A heat treatment free high strength and toughness high corrosion resistant magnesium alloy and a preparation method thereof

Abstract

The application discloses a heat treatment-free high-strength high-toughness high-corrosion-resistance magnesium alloy and a preparation method thereof, and the weight percentage of each component of the magnesium alloy is as follows: Al 3-8%; Mn 0.1-0.5%; Zn 0.002-2%; R 0.5-8%; M 0.001-1%; D 0.001-1%, and the total amount of other impurities is less than or equal to 0.3%, and the balance is Mg; R is at least one of La and Ce, M is at least one of Cu and Ga, and D is at least one of Be, Ca and Sr. The alloy is compounded with Zn and M elements in Mg-Al-Mn-R, high-content high-width LPSO phases are formed, the strength and toughness of the alloy are significantly improved, the D element is added, the corrosion resistance of the alloy is improved, the alloy has good die-casting performance, and can be used for forming automobile integrated rear floor, front cabin or two-wheeled vehicle main frame and other parts, and the application scenarios of the magnesium alloy are greatly expanded.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of magnesium alloy materials, in particular to a heat-treatment-free high-strength high-toughness high-corrosion-resistance magnesium alloy and a preparation method thereof. BACKGROUND

[0002] As the lightest metal structural material in practical applications, magnesium alloys have a series of advantages such as high specific strength and specific stiffness, good damping and shock attenuation, excellent electromagnetic shielding performance and easy recycling, and have broad application prospects in the fields of automobiles, aerospace, 3C electronic products and the like. Among them, the die casting technology has become the most important forming process of magnesium alloys because of its high production efficiency, good part surface quality and the ability to manufacture complex thin-walled components. However, with the continuous improvement of the performance requirements of structural parts in various industries, the development of magnesium alloys with high strength, high toughness and excellent corrosion resistance has become a key technical challenge to promote the large-scale commercial application of magnesium alloys.

[0003] Traditional commercial magnesium alloys such as AZ91D and AM60B have β-Mg 17 Al 12 as the main strengthening phase, which is distributed along the grain boundaries in a network, and the strength and toughness of the alloy are difficult to improve simultaneously, and the corrosion resistance is poor, so it cannot meet the requirements of high-end structural parts on mechanical properties and corrosion performance. Heat treatment is usually an effective method to improve the strength of the alloy, but for large or complex structural parts, heat treatment not only increases the cost and energy consumption, reduces the production efficiency, and the pores existing in the die casting may cause the parts to bulge, deform or even be scrapped due to gas expansion during the heat treatment process.

[0004] Chinese patent CN202211380427.X discloses "a high-performance heat-resistant and corrosion-resistant magnesium alloy casting and a preparation method thereof", which comprises 3.5-4.5wt% Y, 2-3wt% Nd, 0-1wt% Gd, >0 and ≤1wt% Zr, >0 and ≤1.6wt% Zn, and the balance of Mg; the addition of Zn element in the alloy forms LPSO phase, which improves the strength of the magnesium alloy casting, but the rare earth elements Y, Nd and Gd used in the application are expensive, and heat treatment is needed to obtain high mechanical properties, and chemical nickel plating is also needed to improve the corrosion resistance of the alloy. The overall cost of the magnesium alloy casting prepared by the application is high, which cannot meet the large-scale industrial application.

[0005] Chinese patent CN202411385109.1 discloses "a renewable heat treatment-free high strength and toughness magnesium alloy and a preparation method thereof", the weight percentage of each component is Al: 3.0-6.0%, RE: 4.0-6.0%, Mn: 0.2-1.0%, Zr: 0.1-0.5%, Fe: 0.03-0.15%, Si≤0.001%, Ni≤0.001%, the balance is Mg, and RE is selected from any one of rare earth La, Ce and Y. The magnesium alloy has high strength and toughness and high hydrogen embrittlement resistance, and uses recycled waste magnesium as raw material, and has low cost. However, Al4RE, Al2RE and Zr2Fe phases in the alloy are high potential phases, the potential difference with the magnesium matrix is large, and the content of various impurity elements in the recycled waste magnesium is high, so it can be expected that the alloy has poor corrosion resistance and is difficult to be widely promoted.

[0006] In summary, the existing magnesium alloy material cannot balance the mechanical properties, corrosion resistance, cost and processability in the heat treatment-free state, resulting in that the existing magnesium alloy cannot meet the demand of large-scale integrated magnesium alloy structural parts, and it is urgent to develop a new heat treatment-free high strength and toughness high corrosion resistance magnesium alloy. SUMMARY

[0007] The purpose of the present application is to provide a heat treatment-free high strength and toughness high corrosion resistance magnesium alloy and a preparation method thereof. Under the premise of ensuring good casting performance, the problem that the existing magnesium alloy cannot simultaneously balance high strength and toughness and high corrosion resistance in the heat treatment-free state is solved, thereby the application scenarios of the magnesium alloy can be widened, the magnesium alloy is used on the automobile integrated rear floor, front cabin, or two-wheeled vehicle main frame, baffle, or other parts, replaces the traditional die-casting aluminum alloy or steel or plastic parts, significantly reduces the weight of the parts and vehicle body, and improves the light weight technology level of China.

[0008] In order to achieve this purpose, in the early stage of the present application, it is found in the research on Mg-Al-R magnesium alloy that: by adding Zn element, LPSO phase (long period stacking ordered phase) can be generated in the alloy, there is long-range ordered atomic arrangement in the LPSO phase, and periodic stacking is performed. This structure can produce stacking fault strengthening, and use the stacking fault to hinder dislocation slip, so as to improve the strength; at the same time, the layer characteristics have strong coordination deformation ability, and can excite non-basal plane slip in the deformation process, so as to promote the uniform distribution of stress, thereby improving the plasticity. The existence of LPSO phase can significantly change the material performance, so that the magnesium alloy has high strength and good plasticity. Too little Zn element produces too little LPSO phase, and the strengthening effect is not obvious, and too much Zn element will cause the casting performance of the alloy to be poor, therefore the content of Zn element is controlled to be 0.002-2% in the present application.

[0009] The present application further studies and finds that: in the Mg-Al-R-Zn magnesium alloy, adding M element, and the M element is at least one of Cu, Ga element, can improve the content and width of LPSO phase in the alloy without heat treatment, and then can significantly improve the strength and plasticity of the alloy; Cu, Ga element is located on both sides of Zn element in the periodic table, so its atomic radius, physicochemical properties are more similar, Cu, Ga element can replace Zn atom in LPSO phase or solid solution in LPSO phase; Cu, Ga element can promote the precipitation and formation of LPSO phase, thereby increasing the content of LPSO phase in the alloy, and the width of LPSO phase formed by containing Cu, Ga is wider, and the strengthening effect is more significant. Too little Cu, Ga element cannot improve the content and width of LPSO phase, and too much Cu, Ga element will affect the corrosion resistance of the alloy, so the content of Cu, Ga element is controlled to be 0.001-1% in the present application. In addition, in the process of our experiment, we also tried the scheme of using Sn, Bi, Ti, V, Zr, Ni, Cr and other elements as M element, but all failed to improve the content and width of LPSO phase and improve the strength and toughness of the alloy. The present application also finds that when the weight percentage of Zn and M elements in the alloy satisfies 0.5≤Zn / M≤2, the content and width of LPSO phase in the alloy are higher, and the tensile strength of the alloy can be above 300 MPa; further, when M is Cu and Ga, the tensile strength of the alloy is higher, above 310 MPa.

[0010] Cu, Ga element is a high potential element, even if the adding amount is not large, it will also have a certain degree of negative impact on the corrosion resistance of the alloy, so the present application further adds D element in the above alloy, the D element is at least one of Be, Ca, Sr element. Be, Ca, Sr element can repair the pores of the magnesium alloy surface oxide film, improve the density of the oxide film, and can reduce the potential difference between the magnesium matrix and the second phase, thereby improving the corrosion resistance of the alloy. Too little Be, Ca, Sr element cannot inhibit the influence of M element on the corrosion resistance, and too much Be, Ca, Sr element will significantly increase the tendency of thermal cracking of the alloy, so the content of Be, Ca, Sr element is controlled to be 0.001-1% in the present application. The present application also finds that when the weight percentage of M and D elements in the alloy satisfies D / M≥1, the corrosion resistance of the alloy is higher, and the corrosion rate in 5% NaCl neutral salt spray for 168 h can be below 0.6 mm / year; further, when D is Be and D1, and D1 is at least one of Ca and Sr, the corrosion resistance of the alloy is better, and the corrosion rate is below 0.5 mm / year.

