Dissolved gas flotation (DGF) is used for removing inclusions from molten steel. The supersaturated gas forms bubbles on inclusions and carry them to the melt's surface.
Hydrogen is introduced by moisture. ... Introducing inert gases such as argon or nitrogen into the molten metal can be used to remove hydrogen. As inert gas bubbles move up through the molten aluminum, hydrogen diffuses into the inert gas bubbles and essentially disappears.