Magnesium alloy, magnesium alloy structural part, preparation method of magnesium alloy structural part and vehicle

Abstract

The invention discloses a magnesium alloy, a magnesium alloy structural part, a preparation method of the magnesium alloy structural part and a vehicle, and belongs to the technical field of alloy materials. The magnesium alloy comprises the following components in percentage by mass: 4.8-6.2% of zinc, more than or equal to 0.45% of manganese, more than 0 and less than or equal to 0.4% of scandium, less than or equal to 0.15% of impurity elements and the balance of magnesium. The magnesium alloy and the magnesium alloy structural part prepared from the magnesium alloy not only have good mechanical properties such as strength and plasticity, but also have good corrosion resistance and thermal deformation capacity, and can be widely applied to vehicles, especially new energy automobiles.

Description

Technical Field

[0001] The present application relates to the technical field of alloy materials, and in particular to a magnesium alloy, a magnesium alloy structural part, a preparation method thereof, and a vehicle. Background Art

[0002] Magnesium alloys have the advantages of excellent specific strength and specific stiffness, good cutting performance, good shock absorption performance and electromagnetic shielding performance. They are usually used in related parts in automobiles, such as body, interior and exterior systems, chassis systems, and structural parts of power systems. They play an important role in the lightweight development of the automotive industry.

[0003] Common magnesium alloys include Mg-Zn alloys. Mg-6Zn-0.5Mn alloy is an alloy with a higher degree of alloying in the Mg-Zn series and has higher strength and plasticity. However, this type of alloy has severe galvanic corrosion. When it is used in electric drive scenarios, such as electric drive housings, it will cause unwanted galvanic corrosion of the electric drive housings.

[0004] It can be seen that it is necessary to provide a magnesium alloy which not only has high strength and plasticity but also has strong corrosion resistance. Summary of the invention

[0005] The present application provides a magnesium alloy, a magnesium alloy structural part, a method for preparing the same, and a vehicle to solve the technical problems existing in the related art. The technical solutions include the following:

[0006] In a first aspect, the present application provides a magnesium alloy, wherein the magnesium alloy comprises the following components in percentage by mass:

[0007] Zinc 4.8%-6.2%, manganese ≥0.45%, 0<scandium ≤0.4%, impurity elements ≤0.15%, and magnesium as the balance.

[0008] In some possible implementations, the mass percentage of scandium is 0.2%-0.4%.

[0009] In some possible implementations, the mass percentage of manganese is 0.45%-0.7%.

[0010] In a second aspect, the present application provides a magnesium alloy structural part, which is prepared by using the magnesium alloy described in any one of the first aspects of the present application.

[0011] In some possible implementations, the magnesium alloy structural component is a rolled magnesium alloy.

[0012] In some possible implementations, the magnesium alloy structural member simultaneously satisfies the following physical parameters: tensile strength greater than or equal to 340 MPa, yield strength greater than or equal to 200 MPa, elongation greater than or equal to 10%, and electrochemical corrosion rate less than or equal to 0.3 mm·y -1 .

[0013] In some possible implementations, the magnesium alloy structural component is a housing of an electrical device.

[0014] In some possible implementations, the magnesium alloy structural component is a housing of an electric drive device.

[0015] In a third aspect, the present application provides a vehicle, comprising the magnesium alloy structural component as described in any one of the second aspect of the present application.

[0016] In some possible implementations, the vehicle is a new energy vehicle, and the magnesium alloy structural component is a housing of an electric drive device in the new energy vehicle.

[0017] In a fourth aspect, the present application provides a method for preparing a magnesium alloy structural part, and the magnesium alloy structural part is as described in any one of the second aspect of the present application, and the method for preparing the magnesium alloy structural part comprises: using a magnesium alloy raw material to prepare a magnesium alloy intermediate through an alloying process; and processing the magnesium alloy intermediate to prepare a magnesium alloy structural part.

[0018] In some possible implementations, the preparation method further includes: performing a rolling process on the magnesium alloy structural part to prepare a rolled magnesium alloy structural part.

[0019] The beneficial effects of the technical solution provided by this application include at least:

[0020] The magnesium alloy provided in the embodiment of the present application has an improved formula. Based on a specific ratio of zinc, manganese and magnesium, the magnesium alloy has high strength and strong plasticity characteristics. Furthermore, by adding a specific ratio of scandium thereto, it synergizes with the specific ratio of zinc, manganese and magnesium. On the one hand, the scandium element is conducive to increasing the solidification temperature of the magnesium alloy, increasing the solubility of zinc in the magnesium alloy, and improving the element segregation phenomenon of the cast magnesium alloy, which is beneficial for improving the mechanical properties of the magnesium alloy, improving its processing properties, and enhancing corrosion resistance. On the other hand, the scandium element is also conducive to improving the heat resistance of the magnesium alloy, allowing the temperature to rise during the deformation of the alloy, which is conducive to selecting a higher deformation temperature to improve the thermal deformation ability of the magnesium alloy and improve the forming rate. In summary, the magnesium alloy structural parts based on the above-mentioned magnesium alloy not only have high strength and plasticity, but also have excellent corrosion resistance, so that it can be used in electric drive scenarios, such as new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 is a metallographic diagram of the as-cast Mg-6Zn-0.5Mn alloy of Comparative Example 1 provided in the present application;