[0011] Meanwhile, the content of the Al element is controlled at 3-8%, and the content of the rare earth R element is controlled at 0.5-8%. Too little Al element will result in poor casting performance of the alloy, and too little R element will not generate the LPSO phase. When the content of the Al element or the R element is too much, the content of the second phase in the alloy is too high, and at this time, the promotion effect of the LPSO phase on the alloy performance is significantly weakened. The rare earth element R used in the application is at least one of La and Ce, which are high-abundance and inexpensive rare earth elements, so that the cost of the alloy is low, and the demand of industrial application can be met. It is also found that when the content of the R element in the alloy is too high, brittle MgR phase will be generated, which significantly reduces the plasticity of the alloy and increases the thermal cracking tendency of the alloy in the casting process. Therefore, the content of Al and R in the application preferably satisfies the following condition: Al / R is greater than or equal to 0.4.

[0012] The application also adds a small amount of Mn element in the above alloy, and the content of the Mn element is controlled at 0.1-0.5%. The Mn element can combine and remove impurity elements such as Fe and Ni in the magnesium melt, on the one hand, ensures the purity of the magnesium melt, and on the other hand, can reduce the galvanic corrosion of the impurity elements and the magnesium matrix, and enhance the corrosion resistance of the alloy. The excess Mn element is dissolved in the magnesium matrix to ensure the strength of the alloy.

[0013] Based on the above technical problems to be solved and a large number of experimental tests, the application specifically proposes the following technical scheme:

[0014] In a first aspect, the application provides a heat treatment-free high-strength and high-toughness high-corrosion-resistant magnesium alloy, and the weight percentage of each component in the magnesium alloy is as follows:

[0015] Al: 3-8%;

[0016] Mn: 0.1-0.5%;

[0017] Zn: 0.002-2%;

[0018] R: 0.5-8%;

[0019] M: 0.001-1%;

[0020] D: 0.001-1%, the total amount of other impurities is less than or equal to 0.3%, and the balance is Mg;

[0021] Among them, R is at least one of La and Ce, and the weight percentage of Al and R elements needs to satisfy Al / R≥0.4;

[0022] M is at least one of Cu and Ga;

[0023] D is at least one of Be, Ca and Sr.

[0024] On the basis of the selection and adjustment of the components of the magnesium alloy, the weight percentages of Al and rare earth elements R in the magnesium alloy are regulated, which is also beneficial to further improve the mechanical properties of the magnesium alloy. For example, in the mechanical properties of the magnesium alloy prepared under the condition, the yield strength is above 170 MPa, the tensile strength is above 280 MPa, and the elongation is above 10%. Moreover, under the potential balance effect of the added D element, the corrosion rate of the magnesium alloy is significantly reduced, and the corrosion rate under the neutral salt spray of 5% NaCl for 168 h is below 0.8 mm / year -1 In the following, the magnesium alloy material of the present application can obviously better balance the mechanical properties, corrosion resistance, cost and processability in the heat treatment-free state.

[0025] Preferably, the magnesium alloy satisfies at least one of the following conditions:

[0026] (1) The weight percentages of Zn and M satisfy the following condition: 0.5≤Zn / M≤2;

[0027] (2) M is a combination of Cu and Ga;

[0028] (3) The weight percentages of M and D satisfy the following condition: D / M≥1;

[0029] (4) D is a combination of Be and D1, wherein D1 is at least one of Ca and Sr.

[0030] Among them, condition (1) and condition (2) are beneficial to improve the tensile strength of the magnesium alloy, for example, to increase the tensile strength of the magnesium alloy to above 300 MPa, and preferably to increase the tensile strength of the magnesium alloy to above 310 MPa. Among them, the mixing ratio of Cu and Ga is not particularly limited and can be any ratio.

[0031] Conditions (3) and (4) are beneficial to improve the corrosion resistance of the alloy, for example, to reduce the corrosion rate of the magnesium alloy under the neutral salt spray of 5% NaCl for 168 h to below 0.6 mm / year, and preferably to below 0.5 mm / year. Among them, when the D is a combination of Be, Ca and Sr, the mixing ratio is not particularly limited and can be any ratio.

[0032] Preferably, when R in the magnesium alloy is a combination of La and Ce, the mixing ratio is not particularly limited and can be any ratio.

[0033] Preferably, in the magnesium alloy, the weight percentages of Zn and M satisfy the following condition: 0.5≤Zn / M≤2;

[0034] The weight percentages of M and D satisfy the following condition: D / M≥1;

[0035] The tensile strength of the magnesium alloy is above 300 MPa, and the corrosion rate in 5% NaCl neutral salt spray for 168 h is below 0.6 mm / year.

[0036] More preferably, in the magnesium alloy, M is Cu and Ga in combination;

[0037] D is Be and D1 in combination, wherein D1 is at least one of Ca and Sr;

[0038] The tensile strength of the magnesium alloy is above 310 MPa, and the corrosion rate in 5% NaCl neutral salt spray for 168 h is below 0.5 mm / year.

[0039] More preferably, the yield strength of the magnesium alloy is above 181 MPa, the tensile strength is above 312 MPa, the elongation is above 18%, and the corrosion rate is below 0.46 mm / year. -1 The following.

[0040] In a second aspect, the present application further provides a preparation method of the heat-treatment-free high-strength-and-ductility high-corrosion-resistance magnesium alloy as described above, and the method comprises the following steps:

[0041] S1, material preparation: raw materials are weighed according to the weight percentage of each component of the magnesium alloy; optionally, Mg, Al, Zn and Ga are prepared in the form of pure metals, R, Cu, Ca, Sr and Mn are prepared in the form of pure metals or magnesium-containing intermediate alloy or aluminum-containing intermediate alloy, and Be is prepared in the form of magnesium-containing or aluminum-containing intermediate alloy;

[0042] S2, step-by-step melting:

[0043] First-stage melting: the crucible is preheated to 300-500 ℃, and the pure Mg ingot is placed in the crucible for melting;

[0044] Second-stage melting: the temperature is raised to 750-800 ℃, R, Mg-R intermediate alloy and / or Al-R intermediate alloy are added, part of M is added, and pure Mn or Mg-Mn intermediate alloy or Al-Mn intermediate alloy is added;

[0045] Third-stage melting: the temperature is lowered to the third-stage melting temperature T, T is 720-750 ℃, and then pure Al, pure Zn, the remaining M, and D are added to obtain a magnesium alloy melt;

[0046] S3, powder injection refining: the temperature of the magnesium alloy melt is kept within the range of T, and a refining agent powder is injected into the melt for powder injection refining and slag removal treatment to obtain a refined melt;

[0047] S4, casting or die casting: the refined melt is adjusted to a casting temperature, and then casting or die casting is performed to obtain an alloy cast ingot or a die-cast alloy part.

[0048] Preferably, M is Cu, Ga, and is added in the second and third melting steps, respectively, including:

[0049] In the second melting step, the added part of M is Cu, Mg-Cu intermediate alloy and / or Al-Cu intermediate alloy;

[0050] In the third melting step, the added remaining part of M is Ga.

[0051] Preferably, the third melting step further satisfies at least one of the following:

[0052] (1) D in the magnesium alloy includes Be, and Mg-Be intermediate alloy and / or Al-Be intermediate alloy is added in the third melting step;

[0053] (2) D in the magnesium alloy includes Ca, and pure Ca, Mg-Ca intermediate alloy and / or Al-Ca intermediate alloy is added in the third melting step;

[0054] (3) D in the magnesium alloy includes Sr, and pure Sr, Mg-Sr intermediate alloy and / or Al-Sr intermediate alloy is added in the third melting step.

[0055] Preferably, in step S1, the prepared raw materials are preheated to 150-250 ℃ and subjected to drying treatment.

[0056] Preferably, the raw materials in step S1 are preheated to the alloy ingot or die-casting alloy part obtained in step S4, and both are carried out in a protective atmosphere or in a vacuum environment.

