The Effects of Heating on the Three-Dimensional Evolution of Microsegregation in Continuous Casting Blooms of Gear Steel

Microsegregation of the steel in continuous casting is inevitable and results in the banded structure of the rolled steel, which reduces the anisotropy machinability and service life of the steel. Microsegregation can be categorized into dendrite segregation and porosity segregation, with the latter posing a more significant risk, which can only be improved by high-temperature diffusion of hot charging. To accurately characterize the degree of microsegregation, a new evaluation method based on clustering algorithm is developed in this work, which takes into account the influence of area distribution on the segregation ratio. On this basis, a three-dimensional carbon diffusion kinetic model is established, which could predict the circumferential carbon diffusion of dendrites segregation and porosity segregation together during heating process as well as determining the optimal heating process. Combining with orthogonal experiments, the effects of heating time and temperature on the improvement elimination of porosity segregation in gear steel continuous casting blooms were investigated, and the average prediction error of three-dimensional diffusion kinetic model was no less than 4.62 pct. The results indicate that the optimum conditions for diffusing porosity segregation are achieved by holding at 1250 degrees C for 1.5 hours.