Redesign of maraging steel: Realization of lightweightness and cost-efficiency without sacrificing mechanical properties

초록

Maraging steels are ultrahigh-strength materials with a robust α′ martensitic matrix hardened by nanoscale intermetallic precipitates and are used in demanding structural applications. However, conventional maraging steels contain substantial amounts of alloying elements such as Ni, Co, and Mo (>20 wt%), which limit mass production and broader adoption due to high material costs and high density. Here, we introduce a new maraging steel with a low-Ni, Co-free, and Mo-free composition (Fe–5Mn–9Ni–4Al-0.04C) designed to overcome these limitations. This steel offers improved economic feasibility and reduced density through lean Ni content, cost-effective Mn substitution, and the addition of lightweight Al. Moreover, it exhibits an excellent strength–ductility balance exceeding 25,000 MPa% while maintaining high strength above ∼1.5 GPa, enabled by the formation of nanoscale Ni(Al, Mn) B2 precipitates and a high fraction of retained austenite. This alloy therefore provides a promising route to expand the practical use of maraging steels in broader structural applications.

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