High-toughness wrought magnesium alloy and method for producing same

Abstract

The application belongs to the technical field of non-ferrous metal materials, and more particularly relates to a high-strength and high-toughness wrought magnesium alloy and a preparation method thereof. The high-strength and high-toughness wrought magnesium alloy comprises, by mass percentage, Mg 92.15-93.2%, Zn 5.8-6.3%, Zr 0.6-0.9%, Y 0.4-0.6%, and inevitable impurities. The high-strength and high-toughness wrought magnesium alloy is prepared by adding RJ-5 flux for smelting, casting to obtain a magnesium alloy cast rod, and then performing homogenization treatment, followed by water cooling to room temperature, and then sequentially performing hot extrusion and heat treatment, and cooling. The high-strength and high-toughness wrought magnesium alloy rod and plate material obtained has a tensile strength of 340 MPa, a yield strength of 300 MPa, and an elongation of 13% at room temperature. The high-strength and high-toughness wrought magnesium alloy pipe material has a tensile strength of 310 MPa, a yield strength of 260 MPa, and an elongation of 9% at room temperature, and has a wide application prospect in the field of aerospace and military industry.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of non-ferrous metal materials, and more particularly to a high-strength and high-toughness deformed magnesium alloy and a preparation method thereof. BACKGROUND

[0002] Magnesium alloy is a relatively light structural metal in industrial applications, and the density of pure magnesium is 1.74 g·cm -3 , which is 2 / 3 of aluminum and 1 / 4 of steel. Magnesium alloy has high specific stiffness, good thermal and electrical conductivity, damping vibration, electromagnetic shielding, easy processing and forming, and easy recycling, and has more and more important application value and broad application prospect in the fields of automobiles, 3C products, aerospace, national defense and military industry.

[0003] However, due to the poor mechanical properties of the magnesium alloy at present, the problems of not being able to simultaneously consider strength and toughness to some extent limit the development of industrial application. In view of the above problems, domestic and foreign researchers often control the microstructure of magnesium alloy by alloying, plastic deformation and heat treatment to prepare magnesium alloy materials with excellent high strength and toughness. Although a certain strengthening and toughening effect is obtained, it is very important to further improve the high strength and toughness of magnesium alloy to meet the needs of multiple fields. SUMMARY

[0004] The purpose of the present application is to provide a high-strength and high-toughness deformed magnesium alloy and a preparation method thereof. By controlling the types and contents of alloying elements and combining the method of hot extrusion, the problems existing in the prior art are solved, the preparation of high-strength and high-toughness magnesium alloy material is realized, and it has significant significance for widening the application of magnesium alloy material.

[0005] To achieve the above purpose, the present application provides the following scheme:

[0006] One of the technical schemes of the present application: a high-strength and high-toughness deformed magnesium alloy is provided, and the components include, by mass percentage:

[0007] Mg 92.15-93.2%, Zn 5.8-6.3%, Zr 0.6-0.9%, Y 0.4-0.6%, and inevitable impurities.

[0008] Optionally, the high-strength and high-toughness deformed magnesium alloy includes, by mass percentage: Zn 6%, Zr 0.75%, and Y 0.6%, and the balance is Mg and inevitable impurities.

[0009] Optionally, the high-strength and high-toughness deformed magnesium alloy includes, by mass percentage: Zn 6.3%, Zr 0.8%, and Y 0.4%, and the balance is Mg and inevitable impurities.

[0010] Optionally, the high-toughness wrought magnesium alloy comprises, by mass percentage, Zn 6.4%, Zr 0.9%, and Y 0.5%, with the balance being Mg and unavoidable impurities.

[0011] The second aspect of the present application provides a preparation method of the high-toughness wrought magnesium alloy, comprising the following steps:

[0012] According to the component ratio of the high-toughness wrought magnesium alloy, pure magnesium, pure zinc, magnesium-zirconium intermediate alloy, and magnesium-yttrium intermediate alloy are weighed, and RJ-5 flux is added for smelting, so as to obtain a magnesium alloy cast rod after casting.

