From Slab Corner Cracks to Edge-Defects in Hot Rolled Strip - Experimental and Numerical Investigations

The systematic investigation of the formation of edge defects on hot strips resulting from slab corner cracks generated in continuous casters, affords the development of model-based concepts for the identification of such initial slab cracks. This enables the reduction of material losses during trimming of defective edges. Utilizing the commercial finite element package Deform-3D (developed by SFTC, Columbus, Ohio, USA), systematic massive forming simulations of several consecutive flat and edging passes were performed. The main simulation challenges result from the occurrence of different length scale values in the slab and strip models including edge cracks. The numerical results clearly point out the significant morphological changes of the cracks during rolling and afford valuable indications for a deeper understanding of the underlying process details. The results from metal forming simulations coincide very satisfactorily with the unetched cross-sectional micrographs obtained from an experimental rolling mill. Systematic variation of geometry data enables the identification of the topology of initial slab corner cracks from edge defects detected after hot rolling.