Effect of a Novel Hot-core Heavy Reduction Rolling Process after Complete Solidification on Deformation and Microstructure of Casting Steel

摘要

Hot-core Heavy Reduction Rolling (HHR~2) is a novel technology designed for eliminating center defects of casting steel by using the large temperature gradient, which performed heavy reduction to bloom or slab with rolling mill after the position of solidification end of the strand. This works mainly focus on the effect of HHR~2 process on the shrinkage elimination and microstructure evolution. Firstly, bonding plate rolling experiment were carried out, which proved HHR~2 process with large temperature gradient in thickness direction could improve the internal deformation of workpiece. Meanwhile, the deformation permeability was beneficial to the microstructure refinement of center layer. Secondly, the HHR~2 process was studied by analysis of the results of FEM to explore the influence of some process parameters on shrinkage closure. In this study, the G_m index and volumetric residual percentage V/V_o were used as evaluation index in mechanical analyses and quantitative comparison, the results reflected the void tend to closing with the reduction ratio and roll diameter increasing, as well as with the reduction position moving towards the solidification end after complete solidification. Finally, the pilot plant trail of HHR~2 was carried out before industrial application, and the results reflects the HHR~2 process can eliminate the large central shrinkage cavity and refine the center microstructure.