Aluminum Refining Flux should be added in proportion. The aluminum refining agent is generally 0.3% of aluminum alloy. Method Use a seamless steel pipe inserted 20cm from the bottom of the molten aluminum, and spray the refining agent with nitrogen or argon. After the refining spray, the nitrogen or argon is blown for another 15-20 minutes. Calm for 10-15 minutes after refining, and remove aluminum slag.
Various cast non-ferrous metals have the characteristic of absorbing gas. In the process of smelting or holding the alloy liquid, with the increase of alloy temperature, the solubility of the absorbed gas increases rapidly. Therefore, in addition to the correct control of the entire smelting and pouring process, the heat preservation of the gold liquid at high temperatures should be minimized to avoid overheating of the alloy liquid. For alloys that are very easy to attract, smelting under the protection of covering agents can avoid the generation of pores and pinholes.
In order to reduce the oxidation of aluminum alloy, in addition to choosing an appropriate melting furnace, a holding furnace should be used for heat preservation in die casting production. Never melt and die-casting production, reduce stirring as much as possible, and keep the oxide film on the liquid surface intact. Avoid unnecessary overheating of the alloy liquid and try to shorten the time of the alloy in the holding furnace.
During die casting, part of the gas in the cavity of the pressure chamber cannot be discharged from the cavity, but is involved in the molten metal. During the filling process, back pressure will be generated to reduce the flow rate, resulting in cold isolation, under-casting, pores, and looseness of the casting. And other defects. In order to eliminate the casting defects caused by this, the mold must be equipped with an exhaust groove. The exhaust groove is generally matched with the overflow groove and is arranged at the rear end of the overflow groove. In some cases, the exhaust groove can also be arranged separately in the cavity.
The higher the alloy melting temperature, the longer the melting time and the retention time of molten aluminum after melting, the more fully the diffusion of hydrogen in the molten aluminum, the greater the amount of hydrogen absorbed by the molten aluminum, the greater the probability of pinholes. Someone has done an experiment. The longer the molten aluminum is stored, the gas volume in the aluminum alloy increases approximately proportionally. Aluminum Refining Flux can remove the gas in molten aluminum. Most aluminum foundry choose AdTech aluminum refining flux, AdTech fluxes have a good performance in degassing and deslagging.