WO2018159890A1 - Grain-oriented zinc-aluminum alloy and manufacturing method therefor - Google Patents

Abstract

A zinc-aluminum alloy according to the present invention is manufactured by a method comprising the steps of: obtaining a zinc-aluminum mother alloy through casting; and remelting the zinc-aluminum master alloy and unidirectionally solidifying the remolten master alloy at a unidirectional growth rate of 1 to 500 μm/sec in a molten metal at 450 to 700°C to grow the mother alloy such that the texture thereof has an orientation, whereby grains of the zinc-aluminum alloy have an average aspect ratio of 3 to 12. According to the present invention, grains and precipitates obtain an orientation by unidirectional solidification or continuous casting, and mechanical properties such as hardness, tensile strength, and elongation are thus improved. Further, the addition of copper makes such an effect more superior. Particularly, there is a great significance in that tensile strength and ductility which have properties opposite to each other and are thus hardly improved at the same time are enhanced together.

Description

Zinc-Aluminum Alloy with Aromatic Grain and its Manufacturing Method

The present invention relates to a zinc-aluminum alloy and a method for manufacturing the same, and more particularly, to a zinc-zinc aluminum alloy having a directional crystal grain by unidirectional solidification to continuous casting method and a method for producing the same.

Zinc-aluminum alloy is a low-cost, low-melting die-cast alloy, and is mainly used as a compact structural material in the electronics industry, transportation industry and construction industry. However, its use is limited because it is relatively low in strength and brittle fracture easily occurs compared to other structural materials.

Therefore, it is very important to improve the mechanical strength and ductility (machinability) of the zinc-aluminum alloy, but the mechanical strength and ductility of the metal material have mutually opposite characteristics, so it is very difficult to improve them simultaneously.

For this reason, many studies have been conducted to simultaneously improve mechanical strength and ductility of zinc-aluminum alloys through methods such as alloy design and process improvement.

Conventionally, since the zinc-aluminum alloy was manufactured by a general die casting method, the above limitations were not exceeded. Such a zinc-aluminum die-cast alloy has been disclosed in Korean Patent Registration No. 10-0961081 (Jun. 10, 2010).

<Preceding technical literature>

Republic of Korea Patent No. 10-0961081 (Jun. 2010)

Accordingly, an object of the present invention is to provide a zinc-aluminum alloy in which mechanical properties such as hardness, tensile strength, and ductility are improved by having the grains directional through unidirectional solidification or continuous casting, and a method of manufacturing the same. .

The zinc-aluminum alloy which concerns on this invention for achieving the said subject is characterized by having a directional crystal grain.

It is preferable that the average aspect ratio of the said crystal grain is 3-12.

The zinc-aluminum alloy according to the present invention preferably contains 3 to 5 wt% aluminum and 2 to 5 wt% copper based on the total weight.

Zinc-aluminum alloy according to the present invention has the characteristics of hardness 60 ~ 150 Hv, tensile strength 240 ~ 400 MPa, elongation 5 ~ 45%.

The zinc-aluminum alloy according to the present invention is characterized in that the aromatic grains are obtained by unidirectional solidification or continuous casting.

The one-way solidification is preferably made of a one-way growth rate of 1 ~ 500㎛ / sec in the molten 450 ~ 700 ℃.

The zinc-aluminum alloy according to the present invention may be further processed into a plate, a wire, or a bar after solidifying into a rod shape by the unidirectional solidification.

Zinc-aluminum alloy manufacturing method according to the present invention for achieving the above object,

Obtaining a zinc-aluminum mother alloy through a casting method; And

Re-dissolving the zinc-aluminum mother alloy to solidify in one direction at a one-way growth rate of 1 ~ 500㎛ / sec in the molten metal at 450 ~ 700 ℃ to grow the tissue to have a directional; including, the average aspect ratio of the crystal grain is 3 ~ It is characterized by 12.

The molten metal is preferably placed under an inert gas atmosphere.

