KR20150144593A - High ignition-resistance with high-strength magnesium alloy and method of manufacturing the same - Google Patents

Abstract

The present invention provides a high strength magnesium alloy with excellent ignition resistance and a method for manufacturing the same. The present invention comprises 6-10% by weight of zinc (Zn), 2-6% by weight of aluminum (Al), 0.4-0.7% by weight of manganese (Mn), 0.5-1.5% by weight of calcium (Ca), and magnesium (Mg) and inevitable impurities as the remainder.

Description

TECHNICAL FIELD [0001] The present invention relates to a high-strength magnesium alloy excellent in ignition resistance and a method of manufacturing the same.

The present invention relates to a metal alloy, and more particularly, to a high-strength magnesium alloy excellent in ignition resistance used for parts having high resistance to ignition for the safety of passengers in the event of an accident of an aircraft or a high- And a manufacturing method thereof.

Recently, studies are underway to reduce the weight of transportation equipment such as aircraft and high-speed railway in order to reduce environmental load and energy. Therefore, magnesium alloys have the lowest specific gravity among practical structural materials, excellent non-strength and rigidity, and demand for lightweight materials is increasing.

The study of existing magnesium alloys has focused on cast magnesium alloy for application to parts of automobiles and IT products based on excellent casting of magnesium, but in recent years, magnesium for processing which can be more variously applied to parts where lightness is required, Alloys have been studied more actively.

Particularly, studies on magnesium (Mg) -zinc (Zn) -based high-strength magnesium alloys have been actively carried out. However, existing studies are focused on the development of magnesium alloys having high strength and high elongation or excellent molding characteristics, For this reason, it is difficult to add noble metal such as silver (Ag) which affects the aging behavior or to perform double aging treatment for a long time.

In addition, since alloys developed in the past do not focus on ignition resistance, they are not used as parts of transportation equipment such as aircraft and high-speed railway for which passenger resistance is important for the safety of passengers. Therefore, there is a growing need to develop a magnesium alloy for machining that has excellent ignition resistance and high strength.

United States Patent Application Publication No. 20090068053 (Mar. 12, 2009)

The present invention provides a high strength magnesium alloy having an ignition temperature of about 900 ° C or higher, a non-heat treatment type and a yield strength of about 220 MPa or more and excellent ignition resistance, and a method for manufacturing the magnesium alloy. . However, these problems are illustrative and do not limit the scope of the present invention.

According to an aspect of the present invention, a high strength magnesium alloy having excellent ignition resistance includes 6 to 10 wt% zinc (Zn), 2 wt% to 6 wt% aluminum (Al), 0.4 wt% to 0.7 wt% Manganese (Mn) and 0.5 to 1.5% by weight of calcium (Ca), the balance being magnesium (Mg) and inevitable impurities.

The calcium may be calcium reduced from calcium oxide (CaO) added to the magnesium molten metal to form a matrix of the magnesium alloy.

The calcium is present in the calcium-magnesium (Mg) -Zn (Zn), aluminum (Al) -calcium (Ca) or magnesium (Mg) -calcium (Ca) phase in the base of the magnesium alloy .

A group consisting of titanium (Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc), barium (Ba), yttrium (Y), and rare earth metals And 0.001% by weight to 1.0% by weight of at least one element selected from the group consisting of

The ignition temperature of the magnesium alloy may be 900 DEG C or higher.

According to another aspect of the present invention, there is provided a method of manufacturing a high strength magnesium alloy having excellent ignition resistance, comprising the steps of: 6 to 10% by weight of zinc; 2 to 6% by weight of aluminum; Preparing a cast material from an alloy melt containing manganese (Mn) in an amount of 0.5 to 1.5% by weight and calcium (Ca) in an amount of 0.5 to 1.5% by weight, the balance being magnesium (Mg) and unavoidable impurities; And preparing the cast material as a billet, preheating the billet, and extruding the billet.

(Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc), barium (Ba), yttrium metals may be added in an amount of 0.001 wt% to 1.0 wt%.

Extruding the billet; And subsequently heating the billet to further improve the mechanical properties of the billet after the heat treatment than the billet prior to the heat treatment.

The heat treatment may include at least one of annealing, aging, and double aging.

According to one embodiment of the present invention, as described above, it is possible to provide an ignition resistant material which can be used as a material for manufacturing parts of a transportation device such as an aircraft or a high-speed railway which requires light weight and high ignition resistance and strength, This excellent high strength magnesium alloy and its manufacturing method can be implemented. Of course, the scope of the present invention is not limited by these effects.

