Effect of Direct Rolling of Without-Heating on the Differentiation of Mechanical Properties of Rebar

This paper focuses on the mechanical property differentiation and phase content differentiation of HRB400 rebars under the direct rolling of without-heating (DROW) process. The results showed that the temperature distribution from the head region to the tail region of the billet before rolling under the DROW process was different compared to the traditional hot rolling (THR) process, which resulting in the difference of each phase volume fractions and the grain size of the rebar. Compared with the THR process, the phase distribution of the rebars under the DROW process is not uniform, showing the characteristics of low ferrite content in the head region, followed by the tail region, and the highest in the middle region. It was demonstrated that the DROW process could improve the mechanical properties of the rebar, but the difference in phase content and grain size distribution leads to a large variability in the enhancement of the mechanical properties of rebar rolled in different areas of the billet.