[0023] Figure 2 It is the RD-TD surface metallographic image of the rolled Mg-6Zn-0.5Mn alloy of Comparative Example 1 provided in the present application;

[0024] Figure 3 is a metallographic diagram of the cast Mg-6Zn-0.5Mn-0.4Sc alloy of Example 4 provided in the present application;

[0025] Figure 4 It is the RD-TD surface metallographic image of the rolled Mg-6Zn-0.5Mn-0.4Sc alloy of Example 4 provided in the present application. DETAILED DESCRIPTION

[0026] In view of the technical problem that although magnesium alloys currently have high strength and plasticity, galvanic corrosion is relatively serious, when they are used in electric drive scenarios, such as electric drive housings, undesirable galvanic corrosion of the electric drive housings may occur. An embodiment of the present invention provides a magnesium alloy that not only has high strength and plasticity, but also has strong corrosion resistance, so that it can be used in electric drive scenarios, such as in new energy vehicles.

[0027] The first aspect of the present application discloses a magnesium alloy, which includes the following components in mass percentage: zinc (Zn) 4.8%-6.2%, manganese (Mn) ≥0.45%, 0<scandium (Sc) ≤0.4%, impurity elements ≤0.15%, and magnesium (Mg) as the balance.

[0028] The magnesium alloy provided in the embodiment of the present application has an improved formula. Based on a specific ratio of zinc, manganese and magnesium, the magnesium alloy has high strength and strong plasticity characteristics. Further, by adding a specific ratio of scandium thereto, it synergizes with the specific ratio of zinc, manganese and magnesium. On the one hand, the scandium element is conducive to increasing the solidification temperature of the magnesium alloy, increasing the solubility of zinc in the magnesium alloy, and improving the element segregation phenomenon of the cast magnesium alloy, which is beneficial for improving the mechanical properties of the magnesium alloy, improving its processing properties, and enhancing corrosion resistance. On the other hand, the scandium element is also conducive to improving the heat resistance of the magnesium alloy, allowing the temperature to rise during the deformation of the alloy, which is conducive to selecting a higher deformation temperature to improve the thermal deformation ability of the magnesium alloy and improve the forming rate. In summary, the magnesium alloy structural parts based on the above-mentioned magnesium alloy not only have high strength and plasticity, but also have excellent corrosion resistance, especially corrosion resistance, so that it can be used in electric drive scenarios, such as new energy vehicles.

[0029] The magnesium alloy involved above can be a magnesium alloy ingot prepared based on an alloying process, or can be a magnesium alloy structural part prepared by molding based on the magnesium alloy ingot.

[0030] The composition and content of each element in the magnesium alloy are further exemplified below.

[0031] Elemental zinc (Zn), for example, can be dissolved into the crystal lattice of metallic magnesium through a solid solution mechanism to increase the strength and hardness of the magnesium alloy.

[0032] The mass percentage of element zinc (Zn) in the magnesium alloy can be 4.8%-6.2%, for example, it can include but is not limited to 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, etc., or other values ​​within the above range, and the present application does not impose any limitation on this.

[0033] Manganese (Mn) can be used for, but not limited to, refining the grain size of magnesium metal to improve the strength and toughness of magnesium alloys. In particular, manganese (Mn) can also combine with some impurity elements in magnesium metal (such as iron (Fe) elements, silicon (Si) elements, etc.) to form stable compounds, thereby improving the corrosion resistance of magnesium alloys.

[0034] In some embodiments, the mass percentage of element manganese (Mn) in the magnesium alloy is ≥0.45%, for example, it may include 0.45%, 0.48%, 0.51%, 0.54%, 0.57%, 0.60%, 0.63%, 0.66%, 0.69%, 0.72%, 0.75%, 0.78%, 0.81%, 0.84%, 0.87%, 0.90%, etc., or other values ​​within the above range, and the present application does not impose any limitations on this.

[0035] In some other embodiments, the mass percentage of the element manganese (Mn) in the magnesium alloy can further be 0.45%-0.7%, for example, it can be 0.45%, 0.48%, 0.51%, 0.54%, 0.57%, 0.60%, 0.63%, 0.66%, 0.69%, 0.70%, etc., or other values ​​within the above range, and the present application does not impose any limitation on this.

[0036] The element scandium (Sc) can be used for, but not limited to, increasing the solidification temperature of magnesium alloys, allowing magnesium alloys to select a higher deformation temperature, thereby improving the thermal deformation capacity of magnesium alloys; at the same time, the element scandium (Sc) can also improve the corrosion resistance of magnesium alloys. In particular, a higher solidification temperature of magnesium alloys is conducive to improving the solubility and diffusivity of other elements in magnesium alloys, thereby avoiding the element segregation phenomenon that may occur during the casting process of magnesium alloys, and ensuring the mechanical properties of magnesium alloys.

[0037] In some embodiments, the mass percentage of the element scandium (Sc) in the magnesium alloy is 0<scandium (Sc)≤0.4%, for example, it may include 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, etc., or other values ​​within the above range, and the present application does not impose any limitations on this.