FIG. 1 is a process flowchart schematically showing a method of manufacturing a high-strength magnesium alloy having excellent ignition resistance according to an embodiment of the present invention.
2 shows the results of measurement of the ignition temperature of magnesium alloy specimens according to Examples and Comparative Examples of the present invention.
3 shows the results of measurement of mechanical properties of magnesium alloy specimens according to Examples and Comparative Examples of the present invention.
4 is a view showing a microstructure of a magnesium alloy specimen according to Example 4 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, Is provided to fully inform the user. Also, for convenience of explanation, the components may be exaggerated or reduced in size.

FIG. 1 is a process flowchart schematically showing a method of manufacturing a high-strength magnesium alloy having excellent ignition resistance according to an embodiment of the present invention.

Referring to FIG. 1, a method of manufacturing a high strength magnesium alloy having excellent ignition resistance includes a step (S100) of producing a cast material from a magnesium alloy melt, a step (S200) of forming a cast material as a billet, Step S300.

The magnesium alloy melt can be prepared, for example, from about 6 wt.% To 10 wt.% Zinc (Zn), from about 2 wt.% To 6 wt.% Aluminum Al), about 0.4 wt% to 0.7 wt% manganese (Mn), and about 0.5 wt% to 1.5 wt% calcium (Ca), with the balance magnesium (Mg) and inevitable impurities. Here, the impurities may include all of impurities which are inevitably mixed in a small amount during the alloying process or the manufacturing process of the product.

The magnesium alloy molten metal may be at least one selected from the group consisting of titanium (Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc), barium (Ba), yttrium About 0.001 wt% to 1.0 wt% of at least one element selected from the group consisting of rare earth metals may be further added. The cast material may be manufactured from the magnesium alloy melt and the cast material may be homogenized at a predetermined temperature for a predetermined period of time before being made into a billet. The prepared billet can be preheated at a predetermined temperature and then extruded. By further heat treating the billet after extruding the billet, the mechanical properties of the billet after the heat treatment can be further improved than before the heat treatment. At this time, the heat treatment may include at least one of, for example, annealing, aging and double aging.

The reasons for the addition and content of each alloy element are as follows.

Zinc (Zn) is the most effective element to improve strength after magnesium alloy to aluminum. The zirconium (Zr) or rare earth metals together with heat treatment can form a precipitate phase to show an aging strengthening behavior. When zinc is added to the molten magnesium alloy in an amount of less than about 6% by weight, the strength required for the material can not be obtained. When more than about 10% by weight is added, a large amount of equilibrium phase is formed in the grain boundaries, Can be increased.

In addition, during the extrusion of the billet, incipient-melting of the alloy due to a temperature rise occurs, which is not only difficult to apply to processes such as extrusion, and may also deteriorate the mechanical properties of the alloy. Accordingly, in the present invention, the range of zinc addition may be limited to a range of about 6 wt% to 10 wt%, and strictly limited to about 7 wt% to 9 wt%.

Aluminum (Al) is the most representative element of the magnesium alloy, and can improve the strength and hardness of the alloy. However, when aluminum is added to the magnesium alloy melt at less than about 2 wt%, the strength required for the material is not obtained. When the magnesium alloy is added in an amount exceeding about 6 wt%, the crystal grains become coarse Mg ₁₇ Al ₁₂ phase phase may be poured to reduce the strength and fracture strength of the alloy. Therefore, in the present invention, the addition range of aluminum may preferably be limited to a range of about 2 wt% to 6 wt%.

Manganese (Mn) improves the strength and elongation of the alloy and improves the corrosion resistance by refining the precipitated phase of the magnesium-zinc alloy. Generally, manganese should be added in an amount of about 0.3% by weight or more to obtain the above-mentioned effect. When the manganese alloy is added to the magnesium alloy melt in an amount of more than about 1% by weight, the alloy is separated from the magnesium alloy melt due to the difference in specific gravity when an aluminum-manganese phase is formed to prepare the magnesium alloy melt, Making it difficult to manufacture. Therefore, the range of addition of manganese in the present invention may be preferably limited to a range of about 0.4 wt% to 0.7 wt%.

Calcium (Ca) improves the resistance to oxidation and ignition of magnesium alloys and also enhances the oxidation resistance of calcium-magnesium (Mg) -zinc (Zn), aluminum (Al) -calcium (Ca) or magnesium (Mg) Ca), and the like, so that it is effective in improving the strength of the magnesium alloy. If less than about 0.5% by weight of calcium is added to the magnesium alloy melt, the magnesium alloy does not contribute to improving the ignition resistance. If calcium is added in an amount exceeding about 1.5% by weight, the magnesium alloy becomes brittle, . Here, the calcium contained in the high-strength magnesium alloy excellent in ignition resistance according to an embodiment of the present invention may be reduced from calcium oxide added to the magnesium melt to form a matrix of a magnesium alloy.

