KR20030065018A - Check valve made of aluminum alloy - Google Patents

Abstract

PURPOSE: A check valve made of aluminum alloy capable of obtaining stabilization of stress corrosion breaking and tension characteristics as maintaining superior casting properties or mechanical or physical properties by applying aluminum alloy to check valve is provided. CONSTITUTION: The aluminum alloy for valves comprises 90 wt.% of aluminum, 7.4 to 8.4 wt.% of magnesium, 1.2 to 1.7 wt.% of zinc, 0.1 to 0.2 wt.% of copper and 0.2 to 0.3 wt.% of manganese. The check valve is made of an aluminum alloy comprising 90 wt.% of aluminum, 7.4 to 8.4 wt.% of magnesium, 1.2 to 1.7 wt.% of zinc, 0.1 to 0.2 wt.% of copper and 0.2 to 0.3 wt.% of manganese, wherein the check valve is manufactured by performing CNC screw processing and anodizing film treatment on the formed aluminum alloy after forming the aluminum alloy by die-casting.

Description

Check valve made of aluminum alloy

The present invention relates to a check valve made of an aluminum alloy, and more particularly to a new aluminum alloy check valve further improved the stress corrosion cracking and stabilization of tensile properties.

In general, the check valve is used as a mechanism for preventing the back flow of the fluid, or as a mechanism for preventing leakage in the flow direction due to the pressure block. The sealing force necessary to close the check valve may be generated by a spring or, if the check valve is installed vertically, by the weight of the closing member itself, and the pressure difference in the check valve overcomes the sealing force so that the closing member It is common for the valve to open by pushing on.

For example, check valves used in air compressors, etc., are made of a material such as brass, which is cut, heated, forged, trimmed and shot blasted, followed by CNC lathe machining and a separate dedicated machine. After screwing by machine, nipple hole and the like are formed and plated to complete.

However, the conventional check valve cast of brass has a problem that the weight of the material is large, the check valve itself is heavy, and eventually increase the total weight of the device in which such a check valve is used.

On the other hand, since aluminum alloys are lightweight and have excellent ductility, tensile strength and corrosion resistance, various castings have been proposed. Especially, casting alloys made of 90% aluminum and 10% magnesium are light and excellent mechanical as described above. It is known to meet the needs of maintaining properties.

However, the Al-Mg alloy has a problem in that its mechanical properties change with time, and a significant decrease in ductility occurs after a very long time.

Accordingly, the present invention has been made to solve the above problems, the application of the aluminum alloy to the check valve, while maintaining excellent casting properties or mechanical or physical properties, the new aluminum that can promote the stress corrosion cracking and tensile properties stabilization The purpose is to provide a check valve made of alloy.

The present invention for achieving the above object consists of 90% aluminum, 7.4% -8.4% magnesium, 1.2% -1.7% zinc, 0.1% -0.2% copper, 0.2% -0.3% manganese It is made by manufacturing a check valve made of aluminum alloy for valves.

Hereinafter, the present invention will be described in more detail.

The check valve according to the present invention is made of an aluminum alloy containing Zn, Cu, and Mn in a conventional Al-Mg alloy as described above with a change in Mg content of 10%. In order to determine the preferred content of these components, the Applicant performed stress corrosion test while changing the contents of Cu and Mn after fixing Mg to 8% and Zn to 1.5%. It was added slightly and contained some Be to inhibit oxidation during dissolution and casting. The molten metal was heated at 496 ° C for 8 hours, and was generally ejected as chlorine gas when the casting temperature was lowered to 440 ° C. The two-stage solution heat treatment is heated for at least 440 ° C for 8 hours, followed by 8 hours at 496 ° C, and quenching to complete boiling water at 496 ° C. Because the casting is very thick, it can be cooled at 440 ° C before quenching to eliminate the possibility of quench cracking.

Here, the stress corrosion test is continued in the laboratory by applying a load on the tensile specimens corresponding to a stress of about 75% of the tensile force, the specimen is continuously placed in a corrosion solution of 5.3% sodium chloride and 0.3% hydrogen peroxide. . If stress corrosion cracking has not occurred in 14 days, the material is considered to have excellent resistance to stress corrosion cracking. The specimens heated for 30 hours at 100 ° C. after quenching were tested directly.

By the test described above, an aluminum alloy consisting of 90% Al, 7.4%-8.4% Mg, 1.2%-1.7% Zn, 0.1%-0.2% Cu, 0.2%-0.3% Mn Preferred compositions were determined to be 90% Al, 8% Mg, 1.5% Zn, 0.15% Cu, 0.25% Mn.