[0057] Preferably, in step S2, after preheating, a protective atmosphere is formed by introducing a protective gas, and the protective gas is pure SF6 or a mixed gas of SF6 and a base gas, the base gas being selected from at least one of N2, CO2 and Ar, and the volume ratio of SF6 to the base gas being (0.5-1.5):(98.5-99.5), preferably 1:99.

[0058] Preferably, in step S2, the crucible is preheated after applying a layer of covering agent in the crucible, and a layer of covering agent is applied to cover the melt after the pure Mg is melted, and the solvent density of the covering agent is <1.58 g / cm 3 .

[0059] Preferably, in step S3, a protective gas is introduced, and the refining agent is carried in with the gas flow of the protective gas, and the refining agent includes salt fluxes that can absorb impurities in the melt, and the types can be selected according to conventional methods in the art and can be obtained through ordinary commercial channels.

[0060] Preferably, the amount of the refining agent is 0.3-2.0% of the total weight of the magnesium alloy melt.

[0061] Preferably, in step S3, the protective gas includes argon.

[0062] Preferably, in step S2, after the third melting, the step of placing and testing the composition of the melt in the furnace is further included after the stirring of the melt is completed, and the composition of the magnesium alloy melt is detected, and the melt with content deviation is supplemented or diluted to make the composition reach the qualified range.

[0063] Preferably, in step S3, after the powder spraying refining and slag removal treatment, the step of placing and testing the composition of the melt in the furnace is further included. More preferably, the placing time is 5-15 min.

[0064] Preferably, in step S4, the casting temperature of the refined melt is adjusted to 670-750 ℃, and the die-casting alloy part is obtained by high-pressure casting, the high-speed injection speed of the high-pressure casting is 2-8 m / s, and / or the casting pressure is 30-120 MPa.

[0065] Preferably, in step S4, the casting temperature is 680-750 ℃. By adjusting the casting temperature and cooperating with the high-speed injection speed and the casting pressure, the effect of improving the strength and toughness and the corrosion resistance can be further achieved.

[0066] Compared with the prior art, the present application has the following beneficial effects:

[0067] 1. The heat treatment-free high-strength and toughness high-corrosion-resistant magnesium alloy disclosed by the present application is based on the conventional Mg-Al-Mn-R magnesium alloy, and Zn and M elements are compounded to form a high-content and high-width LPSO phase in the alloy, which significantly improves the strength and toughness of the alloy; and by adding D elements, the negative influence of the corrosion resistance reduction caused by M elements is inhibited, so that the magnesium alloy has good cooperation effect of strength and toughness and corrosion resistance under heat treatment-free condition.

[0068] 2. The magnesium alloy obtained by the present application has high strength, toughness and corrosion resistance under heat treatment-free condition, the yield strength can reach more than 170 MPa, the tensile strength can reach more than 280 MPa, the elongation can reach more than 10%, and the corrosion rate under 5% NaCl neutral salt spray for 168 h is less than 0.8 mm / year; the strength, toughness and corrosion resistance of the alloy are far superior to those of traditional magnesium alloys such as AZ91D and AM60B, and in addition, the alloy also has good die-casting performance, and can be used for forming automobile integrated rear floor, front cabin, or two-wheeled vehicle main frame, baffle, or other parts, which greatly expands the application scenarios of magnesium alloy.

[0069] 3. The present application is further based on the improvement of tensile strength, by adjusting the weight percentage of Zn, M elements, the tensile strength of the magnesium alloy is further improved to more than 300 MPa; by selecting the weight percentage range of M, D elements, the corrosion rate of the magnesium alloy under 5% NaCl neutral salt spray for 168 h is further reduced to below 0.6 mm / year, effectively improving the corrosion resistance of the magnesium alloy. On the basis of meeting the above performance, it is further explored that when the M element in the magnesium alloy is Cu and Ga, the tensile strength of the magnesium alloy prepared thereby is higher, which can be more than 310 MPa, and when the D element in the magnesium alloy is Be and D1 (D1 is Ca and / or Sr), the corrosion resistance of the magnesium alloy prepared thereby is better, and the corrosion rate can be below 0.5 mm / year. BRIEF DESCRIPTION OF DRAWINGS

[0070] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments thereof, read in conjunction with the accompanying drawings:

[0071] Figure 1 is a microstructure photo of the magnesium alloy part obtained in Example 1 of the present application; wherein, Figure 1 A is a microstructure photo; Figure 1 B is a microstructure photo of the LPSO phase under a higher magnification.

[0072] Figure 2 is a microstructure photo of the magnesium alloy part obtained in Comparative Example 1 of the present application; wherein, Figure 2 A is a microstructure photo; Figure 2 B is a microstructure photo of the LPSO phase under a higher magnification.

[0073] Figure 3 is a tensile curve of the die-casting alloy part obtained in Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0074] The present application will be described in detail below with specific embodiments. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These all belong to the protection scope of the present application.

[0075] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Multiple" generally includes at least two.

[0076] It is also important to note that the terms "including" or "comprising" and any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not exclude the existence of additional identical elements in the process, method, article, or apparatus including the recited element.

[0077] Example 1

[0078] The present embodiment provides a method for preparing a heat treatment-free high strength and toughness high corrosion resistant magnesium alloy, and the specific steps are as follows:

[0079] 1) According to the theoretical weight percentage of each component Mg-5.5Al-2La-2.5Ce-0.3Mn-0.07Zn-0.03Cu-0.06Ga-0.1Be-0.3Ca-0.2Sr, the pure Mg ingot, pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-30La, Mg-30Ce, Al-20Mn, Al-50Cu, Mg-3Be, Mg-30Ca, Al-10Sr intermediate alloy are designed and selected as raw materials, and the raw materials are preheated to 200 ℃ for drying treatment;

[0080] 2) Preheat the crucible to 200 ℃, evenly coat the crucible with the crucible coating (mainly used to prevent the magnesium liquid from sticking to the crucible, which can be selected from the conventional types in the art and can be obtained through ordinary commercial channels, the same below) on the inner wall of the crucible, and after drying, heat to 400 ℃, and introduce CO2+SF6 mixed gas (mixed volume ratio CO2: SF6 is 99: 1), put the pure Mg ingot into the crucible, completely melt it under the protection of the mixed protective gas of CO2 and SF6, then heat to 780 ℃, add Mg-3Be intermediate alloy, after the alloy is completely melted, add Mg-30La, Mg-30Ce intermediate alloy until it is completely melted, cool to 735 ℃, add pure Al ingot, pure Zn ingot, pure Ga ingot, Al-20Mn, Al-50Cu, Mg-30Ca, Al-10Sr intermediate alloy, completely melt and stir thoroughly, stand still and conduct pre-furnace composition analysis, detect the composition content of the alloy melt, and supplement or dilute the melt with content deviation to make the composition reach the designed magnesium alloy composition range;

[0081] 3) Heat the melt to 730 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, and introduce 1% of the total weight of the melt of the refining agent (specifically the torch magnesium alloy refining agent in the present embodiment, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, then continue to ventilate for 10 min to remove slag and gas;

[0082] 4) The refined melt was left for 10 min and then tested again for pre-furnace component analysis. After the components were qualified, high-pressure casting was performed at 710±5℃, with a injection speed of 5 m / s and a casting pressure (boost pressure) of 80 MPa. A die casting test bar die was used during the production process.

[0083] Example 2

[0084] The present embodiment provides a heat treatment-free high-strength and high-toughness high-corrosion-resistant magnesium alloy and a preparation method thereof. The specific steps are as follows:

[0085] 1) The raw materials were designed to be pure Mg ingot, pure Al ingot, pure Zn ingot, Al-60La, Mg-90Ce, Mg-10Mn, Al-50Cu, Mg-5Be, Mg-30Ca, and Mg-30Sr intermediate alloy, with the theoretical weight percentage of each component being Mg-6Al-1.5La-3.5Ce-0.2Mn-0.4Zn-0.006Cu-0.2Be-0.1Ca-0.6Sr. The raw materials were preheated to 220℃ and dried.