[0013] The magnesium alloy cast rod is subjected to homogenization treatment, and then is water-cooled to room temperature to obtain a homogenized magnesium alloy cast rod.

[0014] After the homogenized magnesium alloy cast rod is subjected to hot extrusion, it is subjected to heat treatment, and then is cooled to obtain the high-toughness wrought magnesium alloy.

[0015] Further, the amount of the RJ-5 flux is 7% of the mass of the pure magnesium.

[0016] Further, the smelting temperature is 690-710℃, and the temperature rising rate is 120℃ / h.

[0017] Further, the homogenization treatment temperature is 415-425℃, the time is 14h, and the temperature rising rate is 200℃ / h.

[0018] The homogenization treatment can improve the segregation problem in the cast rod, improve the hot extrusion performance of the material, and make the low-temperature phase in the cast rod dissolve in the matrix, so as to play the effect of precipitation strengthening in the subsequent heat treatment process.

[0019] Further, the mold for hot extrusion needs to be preheated to 450-460℃, and the temperature of the homogenized magnesium alloy product during hot extrusion is 390-410℃.

[0020] Further, the extrusion ratio of the hot extrusion is 13-41:1, and the extrusion speed is 0.4-0.7mm / s.

[0021] After hot extrusion, a magnesium alloy rod, a magnesium alloy plate, or a magnesium alloy pipe can be obtained.

[0022] Optionally, when the magnesium alloy rod is obtained after hot extrusion, the extrusion ratio of the hot extrusion is 13.98:1, and the extrusion speed is 0.7mm / s.

[0023] Optionally, when the magnesium alloy plate is obtained after hot extrusion, the extrusion ratio of the hot extrusion is 13.03:1, and the extrusion speed is 0.7mm / s.

[0024] Optionally, when the magnesium alloy pipe is obtained after hot extrusion, the extrusion ratio of the hot extrusion is 40.23:1, and the extrusion speed is 0.4 mm / s.

[0025] The hot extrusion treatment can improve the crystal organization of the casting rod, refine the grains, and also improve the defects such as porosity and pores in the casting rod, and form the required profile through the extrusion die.

[0026] Further, the temperature of the heat treatment is 190 DEG C, and the time is 16 h.

[0027] The heat treatment can precipitate the second phase in the material, and the second phase can hinder the dislocation movement in the process of material deformation, and play a strengthening role.

[0028] The third technical scheme of the present application provides the application of the high-toughness deformed magnesium alloy in aerospace and military industry.

[0029] The present application discloses the following technical effects:

[0030] The high-toughness deformed magnesium alloy rod and plate of the present application can reach 340 MPa of tensile strength, 300 MPa of yield strength and 13% of elongation at room temperature, and the high-toughness deformed magnesium alloy pipe of the present application can reach 310 MPa of tensile strength, 260 MPa of yield strength and 9% of elongation at room temperature, and has wide application prospect in the field of aerospace and military industry.

[0031] The present application effectively refines the grains in the magnesium alloy matrix organization by regulating the types and contents of alloying elements, and combines the hot extrusion and heat treatment after extrusion, increases the number of magnesium alloy grain boundaries and hinders the slip of dislocation, and further makes the magnesium alloy matrix organization more dense through the hot extrusion process, and finally obtains a high-toughness magnesium alloy material.

[0032] The method of the present application is simple in process, high in production efficiency, and can realize industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0033] The drawings constituting a part of the present application are used to provide further understanding of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.

