Relation between Molten Cast Iron and Critical Cooling Rate for Chilling Tendency

摘要

One main raw material in cast iron melting is steel scrap. The source is chiefly the automotive steel sheet. Because the use rate of high tensile strength steel sheet and surface heated steel sheet increases, a small amount of elements which may affect the mechanical properties of cast iron will be contained as molten cast iron. Consequently, the melting properties of the molten cast iron may have changed considerably. In this study, the relations between molten cast iron and different contents of small amounts of graphitizer (#SIGMA# G) and stabilizer (#SIGMA# R) elements newly defined in this research were investigated.The results clarified that there is excellent correlation between the undercooling degree of eutectic solidification (#DELTA# a) and the critical cooling rate for the chilling tendency (R_c). In high purity molten cast iron containing a small amount of #SIGMA# G and #SIGMA# R, numerous findings were obtained, such as the R_c increase with the marked decrease in undercooling with inoculation.R_c is therefore considered to be a potential parameter for evaluating the molten iron by comparing #SIGMA# G and #SIGMA# R.