[0086] 2) The crucible was preheated to 220℃, the inner wall of the crucible was evenly coated with crucible paint, and after drying, it was heated to 320℃. Ar+SF6 mixed gas (mixed volume ratio Ar:SF6 is 99:1) was introduced, the pure Mg ingot was put into the crucible and completely melted under the protection of the mixed protective gas of Ar and SF6. Then, the temperature was raised to 750℃, the Mg-5Be intermediate alloy was added, and after the alloy was completely melted, the Al-60La and Mg-90Ce intermediate alloys were added until they were completely melted. The temperature was lowered to 720℃, and the pure Al ingot, pure Zn ingot, Mg-10Mn, Al-50Cu, Mg-30Ca, and Mg-30Sr intermediate alloys were added. After complete melting, the melt was stirred thoroughly, and the composition of the alloy melt was analyzed. If the content of the alloy melt deviated, the melt was supplemented or diluted to make the composition of the magnesium alloy reach the designed range.

[0087] 3) The melt was heated to 720℃, argon gas with a pressure of 0.2 MPa was introduced into the melt to bring in 0.3% of the total weight of the melt of the refining agent (in this embodiment, it is specifically a torch magnesium alloy refining agent, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.), and then the gas was continued for 10 min to remove slag and gas;

[0088] 4) The refined melt was left for 5 min and then tested again for pre-furnace component analysis. After the components were qualified, high-pressure casting was performed at 680±5℃, with a injection speed of 5 m / s and a casting pressure of 40 MPa. A die casting test bar die was used during the production process.

[0089] Example 3

[0090] This embodiment provides a method for preparing a high-strength, high-toughness, and high-corrosion-resistant magnesium alloy without heat treatment. The specific steps are as follows:

[0091] 1) Based on the theoretical weight percentage of each component as Mg-8Al-1.2La-0.4Mn-0.004Zn-0.003Cu-0.1Be-0.2Ca-0.4Sr, pure Mg ingots, pure Al ingots, pure Zn ingots, pure Sr ingots, Al-90La, Al-10Mn, Al-50Cu, Mg-3Be, and Mg-30Ca master alloys were selected as raw materials, and the raw materials were preheated to 210 ℃ and dried.

[0092] 2) Preheat the crucible to 210 ℃, evenly coat the inner wall of the crucible with crucible coating, dry it and then heat it to 500 ℃. Introduce pure SF6 gas, put pure Mg ingot into the crucible, and melt it completely under the protection of pure SF6 protective gas. Then raise the temperature to 760 ℃, add Mg-3Be master alloy, and after the alloy is completely melted, add Al-90La master alloy until it is completely melted. Cool down to 725 ℃, add pure Al ingot, pure Zn ingot, pure Sr ingot, Al-10Mn, Al-50Cu, and Mg-30Ca master alloy, and stir thoroughly after complete melting. Let it stand and perform pre-furnace composition analysis to detect the composition content of the alloy melt. For melts with deviations in content, add materials or dilute them to make the composition reach the designed magnesium alloy composition range.

[0093] 3) Heat the melt to 750 °C, introduce argon gas at a pressure of 0.2 MPa into the melt, and introduce 0.5% of the total weight of the refining agent (specifically, Torch brand magnesium alloy refining agent, purchased from Zhangjiagang Haohua Light Alloy Materials Co., Ltd.) powder into the melt, and then continue to purge for 10 min to remove slag and gas;

[0094] 4) After refining, the melt is allowed to stand for 4 minutes, and then a pre-furnace composition analysis test is performed. If the composition is qualified, high-pressure casting is carried out at 740±5℃, with an injection speed of 8 m / s and a casting pressure of 110 MPa. The mold used in the production process is a die-casting test rod mold.

[0095] Example 4

[0096] This embodiment provides a method for preparing a high-strength, high-toughness, and high-corrosion-resistant magnesium alloy without heat treatment. The specific steps are as follows:

[0097] 1) According to the theoretical weight percentage of each component Mg-4Al-2Ce-0.42Mn-1Zn-0.03Cu-0.04Ga-0.2Be, pure Mg ingot, pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-90Ce, Mg-20Mn, Mg-3Be, Al-50Cu intermediate alloy are selected as raw materials, and the raw materials are preheated to 195 ℃ for drying treatment;

[0098] 2) The crucible is preheated to 195 ℃, the inner wall of the crucible is evenly coated with crucible paint, and after drying, it is heated to 480 ℃, N2+SF6 mixed gas (mixed volume ratio N2:SF6 is 99:1) is introduced, pure Mg ingot is put into the crucible, and it is completely melted under the protection of mixed N2 and SF6 protective gas, then the temperature is raised to 790 ℃, Mg-3Be intermediate alloy is added, after the alloy is completely melted, Mg-90Ce intermediate alloy is added until it is completely melted, the temperature is lowered to 750 ℃, pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-20Mn, Al-50Cu intermediate alloy are added, after completely melting, it is fully stirred, and then it is placed and analyzed for composition, the composition of the alloy melt is detected, and the melt with content deviation is supplemented or diluted to make the composition reach the designed magnesium alloy composition range;

[0099] 3) The melt is cooled to 745 ℃, argon gas with a pressure of 0.2 MPa is introduced into the melt, and 1.1% of the total weight of the melt is added into the melt as a refining agent (in this embodiment, it is specifically a torch magnesium alloy refining agent, which is purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.), and then the gas is continued for 10 min to remove slag and gas;

[0100] 4) The refined melt is placed for 6 min, and then analyzed for composition, and after the composition is qualified, high-pressure casting is carried out at 745±5 ℃, the injection speed is 3 m / s, and the casting pressure is 120 MPa. The mold used in the production process is a die casting test bar mold.

[0101] Example 5

[0102] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistant magnesium alloy, and the specific steps are as follows:

[0103] 1) According to the theoretical weight percentage of each component Mg-4.5Al-5.4La-1Ce-0.1Mn-0.009Zn-0.1Ga-0.004Sr, pure Mg ingot, pure Al ingot, pure Ce ingot, pure La ingot, pure Ga ingot, pure Zn ingot, Al-10Mn, Mg-10Sr intermediate alloy are selected as raw materials, and the raw materials are preheated to 235 ℃ for drying treatment;

[0104] 2) Preheat the crucible to 235 ℃, uniformly coat the inner wall of the crucible with crucible coating, dry it and then heat it to 440 ℃. Cover the crucible with a layer of covering agent (in this embodiment, the specific covering agent used is Torch brand flux, purchased from Zhangjiagang Haohua Light Alloy Materials Co., Ltd.). Place pure Mg ingots into the crucible and wait for them to melt completely. Cover the surface of the melt with another layer of covering agent, then raise the temperature to 760 ℃ and add pure Ce ingots and pure La ingots until they are completely melted. Cool down to 720 ℃ and add pure Al ingots, pure Ga ingots, pure Zn ingots, Al-10Mn, and Mg-10Sr master alloys. After complete melting, stir thoroughly, let stand and perform pre-furnace composition analysis to detect the composition content of the alloy melt. For melts with deviations in content, add materials or dilute to make the composition reach the designed magnesium alloy composition range.

[0105] 3) Heat the melt to 735 °C, introduce argon gas at a pressure of 0.2 MPa into the melt, and introduce 1.5% of the total weight of the refining agent (specifically, Torch brand magnesium alloy refining agent, purchased from Zhangjiagang Haohua Light Alloy Materials Co., Ltd.) powder into the melt, and then continue to purge for 10 min to remove slag and gas.

[0106] 4) After refining, the melt is allowed to stand for 12 minutes, and then a pre-furnace composition analysis test is performed. If the composition is qualified, high-pressure casting is carried out at 690±5℃, with an injection speed of 4.5 m / s and a casting pressure of 50 MPa. The mold used in the production process is a die-casting test rod mold.

[0107] Example 6

[0108] This embodiment provides a method for preparing a high-strength, high-toughness, and high-corrosion-resistant magnesium alloy without heat treatment. The specific steps are as follows:

[0109] 1) Based on the theoretical weight percentage of each component being Mg-3Al-0.4La-0.4Ce-0.5Mn-1.3Zn-0.4Cu-0.09Ca, pure Mg ingots, pure Al ingots, pure Zn ingots, Mg-60La, Mg-60Ce, Mg-5Mn, Al-50Cu, and Mg-30Ca master alloys were selected as raw materials, and the raw materials were preheated to 150 ℃ and dried.