[0034] Figure 1 It is a process flow diagram for preparing the high-toughness deformed magnesium alloy;

[0035] Figure 2 It is the metallographic organization diagram of the magnesium alloy casting rod before and after homogenization treatment, wherein (a) is before homogenization treatment, and (b) is after homogenization treatment;

[0036] Figure 3TD-ND plane metallographic structure diagram of the magnesium alloy rod, plate and pipe to be heat treated prepared by hot extrusion of Example 1, wherein (a) is the rod, (b) is the plate, and (c) is the pipe;

[0037] Figure 4 TD-ND plane metallographic structure diagram of the high strength and toughness deformed magnesium alloy rod, plate and pipe prepared by Example 1, wherein (a) is the rod, (b) is the plate, and (c) is the pipe. DETAILED DESCRIPTION

[0038] The various illustrative embodiments of the present application will now be described in detail in connection with the accompanying drawings. This description is made for the purpose of demonstrating certain aspects of the present application and is not intended to limit the present application in any manner. Those skilled in the art will recognize that there are numerous variations of the illustrative embodiments described herein that are encompassed by the present application.

[0039] It should be understood that the terms used herein are merely descriptive, but are not intended to limit the present application. In addition, for the numerical ranges in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intermediate value in the stated range, is also encompassed within the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict, the present specification will control.

[0041] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application.

[0042] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional, unrecited elements or method steps.

[0043] The purity of the pure magnesium (magnesium ingot) used in the specific embodiments of the present application is 99.99%; the purity of the pure zinc (zinc ingot) is 99.99%; the mass fraction of zirconium in the magnesium-zirconium intermediate alloy is 30%; and the mass fraction of yttrium in the magnesium-yttrium intermediate alloy is 30%.

[0044] The alloying efficiency of pure zinc used in the embodiment of the present application is 100%, the alloying efficiency of magnesium-zirconium intermediate alloy is 40%, and the alloying efficiency of magnesium-yttrium intermediate alloy is 95%.

[0045] Unless otherwise specified, "room temperature" and "normal temperature" in the embodiment of the present application refer to 20-30°C.

[0046] Figure 1 A process flow diagram for preparing the high-strength and high-toughness wrought magnesium alloy.

[0047] Example 1

[0048] The preparation steps of the high-strength and high-toughness wrought magnesium alloy include:

[0049] S1. Prepare magnesium ingots, zinc ingots, magnesium-zirconium intermediate alloy, and magnesium-yttrium intermediate alloy according to the ratio of Mg-6Zn-0.75Zr-0.6Y, and RJ-5 flux with a mass of 7% of the magnesium ingots, for standby;

[0050] S2. Mix the magnesium ingots and RJ-5 flux with a mass of 6.5% of the magnesium ingots, and heat to 710°C for stirring and melting. After the magnesium ingots are completely melted, add zinc ingots, magnesium-zirconium intermediate alloy, magnesium-yttrium intermediate alloy, and RJ-5 flux with a mass of 0.5% of the magnesium ingots, and hold for 15 min for smelting. After the holding is completed, introduce argon for 10 min for refining treatment. After the refining is completed, hold for 10 min, and then cast into a cast bar;

[0051] S3. Put the magnesium alloy cast bar into an induction resistance furnace and heat to 420°C, and hold for 14 h. After the holding is completed, water cool to room temperature to obtain a homogenized magnesium alloy cast bar;

[0052] S4. Put the homogenized magnesium alloy cast bar into a resistance furnace and heat to 400°C, and preheat the mold to 460°C for hot extrusion;

[0053] The extrusion ratio of the bar mold is 13.98:1, the extrusion speed is 0.7 mm / s; the extrusion ratio of the plate mold is 13.03:1, the extrusion speed is 0.7 mm / s; and the extrusion ratio of the tube mold is 40.23:1, the extrusion speed is 0.4 mm / s.

[0054] S5. Heat treat the extruded bar, plate, and tube in a heat treatment furnace, the heat treatment process is heating to 190°C, holding for 16 h, and naturally cooling to room temperature to obtain the Mg-6Zn-0.75Zr-0.6Y high-strength and high-toughness wrought magnesium alloy bar, plate, and tube.