The calcium oxide added to the magnesium molten metal is applied to the surface of the molten metal in the form of powder and can be reduced to calcium by causing the surface reaction of the molten metal through agitation (surface agitation) of the upper portion of the molten metal. Here, in the surface reaction, the calcium reduced from the calcium oxide is supplied to the alloying element in the magnesium molten metal through the stirring of the calcium oxide applied to the surface of the molten metal, and the oxygen component is released into the atmosphere. It may be important that such a surface reaction is carried out in the atmosphere, rather than under ambient gas.

[Examples and Comparative Examples]

The high strength magnesium alloy having excellent ignition resistance according to one embodiment of the present invention will be described in detail with reference to various examples and comparative examples.

zinc aluminum manganese calcium magnesium Example 1 7.0 2.0 0.5 0.7 Honey. Example 2 7.0 5.0 0.5 0.7 Honey. Example 3 9.0 2.0 0.5 0.7 Honey. Example 4 9.0 5.0 0.5 0.7 Honey. Comparative Example 1 7.0 5.0 - 0.7 Honey. Comparative Example 2 9.0 5.0 0.5 - Honey. Comparative Example 3 9.0 5.0 0.5 0.3 Honey. Comparative Example 4 5.0 2.0 0.5 0.7 Honey. Comparative Example 5 1.0 3.0 0.2 - Honey. Comparative Example 6 6.0 6.0 1.0 - Honey.

Table 1 shows the compositions of the magnesium alloy specimens of various examples and comparative examples. In order to manufacture a high strength magnesium alloy having excellent ignition resistance according to an embodiment of the present invention, a magnesium alloy having the composition shown in Table 1 was melted in a steel crucible using a conventional electric resistance furnace, Billets were prepared using a steel mold preheated to < RTI ID = 0.0 > 200 C < / RTI >

The prepared billet is preheated at about 150 ° C to 300 ° C for about 20 minutes to 2 hours, and then processed such as extrusion, rolling, forging and drawing at the same temperature zone.

Since the magnesium alloy can not ensure workability at room temperature, it is subjected to high temperature processing to obtain a sound processing material. The processing temperature is set within a range in which the soundness of the processing material can be ensured through the experiment. In the extrusion process, . The extruded specimen was processed into a bar-like specimen having a gage length of about 30 mm and a diameter of about 6 mm in the same manner as in No. 14A test specimen of KS B 0801 (metal material tensile test piece), and subjected to a tensile test at room temperature at a speed of about 1 mm / Respectively.

Further, the extruded specimen was processed into a spherical shape of about 20 mg or less so as to prevent abnormal ignition at the corner portion, and the ignition temperature was measured using an SDT Q600 instrument manufactured by TA Instruments. The ignition temperature was measured in an atmosphere in which dry air was flowing at a rate of about 100 ml / min. The analytical temperature range was about 100 ° C to 1100 ° C and the rate of temperature rise was measured at about 10 ° C / min.

Table 2 below shows the measurement results of the mechanical properties and the ignition temperature of the magnesium alloy specimens according to Examples and Comparative Examples.

Yield strength (MPa) Tensile Strength (MPa) Elongation (%) Ignition temperature (℃) Example 1 225 303 15.8 935.3 Example 2 231 310 13.9 941.8 Example 3 246 329 10.4 912.6 Example 4 250 334 8.4 965.0 Comparative Example 1 195 297 13.2 948.2 Comparative Example 2 219 298 14.4 591.4 Comparative Example 3 231 315 11.6 782.7 Comparative Example 4 187 279 18.1 947.8 Comparative Example 5 200 225 12 590.3 Comparative Example 6 225 359 26 596.7

FIG. 2 shows the results of measurement of the ignition temperature of the magnesium alloy specimens according to Examples and Comparative Examples of the present invention, and FIG. 3 shows the results of measurement of mechanical properties of the magnesium alloy specimens according to Examples and Comparative Examples of the present invention.

Referring to Table 2, FIG. 2 and FIG. 3, it can be seen that the magnesium alloy specimen according to the embodiments of the present invention has excellent ignition resistance and mechanical properties. That is, the magnesium alloy specimen according to Examples 1 to 4 had a room-temperature yield strength of about 225 MPa or more and an ignition temperature of about 910 ° C or more.

