Low Density Fe–Mn–Al–C Steels: Phase Structures, Mechanisms and Properties

Abstract

This review introduces the structural phases, microstructural characteristics, and the most relevant room and cryogenic properties of low density Fe–Mn–Al–C steels. The combination of outstanding physical and mechanical properties while offering a weight reduction of up to 18% make low density Fe–Mn–Al–C steels attractive structural materials as lightweight crash-resistant car body structures and structural components in the cryogenic industry. In this review, the latest alloy design strategies are introduced. In particular, the novel aspects of the phase structures and their deformation behavior, in particular, those related to L’1₂ (Fe, Mn)₃AlC carbides (κ-carbides) and B2-type Ni/Cu-rich precipitates, are critically summarized. Future scientific and technical challenges are provided to establish these steels as structural materials for industrial applications.

Tensile elongation (TE) vs. ultimate tensile strength (UTS) diagram at room temperature for several types of low density Fe–Mn–Al–C steels. The plot includes the tensile properties of some conventional high strength steels, namely, IF (interstitial-free), Mild, BH (bake hardenable), CMn, HSLA (high-strength low-alloy), TRIP (transformation induced plasticity), DP (dual-phase) and MART (martensitic). (Online version in color.)