In the following Table 1, it can be seen that the specimen of the aluminum alloy according to the present invention at full boiling water and room temperature was tolerated for 14 days without defects.

14 day trial Hardening Conventional The present invention Perfect boiling water 1 day No defect Hindered boiling water No defect No defect

Tolerances to minor errors from this composition will be needed for mass production. The limits of Mg of 7.4% to 8.4% and Zn of 1.2% to 1.7% are first set by the results of the stress corrosion test, and the tensile and tensile strength of the aluminum alloy according to the present invention increases with increasing Mg and Zn.

Meanwhile, after fixing Mg to 8% and Zn to 1.5%, the effects of Cu and Mn on tensile properties and stress corrosion within various composition limits are shown in Table 2 below.

Influence of Cu and Mn Cu (%) Mn (%) Tensile strength (psi) Yield Point (psi) % Elongation 14 days stress corrosion 0.01 0.01 52700 28500 24 10 days 0.15 0.01 54100 28500 20 No defect 0.35 0.01 49400 27100 14 2 days 0.15 0.25 56400 29500 10 No defect 0.15 0.50 52900 32200 13 10 days

Here, the addition of 0.15% Cu is important for increasing the resistance to stress corrosion cracking, it can be seen that the improvement in the tensile properties, the addition of 0.25% Mn is effective in the resistance to stress corrosion cracking and tensile properties It helps. On the other hand, excessive increases of Cu and Mn interfere with tensile properties and resistance to stress corrosion, so the limits of 0.1% to 0.2% Cu and 0.2% to 0.3% Mn are adopted.

Mechanical properties of the aluminum alloy according to the composition as described above are as follows.

Tensile strength (psi) Tensile Yield Drag (psi) % Elongation Brinell Hardness (psi) Compression Yield Tension (psi) Shear strength (psi) 55000 28000 18 90 30000 35000

In addition, the physical properties are as follows.

specific heat 2.64 Conductivity (% of international standard Cu) 24 Weight (bl / cuin) 0.095 Thermal Conductivity at 25 ℃ 0.24 Mean coefficient of thermal expansion 68 ~ 212 ℉ 13.4X10e-6 68 ~ 392 ℉ 14.1X10e-6 68 ~ 572 ℉ 14.5X10e-6 Melting Range (℉) 850-1135

Moreover, computer analysis of the aluminum alloy according to the present invention was carried out by the Ansys 5.6 program. The alloy was formed in a pipe shape, and then the stress distribution with respect to internal pressure (10 bar or more) was analyzed. Here, the modulus of elasticity was 73 GPa, the ratio of Poisson was 0.33, and the tensile strength was set to 325 GPa. The maximum and minimum stresses for a given pressure among the analysis results are shown in Table 5 below.

10 (bar) 12 (bar) 15 (bar) 20 (bar) 30 (bar) 50 (bar) Max 4.8 MPa 5.76 MPa 7.21 MPa 9.61 MPa 14.4 MPa 24 MPa Min 0.75 0.9 MPa 1.14 MPa 1.51 MPa 2.27 MPa 3.79 MPa

According to the results of the analysis, it is determined that the aluminum alloy according to the present invention is very suitable for the check valve requiring good ductility, high tensile strength and excellent corrosion resistance.

Now, the production of the check valve of the aluminum alloy according to the present invention will be described, but the production thereof is based on the well-known die casting (die casting), first prepared by the materials according to the composition as described above Melt, shape and heat treatment. Subsequently, it is threaded by CNC and then finished by anodizing. As such, since the die is simply manufactured by screwing and coating after the die casting, the overall manufacturing process may be simplified, and manufacturing cost and manufacturing time may be reduced.

As described above, according to the present invention, by applying an aluminum alloy to the check valve, by reducing the content of Mg and by adding Zn, Mn, Cu, etc. instead of maintaining excellent casting properties or mechanical or physical properties stress corrosion cracking and tensile properties There is a great effect on stabilization of. Therefore, it is very suitable for the check valve requiring good ductility, high tensile strength and excellent corrosion resistance. In addition, the manufacturing process of the check valve is simplified, thereby reducing the manufacturing cost and manufacturing time.

Claims (3)

Aluminum alloy for valves consisting of 90% aluminum, 7.4% to 8.4% magnesium, 1.2% to 1.7% zinc, 0.1% to 0.2% copper and 0.2% to 0.3% manganese. In the check valve, A check valve comprising an aluminum alloy consisting of 90% aluminum, 7.4% to 8.4% magnesium, 1.2% to 1.7% zinc, 0.1% to 0.2% copper and 0.2% to 0.3% manganese. 3. The check valve according to claim 2, wherein the aluminum alloy is manufactured by die casting, followed by CNC threading and anodizing.