In this study, the influence of the degree of superheat on the solidification structure and macroscopic carbon segregation of 20CrMnTi gear steel billet was studied systematically by numerical simulation and industrial testing. The simulation results were verified by observation of hot acid corrosion macrostructure and carbon segregation detection. It was found that the increase in superheat significantly increases the size of the central shrinkage cavity, inhibits the formation of equiaxed crystal zone, and aggravates the central carbon segregation; The process sensitivity characteristics of superheat control window are revealed: when the superheat degree is within 10–20°C, the change trend of grain number and average grain radius with superheat degree is not obvious; At the same time, the quantitative relationship between the characteristic parameters of solidification structure and the distribution of solute is established, and the negative correlation between the proportion of equiaxed crystal zone and carbon segregation is revealed.
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