[0055] Examples 2-3 and Comparative Examples 1-9

[0056] Compared with Example 1, the difference is that the proportion of alloying elements is different, as shown in Table 1.

[0057] Table 1

[0058] Element % by weight / wt. % Mg Zn Zr Y Example 2 Balance 6.3 0.8 0.4 Example 3 Balance 6.4 0.9 0.5 Comparative Example 1 Balance 6 0.75 -- Comparative Example 2 Balance 6 -- 0.5 Comparative Example 3 Balance -- 0.75 0.5 Comparative Example 4 Balance 6.5 0.75 0.5 Comparative Example 5 Balance 5.6 0.75 0.5 Comparative Example 6 Balance 6 1.0 0.5 Comparative Example 7 Balance 6 0.5 0.5 Comparative Example 8 Balance 6 0.75 0.75 Comparative Example 9 Balance 6 0.75 0.35

[0059] Comparative Example 10

[0060] Compared with Example 1, the difference is that after the hot extrusion is completed, it is directly cooled without subsequent heat treatment.

[0061] Test Example

[0062] The mechanical properties of the high-toughness wrought magnesium alloy rod, rod and pipe prepared in Examples 1-3 and Comparative Examples 1-10 are measured, wherein the rod is shown in Table 2, the plate is shown in Table 3, and the pipe is shown in Table 4.

[0063] Table 2 Mechanical properties of the rod

[0064] Sample Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 352 308 13.5 Example 2 350 303 13.2 Example 3 345 301 13.3 Comparative Example 1 332 280 10 Comparative Example 2 320 278 8.2 Comparative Example 3 280 200 9.1 Comparative Example 4 360 320 10.3 Comparative Example 5 338 288 14.2 Comparative Example 6 348 295 15.1 Comparative Example 7 320 290 15.2 Comparative Example 8 355 310 9.8 Comparative Example 9 345 278 11.9 Comparative Example 10 302 242 14.8

[0065] Table 3 Mechanical properties of the plate

[0066]

[0067]

[0068] Table 4 Mechanical properties of the pipe

[0069] Sample Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 315 264 9.9 Example 2 313 260 9.4 Example 3 312 262 10.0 Comparative Example 1 313 252 8.8 Comparative Example 2 310 236 6.9 Comparative Example 3 268 188 6.0 Comparative Example 4 345 272 6.5 Comparative Example 5 317 254 7.8 Comparative Example 6 326 266 8.1 Comparative Example 7 308 243 7.8 Comparative Example 8 321 267 6.9 Comparative Example 9 328 231 8.1 Comparative Example 10 289 230 11.2

[0070] As can be seen from Table 1, the tensile strength of the high-toughness wrought magnesium alloy rod and plate prepared in the examples of the present application can reach 340 MPa, the yield strength can reach 300 MPa, and the elongation can reach 13%, the tensile strength of the high-toughness wrought magnesium alloy pipe can reach 310 MPa, the yield strength can reach 260 MPa, and the elongation can reach 9%.

[0071] The magnesium alloy cast rod prepared in Example 1 and the high-toughness wrought magnesium alloy rod, plate and pipe are respectively subjected to metallographic structure observation.

[0072] Figure 2 The metallographic structure diagrams of the magnesium alloy cast rod of Example 1 before and after homogenization treatment, wherein (a) is before homogenization treatment, and (b) is after homogenization treatment. As can be seen from the figure, some low-melting-point coarse second phases on the grain boundaries of the homogenization treatment melt into the matrix, improving the extrudability of the material and preparing for subsequent extrusion.

[0073] Figure 3The TD-ND plane metallographic structure diagram of the magnesium alloy rod, plate and pipe prepared by hot extrusion for Example 1 to be heat treated, wherein (a) is the rod, (b) is the plate, and (c) is the pipe. As can be seen from the diagram, the strong plastic deformation process of hot extrusion effectively refines the grains in the magnesium alloy matrix structure, increasing the number of magnesium alloy grain boundaries; in addition, the hot extrusion process makes the magnesium alloy matrix structure more dense.

