Reasons Aanlysis on Red Scale of SAPH440/400 Hot Rolled and Pickled Steel Sheets

By comparing the morphology of SAPH440/400 hot rolled and pickled steel sheets before and after pickling, it was found that the positions where had red scale showed a slight indentation characteristics. And by energy spectrum analysis it was found that except element iron and oxygen, there were also silicon enrichment in the scale. So it could be concluded that the presence of red scale on the steel sheet surface was mainly due to the iron oxide accumulation at the heating furnace bottom, and silicon enrichment made fayalite layer form at the steel sheet head and tail which was difficult to remove during phosphorus removal process and was oxidized and appeared red. Finally improvement measures were adopted and good results were achieved.