High purity (more than 4N) nitrogen gas can be used as a substitute gas for argon gas (5N) in molten aluminum treatment. The effects of nitrogen gas purity on molten aluminum treatment were clarified in this study.
AC8A (modified) alloy, four kinds of nitrogen gases (2N, 3N, 4N and 5N), and argon gas (5N) were prepared.
Equivalent removal of inclusion and fluidity were seen after molten aluminum treatment by each gas.
In comparison to 5N argon gas, the 5N and 4N nitrogen gases had equivalent degassing ability. In applying the nitrogen gas to molten aluminum treatment, above 4N purity is required to obtain the clean molten aluminum obtained by treating with argon gas (5N).