[0038] In some other embodiments, the mass percentage of the element scandium (Sc) in the magnesium alloy can further be 0.2%-0.4%, for example, it can include 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, etc., or other values ​​within the above range, and the present application does not impose any limitation on this.

[0039] In some examples, the magnesium alloy involved above is a magnesium alloy ingot prepared based on an alloying process, and the magnesium alloy ingot can be prepared by the following preparation method.

[0040] Step 1: Weigh the raw materials according to the magnesium alloy formula. The raw materials can be, for example, single metals of magnesium, zinc, manganese, and scandium, alloys or compounds of any two or three of them, and can be selected according to the requirements.

[0041] In some embodiments, the raw material of elemental magnesium (Mg) may, for example, include solid metallic magnesium (e.g., a magnesium ingot), the raw material of elemental zinc (Zn) may, for example, include solid metallic zinc (e.g., zinc particles), the raw material of elemental manganese (Mn) may, for example, include a magnesium-manganese alloy, and the raw material of elemental scandium (Sc) may, for example, include a magnesium-scandium alloy.

[0042] In some embodiments, the magnesium-manganese alloy may include, for example, Mg-10Mn. The number 10 mentioned herein means that the mass of manganese accounts for 10% of the mass of the magnesium-manganese alloy.

[0043] In some embodiments, the magnesium-scandium alloy may include, for example, Mg-10Sc. The number 10 mentioned herein means that scandium accounts for 10% of the weight of the magnesium-scandium alloy.

[0044] Step 2: The graphite crucible is heated to a set temperature, and the preheated elemental magnesium (Mg) raw material is placed in the graphite crucible and then heated and melted to obtain liquid metal magnesium.

[0045] In some embodiments, the set temperature of the graphite crucible can be 380°C-420°C, for example, it can include but is not limited to 380°C, 385°C, 390°C, 395°C, 400°C, 405°C, 410°C, 415°C, 420°C, etc.

[0046] In some embodiments, the smelting temperature of the raw material of elemental magnesium (Mg) can be 745°C-755°C, for example, it can include 745°C, 746°C, 747°C, 748°C, 749°C, 750°C, 751°C, 752°C, 753°C, 754°C, 755°C, etc.; the smelting time can be 1h-2h, for example, it can include 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, etc., or other values ​​within the above range, and the present application does not impose any limitation on the comparison.

[0047] In some embodiments, the preheating temperature of the elemental magnesium (Mg) raw material may be 100°C-160°C, for example, including but not limited to 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, etc.

[0048] In some embodiments, after the elemental magnesium (Mg) raw material is placed in the graphite crucible, a covering agent may be evenly sprinkled on the surface of the elemental magnesium (Mg) raw material. The covering agent may be used, but is not limited to, to isolate oxygen and prevent the raw material in the graphite crucible from burning.

[0049] In some embodiments, the covering agent may include, but is not limited to, magnesium chloride (MgCl 2 ), potassium chloride (KCl), calcium chloride (MgCa 2 ), magnesium oxide (MgO) as the main components.

[0050] Step 3: Add the preheated raw material of elemental zinc (Zn) to the liquid magnesium metal, perform a refining, and obtain a refined liquid metal.

[0051] In some embodiments, after adding the raw material of elemental zinc (Zn) to the liquid magnesium metal, for example, a covering agent may be evenly sprinkled on the surface of the liquid magnesium metal. The covering agent may be used for, but is not limited to, isolating oxygen to prevent the raw material in the graphite crucible from burning.

[0052] In some embodiments, the covering agent may include, but is not limited to, magnesium chloride (MgCl 2 ), potassium chloride (KCl), calcium chloride (MgCa 2 ), magnesium oxide (MgO) as the main components.

[0053] In some embodiments, the preheating temperature of the raw material of elemental zinc (Zn) can be 100°C-160°C, for example, it can include but is not limited to 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, etc.

[0054] Step 4: adding preheated elemental manganese (Mn) raw materials to the liquid metal after primary refining, and performing secondary refining to obtain liquid metal after secondary refining.

[0055] In some embodiments, the temperature of the secondary refining may be 780°C-820°C, for example, including but not limited to 780°C, 785°C, 790°C, 795°C, 800°C, 805°C, 810°C, 815°C, 820°C, etc.

[0056] In some embodiments, the preheating temperature of the elemental manganese (Mn) raw material may be 100°C-160°C, for example, including but not limited to 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, etc.

[0057] In some embodiments, after adding the preheated elemental manganese (Mn) raw material to the liquid metal after the primary refinement, for example, a covering agent can be evenly sprinkled on the surface of the liquid metal after the primary refinement. The covering agent can be used for, but is not limited to, isolating oxygen and preventing the raw material in the graphite crucible from burning.

[0058] In some embodiments, the covering agent may include, but is not limited to, magnesium chloride (MgCl 2 ), potassium chloride (KCl), calcium chloride (MgCa 2 ), magnesium oxide (MgO) as the main components.

[0059] Step 5: Add the preheated raw material of element scandium to the liquid metal after the second refinement, and perform the third refinement to obtain the liquid metal after the third refinement.

[0060] In some embodiments, the preheating temperature of the raw material of elemental scandium may be 100°C-160°C, for example, including but not limited to 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, etc.

