SU1638192A1 - Method of producing aluminium alloy castings - Google Patents

Abstract

The invention relates to foundry and can be used in the production of castings with increased quality requirements. The purpose of the invention is to improve the quality of castings. Before refining the melt with a constant electric current under reduced pressure, it is pre-saturated with hydrogen to a content of at least 0.5 cm3 / 100 g. Quality is stabilized due to more complete removal of gaseous and solid non-metallic inclusions from the melt.

Description

The invention relates to foundry - manufacturing and can be used in the preparation of castings with increased quality requirements.

The purpose of the invention is to improve the quality of the castings.

Improving the quality of castings is achieved by the fact that in the manufacture of castings from aluminum alloys after the charge is melted, the melt is saturated with hydrogen and then subjected to electric current treatment under reduced pressure, standing and pouring of the molds.

The hydrogen saturation of the melt is caused by the fact that aluminum oxide and hydrogen interact with each other. Experiments and theoretical data show that hydrogen and oxide inclusions exist in aluminum alloys in the form of charged particles. Non-metallic inclusions carry a negative charge; hydrogen, in the form of protons, is positive. Therefore, when processing a constant

by electric current, hydrogen ions and oxide inclusions, supersaturated with hydrogen ions, move to the cathode, from where they are removed by vacuumization. At the same time, oxide inclusions not oversaturated with hydrogen ions, having a more electronegative charge, move to the anode, while also being a transporter of hydrogen adsorbed on oxides, and thus making it difficult to remove gas and oxide inclusions from the melt.

The proposed method is carried out as follows.

After the charge is melted, the aluminum melt is saturated with hydrogen over 0.5 cm9 / 100 g with wet asbestos, then subjected to joint treatment with a constant electric current with anode density of 0.4 A / cm2 and vacuum with a residual pressure above the surface of the melt 10 mm Hg. Art. within 15 min After refining, the melt is allowed to stand for 15–20 min and spill-1 (I

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31638192

in form at 700–710tfC. In the case of an electric current, the furnace crucible serves as the anode, the rod serves as the cathode

from t 1

electrode made of titanium rod and immersed at 1/3 of the depth of the molten bath.

The studies were conducted on Al-9 alloy body parts that are not leak tight.

In the manufacture of castings according to the old technology (melting of the charge, refining by direct electric current under reduced pressure, casting out and pouring forms), the following pattern was found.

If, after melting the charge, the gas content in the melt was less than 0.24 cm3 / OO g, then B5 increased for 15–20 min and cast into molds at 700–710 ° C for testing for gas content, mechanical properties, and to obtain castings. The obtained castings were checked for tightness.

The results of the test gas content in the melt is less than 0.05 cm / 100 g; ultimate tensile strength in the range of 21.0–22.0 kg / mm2, and relative elongation of 6.0–7.0%; the marriage of castings on tightness stabilized-- with - in some cases it was reduced to 0%, and in the case of castings operating under pressure within 10 kg / cm

the harsh outburst of rejects for ga- 20 was in the range of 8-10% (up to 40-50% were previously observed),

The present invention allowed to stabilize the quality of the castings due to more complete removal of gas and solid non-metallic inclusions from the melt.

25

ZOVE shells and leaks. For example, in the manufacture of parts of the type of body weighing 1.050 kg with a wall thickness of 2.5 mm, working under a pressure of up to 10 kg / cm2, and stable 8-10% of scrap from 10 heats in 3-4 heats, sharp outliers of up to 40-50 were observed %, In the manufacture of the same castings according to the proposed method, there were no sudden attacks of marriage (it was at the same level of 10%).

Example, Alloy Al-9 was melted in an electric resistance furnace of the type VRP-1o. After reaching 720-740 ° C, the melt was gas-saturated with hydrogen with more than 0.5 g of wet asbestos (the analysis of the melt was performed). Then the melt was subjected to joint treatment with a constant electric current with anode density of 0.4 A / cm2 and vacuum, Q

Claims (1)

Invention Formula The method of producing castings from aluminum alloys, which includes melting the mixture, refining the melt with a constant electric current under reduced pressure, standing and pouring the melt into molds, about t l and -. due to the fact that, in order to improve the quality of castings, before refining the melt, it is saturated with hydrogen to contain at least 0.5 cm3 / 100 g with a residual pressure above the surface of the melt 10 mm Hg. within 15 min After refining. Melt stand for 15–20 min and cast into molds at 700–710 ° C to test for gas content, mechanical properties, and to obtain castings. The resulting castings were checked for leaks. The results of the test gas content in the melt is less than 0.05 cm / 100 g; ultimate tensile strength in the range of 21.0-22.0 kg / mm2, and relative elongation of 6.0-7.0%; the marriage of castings on tightness stabilized-- with - in some cases it was reduced to 0%, and in the case of castings operating under pressure within 10 kg / cm was in the range of 8-10% (up to 40-50% was observed earlier), Invention Formula The method of producing castings from aluminum alloys, which includes melting the mixture, refining the melt with a constant electric current under reduced pressure, standing and pouring the melt into molds, about t l and -. due to the fact that, in order to improve the quality of castings, before refining the melt, it is saturated with hydrogen to contain at least 0.5 cm3 / 100 g