METHOD TO PRODUCE INGOTS FROM ALUMINIUM ALLOYS CONTAINING LITHIUM Russian patent published in 2012 - IPC C22B9/04 C22C1/06 

FIELD: metallurgy.

SUBSTANCE: invention relates to vacuum treatment of aluminium alloys with high-duty lithium with higher requirements to hydrogen content. The prepared melt is poured into a vacuum mixer, and vacuumising is carried out in two stages. The first stage of vacuumising is carried out at residual pressure of not more than 20 mm of mercury column with introduction of inert gas under a layer of the melt, afterwards the inert gas is supplied to develop the pressure above atmospheric one above the melt surface. At the second stage the inert gas is pumped down to 1-20 mm of mercury column, and the melt is soaked. Then the inert gas is supplied, and the melt is settled at the inert gas pressure close to the atmospheric one. Duration of vacuumising at each stage makes not more than 20 minutes. Vacuumising of aluminium alloys that do not contain zinc is carried out at the residual pressure of 1-2 mm of mercury column, and alloys containing zinc - at the pressure of 10-20 mm of mercury column. The melt settling is carried at the pressure of 225-300 mm of mercury column.

EFFECT: lower content of hydrogen and non-metal inclusions in moulded ingots, as a result quantity of defects in produced deformed semi-finished items in a melt is reduced.

5 cl, 1 tbl, 1 ex