INFLUENCE OF HEAVY REDUCTION (HR) ON THE INTERNAL QUALITY OF THE BEARING STEEL GCr15 BLOOM

Heavy reduction (HR) is an effective method to improve the homogeneity and compactness of slab and bloom with large section size. In the present work, the key technologies of bloom heavy reduction including online detection of strand solidification end, online calculation of minimum reduction amount, enhanced final electromagnetic stirring (F-EMS) and convex roll with curving surface were introduced. The plant results after the HR application showed that the center segregation and porosity of GCr15 steel bloom and rolled bar were reduced effectively, and its internal quality meet the requirement of rolling large size bars and profiles successfully.