Mechanism of Red Scale Defect Formation in Si-added Hot-rolled Steel Sheets.

The red scale, which is one of the major defects on hot-rolled Si added steel sheets, is reproduced 6xperimentally.On the basis of detailed observation of the scale properties, we propose the mechanism of formation of the red scale.Imcomplete descaling of FeO prior to hot rolling causes red scale formation even in Si-free steels, since the reaction from FeOto Fe304and red Fe203 is largely accelerated by the breakage of the FeO scale, In Si-added steels, descaling is quite difficult to perform, becausethe eutectic compound of FeO/Fe.SiO* is formed at the scale/steel interface and penetrates irregularly into both upper FeOand lower steel sides.auite high strength of the eutectic compound, even just below the solidus temperature of 11 73'C, can also make it difficult to descale.