JP2013529255A - Aluminum alloy and aluminum alloy casting - Google Patents

Abstract

A metal alloy, more specifically, an aluminum alloy used for electrical, electronic and mechanical parts, and an aluminum alloy casting produced using the aluminum alloy are provided.
An aluminum alloy according to an embodiment of the present invention contains 4 to 13 weight percent silicon, 1 to 5 weight percent copper, 26 to less than 40 weight percent zinc, and the balance aluminum and impurities.
[Selection] Figure 1

Description

[Priority claim]
This application claims the benefit of Korean Patent Application No. 10-2010-0050693, filed with the Korean Intellectual Property Office on May 29, 2010, the disclosure of which is incorporated herein by reference in its entirety. It is.

  The present invention relates to a metal alloy, more specifically, an aluminum alloy used for electrical, electronic and mechanical parts, and an aluminum alloy casting produced using the aluminum alloy.

  In recent years, the need for high strength materials that are more resistant to deformation has increased as electronic products such as notebooks and cell phones have become more complex in terms of their appearance and function. In particular, parts such as brackets that support parts of liquid crystal display (LCD) panels and hinges having thin and complex shapes are made of portable lightweight materials and stainless steel (eg, SUS304). Require strength. However, stainless steel can be formed by compression or casting, but stainless steel is heavy in mass production and precision product shape, and has a specific gravity of 8.00 g / cm3. Thus, there is an increasing need to develop high strength and light alloys.

The present invention is an aluminum alloy that is half the weight of common stainless steel, has a similar strength to stainless steel (eg, SUS304), and is superior to common industrial aluminum even by common die casting methods, and An aluminum alloy casting manufactured using the aluminum alloy is provided. The objects of the present invention are illustrated by way of example, and the scope of the present invention is not limited by these objects.
According to one aspect of the present invention, 4 to 13 wt% silicon (Si); 1 to 5 wt% copper; 26 wt% or more and less than 40 wt% zinc (Zn); and the balance aluminum (Al) And an aluminum alloy containing impurities that cannot be avoided.
According to another aspect of the aluminum alloy, the silicon content is 5 to 10% by weight.
According to another aspect of the aluminum alloy, the silicon content is 5 to 8% by weight. In this case, the copper content is 2 to 5% by weight, and the zinc content is 26 to 35% by weight.
According to yet another aspect of the present invention, 4 to 13 weight percent silicon; 1 to 5 weight percent copper, 26 weight percent or more and less than 40 weight percent zinc; 0.1 weight percent or less strontium (Sr) And an aluminum alloy containing 43 to 69% by weight of aluminum (Al).
According to another aspect of the aluminum alloy, the silicon content is 5 to 10% by weight.
According to another aspect of the aluminum alloy, the silicon content is 5 to 8% by weight. At this time, the copper content is 2 to 5% by weight, and the zinc content is 26 to 35% by weight.
According to another aspect of the aluminum alloy, the content of strontium (Sr) is greater than 0 wt% and not greater than 0.04 wt%.
According to another aspect of the aluminum alloy, the content of strontium (Sr) is greater than 0 wt% and not greater than 0.02 wt%.
According to another aspect of the aluminum alloy, the aluminum alloy further includes titanium (Ti), magnesium (Mg), nickel (Ni), vanadium (V), tin (Sn), iron (Fe), chromium (Cr), One or more atoms selected from the group consisting of zirconium (Zr), scandium (Sc), and manganese (Mn) are contained in total of 3% by weight or less (however, greater than 0).
According to another aspect of the aluminum alloy, an aluminum alloy casting produced using the aluminum alloy is provided.

These and other features and advantages of the present invention will become more apparent from the detailed description of exemplary embodiments thereof with reference to the accompanying drawings. The drawings are as follows:
2 shows tensile test results for an industrial ADC12 aluminum alloy and an aluminum alloy according to aspects of the present invention. The comparative result of the microstructure of an industrial aluminum alloy and the aluminum alloy by the aspect of this invention is shown. The observation result regarding the microstructure of the aluminum alloy by the aspect of this invention is shown. Figure 5 shows another observation regarding the microstructure of an aluminum alloy according to an embodiment of the present invention.

