High-strength and high-plasticity weak-texture magnesium alloy as well as preparation method and application thereof

Abstract

The invention relates to a high-strength and high-plasticity weak-texture magnesium alloy and a preparation method and application thereof. The high-strength and high-plasticity weak-texture magnesium alloy comprises the following components in percentage by mass: 0.5%-2% of Al, 0.5%-1% of Sn, 0.3%-1% of Ca, 0.2%-0.8% of Mn and the balance of Mg, the preparation method comprises the following steps that after raw materials are smelted, casting, cooling and forming are conducted, and an as-cast alloy profile is obtained; the method comprises the following steps: carrying out stepped solution treatment on an as-cast alloy profile, and then carrying out water quenching and cooling to obtain a solid-solution alloy profile; the step solid solution treatment comprises the following steps in sequence: carrying out first heat preservation for 1-6 hours at the temperature of 300-420 DEG C, carrying out second heat preservation for 2-5 hours at the temperature of 480-500 DEG C and carrying out third heat preservation for 5-30 minutes at the temperature of 510-530 DEG C; the solid solution alloy profile is subjected to two-pass rolling treatment in different rolling directions, and an alloy plate is obtained; and the alloy plate is subjected to annealing treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium alloys, and in particular to a high-strength, plastic, weak-texture magnesium alloy and a preparation method and application thereof. Background Art

[0002] Magnesium alloys have broad application prospects in aerospace, transportation, 3C and other fields due to their low density, high specific strength, good shock absorption performance, and green environmental protection. However, magnesium alloys also have problems such as active chemical properties, easy corrosion, and poor strength and plasticity at room temperature.

[0003] The current conventional solution to the above problem is to increase the content of magnesium alloy elements or add rare earth elements to increase the strengthening phase of the magnesium alloy matrix to improve the alloy strength. However, this method not only increases the cost, but also makes the casting process of the magnesium alloy complicated, resulting in difficulty in stable control of the process, which is not conducive to improving the stability of product quality.

[0004] Although traditional rolling methods can effectively refine grains, the close-packed hexagonal crystal structure of magnesium alloys itself results in a lack of sufficient slip systems at room temperature, which leads to edge cracks and strong textures along the rolling direction during rolling, which limits the degree of grain refinement of magnesium alloys and the effect of simultaneous improvement of strength and plasticity is not obvious. Finally, the organization of magnesium alloys is finely controlled through long-term or long-process heat treatment processes, which improves the mechanical properties of the alloys to a certain extent, but also causes higher energy consumption, which is not conducive to the promotion of industrial applications and has certain limitations.

[0005] Therefore, how to achieve the development of high-strength, plastic, weak-textured magnesium alloys with short processes and low costs is one of the problems that need to be solved urgently. Summary of the invention

[0006] Based on this, it is necessary to provide a short-process, low-cost, high-strength, ductile, weak-textured magnesium alloy and its preparation method and application.

[0007] The present application is implemented through the following technical solutions.

[0008] In a first aspect of the present application, a high-strength, ductile, weakly textured magnesium alloy is provided, wherein the magnesium alloy comprises the following composition by mass percentage: Al 0.5%-2%, Sn 0.5%-1%, Ca 0.3%-1% and Mn 0.2%-0.8%, and the balance is Mg and unavoidable impurities ≤0.03%; a method for preparing the magnesium alloy comprises the following steps:

[0009] Providing raw materials according to the composition of the magnesium alloy, melting the raw materials, casting and cooling them into shape, and obtaining a cast alloy profile;

[0010] After the cast alloy profile is subjected to a step solution treatment, it is water quenched to obtain a solid solution alloy profile; wherein the step solution treatment comprises the steps of first heat preservation at 300°C-420°C for 1h-6h, second heat preservation at 480°C-500°C for 2h-5h, and third heat preservation at 510°C-530°C for 5min-30min;

[0011] The solid solution alloy profile is subjected to two rolling processes to obtain an alloy plate; wherein the rolling directions of the solid solution alloy profile in two adjacent rolling processes are different;

[0012] The alloy sheet is annealed to obtain the high-strength, plasticity and weak-texture magnesium alloy.

[0013] The above-mentioned high-strength, plasticity, weak-textured magnesium alloy and preparation method of the present application, through the composition design and process improvement of the magnesium alloy, do not need to add or do not add expensive rare earth elements to the composition, thereby reducing costs, and also generate AlMn phase and CaMgSn phase with good high-temperature thermal stability. In terms of process, through three-stage step solution treatment steps and two rolling processes, there is no need for the long process rolling of 5-10 passes required by traditional technology, which reduces the energy consumption of the rolling process, thereby providing a short-process, low-cost magnesium alloy with high strength, plasticity and weak texture.

[0014] In some of the embodiments, the rolling direction of the solid solution alloy profile in two adjacent rolling processes is adjusted by rotating the angle of the solid solution alloy profile in the rolling fixture.

