A Study on the Impact of Silicon and Manganese on Peritectic Behavior in Low Alloy Steels Assisted by Mold Thermal Mapping Technology and Shell Growth Measurements

Non-uniform shell growth commonly caused by the peritectic transformation in low carbon and low alloy steels has been directly correlated with mold thermal maps using a mold immersion test into a molten steel alloy. Mold thermal maps were obtained by performing real-time temperature measurements with optical fibers embedded 1 mm from the mold working surface. Shell growth measurements were obtained by 3D optical scanning of the recovered steel shell following immersion testing. The effects of silicon and manganese on the shell growth and mold temperature maps have been examined in relation to the peritectic transformation for varying carbon contents. Results of thermodynamic and kinetic simulations using ThermoCalc and its kinetic module-DICTRA predicted that silicon expands the carbon content range to values between (0.12 pct C to 0.21 pct C) where peritectic behavior occurs and that manganese shrinks the carbon content range and shifts the range to lower carbon contents (0.06 pct C to 0.12 pct C). The results of these simulations were used to guide the selection of chemistries examined in the dip test experiments with the aim of validating the software predictions. Dip tests were performed at similar steel making temperatures that were used for the software simulations between 1600 degrees C and 1650 degrees C. Both software results and experimental observation showed relatively good agreement for the compositions examined.