According to the present invention, the grains and precipitates are directional by unidirectional solidification or continuous casting, thereby improving mechanical properties such as hardness, tensile strength, and elongation. The addition of copper makes this effect even better.

In particular, it has great significance in that both tensile strength and ductility which are difficult to improve at the same time are improved together.

In addition, the tensile strength and elongation are further improved when the zinc-aluminum alloy having directional grains is further processed according to the present invention, compared to the case in which the general cast zinc-aluminum alloy is additionally processed into various forms such as wire, plate, and bar. do.

1 is a view for explaining the one-way solidification equipment 1 used for one-way solidification of the present invention;

2 is a microstructure photograph of a zinc-aluminum alloy prepared by general casting;

3 is a microstructure photograph of a unidirectional solidified zinc-aluminum alloy according to the present invention;

Figure 4 is a graph of the mechanical properties of the case of further processing the unidirectional solidified rod-shaped zinc-aluminum alloy.

<Description of the code>

1: one-way solidification equipment 10: furnace

20: alumina tube 30: alumina pipe

40: heating element 50: cooling part

51: coolant 60: support bar

80: gas injection unit 90: Shanghai conveying apparatus

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. The following examples are only presented to understand the content of the present invention, and those skilled in the art will be capable of many modifications within the technical spirit of the present invention. Therefore, the scope of the present invention should not be construed as limited to these embodiments.

Preparation of Zinc-Aluminum Alloy 100 Having Aromatic Grain

1. General casting

Zinc-aluminum alloys 1 to 7 are weighed according to the composition, and cast by 3 kg using a high frequency induction melting furnace. The ingot is then processed into rods 100 mm long and 4.7 mm in diameter. Component contents of the zinc-aluminum alloys 1 to 7 are shown in Table 1 below.

division Component and content (wt%) Zn Al Cu Mg Fe Alloy 1 95 5 - - - Alloy 2 94.9 5 0.1 - - Alloy 3 93 5 2 Alloy 4 92 3 5 Alloy 5 92.89 5 2 0.01 0.1 Alloy 6 92.9 5 2 0.05 0.05 Alloy 7 92.89 5 2 0.1 0.01

2. One-way solidification

One-way solidification equipment 1, as shown in Figure 1, is installed so that the furnace 10 can be moved up and down by the shanghai conveying apparatus (90). An alumina pipe 30 is installed in the center portion of the furnace 10, and a heat generator 40 is installed around the outer side of the alumina pipe 30 so as to heat the alumina pipe 30. The lower part of the alumina pipe 30 is provided with a cooling unit 50 through which the cooling water 51 flows.

The alumina tube 20 is fitted in the alumina pipe 30. The alumina tube 20 has an outer diameter of 8 mm, an inner diameter of 5 mm, and a length of 700 mm, and a hem is blocked. The gas injection unit 80 is installed at the upper end of the alumina tube 20 so that the inside of the alumina tube 20 can be maintained in an inert gas atmosphere such as argon (Ar). A support bar 60 is installed at the bottom of the alumina tube 20.

The one-way coagulation process is described as follows.

First, the bottom end of the alumina tube 20 is sealed and the support bar 60 is charged to the bottom side of the alumina tube 20. Then, the bar material (zinc-aluminum master alloy) manufactured through the general casting as described above is alumina tube. It charges in (20).

Next, after the alumina tube 20 is fixed to the gas inlet 80, the alumina tube 20 thus fixed is charged into the alumina pipe 30 inside the furnace 10.

Subsequently, the alumina tube 20 is heated through the heating element 40 to re-dissolve the bar (zinc-aluminum master alloy) to form the molten metal 70, and then, while the alumina tube 20 is still, the Shanghai conveying apparatus The furnace 10 is moved upward in one direction through the 90. In this process, the unidirectional solidification zinc-aluminum alloy 100 is obtained by unidirectional solidification in this process.

