Evolution of Non-Metallic Inclusions in Secondary Steelmaking: Learning from Inclusion Size Distributions

Non-metallic inclusions have always been the active subject of steelmaking research to improve the steel cleanliness and to develop the so-called oxide metallurgy technology. Inclusions in molten steel form and grow by the sequence of nucleation, chemical and physical growth and removal. Thus, the size distribution of inclusions evolves continuously with time in molten steel, and significant changes in the steel conditions are reflected in the inclusion size distribution as well as in the inclusion chemistry. This study aims to provide a new approach to interpret the inclusion size distributions. The concept of the Population Density Function (PDF) is introduced to objectively represent a given inclusion size distribution. Several possible applications of PDF analysis are presented to demonstrate the advantages of the utilization of the PDF for understanding the inclusion formation mechanism during the steelmaking process. Several ambitious ideas to utilize the PDF for inclusion size control are also presented.