[0061] In some embodiments, the time for the three refinings may be 8 min-12 min, for example, may include but not limited to 8 min, 9 min, 10 min, 11 min, 12 min.

[0062] In some embodiments, after adding the preheated scandium raw material to the liquid metal after secondary refinement, for example, a covering agent can be evenly sprinkled on the surface of the liquid metal after secondary refinement. The covering agent can be used for, but is not limited to, isolating oxygen and preventing the raw material in the graphite crucible from burning.

[0063] In some embodiments, the covering agent may include, but is not limited to, magnesium chloride (MgCl 2 ), potassium chloride (KCl), calcium chloride (MgCa 2 ), magnesium oxide (MgO) as the main components.

[0064] Step 6: Stir the liquid metal after three refinings and remove the surface scum to obtain a liquid magnesium alloy, pour the liquid magnesium alloy into a pre-dried metal mold at a uniform speed, and cool it to obtain a magnesium alloy ingot. The magnesium alloy ingot includes the following components in mass percentage: zinc (Zn) 4.8%-6.2%, manganese (Mn) ≥ 0.45%, 0 < scandium (Sc) ≤ 0.4%, impurity elements ≤ 0.15%, and magnesium (Mg) as the balance.

[0065] The present application also provides a magnesium alloy structural part prepared by using the magnesium alloy as described above. The magnesium alloy structural part may include magnesium alloy products with specific structures and sizes that can meet specific usage requirements, such as plates, profiles, pipes, bars, etc. for bearing and / or supporting, or magnesium alloy structural parts used in wheels, bodies, and vehicle seat brackets in vehicles, or magnesium alloy structural parts used in the housing of electric drive devices of new energy vehicles.

[0066] When preparing magnesium alloy structural parts, they can be directly prepared based on magnesium alloy raw materials, such as the method involved in the above-mentioned magnesium alloy ingot. After obtaining the liquid magnesium alloy, it can be directly cast and optionally rolled to obtain the magnesium alloy structural parts. Alternatively, the magnesium alloy ingot prepared in advance can be melted, and then cast and optionally rolled to obtain the magnesium alloy structural parts.

[0067] As mentioned above, the magnesium alloy provided in the embodiment of the present application adds scandium in a specific ratio, which works synergistically with zinc, manganese and magnesium in a specific ratio, so that the magnesium alloy can exhibit excellent mechanical properties, processing properties, corrosion resistance and thermal deformation capacity. In view of this, the magnesium alloy structural parts prepared by the magnesium alloy described above provided in the embodiment of the present application not only have high strength and plasticity, but also have excellent corrosion resistance, so that it can be used in electric drive scenarios (such as the housing of the electric drive device for new energy vehicles).

[0068] In some embodiments, the magnesium alloy structural part may be, for example, a cast magnesium alloy structural part or a rolled magnesium alloy structural part. The cast magnesium alloy structural part is obtained by casting a liquid magnesium alloy. The rolled magnesium alloy structural part is obtained by rolling a cast magnesium alloy structural part.

[0069] In some embodiments, the magnesium alloy structural member provided in the embodiment of the present application can, for example, simultaneously satisfy the following physical parameters, so that the magnesium alloy structural member provided in the embodiment of the present application not only has high strength and plasticity, but also has excellent corrosion resistance, so as to be used in electric drive scenarios, such as the housing of the electric drive device for new energy vehicles: tensile strength is greater than or equal to 340 MPa, for example, it can include 340 MPa, 345 MPa, 350 MPa, 355 MPa, 360 MPa, 365 MPa, 370 MPa, etc.; yield strength is greater than or equal to 200 MPa, for example, it can include 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, etc.; elongation is greater than or equal to 10%, for example, it can include 10%, 15%, 20%, 25%, 30%, 35%, etc.; electrochemical corrosion rate is less than or equal to 0.3 mm·y -1 , for example, may include 0.3 mm·y -1 、0.25mm·y -1 、0.2mm·y -1 、0.15mm·y -1 、0.1mm·y -1 、0.5mm·y -1 Etc., or other values ​​within the above range, this application does not impose any limitation on this.

[0070] In some embodiments, the magnesium alloy structural member provided in the embodiments of the present application may include, for example, a housing of an electric drive device. The electric drive device is used to indicate any device that can convert electrical energy into mechanical energy, and can be used as the core of a new energy vehicle power system to drive the vehicle. The housing of the electric drive device provided in the embodiments of the present application has good corrosion resistance. When the housing of the electric drive device is applied to a new energy vehicle, it can not only provide a more reliable operating environment for the electric drive device, but also meet the requirements of lightweight vehicles and reduce vehicle energy consumption.

[0071] The present application also provides a method for preparing the magnesium alloy structural part as described above, comprising the following steps.

[0072] Step 1: Using a magnesium alloy raw material, through an alloying process, a magnesium alloy intermediate is prepared. The magnesium alloy raw material can be, for example, the magnesium alloy described in the first aspect of the present application or a magnesium alloy prepared according to the above-mentioned method for preparing a magnesium alloy; the magnesium alloy intermediate can be, for example, a liquid magnesium alloy.

[0073] Step 2: Processing the magnesium alloy intermediate to obtain a magnesium alloy structural part.

