Effects of Minor Elements on Mechanical Properties of Flake Graphite Cast Iron Using High Manganese Steel Sheet Scrap

摘要

Recently, automobile manufacturers adopt high tensile strength steel for the car body to reduce weight and enhance safety. This is expected to produce considerable automobile steel sheet scraps containing high percentage of manganese (Mn). Mn is known as a graphite inhibitor in cast iron. Consequently, either reducing the Mn percentage or removing the Mn in steel sheet scraps will be necessary for using high Mn steel sheet scraps in cast iron. In this study, flake graphite cast iron was produced using high Mn steel sheet scraps. For the purpose of increasing high Mn steel scrap recycling efficiency, Mn was not removed and mechanical properties were investigated. Rare earth element (RE) was added to the melt which included automobile steel sheet scrap (high Mn steel sheet scrap). The specimens were found to satisfy JIS standards and high strength flake graphite cast iron could be produced using high Mn steel sheet scrap as a raw material. By comparing with cast iron melt using high purity pig iron high hardness was thought to be caused by the influence of a minor elements.