  The invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The present invention, however, may be practiced in many different forms and should not be limited to the embodiments described herein. Rather, these aspects are provided so that this disclosure will convey the concept of the invention completely and thoroughly to those skilled in the art.

  In the embodiment of the present invention, the weight% (wt%) represents the weight that one component occupies in the total weight of one alloy. It may be understood that the boundary value is not included when the weight percent range is greater or less, and is included when simply indicated as equal, greater than, or equal to or less than.

  In the embodiment of the present invention, impurities that cannot be avoided refer to impurities that are unintentionally introduced during the production of an aluminum alloy or into an aluminum casting.

  An aluminum alloy according to an aspect of the present invention can be formed by adding silicon (Si), copper (Cu) and zinc (Zn) to the main component aluminum (Al). The content of aluminum as the main component of the aluminum alloy occupies a balance (remaining) other than the additional atoms. Thus, the aluminum content varies with the content of additional atoms. Aluminum alloys contain unavoidable impurities that are contained in each atom itself or are unintentionally included during the operation of the alloy.

  For example, an aluminum alloy contains 4-13 wt% silicon, 1-5 wt% copper, and 26 wt% to less than 40 wt% zinc, with the balance being the aluminum and unavoidable impurities.

  Silicon is added to increase the fluidity of the molten aluminum and to improve the feed capability during solidification. In the case of an aluminum-silicon alloy (Al-Si alloy), a composite structure having a primary α-aluminum phase and a eutectic silicon phase is formed during casting. The mechanical strength can be remarkably improved when the structure of the eutectic silicon phase is refined by modifying from a needle shape to a specific shape or fiber shape.

  However, the product can be damaged as it is released from the mold during the die casting process, since in some cases the mechanical properties are reduced due to the increased brittleness of the alloy. Therefore, when considering all the above effects, the silicon content according to embodiments of the present invention is 4 to 13% by weight, in particular 5 to 10% by weight, more particularly 5 to 8% by weight. It is limited to the range.

  Copper has a maximum solubility of 5.6% in aluminum at a eutectic temperature of 548 ° C., and exhibits a solid solution strengthening effect when dissolved in aluminum. Copper also reacts with zinc and aluminum to form an Al-Zn-Cu compound when copper is added to aluminum along with zinc. Since the Al—Zn—Cu compound acts as an obstacle to prevent the movement of dislocations during deformation of the alloy or prevents the growth of particles, the compound can contribute to the improvement of the strength of the alloy.

  However, if the copper content is too high, the mechanical properties decrease due to increased brittleness. Also, since copper is heavier than aluminum, it is not effective to reduce the specific gravity of the alloy. More than that, excessive copper content degrades the castability of aluminum. Therefore, in consideration of all the above effects, the copper content in this embodiment can be limited to a range of 1 to 5% by weight, particularly 2 to 5% by weight.

  When 80% by weight of zinc is added to aluminum, it dissolves at 382 ° C., but the solubility of zinc decreases rapidly with decreasing temperature. Thus, in the case of the aluminum alloy according to the invention, 18% by weight of zinc is dissolved in the matrix of the cast aluminum alloy. At this time, undissolved excess zinc reacts with aluminum and copper to form an Al—Zn—Cu compound as described above. Therefore, in order to obtain both the solid solution strengthening effect and the compound forming effect by zinc, it is necessary to add 26% by weight or more of zinc to aluminum.

