Modeling of Species Transport and Macrosegregation in Heavy Steel Ingots

In the current study, two significant phenomena involved in heavy steel ingot casting, i.e., species transport and macrosegregation, were numerically simulated. First, a ladle–tundish–mold species transport model describing the entire multiple pouring process of heavy steel ingots was proposed. Carbon distribution and variation in both the tundish and the mold of a 292-ton steel ingot were predicted. Results indicate high carbon concentration in the bottom of the mold while low concentration carbon at the top of mold after the pouring process. Such concentration distribution helps in reducing both negative segregation in the bottom of the solidified ingot and positive segregation at the top. Second, a two-phase multiscale macrosegregation model was used to simulate the solidification process of industrial steel ingots. This model takes into account heat transfer, fluid flow, solute transport, and equiaxed grain motion on a system scale, as well as grain nucleation and growth on a microscopic scale. The model was first used to analyze a three-dimensional industry-scale steel ingot as a benchmark. Then, it was applied to study macrosegregation formation in a 53-ton steel ingot. Macrosegregation predicted by the numerical model was presented and compared with experimental measurements. Typical macrosegregation patterns in heavy steel ingots are found to be well reproduced with the two-phase model.