Dedescaling nozzle as a key component affects the surface quality of hot-rolled products directly, if the descaling nozzle is not used properly, the surface of the product is easy to press into the iron oxide or produce black marks and other surface quality problems; will also increase roll consumption.
When the high-temperature slab is subjected to high-pressure water jetting, due to the different degrees of shrinkage of the slab's mother material and the iron oxide skin and the tangential shear force, prompting the iron oxide skin from the mother slab off. If the water volume is not appropriate, the iron oxide peeling effect is poor or the slab is too cold.
Due to the uneven thickness of the iron oxide layer or cracks, the water flow with pressure may "drill" between the iron oxide and the slab matrix, in an almost closed space, suddenly heated vapour and explosion, so that the iron oxide peels off and is not rolled and pressed into the slab matrix.
The strike force of the descaling nozzle is influenced by the system pressure, pipeline direction, spray height, nozzle installation angle, etc., The type and structure of nozzle determine the spray shape and spray granularity.
The material of the nozzle is mainly considered in terms of wear resistance, processing performance, cost and other factors. Hardened stainless steel and tungsten carbide as common material the wear resistance of tungsten carbide is far higher than of hardened stainless steel, can service long time. The disadvantage of hardened stainless steel descaling nozzles is the short service life and has to be replaced frequently.