[0074] In some embodiments, the magnesium alloy structural part may include, for example, a cast magnesium alloy structural part, and processing the magnesium alloy intermediate may include, for example: performing a casting process on the magnesium alloy intermediate through a casting process to obtain a cast magnesium alloy structural part.

[0075] In some embodiments, the magnesium alloy structural part may include, for example, a rolled magnesium alloy structural part, and the processing of the magnesium alloy intermediate may include, for example: casting the magnesium alloy intermediate through a casting process to obtain a cast magnesium alloy structural part; processing the cast magnesium alloy structural part through a rolling process to obtain a rolled magnesium alloy structural part.

[0076] In some embodiments, the method of processing a cast magnesium alloy structural part by a rolling process may, for example, include: cutting and grinding the cast magnesium alloy structural part; repeatedly rolling and annealing the cut and ground cast magnesium alloy structural part at a set rolling speed using a rolling roller heated to a rolling temperature to obtain a rolled magnesium alloy structural part.

[0077] In some embodiments, the rolling temperature may be 180°C-220°C, for example, may include but is not limited to 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, etc.

[0078] In some embodiments, the set rolling speed may be 1.8 r / min-2.2 r / min, for example, may include but is not limited to 1.8 r / min, 1.9 r / min, 2.0 r / min, 2.1 r / min, 2.2 r / min, etc.

[0079] In some embodiments, the number of repeated rolling and annealing treatments may be 7 to 11 times, for example, including but not limited to 7 times, 8 times, 9 times, 10 times, 11 times, etc.

[0080] In some embodiments, the temperature of the annealing treatment can be 280℃-320℃, for example, it can include but is not limited to 280℃, 285℃, 290℃, 295℃, 300℃, 305℃, 310℃, 315℃, 320℃, etc.; the holding time of the annealing treatment can be 8min-12min, for example, it can include but is not limited to 8min, 9min, 10min, 11min, 12min, etc.

[0081] The present application also provides a vehicle, which includes the magnesium alloy structural component as described above.

[0082] In some embodiments, the vehicle provided in the present application is a new energy vehicle, and the magnesium alloy structural part is the housing of the electric drive device in the new energy vehicle. Among them, the magnesium alloy structural part can be, for example, the magnesium alloy structural part as described above or a magnesium alloy structural part prepared according to the preparation method of the magnesium alloy structural part as described above. In the embodiments of the present application, the magnesium alloy structural part has high strength and plasticity, and excellent corrosion resistance, so that when it is applied to new energy vehicles, especially the housing of the electric drive device in new energy vehicles, it can not only meet the demand for lightweight vehicles and reduce the energy consumption of vehicles; it can also provide a more stable and reliable operating environment for the electric drive device of new energy vehicles.

[0083] The exemplary embodiments of the present invention will be described in more detail below. Although the exemplary embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. In the embodiment, if specific techniques or conditions are not indicated, the techniques or conditions described in the document in this area or the product instructions are carried out. The reagents used or the instruments that are not indicated by the manufacturer are all conventional products that can be obtained commercially.

[0084] Example 1

[0085] Embodiment 1 provides a rolled magnesium alloy sheet, which includes the following components in mass percentage: 6% by mass of zinc, 0.5% by mass of manganese, 0.1% by mass of scandium, and the remainder being magnesium and unavoidable impurities. The magnesium alloy is referred to as Mg-6Zn-0.5Mn-0.1Sc.

[0086] The preparation method of the magnesium alloy sheet is as follows:

[0087] Step 1: Weigh a certain amount of magnesium, zinc, Mg-10Mn and Mg-10Sc according to the magnesium alloy formula.

[0088] Step 2: Heat the graphite crucible to 400°C, put the preheated magnesium into the graphite crucible, and evenly sprinkle the covering agent on the surface of the magnesium, gradually heat to 750°C±5°C, and melt for 1h-2h to obtain liquid magnesium.

[0089] Step 3: Tear off the protective film formed by the covering agent on the surface of the liquid magnesium, add the preheated zinc into the liquid magnesium from the opening, and evenly sprinkle the covering agent at the opening, perform a refining, and obtain the refined liquid metal.

[0090] Step 4: Tear off the protective film formed by the covering agent on the surface of the liquid metal after the primary refinement, add preheated Mg-10Mn to the liquid metal after the primary refinement, raise the temperature to 800°C, perform secondary refinement, and obtain the liquid metal after secondary refinement.

[0091] Step 5: Tear off the protective film formed by the surface covering agent of the liquid metal after secondary refining, add preheated Mg-10Sc to the liquid metal after secondary refining, keep warm for 10 minutes, and perform tertiary refining to obtain tertiary refined liquid metal.

[0092] Step 6: Stir the liquid metal after three refinings for 2 minutes to remove the surface scum to obtain liquid magnesium alloy.

[0093] Step 7: pour the liquid magnesium alloy into a pre-dried metal mold at a uniform speed, and take out the mold and the liquid magnesium alloy after they cool to room temperature to obtain a cast magnesium alloy structural part; use an electric spark wire cutting machine to cut the cast magnesium alloy structural part into a 60mm×40mm×10mm cast magnesium alloy plate.

