High-plasticity Sn-containing magnesium rare earth alloy and preparation method thereof

Abstract

The invention provides a high-plasticity Sn-containing magnesium rare earth alloy and a preparation method thereof. The high-plasticity Sn-containing magnesium rare earth alloy is prepared from the following components in percentage by mass: 6.0 to 7.5 percent of Gd, 3.0 to 4.0 percent of Y, 0.4 to 1.0 percent of Sn, 1.0 to 2.0 percent of Zn, 0.3 to 0.5 percent of Zr, less than or equal to 0.2 percent of other impurity elements and the balance of pure Mg. According to the invention, by adding a trace amount of Sn into the magnesium rare earth alloy, on the basis of not losing the strength, the excellent elongation of 22% is obtained, and the good matching of the strength and the plasticity of the high-strength magnesium alloy is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium alloy materials, and in particular to a high-plasticity Sn-containing magnesium rare earth alloy and a preparation method thereof. Background Art

[0002] Magnesium alloy is regarded as an important practical material after steel and aluminum alloy. Due to its low density, high specific strength, excellent damping performance and good biocompatibility, it shows broad application potential in aerospace, transportation, military equipment, medical equipment and home appliance communications.

[0003] However, since magnesium has a close-packed hexagonal lattice structure, its plasticity is limited, so that its deformation at room temperature can only slide along the bottom surface of the lattice (0001). This characteristic easily forms a strong basal texture, making magnesium alloys have poorer plasticity and forming properties than aluminum alloys, which brings many challenges in the actual processing process. Therefore, in addition to high strength, magnesium alloys also need to have excellent plasticity.

[0004] In the prior art, by adding rare earth elements such as Gd, Y, and Zr to magnesium alloys, solid solution and aging strengthening can be significantly achieved, and the grain size of the structure can be refined, thereby improving its corrosion resistance and mechanical properties, and greatly improving the strength of the alloy. However, when the amount of rare earth elements added to the ultra-high-strength rare earth magnesium alloy exceeds 15wt%, although extremely high strength can be obtained, it also brings about a sharp decrease in plasticity and a significant increase in cost. Summary of the invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a high-plasticity Sn-magnesium rare earth alloy to solve the problem that the rare earth magnesium alloy prepared by the prior art has high strength but poor plasticity; in addition, the present invention also provides a preparation method of the plastic Sn-magnesium rare earth alloy.

[0006] The first aspect of the present invention provides a high-plasticity Sn-magnesium rare earth alloy, which is composed of the following components in percentage by mass: gadolinium Gd: 6.0-7.5%, yttrium Y: 3.0%-4.0%, tin Sn: 0.4-1.0%, zinc Zn: 1.0%-2.0%, zirconium Zr: 0.3%-0.5%, other impurity elements total: ≤0.2%, and the balance is pure Mg; among other impurities, other single impurity elements: ≤0.05%.

[0007] The present invention significantly improves the plasticity without losing strength by adding trace Sn elements to the ultra-high strength Mg-Gd-Y-Zn-Zr alloy, thereby achieving a good match between strength and plasticity. The improvement of plasticity by trace Sn can be mainly attributed to the following two factors: First, during the solution treatment process, Sn not only promotes the precipitation of lamellar LPSO in the crystal, but also accelerates the transformation of LPSO at the grain boundary from block to lamellar, and finally forms a high-density lamellar LPSO in the Sn-containing alloy. It is well known that under the combined action of heat and force, lamellar LPSO is easy to dissolve during the forging process. However, Sn significantly improves the thermal stability of lamellar LPSO, so that most of it is retained during the forging process. The lamellar LPSO in the Sn-containing alloy can be deformed by kinking coordination, thereby delaying the dynamic recrystallization during the forging process, and finally forming a double-peak structure in the Sn-containing alloy. The large grains in the double-peak structure can play the role of storing dislocations, which is conducive to relieving stress concentration and inhibiting the initiation of microcracks, thereby improving plasticity. In addition, the lamellar LPSO can also release stress concentration through kink deformation to improve plasticity. Secondly, Sn can reduce the unstable stacking fault energy of (10-10)<11-20> cylindrical slip, {10-11}[11-23] cone I slip and {11-22}[11-23] cone II slip, promote the activation of multiple slip systems during plastic deformation, and thus greatly improve plasticity. In addition, the promotion effect of Sn-Zn composite addition on non-basal slip is more significant, especially on the cone slip.<c+a> Slip.