[0110] 2) Preheat the crucible to 150 ℃, evenly coat the crucible with the crucible coating on the inner wall of the crucible, and after drying, heat to 360 ℃, cover a layer of covering agent (the specific covering agent used in this example is the torch brand flux, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) in the crucible, put the pure Mg ingot into the crucible until it is completely melted, cover another layer of covering agent on the surface of the melt, heat to 795 ℃, add Mg-60La, Mg-60Ce intermediate alloy until it is completely melted, cool to 745 ℃, add pure Al ingot, pure Zn ingot, Mg-5Mn, Al-50Cu, Mg-30Ca intermediate alloy, completely melt and stir thoroughly, stand and analyze the composition of the alloy melt, detect the composition content of the alloy melt, and supplement or dilute the melt with the composition deviating from the designed magnesium alloy composition range;

[0111] 3) Reduce the melt to 720 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, and introduce 2% of the total weight of the melt of the refining agent (specifically the torch brand magnesium alloy refining agent in this example, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, then continue to ventilate for 10 min to remove slag and gas;

[0112] 4) After refining, the melt is left to stand for 11 min, and the composition is analyzed and tested again, and after the composition is qualified, high-pressure casting is carried out at 690±5 ℃, the injection speed is 2 m / s, and the casting pressure is 45 MPa. The mold used in the production process is a die casting test bar mold.

[0113] Example 7

[0114] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistant magnesium alloy, and the specific steps are as follows:

[0115] 1) According to the theoretical weight percentage of each component Mg-7.4Al-1.7La-1.9Ce-0.18Mn-2Zn-0.003Cu-0.006Ga-0.004Be-0.003Ca, design and select pure Mg ingot, pure Al ingot, pure Zn ingot, pure Ga ingot, Al-90La, Al-90Ce, Mg-3Be, Mg-5Mn, Mg-20Ca, Al-50Cu intermediate alloy as raw materials, and the raw materials are preheated to 250 ℃ and dried;

[0116] 2) preheat the crucible to 250 ℃, evenly coat the inner wall of the crucible with crucible coating, dry and heat to 380 ℃, introduce pure SF6 gas, put the pure Mg ingot into the crucible, completely melt under the protection of SF6 protective gas, then heat to 800 ℃, add Mg-3Be master alloy, after the alloy is completely melted, add Al-90La, Al-90Ce master alloy until it is completely melted, cool to 735 ℃, add pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-5Mn, Mg-20Ca, Al-50Cu master alloy, completely melt, stir well, stand and carry out pre-furnace composition analysis, detect the composition content of the alloy melt, supplement or dilute the melt with content deviation to make the composition reach the designed magnesium alloy composition range;

[0117] 3) reduce the melt to 725 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, bring in 0.8% of the total weight of the melt of the refining agent (specifically torch magnesium alloy refining agent in this embodiment, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, then continue to ventilate for 10 min to remove slag and gas;

[0118] 4) after refining, the melt is placed for 12 min, and pre-furnace composition analysis test is carried out again, after the composition is qualified, high-pressure casting is carried out at 695±5 ℃, the injection speed is 5.5 m / s, and the casting pressure is 60 MPa. The mold used in the production process is a die casting test bar mold.

[0119] Example 8

[0120] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, and the specific steps are as follows:

[0121] 1) according to the theoretical weight percentage of each component Mg-7Al-5.3La-2.2Ce-0.05Mn-0.6Zn-0.03Cu-0.02Be-0.02Sr, design and select pure Mg ingot, pure Al ingot, pure Zn ingot, Mg-30La, Mg-30Ce, Mg-10Mn, Al-5Be, Mg-10Sr, Al-50Cu master alloy as raw materials, and preheat the raw materials to 175 ℃ for drying treatment;

[0122] 2) Preheat the crucible to 175 ℃, evenly coat the inner wall of the crucible with crucible coating, and after drying, heat to 460 ℃, introduce Ar+SF6 mixed gas (mixed volume ratio Ar: SF6 is 99:1), put pure Mg ingot into the crucible, completely melt under the protection of Ar and SF6 mixed protective gas, then heat to 755 ℃, add Al-5Be master alloy, after the alloy is completely melted, add Mg-30La, Mg-30Ce master alloy until it is completely melted, cool to 745 ℃, add pure Al ingot, pure Zn ingot, Mg-10Mn, Mg-10Sr, Al-50Cu master alloy, completely melt, stir well, stand and carry out pre-furnace composition analysis, detect the composition content of the alloy melt, and supplement or dilute the melt with content deviation to make the composition reach the designed magnesium alloy composition range;

[0123] 3) Heat the melt to 750 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, and bring in 1.3% of the total weight of the melt of the refining agent (in this embodiment, it is specifically torch magnesium alloy refining agent, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, and then continue to ventilate for 10 min to remove slag and gas;

[0124] 4) After refining, the melt is placed for 10 min, and pre-furnace composition analysis test is carried out again, and after the composition is qualified, high-pressure casting is carried out at 725±5 ℃, the injection speed is 7.5 m / s, and the casting pressure is 105 MPa. The mold used in the production process is a die casting test bar mold.

[0125] Example 9

[0126] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, and the specific steps are as follows:

[0127] 1) According to the theoretical weight percentage of each component being Mg-3.2Al-1.5La-3.8Ce-0.46Mn-0.9Zn-0.9Ga-0.3Ca-0.1Sr, pure Mg ingot, pure Al ingot, pure Zn ingot, pure La ingot, pure Ce ingot, pure Ga ingot, Mg-5Mn, Mg-30Ca, and Mg-10Sr master alloy are designed and selected as raw materials, and the raw materials are preheated to 165 ℃ and dried;

[0128] 2) Preheat the crucible to 165 ℃, evenly coat the crucible coating on the inner wall of the crucible, and after drying, heat to 470 ℃, and then introduce N2+SF6 mixed gas (the mixed volume ratio of N2: SF6 is 99: 1), put the pure Mg ingot into the crucible, and completely melt under the protection of the mixed protective gas of N2 and SF6, then heat to 780 ℃, add pure La ingot, pure Ce ingot to completely melt, cool to 740 ℃, add pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-5Mn, Mg-30Ca, Mg-10Sr intermediate alloy, completely melt, and then fully stir, stand and carry out pre-furnace component analysis, detect the component content of the alloy melt, and supplement or dilute the melt with content deviation to make the component reach the designed magnesium alloy component range;

[0129] 3) Keep the melt at 740 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, and bring in 1.8% of the total weight of the melt of the refining agent (in this embodiment, it is specifically a torch magnesium alloy refining agent, which is purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, and then continue to ventilate for 10 min to remove slag and gas;

[0130] 4) After refining, the melt is placed for 8 min, and then pre-furnace component analysis test is carried out again, and after the component is qualified, high-pressure casting is carried out at 740±5 ℃, the injection speed is 2.5 m / s, and the casting pressure is 75 MPa. The mold used in the production process is a die casting test bar mold.

[0131] Example 10

[0132] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, and the specific steps are as follows:

[0133] 1) According to the theoretical weight percentage of each component Mg-3.2Al-8La-0.35Mn-0.002Zn-0.001Cu-0.001Be, design and select pure Mg ingot, pure Al ingot, pure Zn ingot, Mg-60La, Al-10Mn, Al-50Cu, Al-3Be intermediate alloy as raw materials, and preheat the raw materials to 190 ℃ for drying treatment;

[0134] 2) Preheat the crucible to 190 ℃, evenly coat the inner wall of the crucible with crucible coating, and after drying, heat to 410 ℃, introduce CO2+SF6 mixed gas (the mixed volume ratio of CO2: SF6 is 99: 1), put the pure Mg ingot into the crucible, completely melt under the protection of the mixed protective gas of CO2 and SF6, then heat to 760 ℃, add Al-3Be master alloy, after the alloy is completely melted, add Mg-60La master alloy until it is completely melted, cool to 725 ℃, add pure Al ingot, pure Zn ingot, Al-10Mn, Al-50Cu master alloy, completely melt, fully stir, stand and carry out pre-furnace composition analysis, detect the composition content of the alloy melt, and supplement or dilute the melt with content deviation to make the composition reach the designed magnesium alloy composition range;

[0135] 3) Keep the melt at 725 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, and bring in 0.4% of the total weight of the melt of the refining agent (in this embodiment, it is specifically torch magnesium alloy refining agent, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, and then continue to ventilate for 10 min to remove slag and gas;

[0136] 4) After refining, the melt is placed for 13 min, and pre-furnace composition analysis test is carried out again, and after the composition is qualified, high-pressure casting is carried out at 715±5 ℃, the injection speed is 4 m / s, and the casting pressure is 95 MPa. The mold used in the production process is a die casting test bar mold.

