Effect of final electromagnetic stirring on solidification microstructure of GCr15 bearing steel in simulated continuous casting

The effect of final electromagnetic stirring on the solidification structure, element segregation, and carbides of GCr15 bearing steel was investigated. The experiment of continuous casting of the steel was carried out by using a continuous casting physical simulation apparatus with the final electromagnetic stirring. The liquid core profile was revealed by the pour-out method during the solidification process. Eight ingots were produced under different electromagnetic stirring parameters for comparison. The results show that, at the final stage of solidification, intense electromagnetic stirring exacerbates the central carbon segregation, resulting in more serious precipitation of the primary carbides. It is also found that the carbides in the segregation area are dominantly M₃C type, together with a small amount of M₇C₃-type and M₃C₂-type carbides. In this physical simulation model, the optimal stirring parameters to obtain a fine and homogeneous structure are the liquid pool width of 15 mm, current intensity of 150 A, and stirring frequency of 5 Hz.