Effect of Continuous Casting Process Parameters on Carbon Segregation in φ390mm GCr15 Large Round Billet

The effects of continuous casting process parameters on carbon segregation of φ390 mm round billet of GCr15 bearing steel were studied, mainly including the effects of drawing speed, electromagnetic stirring in secondary cooling zone(S-EMS), electromagnetic stirring at end of solidification (F-EMS) and superheat on carbon segregation.The results show that with the increase of the drawing speed, the carbon segregation of the cross section of the continuous casting billet is gradually serious; when the drawing speed decreases from 0.55 m/min to 0.50 m/min, the carbon segregation coefficient at the center and R/2 of billet decreases by 9.5% and 4.2% respectively, and the fluctuation range decreases by 39.9% and 52.3% respectively.S-EMS has an important influence on the fluctuation range of carbon segregation at the center and R/2 of the cross section of the continuous casting billet.Compared with those without S-EMS, the carbon segregation fluctuations at the center and R/2 of the billet are reduced by 33.2% and 50.7%-64.6%, respectively.When the F-EMS parameter is 500 A/2 Hz, the carbon range of the cross section of the continuous casting billet is the smallest.When the superheat degree is 22-33℃, the low superheat degree can significantly reduce the carbon range of the cross section of the continuous casting billet, and the superheat degree has a linear positive correlation with the carbon range.