Analysis and discussion on the surface linear defect of cold-rolling sheet steel

摘要

A series of surface linear defects of cold-rolling sheet steel have been investigated by Scanning Electron Microscope (SEM) and X-ray Energy Dispersive Spectrometry(EDS).The results show that a lot of inclusions, gas holes and some feature of free surface like spore exist behind or on the defects, and a lot of bigger nonmetallic inclusions have the same composition as the hot-rolling steel plate, by means of simulation figure, it is described that the inclusions (or gas holes) within the slab could expose upon the surface of sheet steel after hot-rolling and cold-rolling, and finally become the linear surface defects whose appearance are bubble, crumple and darking-down. Meanwhile, it's regarded that the amount, size and shape of the nonmetallic inclusions (or remant gas holes) within the slab are a very important affecting factor on the surface quality of cold-rolling sheet steel, although they could not do harm to the surface quality of hot-rolling steel products.