[0074] Figure 4 The TD-ND plane metallographic structure diagram of the high strength and toughness deformed magnesium alloy rod, plate and pipe prepared for Example 1, wherein (a) is the rod, (b) is the plate, and (c) is the pipe. As can be seen from the diagram, after the extruded profile is heat treated, first of all, the flat fibrous structure inside the material is reduced, and the crystal has undergone obvious recovery recrystallization phenomenon. Secondly, fine second phases are precipitated inside the material grains, which hinder the movement of dislocations in the subsequent plastic deformation process, greatly improving the mechanical properties of the material.

[0075] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0076] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-ductility wrought magnesium alloy, characterized by, The components are, by mass percentage: Mg 92.15~93.2%, Zn 5.8~6.3%, Zr 0.6~0.9%, Y 0.4~0.6%, and inevitable impurities; The preparation steps of the high-toughness wrought magnesium alloy include: weighing pure magnesium, pure zinc, magnesium-zirconium intermediate alloy, and magnesium-yttrium intermediate alloy, adding RJ-5 flux for smelting, and pouring to obtain a magnesium alloy casting rod; homogenizing the magnesium alloy casting rod, and then water cooling to room temperature to obtain a homogenized magnesium alloy casting rod; hot extruding the homogenized magnesium alloy casting rod, and then performing heat treatment, and cooling to obtain the high-toughness wrought magnesium alloy; The amount of the RJ-5 flux is 7% of the mass of the pure magnesium; The smelting temperature is 690~710℃, and the heating rate is 120℃ / h; The homogenizing temperature is 415~425℃, the time is 14h, and the heating rate is 200℃ / h; The mold for hot extrusion needs to be preheated to 450~460℃, and the temperature of the homogenized magnesium alloy product during hot extrusion is 390~410℃; The extrusion ratio of the hot extrusion is 13~41:1, and the extrusion speed is 0.4~0.7mm / s; The heat treatment temperature is 190℃, and the time is 16h.

2. The high tough wrought magnesium alloy according to claim 1, wherein The components are, by mass percentage: Zn 6%, Zr 0.75%, and Y 0.6%, and the balance is Mg and inevitable impurities.

3. The high tough wrought magnesium alloy according to claim 1, wherein The components are, by mass percentage: Zn 6.3%, Zr 0.8%, and Y 0.4%, and the balance is Mg and inevitable impurities.

4. A method of producing a high-ductility wrought magnesium alloy, characterized by the steps of Comprise: The components of the high-toughness wrought magnesium alloy according to any one of claims 1~3 are weighed, pure magnesium, pure zinc, magnesium-zirconium intermediate alloy, and magnesium-yttrium intermediate alloy are added, RJ-5 flux is added for smelting, and a magnesium alloy casting rod is obtained after pouring; The magnesium alloy casting rod is subjected to homogenizing treatment, and then water cooled to room temperature to obtain a homogenized magnesium alloy casting rod; The homogenized magnesium alloy casting rod is hot extruded, and then subjected to heat treatment, and cooled to obtain the high-toughness wrought magnesium alloy; The amount of the RJ-5 flux is 7% of the mass of the pure magnesium; The smelting temperature is 690~710℃, and the heating rate is 120℃ / h; The homogenizing temperature is 415~425℃, the time is 14h, and the heating rate is 200℃ / h; The mold for hot extrusion needs to be preheated to 450~460℃, and the temperature of the homogenized magnesium alloy product during hot extrusion is 390~410℃; The extrusion ratio of the hot extrusion is 13~41:1, and the extrusion speed is 0.4~0.7mm / s; The heat treatment temperature is 190℃, and the time is 16h.

5. The high-toughness wrought magnesium alloy according to any one of claims 1~3 is applied in aerospace and military industry.

Images