[0008] In one embodiment of the present invention, the high plasticity Sn-containing magnesium rare earth alloy is composed of the following components in percentage by mass: gadolinium Gd: 6.0-7.5%, yttrium Y: 3.0%-4.0%, tin Sn: 0.4-1.0%, zinc Zn: 1.0%-2.0%, zirconium Zr: 0.3%-0.5%, and the balance is Mg.

[0009] The second aspect of the present invention provides a method for preparing the above-mentioned high plasticity Sn-containing magnesium rare earth alloy, comprising the following steps:

[0010] S1. Alloy casting: weigh the formulated amount of pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Zr master alloy as raw materials, and cast them into alloy ingots after melting;

[0011] S2, solution treatment: the alloy ingot obtained in S1 is placed in a heat treatment furnace for homogenization, heated to 480°C, kept at this temperature for 24 hours, and processed into forging plates;

[0012] S3, forging: preheat the forging plate after homogenization treatment to 450℃-470℃, preheat the upper and lower anvils to 400℃, and perform upsetting and drawing multi-directional forging on the forging plate, with a downsetting amount of 35-40% for the upsetting pass and a downsetting amount of 10-15% for the drawing pass, and the down-pressing speed is controlled at 200-400mm / min, and the above three upsetting and drawing treatments are performed;

[0013] S4, aging treatment: heat-treat the forged sheet material after the treatment in step S3 at 210° C. for 40-50 hours to obtain a high-plasticity Sn-containing magnesium rare earth alloy.

[0014] In one embodiment of the present invention, the mass percentage of Gd in the Mg-Gd master alloy is 30%, the mass percentage of Y in the Mg-Y master alloy is 30%, and the mass percentage of Zr in the Mg-Zr master alloy is 30%.

[0015] In one embodiment of the present invention, step S1 is:

[0016] S11. According to the mass percentage of each element of the high plasticity Sn-containing magnesium rare earth alloy, pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Zr master alloy are weighed, and the mixtures are cleaned, dried, preheated to 300° C., and smelted respectively;

[0017] S12. Under the protection of a mixed gas of CO2 and SF6, first heat pure magnesium, pure tin, pure zinc, Mg-Gd intermediate alloy, and Mg-Y intermediate alloy to 690-730°C until completely melted, then heat the melt to above 770°C, add Mg-Zr intermediate alloy, and after complete melting, stir and remove slag every 30 minutes. During the last stirring, sprinkle refining agent, cool to 740-760°C, let stand for 30-40 minutes, scrape off slag on the surface of the melt, obtain alloy liquid, and finally cast to obtain alloy ingot.

[0018] In one embodiment of the present invention, the volume ratio of CO2 to SF6 is 99.5:0.5.

[0019] In one embodiment of the present invention, step S3 is: when performing forging processing, the forging sheet after homogenization treatment is preheated to 450°C-470°C, the upper and lower anvils are preheated to 400°C, and the forging sheet is subjected to upsetting and drawing multi-directional forging, with the upsetting pass having a reduction of 35-40%, the drawing pass having a reduction of 10-15%, the pressing speed being controlled at 200-400mm / min, and the above three upsetting and drawing treatments are performed.

[0020] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0021] 1. The high-plasticity Sn-containing magnesium rare earth alloy provided by the present invention achieves an excellent elongation of 22% without losing strength by adding a small amount of Sn to the high-strength Mg-Gd-Y-Zn-Zr alloy, thereby achieving a good match between the strength and plasticity of the high-strength magnesium alloy.

[0022] 2. The Sn-containing magnesium rare earth alloy provided by the present invention can be formed by one-fire forging to obtain a high-plasticity magnesium alloy forging plate. The preparation process is simple and easy to operate, and the cost is low, which is suitable for industrial production. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0024] Example 1

[0025] This embodiment provides a high plasticity Sn-magnesium-containing rare earth alloy, which is composed of the following components in mass percentage: gadolinium Gd: 7.0%, yttrium Y: 3.5%, tin Sn: 0.7%, zinc Zn: 1.5%, zirconium Zr: 0.5%, and the balance is Mg.