On the other hand, Comparative Example 1 is a magnesium alloy specimen in which no manganese alloy component is present, Comparative Example 2 is a magnesium alloy specimen in which no calcium component is present, and Comparative Example 3 is a comparatively small amount It is a magnesium alloy specimen to which calcium oxide is added. Comparative Example 5 is a commercially available magnesium alloy specimen in which no calcium component is present, and Comparative Example 6 is a magnesium alloy specimen having a relatively large content of manganese as compared with Examples.

The magnesium alloy specimens according to the examples and the magnesium alloy specimens according to the comparative example 1 and the comparative example 4 were compared with each other in the case of the magnesium alloy specimens of the comparative example 1 and the comparative example 4 and the ignition temperature But the yield strength is less than about 220 MPa.

Comparative Example 2 and Comparative Example 3, which are magnesium alloy specimens having no calcium component or having a smaller composition than those of the Examples, are satisfactory in yield strength but have an ignition temperature of less than about 900 占 폚, It can be seen that the ignition temperature required for the material is not satisfied.

The ignition temperature of Comparative Example 5 and Comparative Example 6, which are magnesium alloy specimens having no calcium alloy component, is less than about 600 ° C., and ignition occurs near the melting temperature of a general magnesium alloy.

4 is a view showing a microstructure of a magnesium alloy specimen according to Example 4 of the present invention.

Referring to FIG. 4, the microstructure of the magnesium alloy specimen according to Example 4 of the present invention is shown in which the second phases are distributed parallel to the extrusion direction, and the grain size of the magnesium alloy specimen is about 10 μm or less Is formed. Therefore, the magnesium alloy specimen according to Example 4 has the highest yield strength due to the strengthening effect due to the fine grain size and the strengthening effect of the second phases.

As described above, in the present invention, about 6 to 10 wt% of zinc (Zn), about 2 to 6 wt% of aluminum (Al), about 0.4 to 0.7 wt% of manganese (Mn) A magnesium alloy and a magnesium alloy extruded material containing 0.5 to 1.5% by weight of calcium (Ca), the balance being magnesium (Mg) and unavoidable impurities, can be produced.

Further, in the present invention, in adding calcium to the magnesium alloy melt, calcium oxide (CaO) is added to the magnesium melt to produce a high strength magnesium alloy having excellent ignition resistance, characterized in that the calcium is reduced from calcium oxide have.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (9)

(Al), 0.4 wt% to 0.7 wt% manganese (Mn), and 0.5 wt% to 1.5 wt% calcium (Ca (Ca) ), And the balance being magnesium (Mg) and unavoidable impurities. The method according to claim 1,
Wherein the calcium is calcium reduced from calcium oxide (CaO) added to a magnesium molten metal for forming a matrix of the magnesium alloy, wherein the magnesium is a high strength magnesium alloy excellent in ignition resistance. 3. The method of claim 2,
The calcium is present in the base of the magnesium alloy in the form of calcium (Ca) -magnesium (Mg) -zinc (Zn), aluminum (Al) -calcium (Ca) or magnesium (Mg) High-strength magnesium alloy excellent in ignition resistance. The method according to claim 1,
A group consisting of titanium (Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc), barium (Ba), yttrium (Y), and rare earth metals , Further comprising 0.001 wt% to 1.0 wt% of at least one element selected from the group consisting of magnesium, magnesium, and magnesium. 5. The method according to any one of claims 1 to 4,
Wherein the magnesium alloy has an ignition temperature of 900 DEG C or higher and is excellent in ignition resistance. (Al), 0.4 wt% to 0.7 wt% manganese (Mn), and 0.5 wt% to 1.5 wt% calcium (Ca (Ca) ), The balance being magnesium (Mg) and inevitable impurities; And
And a step of preparing the cast material as a billet, preheating the billet, and then extruding the cast billet, wherein the high strength magnesium alloy is excellent in ignition resistance. The method according to claim 6,
In the molten alloy,
A group consisting of titanium (Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc), barium (Ba), yttrium (Y), and rare earth metals By weight of at least one element selected from the group consisting of titanium, titanium and zirconium. The method according to claim 6,
Extruding the billet; Further comprising the step of heat treating the billet to further improve the mechanical properties of the billet after the heat treatment than the billet prior to the heat treatment. 9. The method of claim 8,
Wherein the heat treatment includes at least one of annealing, aging, and double aging, wherein the high strength magnesium alloy is excellent in ignition resistance.

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