Numerical Simulation on Microstructure of GCr15 Bearing Steel Bloom

The solidification mathematical model was established by ProCAST software on a GCr15 steel bloom and then the CAFE model was used to simulate the solidification structure of the bloom.The effects of superheat,casting speed and secondary cooling intensity on the solidification structure of bloom were studied.The results showed that superheat had great influence on solidification structure of bloom.With the increase of superheat degree,the average grain radius increased at the same position of the columnar zone,the columnar region increased,the equiaxial crystal ratio decreased and the CET transition was delayed.When the superheat degree decreased from 40 ℃ to 10 ℃,the equiaxial crystal ratio increased by 21.14%.The casting speed and the secondary cooling intensity had little influence on the solidification structure of the bloom.With the increase of the casting speed or the decrease of the secondary cooling intensity,the columnar region decreased,the equiaxial crystal ratio increased,and the CET transition ahead of time,but the changes were not obvious.In the actual production process,the grain size of the solidification structure of the billet can be refined by reducing superheat.