Dual-phase steel rebars for high-ductile r.c. structures, Part 1: Microstructural and mechanical characterization of steel rebars

The considerable influence of steel’s mechanical behaviour on the dissipative capacity of r.c. structures has led to increasing interest in optimizing the mechanical properties of the reinforcing bars used for seismic applications.The work presented herein is part of a broad-ranging study on the potential utilization of highly innovative types of steel for reinforced concrete earthquake-resistant structures. In particular, we present the main results obtained in experimental trials on a low-C, Mn–Si steel in the form of concrete reinforcing bars subjected to intercritical tempering treatment in a temperature range between 740 and 820 ∘C to obtain various dual-phase ferrite–martensite structures. The samples were characterized via mechanical tests and metallographic analyses in order to correlate the bars’ characteristics with the microstructure of the steel itself.Experimental characterization of this steel has allowed for the development of a mathematical model to enable the evaluation of the ductility performance of concrete structural elements reinforced with dual-phase steel bars.