[0015] In some embodiments, the solid solution alloy profile forms an angle of 60°-130° in the rolling direction of two adjacent rolling processes.

[0016] In some embodiments, the step of subjecting the solid solution alloy profile to two-pass rolling treatment comprises the following steps:

[0017] Firstly, heat at 300℃-400℃ for 5min-15min before first rolling;

[0018] Then the solid solution alloy profile is rotated by an angle, and after being kept at 250° C.-400° C. for 5 min-15 min, a second rolling is performed, wherein the second rolling is performed in a different rolling direction from the first rolling.

[0019] In some embodiments, the first rolling pass and the second rolling pass have a reduction of 40%-60%; and / or,

[0020] The roller speed of the first rolling pass and the second rolling pass is 40rad / min-70rad / min, and the roller temperature is 80℃-120℃.

[0021] In some embodiments, smelting the raw materials comprises the following steps: keeping the raw materials at 650° C.-750° C. for 10 min-30 min, stirring with ultrasonic waves for 5 min-15 min, and then keeping them at the temperature for 10 min-30 min; and / or,

[0022] The casting cooling molding comprises the following steps: casting the melt obtained by smelting the raw materials into a sub-rapid water-cooled copper mold for cooling molding, the water cooling temperature of the cooling molding is 20°C-40°C, and the solidification cooling rate is 100 K / s-400K / s.

[0023] In some embodiments, the annealing process comprises the following steps:

[0024] The alloy plate is annealed at 200° C.-300° C. for 5 min-20 min and then water-quenched to room temperature.

[0025] In some embodiments, the average grain size of the high-strength, ductile, weakly textured magnesium alloy is 2 μm-4 μm; and / or,

[0026] The texture strength of the high-strength, ductile, weakly textured magnesium alloy is 3-6.

[0027] The second aspect of the present application provides a method for preparing a high-strength, ductile, weakly textured magnesium alloy, comprising the following steps:

[0028] Providing raw materials according to the composition of the magnesium alloy, smelting the raw materials, casting and cooling to form a cast alloy profile; the magnesium alloy comprises the following composition by mass percentage: Al 0.5%-2%, Sn 0.5%-1%, Ca 0.3%-1% and Mn 0.2%-0.8%, and the balance is Mg and unavoidable impurities ≤0.03%;

[0029] After the cast alloy profile is subjected to a step solution treatment, it is water quenched to obtain a solid solution alloy profile; wherein the step solution treatment comprises the steps of first heat preservation at 300°C-420°C for 1h-6h, second heat preservation at 480°C-500°C for 2h-5h, and third heat preservation at 510°C-530°C for 5min-30min;

[0030] The solid solution alloy profile is subjected to two rolling processes to obtain an alloy plate; wherein the rolling directions of the solid solution alloy profile in two adjacent rolling processes are different;

[0031] The alloy sheet is annealed to obtain the high-strength, plasticity and weak-texture magnesium alloy.

[0032] In a third aspect, the present application further provides a magnesium alloy product comprising the above-mentioned high-strength, ductile, weakly textured magnesium alloy. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0035] "Scope" disclosed in the present application can be limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or excluding end values, and any end value can be included or not included independently, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 listed, and if the maximum range values ​​3,4 and 5 are also listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0037] In the present application, "plurality", "multiple" and the like, unless otherwise specified, refer to a number greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0038] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0039] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. The "implementation methods" mentioned herein have a similar understanding.

[0040] Those skilled in the art will appreciate that, in the methods of each embodiment or example, the order in which each step is written does not mean a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible internal logic. If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0041] In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0042] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "option" is independent.

[0043] In a first aspect of the present application, a high-strength, ductile, weakly textured magnesium alloy is provided, wherein the magnesium alloy comprises the following composition by mass percentage: Al 0.5%-2%, Sn 0.5%-1%, Ca 0.3%-1% and Mn 0.2%-0.8%, and the balance is Mg and unavoidable impurities ≤0.03%. The preparation method of the magnesium alloy comprises the following steps S10-S40:

[0044] S10, providing raw materials according to the composition of the magnesium alloy, melting the raw materials, casting and cooling them into shape, and obtaining a cast alloy profile.

[0045] S20. After subjecting the cast alloy profile to a step solution treatment, the cast alloy profile is water quenched to obtain a solid solution alloy profile; wherein the step solution treatment comprises the steps of first heat preservation at 300°C-420°C for 1h-6h, second heat preservation at 480°C-500°C for 2h-5h, and third heat preservation at 510°C-530°C for 5min-30min.

[0046] S30, subjecting the solid solution alloy profile to two rolling processes to obtain an alloy plate; wherein the rolling directions of the solid solution alloy profile in two adjacent rolling processes are different.

[0047] S40, annealing the alloy sheet to obtain the high-strength, plasticity, weak-texture magnesium alloy.