At this time, in order to prevent oxidation of the molten metal 70, the inside of the alumina tube 20 is preferably in an inert gas atmosphere, and in order to make the average aspect ratio of the crystal grains about 3-12, the molten metal 70 having a temperature of 450 to 700 ° C. It is desirable to achieve one-way solidification at a speed of 1 ~ 500㎛ / sec.

The one-way solidified zinc-aluminum alloy 100 was grown to 60 mm at the initial position, and then cooled by water to obtain a rod shape.

Measurement of Mechanical Properties of Unidirectional Solidified Zinc-Aluminum Alloy (100)

 Table 2 below shows the hardness measurement results for the zinc-aluminum alloy prepared by general casting and the unidirectional solidified zinc-aluminum alloy 100 according to the present invention. Hardness measurement was performed under the conditions of 100 gf load and 10 seconds load application time.

division Hardness (Hv) Hardness increase after unidirectional solidification After normal casting After one-way solidification Alloy 1 65.5 75.9 + 10.4 Alloy 2 86.2 88.5 + 2.3 Alloy 3 94.5 99.1 + 4.6 Alloy 4 126.6 127.7 + 1.1 Alloy 5 107.3 110.6 + 3.3 Alloy 6 110.8 113.1 + 2.3 Alloy 7 105.0 106.3 + 1.3

Table 3 below shows the tensile strength measurement results for the zinc-aluminum alloy prepared by the general casting and the unidirectional solidified zinc-aluminum alloy 100 according to the present invention.

division Tensile Strength (MPa) Tensile strength increase after unidirectional solidification After normal casting After one-way solidification Alloy 1 170.97 270.02 + 99.05 Alloy 3 214.40 330.20 + 115.8

Table 4 below shows the elongation measurement results for the zinc-aluminum alloy prepared by general casting and the unidirectional solidified zinc-aluminum alloy 100 according to the present invention. Evaluation of tensile properties, such as tensile strength and elongation, was made under conditions of a tensile rate of 2 mm / min.

division Elongation (%) Tensile strength increase after unidirectional solidification After normal casting After one-way solidification Alloy 1 0.88 1.57 + 0.69 Alloy 3 1.16 5.94 + 4.78

Looking at the above Table 2 to Table 4, it can be seen that the hardness, tensile strength, elongation are all improved after the one-way solidification compared to the general casting. As mentioned above, although the tensile strength and ductility have characteristics opposite to each other, it is difficult to improve them at the same time, but in the case of the present invention, they have great significance in that they can obtain the effect of improving them simultaneously.

The tensile properties of Table 3 and Table 4 show that the tensile strength and elongation of Alloy 3 are better than that of Alloy 1. However, when copper is added to the zinc-aluminum alloy, the grain boundary of the zinc-aluminum substrate is increased. A fine particle ε phase composed of a Zn-Cu solid solution is precipitated, thereby improving tensile strength and elongation characteristics.

Microstructure of Unidirectional Solidified Zinc-Aluminum Alloy (100)

2 is a microstructure photograph of a zinc-aluminum alloy prepared by general casting, and FIG. 3 is a microstructure photograph of a unidirectional solidified zinc-aluminum alloy 100 according to the present invention.

Table 5 below summarizes the average grain aspect ratios measured based on these images. At this time, the size of the analyzed image was 1150 μm in width and 850 μm in length.

division Average grain aspect ratio Alloy 1 Alloy 2 Alloy 3 Alloy 4 Alloy 5 Alloy 6 Alloy 7 After normal casting 1.10 1.33 1.16 2.08 1.16 1.30 1.01 After one-way solidification 6.35 9.43 3.65 5.51 6.30 11.82 8.85

As can be seen in Table 5, the grain aspect ratio after one-way solidification is at least 3.65, which is higher than that of the general casting.

