Heat-Flow-Based Analysis of Surface Crack Formation During the Start-Up of the Direct Chill Casting Process: Part I. Development of the Inverse Heat-Transfer Model

摘要

A method for determining the temperature dependence of heat transfer in the direct chill (DC) water regime of the DC casting process has been developed. The technique uses as input the data acquired from one embedded thermocouple and involves the application of one-dimensional (l-D) and two-dimensional (2-D) finite element based heat conduction models in succession. The technique has been verified using hypothetical temperature data obtained from a transient casting simulation conducted with a known, idealized, heat flux profile. The results of the comparison indicate that the technique converges to the applied heat flux profile in approximately 12 seconds process simulation time; thus, it is suitable for investigation of the flow of heat during the start-up phase of the process. The accuracy of the technique was found to be satisfactory with thermocouples placed up to a depth of approximately 10 mm below the face of the ingot. The analysis of industrial thermocouple data, the suggested mechanism for crack formation during the start-up, and the remedial action are presented in part