[0048] The above-mentioned preparation method of the present application mainly realizes the alloy strengthening effect through the interaction between multiple small amounts of alloying elements Al-Sn-Ca-Mn-Mg, and it does not need to add or does not add expensive rare earth elements, wherein some Al elements play a role of solid solution strengthening by being dissolved in the matrix, and in addition, AlMn phase and CaMgSn phase with good high temperature thermal stability are generated, and both increase the toughness of the alloy through the second phase strengthening method. In terms of preparation technology, after the raw materials are melted, cast, cooled and formed to obtain the cast alloy profile, a three-step step solution treatment step is adopted to avoid low temperature phase burning and allow the coarse CaMgSn phase to dissolve back into the matrix, and two rolling processes are adopted in the rolling stage. By controlling the rolling direction, on the one hand, the generation of edge cracks can be effectively controlled, and on the other hand, the base surface texture can be effectively weakened to improve the formability of the alloy. Finally, the alloy is completely recrystallized through the annealing process, the deformation stress of the alloy is eliminated, and the comprehensive mechanical properties of the alloy are improved.

[0049] The above-mentioned high-strength, plasticity, weak-textured magnesium alloy and preparation method of the present application, through the composition design and process improvement of the magnesium alloy, do not need to add or do not add expensive rare earth elements to the composition, thereby reducing costs, and also generate AlMn phase and CaMgSn phase with good high-temperature thermal stability. In terms of process, through three-stage step solution treatment steps and two rolling processes, there is no need for the long process rolling of 5-10 passes required by traditional technology, which reduces the energy consumption of the rolling process, thereby providing a short-process, low-cost magnesium alloy with high strength, plasticity and weak texture.

[0050] The high-strength, ductile, and weakly textured magnesium alloy mentioned above in the present application is a Mg—Al—Sn—Ca—Mn alloy.

[0051] As an example, in a magnesium alloy, the mass percentage of Al can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or within a range consisting of any two of the above point values ​​as end values, and the same applies below.

[0052] As an example, the mass percentage of Sn may be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or within a range consisting of any two of the above-mentioned values ​​as end values.

[0053] As an example, the mass percentage of Ca can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or within a range consisting of any two of the above point values ​​as end values.

[0054] As an example, the mass percentage of Mn may be 0.2%, 0.29%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or within a range consisting of any two of the above-mentioned values ​​as end points.

[0055] In some of the embodiments, in S10, the magnesium alloy consists of: Al 0.5%-2%, Sn 0.5%-1%, Ca0.3%-1% and Mn 0.2%-0.8%, and the balance is Mg and unavoidable impurities ≤0.03%.

[0056] In some embodiments, in S10, smelting the raw materials includes the following steps: keeping the raw materials at 650°C-750°C for 10min-30min, stirring them with ultrasonic waves for 5min-15min, and then keeping them still for 10min-30min. Specifically, the smelting is carried out in a vacuum induction melting furnace with ultrasonic stirring function. In this way, after the raw materials are initially smelted, ultrasonic stirring is used to evenly distribute the alloy elements in the melt, reduce smelting segregation, and help reduce the time of subsequent solution treatment.

[0057] As an example, the melting temperature may be 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, or any two of the above values ​​as end values. As an example, the melting holding time may be 10 min, 15 min, 20 min, 25 min, 30 min, or any two of the above values ​​as end values.

[0058] As an example, the ultrasonic stirring time can be 5 min, 8 min, 10 min, 12 min, 15 min, or a range formed by any two of the above values ​​as end values. As an example, the static insulation time after ultrasonic stirring can be 10 min, 15 min, 20 min, 25 min, 30 min, or a range formed by any two of the above values ​​as end values.

[0059] Furthermore, the ultrasonic frequency of ultrasonic stirring is 10KHz-30KHz; as an example, it can be 10KHz, 15KHz, 20KHz, 25KHz, 30KHz, or within a range consisting of any two of the above point values ​​as end values.

[0060] In some of the embodiments, in S10, the casting cooling molding includes the following steps: casting the melt obtained by smelting the raw materials into a sub-rapid water-cooled copper mold for cooling molding, the water cooling temperature of the cooling molding is 20°C-40°C, and the solidification cooling rate is 100 K / s-400K / s.

[0061] As an example, the water cooling temperature for cooling molding can be 20°C, 25°C, 30°C, 35°C, 40°C, or within a range consisting of any two of the above point values ​​as end values.

[0062] As an example, the solidification rate of cooling molding can be 100 K / s, 150 K / s, 200 K / s, 250 K / s, 300 K / s, 350 K / s, 400 K / s, or within a range consisting of any two of the above point values ​​as end values; further, the solidification rate of cooling molding can be 200 K / s-300 K / s.

[0063] The thickness of the cast alloy profile obtained by cooling and forming in the sub-rapid water-cooled copper mold can be set as required, for example, it can be 3 cm-5 cm.