[0026] The preparation method of the high plasticity Sn-containing magnesium rare earth alloy is as follows:

[0027] S1. Alloy casting: pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, Mg-Zr master alloy are used as raw materials, and ingredients are prepared according to the above magnesium alloy components and weight percentages, and the ingredients are melted and cast into alloy ingots;

[0028] S2, solution treatment: the alloy ingot obtained in S1 is placed in a heat treatment furnace for homogenization, heated to 480°C, kept at this temperature for 24 hours, and processed into forging plates;

[0029] S3. Forging: preheat the forging plate after homogenization treatment to 460°C, preheat the upper and lower anvils to 400°C, and perform upsetting and drawing multi-directional forging on the forging plate. The downstroke amount for the upsetting pass is 36%, and the downstroke amount for the drawing pass is 13%. The downstroke speed is controlled at 300 mm / min, and the above three upsetting and drawing treatments are performed.

[0030] S4. Aging treatment: heat treat the forged sheet at 210°C for 45h to obtain a high plasticity Sn-containing magnesium rare earth alloy.

[0031] The mass percentage of Gd in the Mg-Gd alloy is 30%, the mass percentage of Y in the Mg-Y master alloy is 30%, and the mass percentage of Zr in the Mg-Zr master alloy is 30%.

[0032] Wherein, the step S1 is:

[0033] S11. According to the mass percentage of each element of the high plasticity Sn-containing magnesium rare earth alloy, pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Zr master alloy are weighed, and the mixtures are cleaned, dried, preheated to 300° C., and smelted respectively;

[0034] S12. Under the protection of a mixed gas of CO2 and SF6, first heat pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, and Mg-Y master alloy to 730°C until they are completely melted. Then heat the melt to above 770°C and add the Mg-Zr master alloy. After complete melting, stir the solution and remove slag every 30 minutes. During the last stirring, sprinkle in a refining agent, cool to 750°C, let stand for 40 minutes, scrape off the slag on the surface of the melt, obtain the alloy liquid, and finally cast it.

[0035] Wherein, the volume ratio of CO2 to SF6 is 99.5:0.5.

[0036] Among them, the magnesium alloy ingot after homogenization treatment is preheated to 460°C, the upper and lower anvils are preheated to 400°C, and the ingot is subjected to upsetting and drawing multi-directional forging. The upsetting pass has a reduction of 36%, and the drawing pass has a reduction of 13%. The pressing speed is controlled at 300mm / min, and the above three upsetting and drawing treatments are performed.

[0037] Example 2

[0038] This embodiment provides a high plasticity Sn-magnesium-containing rare earth alloy, which is composed of the following components in percentage by mass: gadolinium Gd: 7.5%, yttrium Y: 3.0%, tin Sn: 0.47%, zinc Zn: 1.0%, zirconium Zr: 0.3%, and the balance is Mg.

[0039] The preparation method of the high plasticity Sn-containing magnesium rare earth alloy is as follows:

[0040] S1. Alloy casting: pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, Mg-Zr master alloy are used as raw materials, and ingredients are prepared according to the above magnesium alloy components and weight percentages, and the ingredients are melted and cast into alloy ingots;

[0041] S2, solution treatment: the alloy ingot obtained in S1 is placed in a heat treatment furnace for homogenization, heated to 480°C, kept at this temperature for 24 hours, and processed into forging plates;

[0042] S3. Forging: preheat the forging plate after homogenization treatment to 460°C, preheat the upper and lower anvils to 400°C, and perform upsetting and drawing multi-directional forging on the forging plate. The downstroke amount for the upsetting pass is 36%, and the downstroke amount for the drawing pass is 13%. The downstroke speed is controlled at 300 mm / min, and the above three upsetting and drawing treatments are performed.

[0043] S4. Aging treatment: heat treat the forged sheet at 210°C for 45h to obtain a high plasticity Sn-containing magnesium rare earth alloy.

[0044] The mass percentage of Gd in the Mg-Gd alloy is 30%, the mass percentage of Y in the Mg-Y master alloy is 30%, and the mass percentage of Zr in the Mg-Zr master alloy is 30%.

[0045] Wherein, the step S1 is:

[0046] S11. According to the mass percentage of each element of the high plasticity Sn-containing magnesium rare earth alloy, pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Zr master alloy are weighed, and the mixtures are cleaned, dried, preheated to 300° C., and smelted respectively;

[0047] S12. Under the protection of a mixed gas of CO2 and SF6, first heat pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, and Mg-Y master alloy to 730°C until they are completely melted. Then heat the melt to above 770°C and add the Mg-Zr master alloy. After complete melting, stir the solution and remove slag every 30 minutes. During the last stirring, sprinkle in a refining agent, cool to 750°C, let stand for 40 minutes, scrape off the slag on the surface of the melt, obtain the alloy liquid, and finally cast it.

