Virtual Macroetch for Quality Assessment in Complex Continuous Cast Steel Shapes

In industrial environments, the internal quality of continuously cast steel shapes is typically evaluated afterwards by means of macroetch testing. Nevertheless, this approach becomes increasingly difficult as the product dimensions grow larger. When process parameters change — for example, with an increase in productivity — it is advisable to have a virtual macroetch available to perform a preliminary quality assessment. In the literature, models exist to predict porosity and microstructure of the final product; however, their validity has been tested only for very simple shapes. In this work, using a travelling-slice approach, a virtual macroetch model was developed for billets and blooms. Comparison with experiments shows that, in the case of billets, the approaches available in the literature provide accurate results. For blooms, however, an accurate prediction of porosity requires a modification of Niyama’s criterion, introducing a correction in the exponent q, while Hunt’s criterion remain applicable for microstructure. Based on these results, the case of a beam blank cast at high speed was analyzed. The study confirmed the feasibility of the process, with only a limited increase in porosity and a slight reduction in the equiaxed area in the inner part of the beam blank.