Induction Steel: Inclusion Content and Mechanical Properties of Reinforcing Bars Produced from Pencil Ingots and Continuously Cast Billets

Abstract

In Bangladesh, most of the reinforcing bars are produced by rolling steel produced by melting scrap in induction furnaces. In many plants the molten steel is directly cast in vertical moulds into what are usually called ‘pencil ingots’. In some plants the molten steel is tapped into large ladles, taken to continuous casting machines and cast into continuous billets. In some cases the molten steel is refined in ladles (purged with nitrogen or argon) before casting into continuous billets. This investigation aims at a comparison of the inclusion content and resultant mechanical properties of reinforcing bars produced through these different routes. The samples for this study were collected from the process streams of a steel plant. The inclusion content was determined by direct measurement of inclusions on metallographic specimens and the mechanical properties were determined by using a universal tensile testing machine. Reinforcing bars produced by rolling ladle refined continuously cast billets have the lowest content of inclusion and the best mechanical (yield strength, ultimate tensile strength, percentage elongation, etc.) properties. The highest inclusion content and the worst properties were obtained in the pencil ingots.