[0064] As an example, in S20, in the step solution treatment, the temperature of the first insulation can be 300°C-420°C, or within the range formed by any two of the above point values ​​as end values; the time can be 1h-6h, or within the range formed by any two of the above point values ​​as end values.

[0065] As an example, in S20, in the step solution treatment, the temperature of the second insulation can be 480°C-500°C, or within the range formed by any two of the above point values ​​as end values; the time can be 2h-5h, or within the range formed by any two of the above point values ​​as end values.

[0066] As an example, in S20, in the step solution treatment, the temperature of the third insulation can be 510°C-530°C, or within the range formed by any two of the above point values ​​as end values; the time can be 5min-30min, or within the range formed by any two of the above point values ​​as end values.

[0067] In some of the embodiments, the rolling direction adjustment of the solid solution alloy profile in two adjacent rolling processes is achieved by rotating the angle of the solid solution alloy profile in the rolling fixture. Specifically, the rolling fixture can be two stacked steel liner plates, and the solid solution alloy profile is arranged between the two stacked steel liner plates; further, the two liner plates can be fixed by a fixing member. Furthermore, the thickness of the steel liner plate is 1 cm-3cm. During two adjacent rolling processes, the angle of the solid solution alloy profile in the rolling fixture is adjusted to be different from that of the previous pass in the next pass.

[0068] In some embodiments, the solid solution alloy profile forms an angle of 60°-130° in the rolling direction of two adjacent rolling processes. Specifically, the angle of the solid solution alloy profile in the rolling fixture is rotated by 60°-130° relative to the previous pass in the next pass, for example, by 60°, 90°, 120°, 130°, or within the range formed by any two of the above point values ​​as end values.

[0069] In some embodiments, the step of performing two-pass rolling on the solid solution alloy profile in S30 includes the following steps:

[0070] S31, firstly heat at 300℃-400℃ for 5min-15min and then carry out the first rolling.

[0071] S32, then rotating the solid solution alloy profile obtained in S31 by an angle, and performing a second rolling after keeping it at 250°C-400°C for 5min-15min, wherein the second rolling is in a different rolling direction from the first rolling.

[0072] As an example, the temperature of the first rolling pass can be 300°C, 320°C, 340°C, 350°C, 360°C, 380°C, 400°C, or within the range constituted by any two of the above point values ​​as end values; as an example, the holding time of the first rolling pass can be 5min, 7min, 8min, 10min, 12min, 15min, or within the range constituted by any two of the above point values ​​as end values.

[0073] As an example, the temperature of the second rolling pass can be 250℃, 260℃, 270℃, 280℃, 300℃, 320℃, 325℃, 350℃, 360℃, 380℃, 400℃, or within the range constituted by any two of the above point values ​​as end values; as an example, the holding time of the second rolling pass can be 5min, 7min, 8min, 10min, 12min, 15min, or within the range constituted by any two of the above point values ​​as end values.

[0074] Specifically, after the first rolling pass is completed, the solid solution alloy profile is taken out from the rolling fixture, then rotated at an angle and placed back in the rolling fixture for heat preservation, and then the second rolling pass is performed.

[0075] In some embodiments, the first rolling pass and the second rolling pass have a reduction of 40%-60%. As an example, the first rolling pass and the second rolling pass have a reduction of 40%, 45%, 50%, 55%, 60% or any two of the above values ​​as end values.

[0076] In some embodiments, the roller speed of the first rolling pass and the second rolling pass is 40 rad / min-70 rad / min, and the roller temperature is 80° C.-120° C.

[0077] As an example, the roller speed of the first rolling pass and the second rolling pass can be 40rad / min, 45rad / min, 50rad / min, 55rad / min, 60rad / min, 65rad / min, 70rad / min or within the range constituted by any two of the above point values ​​as end values; as an example, the roller temperature of the first rolling pass and the second rolling pass can be 80℃, 85℃, 90℃, 95℃, 100℃, 110℃, 120℃ or within the range constituted by any two of the above point values ​​as end values.

[0078] In some embodiments, in S40, the annealing treatment includes the following steps: annealing the alloy sheet at 200°C-300°C for 5min-20min and then quenching the alloy sheet with water to room temperature. Through the composition design and process improvement of the magnesium alloy of the present application, the annealing treatment time can be shortened, and a high-strength, plastic, and weak-textured magnesium alloy can be obtained through a short annealing treatment.

[0079] As an example, the annealing temperature can be 200°C, 210°C, 220°C, 240°C, 250°C, 260°C, 270°C, 275°C, 280°C, 300°C, or within the range consisting of any two of the above point values ​​as end values; the annealing time can be 5min, 8min, 10min, 12min, 15min, 20min, or within the range consisting of any two of the above point values ​​as end values.