[0094] Step 8: Grind off the surface oxide layer of the cut cast magnesium alloy sheet; then heat the roller to 200°C, adjust the rolling speed to 2r / min, and perform 9 hot rolling passes to obtain a 1mm thick rolled magnesium alloy sheet. Among them, annealing is performed at 300°C for 10 minutes before the first rolling pass, and annealing is performed between each rolling pass, with the annealing temperature at 300°C and the temperature being kept for 10 minutes.

[0095] Example 2

[0096] Embodiment 2 provides a rolled magnesium alloy sheet, which includes the following components in mass percentage: 6% by mass of zinc, 0.5% by mass of manganese, 0.2% by mass of scandium, and the remainder being magnesium and unavoidable impurities. The magnesium alloy is referred to as Mg-6Zn-0.5Mn-0.2Sc.

[0097] Step 1: Weigh a certain amount of magnesium, zinc, Mg-10Mn and Mg-10Sc according to the magnesium alloy formula.

[0098] Step 2: Heat the graphite crucible to 400°C, put the preheated magnesium into the graphite crucible, and evenly sprinkle the covering agent on the surface of the magnesium, gradually heat to 750°C±5°C, and melt for 1h-2h to obtain liquid magnesium.

[0099] Step 3: Tear off the protective film formed by the covering agent on the surface of the liquid magnesium, add the preheated zinc into the liquid magnesium from the opening, and evenly sprinkle the covering agent at the opening, perform a refining, and obtain the refined liquid metal.

[0100] Step 4: Tear off the protective film formed by the covering agent on the surface of the liquid metal after the primary refinement, add preheated Mg-10Mn to the liquid metal after the primary refinement, raise the temperature to 800°C, perform secondary refinement, and obtain the liquid metal after secondary refinement.

[0101] Step 5: Tear off the protective film formed by the surface covering agent of the liquid metal after secondary refining, add preheated Mg-10Sc to the liquid metal after secondary refining, keep warm for 10 minutes, and perform tertiary refining to obtain tertiary refined liquid metal.

[0102] Step 6: Stir the liquid metal after three refinings for 2 minutes to remove the surface scum to obtain liquid magnesium alloy.

[0103] Step 7: pour the liquid magnesium alloy into a pre-dried metal mold at a uniform speed, and take out the mold and the liquid magnesium alloy after they cool to room temperature to obtain a cast magnesium alloy structural part; use an electric spark wire cutting machine to cut the cast magnesium alloy structural part into a 60mm×40mm×10mm cast magnesium alloy plate.

[0104] Step 8: Grind off the surface oxide layer of the cut cast magnesium alloy sheet; then heat the roller to 200°C, adjust the rolling speed to 2r / min, and perform 9 hot rolling passes to obtain a 1mm thick rolled magnesium alloy sheet. Among them, annealing is performed at 300°C for 10 minutes before the first rolling pass, and annealing is performed between each rolling pass, with the annealing temperature at 300°C and the temperature being kept for 10 minutes.

[0105] Example 3

[0106] Embodiment 3 provides a rolled magnesium alloy sheet, which includes the following components in mass percentage: 6% by mass of zinc, 0.5% by mass of manganese, 0.3% by mass of scandium, and the remainder being magnesium and unavoidable impurities. The magnesium alloy is referred to as Mg-6Zn-0.5Mn-0.3Sc.

[0107] Step 1: Weigh a certain amount of magnesium, zinc, Mg-10Mn and Mg-10Sc according to the magnesium alloy formula.

[0108] Step 2: Heat the graphite crucible to 400°C, put the preheated magnesium into the graphite crucible, and evenly sprinkle the covering agent on the surface of the magnesium, gradually heat to 750°C±5°C, and melt for 1h-2h to obtain liquid magnesium.

[0109] Step 3: Tear off the protective film formed by the covering agent on the surface of the liquid magnesium, add the preheated zinc into the liquid magnesium from the opening, and evenly sprinkle the covering agent at the opening, perform a refining, and obtain the refined liquid metal.

[0110] Step 4: Tear off the protective film formed by the covering agent on the surface of the liquid metal after the primary refinement, add preheated Mg-10Mn to the liquid metal after the primary refinement, raise the temperature to 800°C, perform secondary refinement, and obtain the liquid metal after secondary refinement.

[0111] Step 5: Tear off the protective film formed by the surface covering agent of the liquid metal after secondary refining, add preheated Mg-10Sc to the liquid metal after secondary refining, keep warm for 10 minutes, and perform tertiary refining to obtain tertiary refined liquid metal.

[0112] Step 6: Stir the liquid metal after three refinings for 2 minutes to remove the surface scum to obtain liquid magnesium alloy.

[0113] Step 7: pour the liquid magnesium alloy into a pre-dried metal mold at a uniform speed, and take out the mold and the liquid magnesium alloy after they cool to room temperature to obtain a cast magnesium alloy structural part; use an electric spark wire cutting machine to cut the cast magnesium alloy structural part into a 60mm×40mm×10mm cast magnesium alloy plate.

