Speaker
Description
Predicting contact conditions between the solidified shell and the mold wall is essential to simulate heat transfer and mold friction in continuous casting due to their significant impact on interfacial resistance and normal stress at the mold-strand gap. However, the multi-physics nature of continuous casting coupling fluid flow, heat transfer, solidification, and thermo-mechanical stresses makes it challenging to accurately predict local contact at the mold-strand gap. In this work, a new approach to model the local contact is proposed by considering the thermo-mechanical interactions between ferrostatic pressure, mold taper, and thermal shrinkage under steel solidification and slag infiltration. A newly introduced Contact Index classifies the contact area into three zones: 1) Compression dominant, 2) Ferrostatic dominant, and 3) Shrinkage dominant zones. With the Lubrication Index which divides into liquid and solid slag lubrication zones, normal stress applied on the mold wall or air gap formed at the gap is calculated according to six different scenarios. This approach is tested on a Digital Twin as a proof-of-concept. The simulation reveals that the influence of the thermal expansion coefficient of steel is substantial. A parametric study with different thermal expansion coefficients shows that the same casting process can cause the formation of air gap or excessive taper within a typical range of thermal expansion coefficients. Furthermore, the model demonstrates that the shell expansion by ferrostatic pressure plays an important role in mold friction in spite of its small magnitude compared to thermal shrinkage and mold taper.