Microalloying Strategies and Strengthening Mechanisms in Seismic-Resistant Rebars: A Critical Review

Seismic-resistant reinforcing steels (rebars) are indispensable for improving the safety and resilience of reinforced concrete structures subjected to earthquake loading. To perform effectively under such severe conditions, these steels must combine high strength with adequate ductility, toughness, and fatigue resistance. Achieving this balance depends on the control of the steel’s microstructure. In this context, microalloying with vanadium (V), niobium (Nb), and titanium (Ti) has become an effective strategy for controlling microstructural evolution through grain refinement, precipitation strengthening, recrystallization control, and phase transformation, therefore enhancing both monotonic and cyclic mechanical performance. Although the effects of microalloying and strengthening mechanisms in reinforcing steels are well documented, studies examining their combined influence on seismic applications remain relatively limited. This review therefore provides an integrated perspective by examining how alloy composition, thermomechanical processing routes, microstructural evolution, and strengthening mechanisms interact to determine the mechanical and fatigue performance required for seismic-resistant reinforcing steels. Rather than considering these aspects separately, this review focuses on the interactions between processing, microstructure, and mechanical behavior that determine the overall performance of reinforcing steels. This review also highlights the main scientific and technological challenges in the field, discusses the remaining knowledge gaps, and suggests future research directions for the development of next-generation seismic-resistant reinforcing steels.