SU1425236A1 - Method of degassing aluminium alloy melts - Google Patents

Abstract

The invention relates to the field of non-ferrous metallurgy and can be used for the degassing of molten aluminum alloys. The purpose of the invention is to increase the degree of degassing by reducing the residual hydrogen content in the alloy. The goal is achieved by the fact that the internal volume of the porous element is evacuated at a residual gas pressure above the pressure of the volatile component, and the pore size of the element is chosen less than the critical value according to the proposed ratio. The residual hydrogen content is reduced by 1.5 times in comparison with the known method, the loss of the volatile component and the waste of the metal are significantly reduced. 1 tab.

Description

4 1ЧЭ 01 Ю

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The invention relates to metallurgy and can be used for the degassing of molten aluminum alloys.

The purpose of the invention is to increase the degree of degassing by reducing the residual hydrogen content in the alloy.

The method consists in immersing a probe from a porous material into the molten alloy while simultaneously blowing it with an inert gas and evacuating the internal volume of the porous element to a pressure of residual gases above the pressure of the volatile component of the alloy, and the pore size of the element is chosen from the ratio

Rv.tch - | -Rmetvl.10st - Rlg.

where r st

-radius then, m;

-surface melt tension, N / m;

Ra-pch - atmospheric pressure, metallost- metallostatic pressure,

N / m

Par. - residual gas pressure, N / m Example. As a metal melt choose an alloy based on aluminum, the most volatile component is magnesium. Calculate the critical pore sizes and test results of the proposed method in comparison with the known are given in the table.

In the known method, since there is no limitation on the pore sizes, porous graphite with pore sizes exceeding 12 microns is used as the 2Q probe material, and less than 12 microns for comparison (as in the proposed method).

It can be seen from the table that, at μ, the known method cannot be realized.

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the residual gas pressure mask (Po.r. 25 because the probe is clogged with a melt. For a pH 1.3 mm Hg. Art., µm).

i The experiments were carried out in a laboratory setup, consisting of a resistance furnace,

crucible with melt (alloy weight 2.5 kg).

12 microns The proposed method allows to significantly reduce the consumption of inert gas, reduce the loss of the lightly volatile component and the waste of the metal.

a probe made of a porous material not melted with a melt, with nozzles attached to it for gas supply and pumping out; gas — OCh brand argon with a moisture content of 710 g / cm; a vacuum pump HBP-5H. After the alloy has been melted and a temperature of 1000 K is established, a porous probe is immersed in the melt at a low flow rate of purge gas.

The probe is immersed at 0.01 m into the melt and, at the same time, it stops the gas blowing. The tube connecting the vacuum pump to the porous probe is opened and pumping begins. Samples are taken after 15, 30 and 45 minutes. Over 30 minutes the degassing process is ineffective.

The test results of the proposed method in comparison with the known in the table.

In the known method, since there is no restriction on the pore sizes, porous graphite with pore sizes exceeding 12 microns is used as the probe material and, for comparison, less than 12 microns (as in the proposed method).

It can be seen from the table that, at μ, the known method cannot be realized.

since the probe is clogged up. For gpor

 since the probe is clogged up. For gpor

12 microns The proposed method allows to significantly reduce the consumption of inert gas, reduce the loss of the lightly volatile component and the waste of the metal.

Purge time

1-10

Pressure of residual gases, mm. Hg Initial hydrogen content, g Hydrogen content after 15 min

after 30 minutes after 45 minutes

Carbon,% (oxidation) Loss of volatile component,%

zaasm

1-10

Periodically in the degassing process - a few minutes

one

2.0

1.0

1-1020 s - the time of introduction of the probe into the melt

ten

2.0

0.8

0.6 0.6 5

3 (due to oxidation)

Claims (1)

Invention Formula A method for degassing aluminum alloy melts, including introducing a probe of porous material into the melt, purging with an inert gas and evacuating, in order to increase the degassing degree by reducing the residual hydrogen content in the alloy, purging with an inert gas is carried out at the moment of insertion of the probe into the melt, and the evacuation is carried out to a pressure of residual gases not higher than the pressure of the volatile component alloy, and using a porous material with a pore size that satisfies the ratio g 26 where r a R.t " R Par. g ffr -j- Rnetallost - Ro-g. -radius then, m; -surface melt tension, N / m; -atmospheric pressure, ketallost-metallostatic pressure, - residual gas pressure, N / m1