Experimental Validation of HTC Value on a 27-Tonne Polygonal Steel Ingot by Numerical Simulation

Abstract This research aims to determine and validate the heat transfer coefficient (HTC) values as a function of temperature for ingot casting simulation, in order to optimize the casting process, to enhance ingots quality, save materials and energy resources and reduce production costs. The heat transfer between the cast part and the mould influences the solidification of the metal and directly affects the formation of the most common ingots’ defects, such as macrosegregations and shrinkage porosity. Consequently, an accurate definition of HTC at the interface between mould and steel represents a very critical aspect and must be set properly in numerical simulations to ensure reliable predictions. To address this, this study investigates the casting process of a 27-tonne industrial steel ingot. Eight different thermocouples were placed at different positions of the ingot mould, and one thermocouple in the insulation sleeve to record the temperature during the ingot casting, including filling and subsequent solidification. The experimental results were then compared to those from the numerical simulation of the casting apparatus, which was designed according to the industrial parameters, and incorporating HTC values as function of temperature. Additionally, the study evaluates the formation of solidification defects, such as the secondary shrinkage pipe, by using the pinch-off temperature analysis, proposed as an alternative method to the Niyama criterion for the prediction of this defect.