An optimization study for an efficient hydrogen removal during continuous casting of aluminium alloys

Aluminum alloys can dissolve excessive amount of hydrogen gas in their molten state. Since its solubility decrease with decreasing temperature, gas bubbles are formed and entrapped within the solid structure during solidification. Existance of such imperfections can cause serious failure during manufacturing of sheet and foil products. There exist many methods to remove hydrogen gas from liquid aluminum. The efficiency of removal depends mainly on operational parameters. Inert gas flow rate and rotational speed of the rotor are among those for the systems employing injection and shearing of the gas bubbles for gas removal mechanism. In this study we aim at determining the optimum argon flow rate and the rotor speed for the SNIF system which will result in the most efficient hydrogen removal rate within the liquid metal.The measuments were conducted during 1050 and 3003 aluminum alloy castings. Nine different gas flow rate-rotor speed combinations determined from Design of Experiments were applied during castings. A mathematical equation estimating the hydrogen content as a function of flow rate and rotor speed has been developed using a statistical software. The optimum flow rate/rotor speed combinations were determined for the most effective hydrogen gas removal and implemented in real scale production.