphical abstract