[0114] Step 8: Grind off the surface oxide layer of the cut cast magnesium alloy sheet; then heat the roller to 200°C, adjust the rolling speed to 2r / min, and perform 9 hot rolling passes to obtain a 1mm thick rolled magnesium alloy sheet. Among them, annealing is performed at 300°C for 10 minutes before the first rolling pass, and annealing is performed between each rolling pass, with the annealing temperature at 300°C and the temperature being kept for 10 minutes.

[0115] Example 4

[0116] Embodiment 4 provides a rolled magnesium alloy sheet, which includes the following components in mass percentage: 6% by mass of zinc, 0.5% by mass of manganese, 0.4% by mass of scandium, and the remainder being magnesium and unavoidable impurities. The magnesium alloy is referred to as Mg-6Zn-0.5Mn-0.4Sc.

[0117] Step 1: Weigh a certain amount of magnesium, zinc, Mg-10Mn and Mg-10Sc according to the magnesium alloy formula.

[0118] Step 2: Heat the graphite crucible to 400°C, put the preheated magnesium into the graphite crucible, and evenly sprinkle the covering agent on the surface of the magnesium, gradually heat to 750°C±5°C, and melt for 1h-2h to obtain liquid magnesium.

[0119] Step 3: Tear off the protective film formed by the covering agent on the surface of the liquid magnesium, add the preheated zinc into the liquid magnesium from the opening, and evenly sprinkle the covering agent at the opening, perform a refining, and obtain the refined liquid metal.

[0120] Step 4: Tear off the protective film formed by the covering agent on the surface of the liquid metal after the primary refinement, add preheated Mg-10Mn to the liquid metal after the primary refinement, raise the temperature to 800°C, perform secondary refinement, and obtain the liquid metal after secondary refinement.

[0121] Step 5: Tear off the protective film formed by the surface covering agent of the liquid metal after secondary refining, add preheated Mg-10Sc to the liquid metal after secondary refining, keep warm for 10 minutes, and perform tertiary refining to obtain tertiary refined liquid metal.

[0122] Step 6: Stir the liquid metal after three refinings for 2 minutes to remove the surface scum to obtain liquid magnesium alloy.

[0123] Step 7: pour the liquid magnesium alloy into a pre-dried metal mold at a uniform speed, and take out the mold and the liquid magnesium alloy after they cool to room temperature to obtain a cast magnesium alloy structural part; use an electric spark wire cutting machine to cut the cast magnesium alloy structural part into a 60mm×40mm×10mm cast magnesium alloy plate.

[0124] Step 8: Grind off the surface oxide layer of the cut cast magnesium alloy sheet; then heat the roller to 200°C, adjust the rolling speed to 2r / min, and perform 9 hot rolling passes to obtain a 1mm thick rolled magnesium alloy sheet. Among them, annealing is performed at 300°C for 10 minutes before the first rolling pass, and annealing is performed between each rolling pass, with the annealing temperature at 300°C and the temperature being kept for 10 minutes.

[0125] Comparative Example 1

[0126] Comparative Example 1 provides a rolled magnesium alloy sheet, which includes the following components in mass percentage: 6% by mass of zinc, 0.5% by mass of manganese, and the remainder being magnesium and unavoidable impurities. The magnesium alloy is referred to as Mg-6Zn-0.5Mn.

[0127] Step 1: Weigh a certain amount of magnesium, zinc and Mg-10Mn according to the magnesium alloy formula.

[0128] Step 2: Heat the graphite crucible to 400°C, put the preheated magnesium into the graphite crucible, and evenly sprinkle the covering agent on the surface of the magnesium, gradually heat to 750°C±5°C, and melt for 1h-2h to obtain liquid magnesium.

[0129] Step 3: Tear off the protective film formed by the covering agent on the surface of the liquid magnesium, add the preheated zinc into the liquid magnesium from the opening, and evenly sprinkle the covering agent at the opening, perform a refining, and obtain the refined liquid metal.

[0130] Step 4: Tear off the protective film formed by the covering agent on the surface of the liquid metal after the primary refinement, add preheated Mg-10Mn to the liquid metal after the primary refinement, raise the temperature to 800°C, perform secondary refinement, and obtain the liquid metal after secondary refinement.

[0131] Step 5: Stir the liquid metal after secondary refining for 2 minutes to remove surface scum to obtain liquid magnesium alloy.

[0132] Step 6: pour the liquid magnesium alloy into the pre-dried metal mold at a uniform speed, and take out the mold and the liquid magnesium alloy after they cool to room temperature to obtain a cast magnesium alloy structural part; use an electric spark wire cutting machine to cut the cast magnesium alloy structural part into a 60mm×40mm×10mm cast magnesium alloy plate.

[0133] Step 7: Grind off the surface oxide layer of the cut cast magnesium alloy sheet; then heat the roller to 200°C, adjust the rolling speed to 2r / min, and perform 9 hot rolling passes to obtain a 1mm thick rolled magnesium alloy sheet. Among them, annealing is performed at 300°C for 10 minutes before the first rolling pass, and annealing is performed once between each rolling pass, with the annealing temperature at 300°C and the temperature being kept for 10 minutes.

[0134] Test Case

[0135] The microstructure images of the cast magnesium alloy sheets and the rolled magnesium alloy sheets of Example 4 and Comparative Example 1 were obtained using a metallographic microscope, and the following parameters were tested.

