Effects of hot-core heavy reduction rolling during continuous casting on microstructures and mechanical properties of hot-rolled plates

Abstract

Abstract A slab’s internal defects that are associated with porosities significantly influence the qualities of hot-rolled plates, especially which are rolled with low reduction ratio. Hot-core heavy reduction rolling (HHR2) is an innovative technology to eliminate the porosity defects in casting steel through a single pass rolling, after the final solidification point. In this study, a Nb–Ti-microalloyed steel grade was investigated as the research object. The effects of the HHR2 process on the microstructures and mechanical properties of the final hot-rolled pates were systematically studied to evaluate the effectiveness of the process. Accordingly, the work pieces fabricated with and without the HHR2 process were reheated to 1250 °C, following which they were subjected to hot rolling, then plates with both similar thickness of 40 mm were obtained. Subsequently, the microstructures and mechanical properties of the plates manufactured using two different processes were compared. The experimental results showed that both the microstructure homogeneity and the uniformity of mechanical properties along the thickness of the plate manufactured using the HHR2 process were obviously improved. In addition, the microstructure-inheritance mechanisms of the HHR2 process at three different process stages: continuous casting, reheating, and multi-pass hot rolling, are discussed.