The cast-rolled strip contains slag, flux, various refractory fragments, metal oxides and other impurities, which are called inclusions. There are many kinds of inclusions in cast-rolled strip, mostly black or refractory color, with irregular shapes.
Causes of Inclusions in Strip
The reasons are: aluminum ingots, master alloys, scraps in the raw materials contain impurities such as oil, moisture, etc., which are easy to form oxides and refractory and other inclusions; in the additives, covering agents, slagging agents, refining agents, refiners, etc., Potassium, sodium, and chlorine impurities are easily formed; the combustion medium used for graphite and thermal spraying, the combustion medium used for refining gas, smelting and launder heating, such as heavy oil, liquefied gas, etc., is easy to open into carbon, aluminum nitride, chlorine, Sulfur and other inclusions; furnace burrs, flow supply systems, tools, etc. are not sluggish, casting nozzle fine chips, casting nozzle peeling, slag, etc., are easy to become inclusions such as calcium, silicon, alumina, etc.; improper process operations, such as melt slag is not clean, improper mixing, high melting temperature, etc. are also easy to form.
Preventive Measures of Inclusions in Strip
The preventive measures that can be taken are: to ensure that the raw and auxiliary materials are clean, and the aluminum ingots, intermediate alloys, and waste materials used are free of oil and moisture; select high-quality additives, graphite emulsions and combustion media; the furnace should be cleaned regularly to ensure that the furnace, The flow supply system, tools, etc. are dry and clean; when using thermal spraying or graphite spraying, adjust the ratio and spraying volume to ensure uniform spraying; strengthen refining and degassing and melt filtering to improve filtration accuracy. Minimize the smelting time, appropriately reduce the melt temperature, and avoid the oxide scale being mixed into the melt during production operations; the cavity and roll surface aluminum chips must be purged before the vertical plate to minimize slag; if the casting nozzle is damaged, it must be shut down in time replace.