[0136] Mechanical properties: AG-X plus electronic universal material testing machine was used with a tensile speed of 0.5 mm / min. The test results are shown in Table 1.

[0137] Corrosion resistance: The polarization curve and electrochemical impedance spectroscopy test of the rolled plates of Examples 1-4 and Comparative Example 1 were performed using a CS-350PA electrochemical workstation. The test system was a three-electrode system, in which the auxiliary electrode was a platinum electrode, the reference electrode was a calomel electrode, and the test surface area of ​​the test sample was 0.38 cm 2 The sample is first tested for open circuit potential in the test solution. After the open circuit potential is stable, the impedance spectrum test is performed. The test frequency range of the impedance spectrum is: 10 -1 HZ~10 5 Hz, followed by a polarization curve test, the test range is relative to the open circuit potential ± 0.5V, the test results are shown in Table 2.

[0138] Table 1

[0139]

[0140] Table 2

[0141]

[0142] It can be seen from Table 1 and Table 2 that the magnesium alloy provided by the present invention has better strength and plasticity (expressed as elongation) than the existing Mg-Zn magnesium alloy composition system. In particular, the magnesium alloy provided by the embodiment of the present application has a strong thermal deformation ability, the cast alloy does not need homogenization annealing, and can be directly rolled, and the magnesium alloy structure directly rolled has excellent forming ability, good mechanical properties and corrosion resistance, and has good application prospects in new energy vehicles, especially in the housing of electric drive devices.

[0143] Figure 1 It is the metallographic diagram of the cast Mg-6Zn-0.5Mn alloy of Comparative Example 1 provided in the present application. Figure 2 It is the RD-TD surface metallographic image of the rolled Mg-6Zn-0.5Mn alloy of Comparative Example 1 provided in the present application. Figure 3 It is the metallographic phase diagram of the cast Mg-6Zn-0.5Mn-0.4Sc alloy of Example 4 provided in the present application. Figure 4 It is the RD-TD surface metallographic image of the rolled Mg-6Zn-0.5Mn-0.4Sc alloy of Example 4 provided in the present application.

[0144] from Figure 1 and Figure 3It can be observed that, compared with the metallographic structure of the cast magnesium alloy sheet in Comparative Example 1, the dendrite morphology in the metallographic structure of the cast magnesium alloy sheet in Example 4 is improved, and the amount of the second phase is significantly reduced. Figure 2 and Figure 4 It can be observed that, compared with the RD-TD (Rolling Direction-Transverse Direction) surface metallographic structure of the rolled magnesium alloy sheet in Comparative Example 1, the rolled magnesium alloy sheet in Example 4 has finer dynamically recrystallized grains, and twins are observed in Example 4. It can be seen that the magnesium alloy structural parts prepared from the magnesium alloy provided in the examples of the present application have better mechanical properties.

[0145] The above description is only for the purpose of facilitating the technical solution of the present application to be understood by those skilled in the art, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the principles of the present application shall be included in the protection scope of the present application.

Claims

1. A magnesium alloy, characterized in that: The magnesium alloy comprises the following components in percentage by mass: Zinc 4.8%-6.2%, manganese ≥0.45%, 0<scandium ≤0.4%, impurity elements ≤0.15%, and magnesium as the balance.

2. The magnesium alloy according to claim 1, characterized in that The mass percentage of scandium is 0.2%-0.4%.

3. The magnesium alloy according to claim 1, characterized in that The mass percentage of manganese is 0.45%-0.7%.

4. A magnesium alloy structural part, characterized in that: The magnesium alloy structural part is prepared by the magnesium alloy according to any one of claims 1 to 3.

5. The magnesium alloy structural member according to claim 4, characterized in that: The magnesium alloy structural part is a rolled magnesium alloy.

6. The magnesium alloy structural member according to claim 5, characterized in that: The magnesium alloy structural member satisfies the following physical parameters at the same time: tensile strength greater than or equal to 340 MPa, yield strength greater than or equal to 200 MPa, elongation greater than or equal to 10%, electrochemical corrosion rate less than or equal to 0.3 mm·y -1 .

7. The magnesium alloy structural part according to any one of claims 4 to 6, characterized in that: The magnesium alloy structural member is a housing of an electrical device.

8. The magnesium alloy structural member according to claim 7, characterized in that: The magnesium alloy structural component is a housing of an electric drive device.

9. A vehicle, characterized in that: The vehicle comprises the magnesium alloy structural member according to any one of claims 4 to 8.

10. The vehicle according to claim 9, characterized in that The vehicle is a new energy vehicle, and the magnesium alloy structural component is a shell of an electric drive device in the new energy vehicle.

11. A method for preparing a magnesium alloy structural part, characterized in that: The magnesium alloy structural part is as claimed in any one of claims 4 to 8, and the method for preparing the magnesium alloy structural part comprises: A magnesium alloy intermediate is prepared by using a magnesium alloy raw material through an alloying process; The magnesium alloy intermediate is processed to prepare a magnesium alloy structural part.

12. The method for preparing a magnesium alloy structural part according to claim 11, characterized in that: The preparation method further comprises: performing a rolling process on the magnesium alloy structural part to prepare a rolled magnesium alloy structural part.

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