Formation of a scale on the hole surface of cooling nozzles in the hot strip mill process, obstructing a laminar flow of coolant

We investigated on the formation of a scale on the hole surface of brass cooling nozzles in the hot strip mill process of steel manufacturing. High roughness of a nozzle hole surface due to the scale formation obstructs a laminar flow of coolant, which can result in the diminution of cooling efficiency of strips. Morphology and elemental composition of a scale formed on the hole surface of cooling nozzles used in the hot strip mill process for a long time were characterized with an electron microscope equipped with an energy dispersive X-ray spectroscope. The scale is mainly composed of a foreign substance layer and an oxide layer. In addition, three kinds of cooling water were analyzed to investigate an inflow source for elemental constituents of the foreign substance layer. Copyright © 2012 John Wiley & Sons, Ltd.