A review on low-density steels: effect of processing techniques and parameters on microstructure, and mechanical properties

This review traces the evolution of low-density steels (LDS) and highlights the key mechanisms that link processing routes to microstructural evolution and performance. Beyond fabrication methods, the article emphasizes the fundamental insights that have emerged, particularly the roles of metal carbide/intermetallic network control, segregation mitigation, and grain refinement that govern the unique behavior of LDS across processing routes in achieving superior mechanical behavior. A key insight from the literature is the exceptional potential of mechanical alloying combined with spark plasma sintering to produce ultrafine and highly homogeneous LDS microstructures that are unattainable through traditional melting routes. The review also identifies the emerging role of near-net-shape casting and additive manufacturing as transformative technologies capable of overcoming longstanding challenges related to defects, compositional inhomogeneity, and geometric limitations. Overall, the review emphasizes that optimized processing strategies and parameter control will be crucial to enhance efficiency, unlocking superior mechanical properties and realizing the full lightweight potential of LDS in advanced engineering applications.