  However, zinc is a heavier atom than aluminum and is not preferable for making lightweight alloys. When the zinc content is more than 38% by weight, the content of the eutectic structure having a low strength and a high elongation rate is increased as the two-phase eutectoid transformation into a β-phase β ′ phase and an α-phase composite structure proceeds. Since it decreases, the strength decreases. Also, when the zinc content is 40% by weight, eutectic silicon is present in the primary α phase of the aluminum alloy, so the strength can be lowered due to the reduction in the particle size of the aluminum alloy. Therefore, the amount of zinc added can be limited to less than 40% by weight when considering the effects described above.

  An aluminum alloy according to another aspect of the present invention comprises 4-13 wt% silicon (Si), 1-5 wt% copper (Cu), 26 wt% to less than 40 wt% zinc (Zn), 0.1% It may contain wt% strontium (Sr) and 43-69 wt% aluminum (Al).

  For example, when strontium is added in addition, the strength of the aluminum alloy can be improved because strontium refines the crystal structure of the aluminum alloy. That is, in the case of an aluminum alloy containing silicon, a composite structure of a primary α phase and a eutectic Si phase is obtained during casting, and strontium contributes to improving the strength by refining the structure of the eutectic Si phase. Can do.

  However, if the strontium content is high, the mechanical properties can be weakened due to the crystallization of the strontium containing compound. Therefore, when all these effects are taken into account, the content of strontium (Sr) according to this embodiment can be limited to 0.1% by weight or less, in particular from 0% to 0.02% by weight. .

  Also, trace amounts of additional atoms can be added to the aluminum in addition to silicon, copper, zinc, and strontium to improve the strength of the aluminum alloy. Additional atoms include titanium (Ti), magnesium (Mg), nickel (Ni), vanadium (V), tin (Sn), iron (Fe), chromium (Cr), zirconium (Zr), scandium (Sc), And manganese (Mn). The sum of one or more atoms selected from the above additive atoms does not exceed 3% by weight.

  An aluminum alloy casting according to an aspect of the present invention can be manufactured using the aluminum alloy described above. Here, the casting may include a pure casting produced through casting, a product obtained by molding the casting into a predetermined shape, such as an extrusion billet (bullet-shaped molding), a rotating plate, and the like. Examples of pure casting include sand casting, die casting, gravity casting, low pressure casting, squeeze casting, lost wax casting, thixo casting and the like.

  Gravity casting is a method of pouring a molten alloy into a mold by gravity, and low pressure casting is a method of pouring a melt by applying pressure to the surface of the molten alloy using a gas. Thixo casting is a casting performed in a semi-solid state, and is a combination method employing the advantages of general casting and forging.

  The aluminum alloy casting according to this embodiment can be manufactured by any process including forging, and retains workability without appropriate strength and heat treatment. Instead, the aluminum alloy casting can be subjected to a heat treatment step after production depending on its application and its shape.

  From this, examples are provided to more clearly understand the present invention. However, the following examples are provided only for a clearer understanding of the present invention, but are not intended to limit the scope of the present invention.

  Table 1 shows the results of the tensile strength as the mechanical properties of the experimental examples of the present invention, the alloy compositions of the comparative examples, and the alloy compositions.

  High purity aluminum (99.8%) and zinc (99.9%) are used to produce aluminum alloys in accordance with the present invention, and aluminum master alloys to which silicon, copper, and strontium are added are silicon, copper , And strontium, respectively.

  Each alloy atom was melted using an electric resistance furnace, and degassing and ash removal were performed in a degasser before blowing with argon (Ar) gas for 5 minutes.

  In the case of strontium, an aluminum master alloy containing strontium was added, and after holding for a predetermined time, a test piece was manufactured by tapping.

  In each example, the specimen used to measure the mechanical properties was made by die casting. In particular, the rod-shaped tensile strength test piece is cast using an Toyo die casting machine having a clamping force of 1300 KN, and the tensile test is performed two days after casting the test piece in order to reduce fluctuations in mechanical properties. It was broken. Seven or more specimens were used to measure the mechanical properties and the average value was shown as a result.