[0048] Wherein, the volume ratio of CO2 to SF6 is 99.5:0.5.

[0049] Among them, the magnesium alloy ingot after homogenization treatment is preheated to 460°C, the upper and lower anvils are preheated to 400°C, and the ingot is subjected to upsetting and drawing multi-directional forging. The upsetting pass has a reduction of 36%, and the drawing pass has a reduction of 13%. The pressing speed is controlled at 300mm / min, and the above three upsetting and drawing treatments are performed.

[0050] Example 3

[0051] The present embodiment provides a high plasticity Sn-magnesium-containing rare earth alloy, which is composed of the following components in percentage by mass: gadolinium Gd: 7.5%, yttrium Y: 4.0%, tin Sn: 1.0%, zinc Zn: 2.0%, zirconium Zr: 0.5%, and the balance is Mg.

[0052] The preparation method of the high plasticity Sn-containing magnesium rare earth alloy is as follows:

[0053] S1. Alloy casting: pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, Mg-Zr master alloy are used as raw materials, and ingredients are prepared according to the above magnesium alloy components and weight percentages, and the ingredients are melted and cast into alloy ingots;

[0054] S2, solution treatment: the alloy ingot obtained in S1 is placed in a heat treatment furnace for homogenization, heated to 480°C, kept at this temperature for 24 hours, and processed into forging plates;

[0055] S3. Forging: preheat the forging plate after homogenization treatment to 460°C, preheat the upper and lower anvils to 400°C, and perform upsetting and drawing multi-directional forging on the forging plate. The downstroke amount for the upsetting pass is 36%, and the downstroke amount for the drawing pass is 13%. The downstroke speed is controlled at 300 mm / min, and the above three upsetting and drawing treatments are performed.

[0056] S4. Aging treatment: heat treat the forged sheet at 210°C for 45h to obtain a high plasticity Sn-containing magnesium rare earth alloy.

[0057] The mass percentage of Gd in the Mg-Gd alloy is 30%, the mass percentage of Y in the Mg-Y master alloy is 30%, and the mass percentage of Zr in the Mg-Zr master alloy is 30%.

[0058] Wherein, the step S1 is:

[0059] S11. According to the mass percentage of each element of the high plasticity Sn-containing magnesium rare earth alloy, pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Zr master alloy are weighed, and the mixtures are cleaned, dried, preheated to 300° C., and smelted respectively;

[0060] S12. Under the protection of a mixed gas of CO2 and SF6, first heat pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, and Mg-Y master alloy to 730°C until they are completely melted. Then heat the melt to above 770°C and add the Mg-Zr master alloy. After complete melting, stir the solution and remove slag every 30 minutes. During the last stirring, sprinkle in a refining agent, cool to 750°C, let stand for 40 minutes, scrape off the slag on the surface of the melt, obtain the alloy liquid, and finally cast it.

[0061] Wherein, the volume ratio of CO2 to SF6 is 99.5:0.5.

[0062] Among them, the magnesium alloy ingot after homogenization treatment is preheated to 460°C, the upper and lower anvils are preheated to 400°C, and the ingot is subjected to upsetting and drawing multi-directional forging. The upsetting pass has a reduction of 36%, and the drawing pass has a reduction of 13%. The pressing speed is controlled at 300mm / min, and the above three upsetting and drawing treatments are performed.

[0063] Comparative Example 1

[0064] This comparative example provides a magnesium rare earth alloy, which is composed of the following components in percentage by mass: gadolinium Gd: 7.0%, yttrium Y: 3.5%, tin Sn: 1.3%, zinc Zn: 1.5%, zirconium Zr: 0.5%, and the balance is Mg.

[0065] The preparation method of the magnesium rare earth alloy in this comparative example is consistent with that in Example 1.

[0066] Comparative Example 2

[0067] This comparative example provides a magnesium rare earth alloy, which is composed of the following components in percentage by mass: gadolinium Gd: 7.0%, yttrium Y: 3.5%, zinc Zn: 1.5%, zirconium Zr: 0.5%, and the balance is Mg.

[0068] The preparation method of the magnesium rare earth alloy in this comparative example is consistent with that in Example 1.

