Experimental and Numerical Investigation on the Effect of the Tempcore Process Parameters on Microstructural Evolution and Mechanical Properties of Dual-Phase Steel Reinforcing Rebars

Abstract

One of the most efficient and cheapest ways to improve steel reinforcement bars is the Tempcore process. In this study, the effects of water pressure, water temperature, bar diameter, and its initial temperature, as Tempcore process parameters on microstructural and mechanical properties of reinforcing rebars were numerical and experimental investigated by using the Taguchi experimental design method. Results showed that these Tempcore process parameters influence the cooling intensity, which causes the formation of martensite at the surface layer and fine-grained ferrite–pearlite at the core and improvement of tensile strength. All of the considered parameters strongly affect the volume fraction of ferrite and pearlite in the rebar center and thickness of the martensite layer, but among them, water pressure with a 59% impact has a more substantial effect. Ultimately, to figure out the mechanical characteristics of hot rolled and optimal sample’ rebar, tensile tests were conducted. Outcomes displayed that the Tempcore process increases the yield and ultimate tensile strengths as much as 1.5 and 1.3 times, respectively, but slightly decreases the elongation.