Abstract：The samples of hot rolled strip with surface scars and cold rolled sheet with porosity cluster were investigated by microscopy. And it was found that the scars of black fibrous structure are separated from the base metal due to collision.The collision of steel strip with flipper guide was observed on finish rolling unit. Formation and evolution of scars were studied by hot rolling and cold rolling simulation.The collision of steel strip with flipper guide on finish rolling unit is the reason of scar defect.Porosity cluster of cold rolled sheet is transformed from scars, and it is critical to avoid collision for improving the surface quality of hot rolled strip.
2007, Vol. 42 
