Assessment of Hot Ductility with Various Thermal Histories as an Alternative Method of in situ Solidification

Abstract

Much work has been devoted to improving the hot ductility of steels to make them less prone to transverse cracks during the unbending stage of continuous casting. As a more positive method to avoid cracks, developing a fine grain size within the surface and sub-surface region of a slab through a double phase transformation was proposed. The in situ solidification method is usually adopted for assessing the effect of a double phase transformation, resulting from intensive cooling and reheating, on hot ductility. There exist, however, some weak points to simulating the continuous casting process by an in situ solidification. In the present work, two kinds of thermal history were adopted during the tensile test to assess the effect of a double phase transformation more precisely, instead of in situ solidification, for simulating the unbending operation. Eliminating the perpetual experimental problems of an in situ solidification tensile test, a solidified slab was used throughout the present work.