[0137] Example 11

[0138] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, and the specific steps are as follows:

[0139] 1) According to the theoretical weight percentage of each component Mg-6.2Al-0.5Ce-0.24Mn-0.1Zn-0.4Cu-0.4Ga-0.05Sr, design and select pure Mg ingot, pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-90Ce, Mg-20Mn, Al-50Cu, Al-10Sr master alloy as raw materials, and preheat the raw materials to 210 ℃ for drying treatment;

[0140] 2) Preheat the crucible to 210 ℃, evenly coat the inner wall of the crucible with crucible coating, and after drying, heat to 370 ℃, introduce Ar+SF6 mixed gas (mixed volume ratio Ar: SF6 is 99:1), put pure Mg ingot into the crucible, completely melt under the protection of Ar and SF6 mixed protective gas, then heat to 755 ℃, add Mg-90Ce master alloy to completely melt, cool to 720 ℃, add pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-20Mn, Al-50Cu, Al-10Sr master alloy, completely melt, stir well, stand and carry out pre-furnace composition analysis, detect the composition content of the alloy melt, and supplement or dilute the melt with content deviation to make the composition reach the designed magnesium alloy composition range;

[0141] 3) Reduce the melt to 720 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, and bring in 1.3% of the total weight of the melt of the refining agent (in this embodiment, it is specifically torch magnesium alloy refining agent, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, and then continue to ventilate for 10 min to remove slag and gas;

[0142] 4) After refining, the melt is placed for 14 min, and pre-furnace composition analysis test is carried out again, and after the composition is qualified, high-pressure casting is carried out at 735±5 ℃, the injection speed is 6.5 m / s, and the casting pressure is 110 MPa. The mold used in the production process is a die casting test bar mold.

[0143] Example 12

[0144] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, and the specific steps are as follows:

[0145] 1) According to the theoretical weight percentage of each component Mg-6.8Al-1La-1.5Ce-0.15Mn-0.04Zn-0.05Cu-0.03Ga-0.005Be-0.002Ca-0.002Sr, design and select pure Mg ingot, pure Al ingot, pure Zn ingot, pure Ga ingot, pure Sr ingot, Mg-30La, Mg-30Ce, Mg-20Mn, Al-3Be, and Mg-30Ca master alloy as raw materials, and preheat the raw materials to 235 ℃ for drying treatment;

[0146] 2) Preheat the crucible to 235 ℃, evenly coat the inner wall of the crucible with crucible coating, and after drying, heat to 490 ℃, introduce CO2+SF6 mixed gas (the mixed volume ratio of CO2: SF6 is 99: 1), put the pure Mg ingot into the crucible, completely melt under the protection of the mixed protective gas of CO2 and SF6, then heat to 775 ℃, add Al-3Be master alloy, after the alloy is completely melted, add Mg-30La, Mg-30Ce master alloy until it is completely melted, cool to 750 ℃, add pure Al ingot, pure Zn ingot, pure Ga ingot, pure Sr ingot, Mg-20Mn, Mg-30Ca master alloy, completely melt and stir well, stand and analyze the composition of the alloy melt in front of the furnace, detect the composition content of the alloy melt, and supplement or dilute the melt with composition deviation to make the composition reach the designed magnesium alloy composition range;

[0147] 3) Reduce the melt to 720 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, and bring in 0.7% of the total weight of the melt of the refining agent (specifically torch magnesium alloy refining agent in this embodiment, purchased from Zhangjiagang Haohua Light Alloy Material Co., Ltd.) powder, then continue to ventilate for 10 min to remove slag and gas;

[0148] 4) After refining, the melt is placed for 9 min, and the composition is analyzed and tested in front of the furnace again, and after the composition is qualified, high-pressure casting is carried out at 700±5 ℃, the injection speed is 7.5 m / s, and the casting pressure (boosting) is 120 MPa. The mold used in the production process is a die casting test bar mold.

[0149] Example 13

[0150] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, and the specific steps are as follows:

[0151] 1) According to the theoretical weight percentage of each component being Mg-5.6Al-3.2La-3.5Ce-0.2Mn-0.01Zn-0.01Ga-0.02Ca, design and select pure Mg ingot, pure Al ingot, pure Zn ingot, pure Ga ingot, Al-60La, Mg-30Ce, Mg-10Mn, and Mg-30Ca master alloy as raw materials, and preheat the raw materials to 155 ℃ for drying treatment;

[0152] 2) preheat the crucible to 155 ℃, evenly coat the inner wall of the crucible with crucible coating, dry and heat to 450 ℃, introduce N2+SF6 mixed gas (mixed volume ratio N2: SF6 is 99: 1), put the pure Mg ingot into the crucible, completely melt under the protection of N2 and SF6 mixed protective gas, then heat to 770 ℃, add Al-60La, Mg-30Ce intermediate alloy to completely melt, cool to 735 ℃, add pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-10Mn, Mg-30Ca intermediate alloy, completely melt, stir well, stand and carry out pre-furnace composition analysis, detect the composition content of the alloy melt, supplement or dilute the melt with content deviation to make the composition reach the designed magnesium alloy composition range;

[0153] 3) reduce the melt to 730 ℃, introduce argon gas with a pressure of 0.2 MPa into the melt, bring in 1.6% of the total weight of the melt of the refining agent (specifically torch magnesium alloy refining agent in this embodiment, purchased from Zhangjiagang Hao Hua Light Alloy Material Co., Ltd.) powder, then continue to ventilate for 10 min to remove slag and gas;

[0154] 4) after refining, the melt is placed for 13 min, and pre-furnace composition analysis test is carried out again, and after the composition is qualified, high pressure casting is carried out at 705±5 ℃, the injection speed is 8 m / s, and the casting pressure is 55 MPa. The mold used in the production process is a die casting test bar mold.

[0155] Example 14

[0156] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, and the specific steps are as follows:

[0157] 1) according to the theoretical weight percentage of each component Mg-4.7Al-3Ce-0.35Mn-1.6Zn-0.5Cu-0.5Ga-0.1Be, design and select pure Mg ingot, pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-30La, Mg-30Ce, Mg-20Mn, Mg-20Cu, Mg-3Be intermediate alloy as raw materials, and the raw materials are preheated to 170 ℃ and dried;

[0158] 2) Preheat the crucible to 170℃, evenly coat the inner wall of the crucible with crucible coating, dry and heat to 330℃, introduce pure SF6 gas, put the pure Mg ingot into the crucible, completely melt under the protection of pure SF6 protective gas, then heat to 785℃, add Mg-3Be master alloy, after the alloy is completely melted, add Mg-30La, Mg-30Ce master alloy until it is completely melted, cool to 730℃, add pure Al ingot, pure Zn ingot, pure Ga ingot, Mg-20Mn, Mg-20Cu master alloy, completely melt, stir thoroughly, stand and conduct pre-furnace composition analysis, detect the composition content of the alloy melt, supplement or dilute the melt with content deviation to make the composition reach the designed magnesium alloy composition range;

[0159] 3) Keep the melt at 730℃, introduce argon gas with a pressure of 0.2 MPa into the melt, bring in 1.9% of the total weight of the melt of the refining agent (in this embodiment, it is specifically Huotang magnesium alloy refining agent, purchased from Zhangjiagang HaoHua Light Alloy Material Co., Ltd.), and then continue to ventilate for 10 min to remove slag and gas;

[0160] 4) After refining, the melt is stood for 6 min, and pre-furnace composition analysis is conducted again. After the composition is qualified, high-pressure casting is conducted at 690±5℃, the injection speed is 7 m / s, and the casting pressure is 30 MPa. The mold used in the production process is a die casting test bar mold.

