Evolution of artificial defects from slab to rolled products

Abstract In this study, an operational experiment was conducted where artificial defects were applied to a slab to observe the evolution of surface defects from slab to coated strip. The aim of this work is to find the effect of defect dimension (diameter, depth) and its’ filling (casting powder/open) on the defect shape and position in the strip after hot rolling, cold rolling, and tinning. Three identical sets of artificial defects were drilled in the trial slab made of tin-grade steel. The first set was sampled after hot rolling, the second set was sampled after cold rolling, and the third set was sampled after tinning. The defects were metallographically analyzed in cross-sections using light microscopy and scanning electron microscopy including energy-dispersive X-ray spectroscopy. Many of the induced defects were found to have healed during processing, and the appearance of a single defect was found vary substantially between positions.