Cause Analysis on Surface Upwarping and Edge Defects of Hot Rolled Strip

In order to improve quality of strip steel,the microstructure and chemical composition of surface upwarping and edge defects regions were investigated by OM,SEM,and EDS,and the causes were analyzed.The results show that,there are iron oxides,secondary oxidation and composition of mold flux in surface upwarping regions,which are expected to come from slag entrapment in mold,surface cracks on continuous casting billet,surface scratches on hot strip,flanging in rolling processes. There are iron oxide,secondary oxidation,calcium aluminates and Mn S in edge defects,the reason may be attributed to cracks on continuous casting billet and internal inclusion in steelmaking process. The key to obtain high quality of hot rolled strip are improving the quality of continuous casting billet and controlling defect in hot rolling process.