High-Modulus Steels

High-modulus steels (HMS) open new dimensions for structural material design by addressing all key criteria for superior performance in weight critical applications. This new class of high-performance ferrous alloys is created by blending low-density and stiff particles into strong, tough and ductile steel matrices, resulting in composite steels. However, aiming to improve the physical properties (stiffness and density) without sacrificing the mechanical properties – especially ductility – adds substantial complexity to the already challenging material design process. Especially important is the integration of the synthesis and processing techniques into the alloy development. In order to establish HMS as commercially successful materials, which does not allow for disregarding the associated costs, a comprehensive approach to design these novel steels is required. Consequently, this chapter covers the underlying aspects of physical metallurgy and derived strategies for alloy and process design. Based on these fundamental aspects, it describes the current state of HMS development based on Fe–Ti–B alloys. The chapter culminates in an outlook on critical challenges in this very dynamic field of research and highlights future perspectives and opportunities, for example novel alloy concepts such as Fe–Cr–B–C HMS, as well as potential synergy with additive manufacturing techniques.