Structural and spectroscopic characterisations of the surface oxide scales and inclusions present on edge-burst hot-rolled steel coils

• First investigation and surface study report on edge-bursting issue of steel coils.
• Detailed characterisations of the inclusions and surface oxide scales in steel.
• Influence of a particular type of calcium aluminate phase on process chemistry.

Detailed structural and spectroscopic characterisations have been carried out on the inclusions and the surface oxides present on edge-burst hot-rolled steel coils. Surface scales were characterised through X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. Evidence of different types of regular and non-stoichiometric Fe-oxides was found on the cracked surface of the steel wire. Along with the surface scales inclusions with calcium aluminate and spinel was characterized using Raman spectroscopy. The usefulness of Raman spectroscopy has been explored in detail for the characterisation of these inclusions; especially when XRD information ceases to be a limiting tool. The samples collected from the clogged nozzle area were found to be of grossite (CaO·2Al2O3) phase and this was also observed in the inclusions in the finished coils. It was found that this particular calcium aluminate phase has a detrimental effect on casting and final finished steel products.