CAUSES OF STICKER BREAKOUT DURING CONTINUOUS-CASTING

The causes of sticker breakout during continuous casting have been investigated by (i) a review of published literature, (ii) quality control testing of mould powder supplies, (iii) on-plant monitoring of various casting parameters, (iv) metallographic examination of both the shells removed from the mould following a breakout and the slag films attached to the shell, and (v) simulation experiments. The evidence obtained supports the view that sticker breakouts occur when a carbonaceous agglomerate blocks the flow of slag into the mould/strand gap and a low melting point high carbon meniscus is formed that does not heal during negative strip. It was observed that some breakouts are preceded by the formation of longitudinal grooves on the surface of the skelp* which were attributed to the effects of a CO gas bubble. It was concluded that the carbonaceous agglomerate responsible for the sticker breakout could be formed by either unmelted casting powder or erosion of the refractories used for submerged entry nozzles and stopper rods.