24 3月 Grain Refining of Aluminium
Grain Refining of Aluminium removes non-metallic inclusions, hydrogen, sodium, calcium and lithium from liquid aluminum and aluminum alloys.
Grain Refining is produced in two forms, fine particles and granular.
Grain Refining reacts quickly and effectively removes sodium, lithium and calcium from molten aluminum and aluminum alloys and refractory furnace linings.
In high Mg aluminum alloys, sodium content of less than 1 ppm can be achieved in castings. Grain Refining removes various non-metallic inclusions, such as oxides, carbides and borides, and strengthens the injection during degassing.
Grain Refining is usually used to remove alkali (sodium, lithium, calcium) and non-metallic inclusions from all alloys in primary smelters.
In order to remove non-metallic inclusions, hydrogen and alkaline metals in the molten aluminum in the melting furnace or holding furnace, 250 grams to 1.0 kg of Grain Refining is added per metric ton of metal charge.
Advantages of Grain Refining of Aluminium
a) Improve profile extrusion speed and die life
b) Reduce the number of fractures in continuous casting
c) Eliminate edge cracks when rolling high Mg aluminum alloys
d) Does not contain fluoride. Zero emission of fluorination.
e) harmless compounds
f) Low melting point, fast dispersion (<766°f, 480°C)
g) Not as hygroscopic as magnesium
h) Replace the chlorine in the flux in the furnace
i) Reduce the use of chlorine in the online refining system
j) Low dosage, generally 0.5 kg/ton aluminum
k) Keep the furnace, scrubber, online degasser and casting nozzle free of sludge and scum.
During the smelting process, tools and other factors have an impact on the quality of the aluminum alloy melt. It must be dried before use. It cannot be operated in a cold state and painted with protective coatings to prevent the metal from further absorbing hydrogen and increasing iron.
The moisture content of the refining agent must be controlled below 0.3%, and the purity of the emotional gas must be above 99.99%.
During the refining operation, make the outlet pipe mouth as close as possible to the bottom of the molten pool and drag the outlet pipe back and forth to make the refining agent fully contact with the molten aluminum to achieve the purpose of refining.
During the refining operation, the author can freely control the flow of carrier gas and refining agent through the barometer and the speed of the powder feeder.
So as to control the tumbling degree of the molten aluminum, and reduce the secondary pollution as much as possible. The refining time is controlled at 10-15 minutes, and two refining are taken if necessary.