  The die casting used in this test was performed under conditions of a casting temperature in the range of 963 to 987K and a die temperature range of 463 to 473K. The test piece used for the test is No. 1 in accordance with the KSB0802 standard. It was made as a 14 rod shape proportional specimen.

  Samples were also collected from the center of a tensile test specimen for microstructure observation using an optical microscope. The collected sample was polished with abrasive paper and cloth, washed with alcohol for 20 minutes, and then etched. Also, analysis using a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) was performed to analyze the solubility of zinc in the α-aluminum phase matrix, the type and shape of the eutectic phase formed. .

  Meanwhile, industrial aluminum ADC12 alloy was used as the object to compare the tensile strength of the aluminum alloy according to the example, and FIG. 1 shows the tensile test results of the alloy made according to example 19 and the ADC12 alloy.

  Referring to Table 1, when comparing Example 21 and Comparative Example 1 having the same copper and zinc content, the tensile strength of Example 21 with addition of silicon is comparable to that of Comparative Example 1 without addition of silicon. However, it was 110 MPa large. Therefore, according to an aspect of the present invention, it has been found that in the case of an aluminum alloy, the addition of silicon significantly improves the tensile strength value.

  Also, referring to FIG. 1, the tensile strength of the alloy according to Example 19 of the present invention is excellent that it is 120 MPa higher than the tensile strength of the ADC12 alloy, which is an industrial aluminum alloy having zinc and copper as main components of the alloy atoms. It turns out that a result is obtained.

  Therefore, it can be seen that the aluminum alloy according to the embodiment of the present invention exhibits much better mechanical strength characteristics than a general aluminum alloy.

  The reason why the aluminum alloy according to the embodiment of the present application exhibits superior properties as compared with the ADC 12 is that the alloy structure is refined by adding silicon to aluminum together with zinc and copper.

  After this, for simplicity of description, Al-xZn-ySi-zCu represents an aluminum alloy where x, y and z are each weight percent added to the aluminum of zinc, silicon and copper.

  2 (a), 2 (b) and 2 (c) show SEM observation results respectively obtained from the alloy structures of Al-30Zn, Al-30Zn-6Si-2Cu and Al-40Zn-6Si-2Cu alloys. .

  Referring to FIG. 2A, in the case of an Al-30Zn alloy, it can be understood that the Al—Zn eutectic phase is uniformly distributed at the grain boundaries due to the excess zinc that does not dissolve in the primary α phase.

  In contrast, referring to FIG. 2 (b), the particle size in the Al-30Zn-6Si-2Cu alloy can be significantly reduced to the range of about several μm to 20 μm because the growth of the primary α phase is impeded. Can be understood.

FIG. 3 shows an EDS analysis result of the zinc content (wt%) in each range of the Al-30Zn-6Si-2Cu alloy shown in FIG. 2B together with the table.
As shown in FIG. 3, zinc dissolves up to 18% by weight in the α-aluminum phase (region 1), and zinc is also stable up to 18% by weight around the eutectic silicon phase (region 2). I know it exists. At this time, it is understood that the insoluble excess zinc reacts with aluminum and copper to form an Al—Zn—Cu compound (regions 3 and 4). The Al—Zn—Cu compound contributes to the purification of the particles by preventing the movement of the particles. Therefore, the Al—Zn—Cu compound can contribute to the improvement of the strength of the aluminum alloy, like eutectic silicon.

  However, as shown in FIG. 2C, the eutectic silicon phase is not distributed at the grain boundaries and exists in the primary α-phase. As a result, the particle size increases, and as a result, an increase in strength is expected. Therefore, the zinc content can be adjusted to less than 40% by weight for improving the strength.

The experimental results with the alloy compositions shown in Table 1 are described in more detail below.
Referring to Table 1, Examples 5, 6, 14, 15, 16 and 17 have silicon contents of more than 6 wt% to 8 wt% and copper contents of 2 to 3.5 wt%. A relatively excellent tensile strength in the range of 430 to 445 MPa in terms of zinc content was exhibited.

