1.What are the types of internal inclusions?
Protective slag entrainment; sulfide inclusions; FeO inclusions; component segregation.
2.What are the characteristics and sources of defects caused by the entrapment of protective slag?
During continuous casting, the protective slag used for lubrication and heat preservation is captured by the molten steel and forms stratification after rolling. Na and K components in the protective slag can be detected at a microscopic level.
3.What are the characteristics and sources of sulfide inclusion defects?
If the sulfur content in steel is too high (e.g., >0.02%), MnS with poor plasticity will be formed and stretched into strips or sheets during rolling, becoming a delamination interface.
4.What are the characteristics and sources of FeO inclusion defects?
When molten steel solidifies, excessive oxygen content causes ferrous oxide (FeO) to precipitate along grain boundaries, severely disrupting the continuity of the matrix.
5.What are the characteristics and sources of process and foreign object defects?
Air bubbles originally present inside the steel billet were not completely compressed during hot rolling, leaving behind and forming interlayers.
During production and transportation, non-metallic foreign objects (such as dust, sand, and liner paper fragments) are forcefully pressed into the strip steel matrix.