Since unidirectional solidification is a method of solidifying the material continuously, the solidified tissue becomes directional when the flow of heat proceeds from the liquid phase to the solid phase. When solidifying in one direction as in the present invention, grains and precipitates of the alloy are arranged in one direction as described above, so that tensile strength and elongation characteristics are improved.

Continuous casting also has the direction of organization in the same principle as one-way solidification, so one-way solidification and continuous casting are the same context.

Additional molding of unidirectional solidified zinc-aluminum alloy (100)

As described above, the zinc-aluminum alloy 100 solidified in one direction in the rod shape may be reprocessed in various forms such as wire, plate, and bar through additional processing.

Table 6 below is a result of measuring the mechanical properties when the general casting and unidirectional solidified rod-shaped alloy 3 drawing 30%, 50%, 80%, Figure 4 is a graph illustrating this.

Alloy 3 Cross Section Reduction Rate 0% 30% 50% 80% Casting method General casting Unidirectional coagulation Increase after unidirectional solidification General casting Unidirectional coagulation Increase after unidirectional solidification General casting Unidirectional coagulation Increase after unidirectional solidification General casting Unidirectional coagulation Increase after unidirectional solidification Hardness (Hv) 65.5 94.5 +29 120.7 112.5 -8.2 92.3 91.9 -0.4 68.5 65.3 -3.2 Tensile Strength (Mpa) 214.4 330.2 +116 340.0 351.7 +11.7 251.4 347.1 +95.7 177.0 246.4 +69.4 Elongation (%) 1.16 5.94 +4.78 2.12 25.2 +23.1 9.74 12.32 +2.58 2.58 42.86 +40.3

As can be seen in Figures 4 and 6 it can be seen that the tensile strength and elongation is more improved when the one-way solidified zinc-aluminum alloy 100 is additionally formed compared to the case of additionally forming a general cast zinc-aluminum alloy. have.

According to the present invention, the grains and precipitates are directional by unidirectional solidification or continuous casting, thereby improving mechanical properties such as hardness, tensile strength, and elongation. The addition of copper makes this effect even better.

In particular, it has great significance in that both tensile strength and ductility which are difficult to improve at the same time are improved together.

In addition, the tensile strength and elongation are further improved when the zinc-aluminum alloy having directional grains is further processed according to the present invention, compared to the case in which the general cast zinc-aluminum alloy is additionally processed into various forms such as wire, plate, and bar. do.

Claims (10)

Zinc-aluminum alloy, characterized in that it has an aromatic grain. The zinc-aluminum alloy according to claim 1, wherein the average aspect ratio of the crystal grains is 3 to 12. The zinc-aluminum alloy of claim 1, wherein 3 to 5 wt% of aluminum and 2 to 5 wt% of copper are included with respect to the total weight. The zinc-aluminum alloy according to claim 1, wherein the hardness is 60 to 150 Hv and the tensile strength is 240 to 400 MPa. The zinc-aluminum alloy of Claim 1 whose elongation is 5 to 45%. The zinc-aluminum alloy according to claim 1, wherein the oriented grains are obtained by unidirectional solidification or continuous casting. The zinc-aluminum alloy according to claim 6, wherein the one-way solidification is performed at a unidirectional growth rate of 1 to 500 µm / sec in a molten metal of 450 to 700 ° C. The zinc-aluminum alloy according to claim 7, wherein the zinc-aluminum alloy is obtained by further solidifying into a rod, a wire, or a rod after solidifying into a rod by the unidirectional solidification. Obtaining a zinc-aluminum mother alloy through a casting method; And Re-dissolving the zinc-aluminum mother alloy to solidify in one direction at a one-way growth rate of 1 ~ 500㎛ / sec in the molten metal at 450 ~ 700 ℃ to grow the structure to have a directional; including, the average aspect ratio of the crystal grains 3 ~ The zinc-aluminum alloy manufacturing method characterized by obtaining the zinc-aluminum alloy which is 12. 10. The method of claim 9, wherein the molten metal is placed under an inert gas atmosphere.

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