[0161] Example 15

[0162] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, which is basically same as the method of the embodiment 11, and the difference is that the adding amount of the pure Ga ingot and the Al-50Cu master alloy in the embodiment is 0.04% of Ga in terms of the theoretical weight percentage and 0.04% of Cu in terms of the theoretical weight percentage.

[0163] Example 16

[0164] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, which is basically same as the method of the embodiment 6, and the difference is that the adding amount of the Al-50Cu master alloy in the embodiment is 0.04% of Cu in terms of the theoretical weight percentage.

[0165] Example 17

[0166] The embodiment provides a preparation method of a heat treatment-free high-strength and high-toughness high-corrosion-resistance magnesium alloy, which is basically same as the method of the embodiment 6, and the difference is that the adding amount of the Mg-30Ca master alloy in the embodiment is 0.5% of Ca in terms of the theoretical weight percentage.

[0167] Example 18

[0168] The present example provides a method for preparing a heat treatment free high strength and toughness and high corrosion resistance magnesium alloy. The method is basically the same as that of Example 3, except that the addition amount of the Al-50Cu intermediate alloy used in the present example is added at a Cu theoretical weight percentage of 0.001%. In the present example, a pure Ga ingot is additionally added, and the addition amount is added at a Ga theoretical weight percentage of 0.002%.

[0169] Example 19

[0170] The present example provides a method for preparing a heat treatment free high strength and toughness and high corrosion resistance magnesium alloy. The method is basically the same as that of Example 9, except that the addition amount of the pure Ga ingot used in the present example is added at a Ga theoretical weight percentage of 0.1%. In the present example, an Al-50Cu intermediate alloy is additionally added, and the addition amount is added at a Cu theoretical weight percentage of 0.8%.

[0171] Example 20

[0172] The present example provides a method for preparing a heat treatment free high strength and toughness and high corrosion resistance magnesium alloy. The method is basically the same as that of Example 4, except that the addition amount of the Mg-3Be intermediate alloy used in the present example is added at a Be theoretical weight percentage of 0.05%. In the present example, an Mg-10Sr intermediate alloy is additionally added, and the addition amount is added at a Sr theoretical weight percentage of 0.15%.

[0173] Example 21

[0174] The present example provides a method for preparing a heat treatment free high strength and toughness and high corrosion resistance magnesium alloy. The method is basically the same as that of Example 13, except that the addition amount of the Mg-30Ca intermediate alloy used in the present example is added at a Ca theoretical weight percentage of 0.01%. In the present example, an Mg-5Be intermediate alloy is additionally added, and the addition amount is added at a Be theoretical weight percentage of 0.01%.

[0175] Comparative Example 1

[0176] The present comparative example provides a method for preparing a magnesium alloy, which is basically the same as that of Example 1. The difference is only that no Cu and Ga elements are added in the present comparative example.

[0177] Comparative Example 2

[0178] The preparation method of the magnesium alloy provided by the present comparative example is basically the same as the method of example 1. The difference is that the addition amount of pure Ga and the addition amount of Al-50Cu master alloy in the present comparative example are respectively added in the form of Ga theoretical weight percentage of 0.5% and Cu theoretical weight percentage of 0.6%.

[0179] Comparative example 3

[0180] The preparation method of the magnesium alloy provided by the present comparative example is basically the same as the method of example 1. The difference is that the addition amount of pure Ga and the addition amount of Al-50Cu master alloy in the present comparative example are respectively added in the form of Ga theoretical weight percentage of 0.5% and Cu theoretical weight percentage of 0.6%.

[0181] Comparative example 4

[0182] The preparation method of the magnesium alloy provided by the present comparative example is basically the same as the method of example 4. The difference is that the addition amount of pure Ga, the addition amount of Mg-30Ca master alloy and the addition amount of Mg-3Be master alloy in the present comparative example are respectively added in the form of Ga theoretical weight percentage of 0.7%, Ca theoretical weight percentage of 0.4% and Be theoretical weight percentage of 0.2%.

[0183] Comparative example 5

[0184] The preparation method of the magnesium alloy provided by the present comparative example is basically the same as the method of example 10. The difference is that the addition amount of pure Al ingot in the present example is added in the form of Al theoretical weight percentage of 3.1%, so that Al / R<0.4.

[0185] The weight percentage of each component in the magnesium alloy of examples 1-21 and comparative examples 1-5 of the present application is shown in table 1, and the balance is Mg and other unavoidable impurities.

[0186] Table 1 Unit: weight percentage (%)

[0187]

[0188] Test and result

[0189] 1. Mechanical property test

[0190] The room temperature mechanical property test is carried out according to the method in the standard of GB / T 228.1-2021 "Metallic materials-tensile testing-Part 1: Method of test at room temperature".

[0191] The room temperature tensile property test results of the magnesium alloy of each example and comparative example are shown in table 2.

[0192] 2. Corrosion resistance test

[0193] Salt spray corrosion test was carried out according to the method in GB / T 10125-2021 "Artificial Atmosphere Corrosion Test Salt Spray Test" standard, using 5% neutral NaCl solution, and the experiment was carried out for 168 hours.

[0194] The corrosion resistance results of the magnesium alloys of each embodiment and the comparative example are summarized in Table 3.

[0195] Table 2

[0196]

[0197] Table 3

[0198]

[0199] According to the data in Table 1 and Table 2, the magnesium alloys obtained by the application all have excellent tensile properties; the magnesium alloys prepared in Examples 1, 3, 9, 10, 12, 13, 14, 15, 18, 19, 21 have Al / R≥0.4, and the weight percentage of Zn and M elements satisfies 0.5≤Zn / M≤2, and the tensile strength in the tensile properties is all above 300 MPa; the magnesium alloys prepared in Examples 1, 12, 14, 15, 18, 19 have Al / R≥0.4, and the weight percentage of Zn and M elements satisfies 0.5≤Zn / M≤2, and M is Cu and Ga, and the tensile strength in the tensile properties is all above 310 MPa; the magnesium alloys prepared in Examples 2, 4, 5, 6, 7, 8, 11, 16, 17, 20 have Al / R≥0.4, but the weight percentage of Zn and M elements does not satisfy 0.5≤Zn / M≤2, and the tensile strength in the tensile properties is all above 280 MPa.

[0200] It can be seen from the data in Table 1 and Table 3 that the magnesium alloy obtained by the application has excellent corrosion resistance; the magnesium alloy prepared in Examples 1, 2, 3, 4, 8, 10, 13, 16, 17, 18, 20, and 21 has Al / R≥0.4, and the weight percentage of M and D elements satisfies D / M≥1, and the corrosion rate of the magnesium alloy part is less than 0.6 mm / year; the magnesium alloy prepared in Examples 1, 2, 3, 8, 18, 20, and 21 has Al / R≥0.4, and the weight percentage of M and D elements satisfies D / M≥1, and D is a combination of Be and D1, wherein D1 is at least one of Ca and Sr, and the corrosion rate of the magnesium alloy part is less than 0.5 mm / year; the magnesium alloy prepared in Examples 5, 6, 7, 9, 11, 12, 14, 15, and 19 has Al / R≥0.4, but the weight percentage of M and D elements satisfies D / M<1, and the corrosion rate of the magnesium alloy part is also less than 0.8 mm / year.

[0201] It can be seen from the data in Table 1 and Table 2 and Table 3 that the magnesium alloy prepared in Examples 1, 3, 10, 13, 18, and 21 has Al / R≥0.4, the weight percentage of Zn and M elements satisfies 0.5≤Zn / M≤2, and the weight percentage of M and D elements satisfies D / M≥1, the yield strength in the tensile properties of the magnesium alloy part is more than 180 MPa, the tensile strength is more than 300 MPa, the elongation is more than 12%, and the corrosion rate is less than 0.6 mm / year, which has high strength and toughness and corrosion resistance. Further, Examples 1 and 18 also satisfy the following conditions: M is a combination of Cu and Ga, and D is a combination of Be and D1, wherein D1 is at least one of Ca and Sr, the yield strength in the tensile properties of the magnesium alloy part is more than 181 MPa, the tensile strength is more than 312 MPa, the elongation is more than 18%, and the corrosion rate is less than 0.46 mm / year -1 In the following, excellent high strength and toughness and corrosion resistance are obtained.

