Abstract: The strip breaking defects of grain-oriented silicon steel during the cold rolling were tracked, and the evolution process from skinning to hole formation and then to strip breaking was clarified. The scar defect was studied by peeling electron microscope. The results showed that the main elements in the scar defect were Fe, Si and Al, which were consistent with the matrix, and there were also trace elements such as Ca, Mg, K and Na. Cold rolling peeling and breaking was mainly due to hot rolling edge cracking defects inherited. The reasons why peeling and flaking were that part of the edge during the hot rolling occurred flesh out and splashed and was pressed into the surface of the hot rolled plate, and inconsistency of elongation and matrix during cold rolling. By reducing the slab heating temperature, shortening the furnace time of high temperature section and optimizing the rolling model, the edge crack of hot rolled strip was effectively restrained, and the problem of cold rolling strip breaking was solved.

Key words: grain-oriented silicon steel, cold rolling, edge crack, strip breaking