  Therefore, the aluminum alloy according to the embodiment of the present invention is relatively excellent when the silicon content exceeds 6% by weight compared to when the silicon content is 6% by weight or less, and exhibits stable strength characteristics. Examples 19 to 21 all correspond to an aluminum alloy in which strontium is further added as an additive atom of 0.02 to 0.1 wt% aluminum alloy in addition to silicon, copper and zinc. Examples 19 and 20 increase tensile strength in the range of 20-60 MPa or more when compared to Examples 18 and 2. The significant increase in tensile strength is believed to be due to the purification of the eutectic Si-phase by the addition of strontium.

4 (a) and 4 (b) show an alloy structure of an aluminum alloy obtained by adding 0.04% by weight of strontium to Example 18, which does not contain strontium, and the same silicon, copper, and zinc composition as in Example 18. The SEM observation obtained from is shown.
Comparing the microstructure of the eutectic Si-phase (see arrows) in FIGS. 4 (a) and 4 (b), it is confirmed that a fine eutectic Si-phase is obtained when strontium is added.

  On the other hand, when Examples 19 and 21 were compared, relatively good tensile strength was obtained when the strontium content was 0.02% by weight compared to when the strontium content was 0.1% by weight. It is therefore understood that the strontium content needs to be maintained below 0.1% by weight.

  Aluminum alloys and aluminum alloy castings according to embodiments of the present invention have superior strength compared to general industrial aluminum alloys, and exhibit extremely lightweight characteristics compared to stainless steel. Therefore, the aluminum alloy and the aluminum alloy casting according to the aspect of the present invention can be stably applied to a compact and lightweight product as well as a large product.

  Although the invention has been particularly shown and described with reference to embodiments, various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the following claims. One skilled in the art will appreciate that this is possible.

Claims (14)

4 wt% to 13 wt% silicon (Si);
1 wt% to 5 wt% copper (Cu);
Aluminum alloy consisting of 26 wt% to less than about 40 wt% zinc (Zn); and the balance aluminum (Al) and impurities that cannot be mixed.   The aluminum alloy according to claim 1, wherein the silicon content is 5 wt% to 10 wt%.   The aluminum alloy according to claim 2, wherein the silicon (Si) content is 5 wt% to 8 wt%.   The aluminum alloy according to claim 3, wherein the content of copper (Cu) is 2 wt% to 5 wt%.   The aluminum alloy according to claim 4, wherein the zinc (Zn) content is 26 wt% to 35 wt%. 4 wt% to 13 wt% silicon (Si);
1 wt% to 5 wt% copper (Cu);
26 wt% to less than 40 wt% zinc (Zn);
Up to 0.1% by weight of strontium; and 43% to 69% by weight of aluminum (Al)
An aluminum alloy consisting of   The aluminum alloy according to claim 6, wherein the silicon content is 5% by weight to 10% by weight.   The aluminum alloy according to claim 7, wherein the silicon (Si) content is 5 wt% to 8 wt%.   The aluminum alloy according to claim 8, wherein the content of copper (Cu) is 2 wt% to 5 wt%.   The aluminum alloy according to claim 9, wherein the zinc (Zn) content is 26 wt% to 35 wt%.   The aluminum alloy according to claim 6, wherein the content of strontium (Sr) is 0.04% by weight or less (excluding 0).   The aluminum alloy according to claim 6, wherein the content of strontium (Sr) is 0.02 wt% or less (excluding 0).   Titanium (Ti), magnesium (Mg), nickel (Ni), vanadium (V), tin (Sn), iron (Fe), chromium (Cr), zirconium (Zr), scandium (Sc), and manganese (Mn) The aluminum alloy according to claim 6, comprising one or more atoms selected from the group consisting of 3% by weight or less (greater than 0).   The aluminum alloy casting manufactured using the aluminum alloy in any one of Claims 1-13.