[0080] In some of the embodiments, the average grain size in the above-mentioned high strength, ductility and weak texture magnesium alloy is 2μm-4μm; as an example, the average grain size in the above-mentioned high strength, ductility and weak texture magnesium alloy can be 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm, 3.5μm, 3.6μm, 3.7μm, 3.8μm, 3.9μm, 4μm or within the range formed by any two of the above-mentioned point values ​​as end values.

[0081] In some of the embodiments, the texture strength of the high-strength ductility weakly textured magnesium alloy is 3-6; as an example, the texture strength of the high-strength ductility weakly textured magnesium alloy can be 3, 3.5, 4, 4.5, 4.7, 5, 5.2, 5.5, 6, or within the range formed by any two of the above point values ​​as end values.

[0082] In some of the embodiments, the yield strength of the high-strength ductility weak-texture magnesium alloy may be 243 MPa-271 MPa.

[0083] In some of the embodiments, the tensile strength of the high-strength, ductile, weakly-textured magnesium alloy may be 305 MPa-339 MPa.

[0084] In some of the embodiments, the elongation of the high-strength, ductile, weakly textured magnesium alloy may be 22.1%-26.4%.

[0085] In a second aspect of the present application, a method for preparing a high-strength, ductile, weakly textured magnesium alloy is provided, including the above-mentioned steps S10-S40. The specific details have been described in detail above and will not be repeated here.

[0086] In a third aspect, the present application further provides a magnesium alloy product comprising the above-mentioned high-strength, ductile, weakly textured magnesium alloy.

[0087] In some of the embodiments, the magnesium alloy product may be, but is not limited to, a structural part of a transportation vehicle.

[0088] In order to make the purpose, technical solutions and advantages of the present invention more concise and clear, the present invention is described with the following specific embodiments, but the present invention is by no means limited to these embodiments. The embodiments described below are only preferred embodiments of the present invention, which can be used to describe the present invention and cannot be understood as limiting the scope of the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0089] In order to better illustrate the present invention, the present invention is further described below in conjunction with the embodiments. The following are specific embodiments.

[0090] Embodiment 1:

[0091] Mg-2.0Al-0.5Sn-0.5Ca-0.3Mn alloy, calculated by mass percentage: Al is 2.0%, Sn is 0.5%, Ca is 0.5%, Mn is 0.29%, the inevitable impurity content is ≤0.02%, and the balance is Mg. The preparation method specifically comprises the following steps:

[0092] (1) Casting stage: According to the above-mentioned component ratio, commercially available pure magnesium, commercially available pure aluminum, commercially available pure tin, magnesium-calcium master alloy and magnesium-manganese master alloy are mixed and added into a vacuum induction melting furnace, melted at 680-700°C and kept warm for 30 minutes, then ultrasonic vibration stirring is turned on for 5 minutes, and the ultrasonic frequency is 25KHz. Then, the magnesium alloy melt is obtained after being kept still for 25 minutes. The magnesium alloy melt is then cast into a water-cooled copper mold to obtain a magnesium alloy slab. The water cooling temperature is 35°C and the solidification cooling rate is 200K / s to obtain a cast magnesium alloy slab.

[0093] (2) Three-step solid solution stage: The alloy obtained in step (1) is heated to 400°C and kept for 6 h, then the alloy is heated to 480°C and kept for 2 h, and finally the alloy is heated to 510°C and kept for 30 min, and then quenched in water to room temperature to obtain a solid solution state sheet blank.

[0094] (3) Two-pass rotating liner rolling stage: The solid solution magnesium alloy sheet blank obtained in step (2) is placed in two steel liners, the front and rear ends are tightened with wire, and then heated to 350°C and kept warm for 8 minutes before the first rolling, with a reduction of 50%. Next, the sheet is rotated 90° clockwise and re-clamped into the steel liner for fixation, and then heated to 325°C and kept warm for 5 minutes before the second rolling, with a reduction of 50%. The roller speed for both rollings is 50 rad / min, and the upper and lower roller temperatures are both 100°C.

[0095] (4) After annealing the rolled plate obtained in step (3) at 275° C. for 12 min, the rolled plate is immediately quenched to room temperature to obtain a high-strength and ductile Mg-Al-Sn-Ca-Mn alloy.

[0096] The Mg-2.0Al-0.5Sn-0.5Ca-0.3Mn alloy obtained in Example 1 has no obvious segregation in the cast state (the cast magnesium alloy slab obtained in step (1)), and the eutectic phase is significantly refined and evenly distributed. The rolled annealed alloy (the alloy obtained in step (4)) has an average grain size of 2.7 μm, a texture strength of 4.7 (weak texture), and excellent comprehensive room temperature mechanical properties, including a yield strength of 258 MPa, a tensile strength of 307 MPa, and an elongation of 25.1%.

