Secondary cooling parameter optimisation for vertical continuous casting of AISI H13 large round bloom

The generation of bulging and macro-segregation owing to surface temperature rebound and stress fluctuation are detrimental for the final quality of continuous casting (CC). In this study, physical and mathematical modelling of a large-bloom vertical CC is established. The Sasaki equation is optimised, and the accuracy of calculation model is verified by nail-shooting experiment and the temperature measurement. By regulating specific water flow in secondary cooling zone, the influence on surface temperature, stress fluctuation, macro-segregation and macro-structure are investigated. Results show that the decreasing specific water flow decreases surface temperature rebound and stress fluctuation. Besides, when specific water flow decreases from 0.25 to 0.09 L kg−1, the positive and centre negative segregation of bloom is improved, the content of C at bloom centre increases from 0.25 to 0.32. The equiaxed crystal ratio increase from 38.51% to 43.57%. In conclusion, a lower specific water flow can reduce the defects.