[0069] Experimental Example 1

[0070] In this test example, the properties of the magnesium rare earth alloys obtained in Examples 1-3 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1.

[0071] Table 1 Room temperature mechanical properties of examples and comparative examples

[0072]

[0073] It can be seen from Table 1 that compared with Example 1, Comparative Example 1 is an alloy in which excessive Sn is added, and Comparative Example 2 is an ordinary rare earth magnesium alloy without Sn addition. The material properties invented by this patent have significant advantages, and the comprehensive properties of the alloy are significantly improved. In Comparative Example 1, when the Sn element content is too high, the material microstructure is coarsened and uneven due to the rapid growth of the precipitated phase, resulting in a rapid decline in material properties.

[0074] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A high plasticity Sn-containing magnesium rare earth alloy, characterized in that: The following components are calculated by mass percentage: composition: Gd: 6.0-7.5%, Y: 3.0%-4.0%, Sn: 0.4-1.0%, Zn: 1.0%-2.0%, Zr: 0.3%-0.5%, other impurity elements total: ≤0.2%, the balance is pure Mg.

2. The high plasticity Sn-containing magnesium rare earth alloy according to claim 1, characterized in that: The following components are calculated by mass percentage: composition: Gd: 6.0-7.5%, Y: 3.0%-4.0%, Sn: 0.4-1.0%, Zn: 1.0%-2.0%, Zr: 0.3%-0.5%, and the balance is Mg.

3. The method for preparing a high plasticity Sn-containing magnesium rare earth alloy according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Alloy casting: weigh the formulated amount of pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Zr master alloy as raw materials, and cast them into alloy ingots after melting; S2, solution treatment: the alloy ingot obtained in S1 is placed in a heat treatment furnace for homogenization, heated to 480°C, kept at this temperature for 24 hours, and processed into forging plates; S3, forging: preheat the forging plate after homogenization treatment to 450℃-470℃, preheat the upper and lower anvils to 400℃, and perform upsetting and drawing multi-directional forging on the forging plate, with a downsetting amount of 35-40% for the upsetting pass and a downsetting amount of 10-15% for the drawing pass, and the down-pressing speed is controlled at 200-400mm / min, and the above three upsetting and drawing treatments are performed; S4, aging treatment: heat-treat the forged sheet material after the treatment in step S3 at 210° C. for 40-50 hours to obtain a high-plasticity Sn-containing magnesium rare earth alloy.

4. The method for preparing a high plasticity Sn-containing magnesium rare earth alloy according to claim 3, characterized in that: The mass percentage of Gd in the Mg-Gd master alloy is 30%, the mass percentage of Y in the Mg-Y master alloy is 30%, and the mass percentage of Zr in the Mg-Zr master alloy is 30%.

5. The method for preparing a high plasticity Sn-containing magnesium rare earth alloy according to claim 3, characterized in that: The step S1 is: S11. According to the mass percentage of each element of the high plasticity Sn-containing magnesium rare earth alloy, pure magnesium, pure tin, pure zinc, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Zr master alloy are weighed, and the mixtures are cleaned, dried, preheated to 300° C., and smelted respectively; S12. Under the protection of a mixed gas of CO2 and SF6, first heat pure magnesium, pure tin, pure zinc, Mg-Gd intermediate alloy, and Mg-Y intermediate alloy to 690-730°C until completely melted, then heat the melt to above 770°C, add Mg-Zr intermediate alloy, and after complete melting, stir and remove slag every 30 minutes. During the last stirring, sprinkle refining agent, cool to 740-760°C, let stand for 30-40 minutes, scrape off slag on the surface of the melt, obtain alloy liquid, and finally cast to obtain alloy ingot.

6. The method for preparing a high plasticity Sn-containing magnesium rare earth alloy according to claim 5, characterized in that: The volume ratio of CO2 to SF6 is 99.5:0.

5.

7. The method for preparing a high plasticity Sn-containing magnesium rare earth alloy according to claim 3, characterized in that: The step S3 is: when performing forging processing, the forging plate material after homogenization treatment is preheated to 450°C-470°C, the upper and lower anvils are preheated to 400°C, and the forging plate material is subjected to upsetting and drawing multi-directional forging, the upsetting pass has a reduction of 35-40%, the drawing pass has a reduction of 10-15%, the pressing speed is controlled at 200-400mm / min, and the above three upsetting and drawing treatments are performed.

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