Common Defects Of Cold Rolled Sheet
Edge crack defect
The enrichment of large inclusions at the edges is one of the main sources of induced edge cracks. Since the thin slab adopts a funnel-type crystallizer, the flow inside the mold, the unevenness of heat transfer and the fluctuation of the liquid surface are more complicated than the conventional slab continuous casting, and the slag is often caused during the casting process, and a part of the slag remains. Surface inclusions are formed on the surface of the slab, wherein larger inclusion particles are deposited on the edges of the slab, resulting in enrichment of large oxide inclusions at the edges.
Iron oxide skin indentation defect
The primary iron oxide scale that has not been completely removed is pressed into the strip during subsequent rolling to cause surface defects on the strip. The reason that the secondary descaling water is not opened is the key to the secondary iron oxide skin intrusion defect. The defect tracking results show that the iron oxide indentation defects can be basically eliminated in the subsequent pickling and cold rolling processes, and basically have no effect on the cold rolled sheets.
Black line-like defects on the surface of the strip before cold rolling after pickling. The surface defects of cold-rolled strip steel mainly come from hot-rolled base defects, which are mainly caused by inclusions on the surface of hot-rolled sheet. The possibility of defects in the cold-rolled production line itself is very small.