[0097] Embodiment 2:

[0098] Mg-2.0Al-0.5Sn-0.5Ca-0.5Mn alloy, calculated by mass percentage: Al is 2.0%, Sn is 0.5%, Ca is 0.5%, Mn is 0.5%, the content of inevitable impurities is ≤0.02%, and the balance is Mg. The preparation method specifically comprises the following steps:

[0099] (1) Casting stage: Under the condition of SF6 and CO2 protective gas with a volume ratio of 1:99, commercially available pure magnesium, commercially available pure aluminum, commercially available pure tin, magnesium-calcium master alloy and magnesium-manganese master alloy are mixed according to the above-mentioned component ratio, melted at 680-700°C and kept warm for 30 minutes, and then a titanium alloy probe is inserted into an ultrasonic vibration stirrer for stirring for 5 minutes with an ultrasonic frequency of 25KHz. Then, the mixture is kept still for 25 minutes to obtain a melt with uniform composition. The alloy melt is then cast into a water-cooled copper mold to obtain a magnesium alloy slab. The water cooling temperature is 35°C and the solidification cooling rate is 200K / s to obtain a cast magnesium alloy slab.

[0100] (2) Three-step solid solution stage: The alloy obtained in step (1) is heated to 400°C and kept for 6 h, then the alloy is heated to 480°C and kept for 2 h, and finally the alloy is heated to 510°C and kept for 30 min, and then water quenched to room temperature to obtain a solid solution state sheet blank.

[0101] (3) Two-pass rotating liner rolling stage: The solid solution magnesium alloy sheet blank obtained in step (2) is placed in two steel liners, the front and rear ends are tightened with wire, and then heated to 350°C and kept warm for 8 minutes before the first rolling, with a reduction of 50%. Next, the sheet is rotated 90° clockwise and re-clamped into the steel liner for fixation, and then heated to 325°C and kept warm for 5 minutes before the second rolling, with a reduction of 50%. The roller speed for both rollings is 50 rad / min, and the upper and lower roller temperatures are both 100°C.

[0102] (4) The rolled plate obtained in step (3) was annealed at 275° C. for 12 min and then immediately quenched to room temperature to obtain a high-strength and ductile Mg-Al-Sn-Ca-Mn alloy.

[0103] The Mg-2.0Al-0.5Sn-0.5Ca-0.5Mn alloy obtained in Example 2 has no obvious segregation in the cast state, and the eutectic phase is significantly refined and evenly distributed. The average grain size of the rolled annealed alloy structure is 2.1 μm, the texture strength is 5.2 (weak texture), and the comprehensive room temperature mechanical properties are excellent, among which the yield strength is 269 MPa, the tensile strength is 325 MPa, and the elongation is 26.4%.

[0104] Embodiment 3:

[0105] Mg-2.0Al-0.5Sn-0.5Ca-0.8Mn alloy, calculated by mass percentage: Al is 2.0%, Sn is 0.5%, Ca is 0.5%, Mn is 0.8%, the inevitable impurity content is ≤0.02%, and the balance is Mg. The preparation method specifically comprises the following steps:

[0106] (1) Casting stage: According to the above-mentioned component ratio, commercially available pure magnesium, commercially available pure aluminum, commercially available pure tin, magnesium-calcium master alloy and magnesium-manganese master alloy are mixed and added into a vacuum induction melting furnace, melted at 680-700°C and kept warm for 30 minutes, and then ultrasonic vibration stirring is turned on for 5 minutes, and the ultrasonic frequency is 25KHz. Then, it is kept still for 25 minutes to obtain a magnesium alloy melt, and then the alloy melt is cast into a water-cooled copper mold to obtain a magnesium alloy slab. The water cooling temperature is 35°C, and the solidification cooling rate is 200K / s to obtain a cast magnesium alloy slab.

[0107] (2) Three-step solid solution stage: The alloy obtained in step (1) is heated to 400°C and kept for 6 h, then the alloy is heated to 480°C and kept for 2 h, and finally the alloy is heated to 510°C and kept for 30 min, and then quenched in water to room temperature to obtain a solid solution state sheet blank.

[0108] (3) Two-pass rotating liner rolling stage: The solid solution magnesium alloy plate blank obtained in step (2) is placed in two steel liners, and the front and rear ends are tightened and fixed with wire, and then heated to 350°C and kept warm for 8 minutes before the first rolling, with a reduction of 50%. Next, the plate is rotated 90° clockwise and clamped back into the steel liner, and then heated to 325°C and kept warm for 5 minutes before the second rolling, with a reduction of 50%. The roller speed for both rollings is 50 rad / min, and the upper and lower roller temperatures are both 100°C.

[0109] (4) The rolled plate obtained in step (3) was annealed at 275° C. for 12 min and then immediately quenched to room temperature to obtain a high-strength and ductile Mg-Al-Sn-Ca-Mn alloy.