[0202] Comparative Example 1 is a heat treatment-free high strength and toughness and high corrosion resistance magnesium alloy without adding Cu and Ga elements, and since no Cu and Ga elements form a high-content and high-width LPSO phase, the tensile strength is significantly lower than that of the heat treatment-free high strength and toughness and high corrosion resistance magnesium alloy of Example 1 which adds Cu and Ga elements.

[0203] In Comparative Example 2, the added Cu and Ga elements are too much, which does not satisfy the requirement that the total weight percentage of Cu and Ga elements is 0.001-1%, and the elongation and corrosion resistance are also significantly reduced compared with Example 1.

[0204] Comparative Example 3 is a heat treatment-free high strength and toughness and high corrosion resistance magnesium alloy without adding Be, Ca and Sr elements. Since the compactness of the oxidation film on the surface of the alloy is not improved by Be, Ca and Sr elements, the corrosion resistance of the alloy is significantly lower than that of the heat treatment-free high strength and toughness and high corrosion resistance magnesium alloy of Example 1 which adds Be, Ca and Sr elements.

[0205] In Comparative Example 4, the added Be, Ca and Sr elements are too much, which does not meet the requirement that the total weight percentage of Be, Ca and Sr elements is 0.001-1%, and the alloy has a high tendency of hot cracking and poor formability. The tensile strength and elongation of the alloy are both significantly reduced compared with those of Example 1.

[0206] It can be seen from the data in Table 1 and Table 2 that the weight percentage of Al element in the heat treatment-free high strength and toughness and high corrosion resistance magnesium alloy prepared in Comparative Example 5 is less than 0.4 times the weight percentage of R element, which does not meet the requirement that Al / R≥0.4. Compared with Example 10, the tensile strength and elongation in the tensile performance are significantly reduced.

[0207] Figure 1 The microstructure photo of the magnesium alloy part obtained in Example 1 of the present application is shown in Figure 1 A. It can be seen that there are a large number of LPSO phases in the alloy structure, and the width of the LPSO phase is large. Further observation of the LPSO phase at a higher magnification shows that Figure 1 B. It can be found that the width of the wider LPSO phase is more than 50 nm, and the width of the narrower LPSO phase is about 20 nm. These high-content and high-width LPSO phases can significantly improve the strength of the alloy.

[0208] Figure 2 The microstructure photo of the magnesium alloy part obtained in Comparative Example 1 of the present application is shown in Figure 2 A. It can be seen that there are also LPSO phases in the alloy structure, but the content and width are far less than those of Example 1. Further observation of the LPSO phase at a higher magnification shows that Figure 2 B. It can be found that the width of the wider LPSO phase is about 20 nm, and the width of the narrower LPSO phase is less than 10 nm. The strengthening ability of the low-content and low-width LPSO phase is far less than that of the high-content and high-width LPSO phase in Example 1.

[0209] Figure 3 The tensile curve of the die-casting alloy part of Example 1 and Comparative Example 1 of the present application is shown in

[0210] From the test results in Table 2-3, and Figures 1-3As shown in the content, the application is compounded with Zn and M elements in Mg-Al-Mn-R, to form a high-content and high-width LPSO phase, which significantly improves the strength and toughness of the alloy, the yield strength can reach more than 170 MPa, the tensile strength can reach more than 280 MPa, and the elongation can reach more than 10%; adding D element, the corrosion resistance of the alloy is improved, the corrosion rate under 5% NaCl neutral salt spray for 168 h is less than 0.8 mm / year, and the alloy has good die casting performance. And through the optimization of alloy composition and process parameters, the single and comprehensive performance of the magnesium alloy can be further improved according to the specific application scene, so that the magnesium alloy has a good application prospect in the direction of forming automobile integrated rear floor, front cabin, or two-wheeled vehicle main frame, baffle, or other parts, etc. on the basis of far superior performance to traditional magnesium alloy.

[0211] The above is only an embodiment of the application, not to limit the patent range of the application, any equivalent structure or equivalent process transformation in the application specification, or direct or indirect application in other related technical fields, are also included in the patent protection range of the application.

Claims

1. A heat-treasure-free, high-strength, high-toughness, and high-corrosion-resistant magnesium alloy, characterized in that, The weight percentages of each component in the magnesium alloy are as follows: Al：3~8%； Mn: 0.1~0.5%; Zn: 0.002~2%; R：0.5~8%； M： 0.001~1%； D: 0.001~1%, total other impurities ≤0.3%, balance is Mg; Wherein, R is at least one of La and Ce, and the weight percentage of Al and R elements must satisfy Al / R≥0.4; The magnesium alloy satisfies the following conditions: (1) The weight percentages of Zn and M satisfy the following condition: 0.5 ≤ Zn / M ≤ 2; (2) M is a Cu-Ga composite; (3) The weight percentages of M and D satisfy the following condition: D / M≥1; (4) D is a combination of Be and D1, wherein D1 is at least one of Ca and Sr.

2. The heat-treasure-free, high-strength, high-toughness, and high-corrosion-resistant magnesium alloy according to claim 1, characterized in that, The magnesium alloy has a tensile strength of over 310 MPa and a corrosion rate of less than 0.5 mm / year under 5% NaCl neutral salt spray for 168 h.

3. A method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy as described in claim 1 or 2, characterized in that, The method includes the following steps: S1. Material preparation: Weigh the raw materials according to the weight percentage of each component of the magnesium alloy; S2, Staged Melting: First-stage melting: Preheat the crucible to 300~500 ℃, and melt the pure Mg ingot in the crucible; Second-stage melting: Heat to 750~800 ℃, add R, Mg-R master alloy and / or Al-R master alloy, add some M, add pure Mn or Mg-Mn master alloy or Al-Mn master alloy. Third-stage melting: Cool down to the third-stage melting temperature T, which is 720~750 ℃, and then add pure Al, pure Zn, the remaining M, and D to obtain magnesium alloy melt; S3. Powder spraying refining: Keep the temperature of the magnesium alloy melt within the range of T, and spray refining agent powder into the melt for powder spraying refining and slag removal treatment to obtain a refined melt. S4. Casting or die casting: The refined melt is heated to the casting temperature and then cast or die-cast to obtain alloy casting ingots or die-cast alloy parts.

4. The method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy without heat treatment as described in claim 3, characterized in that, M is a Cu / Ga blend, added during both the second-stage and third-stage smelting processes, including: In the second-stage melting process, the M added is a Cu, Mg-Cu master alloy and / or Al-Cu master alloy; In the third-order smelting, the remaining M is added to form Ga.

5. The method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy as described in claim 3 or 4, characterized in that, Step S1 also includes preheating the weighed raw materials to 150~250 ℃ and drying them.

6. The method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy without heat treatment as described in claim 5, characterized in that, From the raw material preheating in step S1 to the alloy casting ingot or die-cast alloy part obtained in step S4, all are carried out in a protective atmosphere or in a vacuum environment.

7. The method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy without heat treatment as described in claim 3 or 4, characterized in that, In step S2, after preheating, a protective gas is introduced to form a protective atmosphere. The protective gas is pure SF6 or a mixture of SF6 and a base gas. The base gas is selected from at least one of N2, CO2, and Ar.

8. The method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy as described in claim 3 or 4, characterized in that, In step S2, after applying a layer of covering agent to the crucible and preheating the crucible, another layer of covering agent is applied to cover the melt after the pure Mg melts. The solvent density of the covering agent is <1.58 g / cm³. 3 .

9. The method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy as described in claim 3 or 4, characterized in that, In step S3, Ar protective gas is introduced and the refining agent is introduced with the gas flow. The refining agent includes salt flux that adsorbs impurities in the melt and is used in an amount of 0.3 to 2.0% of the total weight of the magnesium alloy melt.

10. The method for preparing a heat-tough, high-strength, and corrosion-resistant magnesium alloy as described in claim 3 or 4, characterized in that, In step S4, the refined melt is heated to a casting temperature of 670~750 ℃, and die-cast alloy parts are obtained by high pressure casting. The high-speed injection speed of high pressure casting is 2~8 m / s, and / or the casting pressure is 30~120 MPa.

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