[0110] The Mg-2.0Al-0.5Sn-0.5Ca-0.5Mn alloy obtained in Example 3 has no obvious segregation in the cast state, and the eutectic phase is significantly refined and evenly distributed. The average grain size of the rolled annealed alloy structure is 2.9μm, the texture strength is 5.5 (weak texture), and the comprehensive room temperature mechanical properties are excellent, with a yield strength of 271MPa, a tensile strength of 339MPa, and an elongation of 23.7%.

[0111] Example 4

[0112] The magnesium alloy of Example 4 contains, by mass percentage: 0.5% Al, 1% Sn, 1% Ca, 0.29% Mn, the content of unavoidable impurities ≤ 0.02%, and the balance Mg. The preparation method specifically comprises the following steps:

[0113] (1) Casting stage: According to the above-mentioned component ratio, commercially available pure magnesium, commercially available pure aluminum, commercially available pure tin, magnesium-calcium master alloy and magnesium-manganese master alloy are mixed and added into a vacuum induction melting furnace, melted at 680-700°C and kept warm for 30 minutes, then ultrasonic vibration stirring is turned on for 5 minutes, and the ultrasonic frequency is 25KHz. Then, the magnesium alloy melt is obtained after being kept still for 25 minutes. The magnesium alloy melt is then cast into a water-cooled copper mold to obtain a magnesium alloy slab. The water cooling temperature is 35°C and the solidification cooling rate is 200K / s to obtain a cast magnesium alloy slab.

[0114] (2) Three-step solid solution stage: The alloy obtained in step (1) is heated to 300°C and kept at this temperature for 1 h, then the alloy is heated to 500°C and kept at this temperature for 5 h, and finally the alloy is heated to 530°C and kept at this temperature for 5 min, and then water quenched to room temperature to obtain a solid solution state sheet blank.

[0115] (3) Two-pass rotating liner rolling stage: The solid solution magnesium alloy sheet blank obtained in step (2) is placed in two steel liners, the front and rear ends are tightened with wire, and then heated to 350°C and kept warm for 8 minutes before the first rolling, with a reduction of 50%. Next, the sheet is rotated 90° clockwise and re-clamped into the steel liner for fixation, and then heated to 325°C and kept warm for 5 minutes before the second rolling, with a reduction of 50%. The roller speed for both rollings is 50 rad / min, and the upper and lower roller temperatures are both 100°C.

[0116] (4) After annealing the rolled plate obtained in step (3) at 275° C. for 12 min, the rolled plate is immediately quenched to room temperature to obtain a high-strength and ductile Mg-Al-Sn-Ca-Mn alloy.

[0117] The magnesium alloy obtained in Example 4 has no obvious segregation in the cast state (the cast magnesium alloy slab obtained in step (1)), and the eutectic phase is significantly refined and evenly distributed. The rolled annealed alloy (the alloy obtained in step (4)) has an average grain size of 3.3 μm, a texture strength of 5.9 (weak texture), and excellent comprehensive room temperature mechanical properties, including a yield strength of 243 MPa, a tensile strength of 305 MPa, and an elongation of 22.1%.

[0118] Comparative Example 1

[0119] Comparative Example 1 is basically the same as Example 1, except that the step solution stage of step (2) is different, which is a secondary stage, and the specific steps are as follows: the alloy obtained in step (1) is heated to 400°C and kept warm for 6 hours, then the alloy is heated to 480°C and kept warm for 2.5 hours, and water quenched to room temperature to obtain a solid solution state plate blank.

[0120] The magnesium alloy obtained in comparative example 1 has partial segregation in the cast state (the cast magnesium alloy slab obtained in step (1)), and the eutectic phase is not obviously refined and has poor uniform distribution. The rolled annealed alloy (the alloy obtained in step (4)) has an average grain size of 5.3 μm, a texture strength of 5.2 (weak texture), and excellent comprehensive room temperature mechanical properties, including a yield strength of 220 MPa, a tensile strength of 285 MPa, and an elongation of 18.7%.

[0121] Comparative Example 2

[0122] Comparative Example 2 is basically the same as Example 1, except that the rolling stage of step (3) is different. It does not rotate and adopts a one-pass rolling, and the specific steps are as follows: the solid solution magnesium alloy plate blank obtained in step (2) is placed in two steel liner plates, the front and rear ends are tightened and fixed with iron wire, and then heated to 350°C and kept warm for 13 minutes, the reduction is 50%, the rolling roller speed is 50 rad / min, and the upper and lower roller temperatures are both 100°C.

[0123] The magnesium alloy obtained in comparative example 2 has partial segregation in the cast state (the cast magnesium alloy slab obtained in step (1)), and the eutectic phase is not obviously refined and has poor uniform distribution. The rolled annealed alloy (the alloy obtained in step (4)) has an average grain size of 4.7 μm, a texture strength of 5.5 (weak texture), and excellent comprehensive room temperature mechanical properties, including a yield strength of 232 MPa, a tensile strength of 293 MPa, and an elongation of 20.1%.

[0124] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A high-strength, ductile, weakly textured magnesium alloy, characterized in that: The magnesium alloy comprises the following composition by mass percentage: Al 0.5%-2%, Sn 0.5%-1%, Ca 0.3%-1% and Mn 0.2%-0.8%, and the balance is Mg and unavoidable impurities ≤0.03%; the preparation method of the magnesium alloy comprises the following steps: Providing raw materials according to the composition of the magnesium alloy, melting the raw materials, casting and cooling them into shape, and obtaining a cast alloy profile; After the cast alloy profile is subjected to a step solution treatment, it is water quenched to obtain a solid solution alloy profile; wherein the step solution treatment comprises the steps of first heat preservation at 300°C-420°C for 1h-6h, second heat preservation at 480°C-500°C for 2h-5h, and third heat preservation at 510°C-530°C for 5min-30min; The solid solution alloy profile is subjected to two rolling processes to obtain an alloy plate; wherein the rolling directions of the solid solution alloy profile in two adjacent rolling processes are different; The alloy sheet is annealed to obtain the high-strength, plasticity and weak-texture magnesium alloy.

2. The high-strength, ductile, weakly textured magnesium alloy according to claim 1, characterized in that: The rolling direction adjustment of the solid solution alloy profile in two adjacent rolling processes is achieved by rotating the angle of the solid solution alloy profile in the rolling fixture.

3. The high-strength, ductile, weakly textured magnesium alloy according to claim 1, characterized in that: The solid solution alloy profile forms an angle of 60°-130° in the rolling direction of two adjacent rolling processes.

4. The high-strength, ductile, weakly textured magnesium alloy according to claim 1, characterized in that: The step of subjecting the solid solution alloy profile to two-pass rolling treatment comprises the following steps: Firstly, heat at 300℃-400℃ for 5min-15min before first rolling; Then the solid solution alloy profile is rotated by an angle, and after being kept at 250° C.-400° C. for 5 min-15 min, a second rolling is performed, wherein the second rolling is performed in a different rolling direction from the first rolling.

5. The high-strength, ductile, weakly textured magnesium alloy according to claim 4, characterized in that: The reduction amounts of the first rolling pass and the second rolling pass are both 40%-60%; and / or, The roller speed of the first rolling pass and the second rolling pass is 40rad / min-70rad / min, and the roller temperature is 80℃-120℃.

6. The high-strength, ductile, weakly textured magnesium alloy according to any one of claims 1 to 5, characterized in that: The smelting of the raw materials comprises the following steps: keeping the raw materials at 650°C-750°C for 10-30 minutes, stirring them with ultrasonic waves for 5-15 minutes, and then keeping them still for 10-30 minutes; and / or, The casting cooling molding comprises the following steps: casting the melt obtained by smelting the raw materials into a sub-rapid water-cooled copper mold for cooling molding, the water cooling temperature of the cooling molding is 20°C-40°C, and the solidification cooling rate is 100 K / s-400K / s.

7. The high-strength, ductile, weakly textured magnesium alloy according to any one of claims 1 to 5, characterized in that: The annealing process comprises the following steps: The alloy plate is annealed at 200° C.-300° C. for 5 min-20 min and then water-quenched to room temperature.

8. The high-strength, ductile, weakly textured magnesium alloy according to any one of claims 1 to 5, characterized in that: The average grain size of the high-strength, ductile, weakly textured magnesium alloy is 2 μm to 4 μm; and / or, The texture strength of the high-strength, ductile, weakly textured magnesium alloy is 3-6.

9. A method for preparing a high-strength, ductile, weakly textured magnesium alloy, characterized in that: The preparation method comprises the following steps: Providing raw materials according to the composition of the magnesium alloy, smelting the raw materials, casting and cooling to form a cast alloy profile; the magnesium alloy comprises the following composition by mass percentage: Al 0.5%-2%, Sn 0.5%-1%, Ca 0.3%-1% and Mn 0.2%-0.8%, and the balance is Mg and unavoidable impurities ≤0.03%; After the cast alloy profile is subjected to a step solution treatment, it is water quenched to obtain a solid solution alloy profile; wherein the step solution treatment comprises the steps of first heat preservation at 300°C-420°C for 1h-6h, second heat preservation at 480°C-500°C for 2h-5h, and third heat preservation at 510°C-530°C for 5min-30min; The solid solution alloy profile is subjected to two rolling processes to obtain an alloy plate; wherein the rolling directions of the solid solution alloy profile in two adjacent rolling processes are different; The alloy sheet is annealed to obtain the high-strength, plasticity and weak-texture magnesium alloy.

10. A magnesium alloy product, characterized in that: The invention comprises the high-strength, ductile and weakly textured magnesium alloy as claimed in any one of claims 1 to 8.