Method of extruding coarse-grained, low-aluminium-content magnesium alloys

Abstract

The present disclosure provides a method of forming an extruded billet from a coarse-grained magnesium alloy billet. The method includes extruding a coarse-grained magnesium alloy billet at a temperature greater than or equal to about 300 °C to less than or equal to about 360 °C to form an extruded billet. The coarse-grained magnesium alloy billet has an average grain size greater than or equal to about 800 µm and has a low aluminum content. The coarse-grained magnesium alloy billet includes greater than or equal to about 0.5 wt% to less than or equal to about 3 wt% aluminum. The extruded billet can have a number of twin crystals having a lentil-like morphology that occupy an area fraction greater than or equal to about 20% of the total area of the extruded billet.

Description

[0001] introduction

[0002] This section provides background information relating to this disclosure, which is not necessarily prior art.

[0003] Lightweight metal components have become a key focus in the manufacture of vehicles, particularly automobiles, where there is a desire for continuous improvements in performance and fuel efficiency. While conventional steels and other metal alloys offer various performance benefits, including high strength, these materials are heavy. Lightweight metal components for automotive applications are typically made from aluminum and / or magnesium alloys. Such lightweight metals can form strong and rigid load-bearing components while maintaining good strength and ductility (e.g., elongation). High strength and ductility are particularly important for the safety requirements and durability of vehicles such as automobiles.

[0004] While magnesium-based alloys are an example of lightweight metals that can be used to form structural components in vehicles, their use can be limited in practice. For instance, although it is generally desirable to reduce the aluminum content of magnesium-based alloys to improve their formability, the reduction of aluminum can adversely affect grain refinement during the casting process, resulting in magnesium-based alloys with low aluminum content typically having a coarse-grained microstructure. In some variants, the coarse-grained microstructure can be refined to improve forgeability by using an extrusion process with a temperature greater than or exactly 380°C at a large aspect ratio (e.g., greater than or equal to about or exactly 15). However, in the case of products formed by forging extruded billets with a large diameter (e.g., greater than or equal to about or exactly 200 mm) (e.g., road wheels), the extrusion ratio is limited (e.g., less than or equal to about or exactly 5). Therefore, in these cases, the coarse-grained microstructure cannot be easily refined using conventional extrusion methods, for example, due to the limited degree of plastic deformation and the small grain boundary fraction in the original microstructure, which limits the number of dynamic recrystallization (DRX) or nucleation sites. Therefore, it is desirable to develop methods to improve the forgeability of magnesium-based alloys with coarse-grained microstructures.

[0005] Overview

[0006] This section provides a general overview of this disclosure and is not a full disclosure of its complete scope or all its features.

[0007] This application relates to the following:

[0008] [1]. A method for forming an extruded billet from a coarse-grained magnesium alloy billet, the method comprising:

[0009] A coarse-grained magnesium alloy billet is extruded at a temperature less than or equal to about 360°C to form an extruded billet, the coarse-grained magnesium alloy billet having an average grain size greater than or equal to about 800 µm.

[0010] [2]. The method described in [1] above, wherein the coarse-grained magnesium alloy billet is extruded at a temperature greater than or equal to about 300°C.

[0011] [3]. The method described in [1] above, wherein the coarse-grained magnesium alloy billet has a low aluminum content and contains more than or equal to about 1.5% by weight to less than or equal to about 3% by weight of aluminum.

[0012] [4]. The method described in [3] above, wherein the coarse-grained magnesium alloy billet contains approximately 2% by weight of aluminum.

[0013] [5]. The method described in [3] above, wherein the coarse-grained magnesium alloy billet further comprises more than or equal to about 0.3% by weight to less than or equal to about 0.6% by weight of manganese.

[0014] [6]. The method described in [5] above, wherein the coarse-grained magnesium alloy billet contains approximately 0.5% by weight of manganese.

[0015] [7]. The method described in [3] above, wherein the coarse-grained magnesium alloy billet further comprises at least one of the following:

[0016] Greater than 0% by weight to less than or equal to about 3% by weight of zinc;

[0017] Tin, greater than 0% by weight to less than or equal to about 3% by weight;

[0018] Calcium greater than 0% by weight to less than or equal to about 0.5% by weight; and

[0019] Rare earth metals greater than 0% by weight to less than or equal to about 5% by weight.

[0020] [8]. The method described in [7] above, wherein the coarse-grained magnesium alloy billet contains approximately 1% by weight of zinc.

[0021] [9]. The method described in [1] above, wherein the extruded preform comprises a plurality of twins having a lenticular morphology.

[0022]

[10] . The method described above [9], wherein the twin-induced dynamic recrystallized grains occupy an area fraction of more than or equal to about 20% of the total area of ​​the billet.

[0023]

[11] . A method of forming a forged component, the method comprising:

[0024] An extruded billet is prepared from a coarse-grained magnesium alloy billet having an average grain size of greater than or equal to about 800 µm by extruding the coarse-grained magnesium alloy billet at a temperature less than or equal to about 360°C, wherein the extruded billet is incorporated into a forging assembly.

[0025]

[12] . The method as described in

[11] above, wherein the method further comprises:

[0026] After extrusion, the extruded billet is moved through a forging die with an opening corresponding to the cross-sectional geometry of the forging assembly.

[0027]

[13] . The method described in

[11] above, wherein the extrusion is performed at a temperature greater than or equal to about 300°C.

[0028]

[14] . The method described in

[11] above, wherein the coarse-grained magnesium alloy billet has a low aluminum content and contains more than or equal to about 1.5% by weight to less than or equal to about 3% by weight of aluminum.

[0029]

[15] . The method described in

[11] above, wherein the coarse-grained magnesium alloy billet comprises:

[0030] Manganese, greater than or equal to about 0.3% by weight and less than or equal to about 0.6% by weight;

[0031] Zinc, greater than or equal to about 0% by weight and less than or equal to about 3% by weight;

[0032] Tin greater than or equal to about 0% by weight and less than or equal to about 3% by weight;

[0033] Calcium greater than or equal to about 0% by weight and less than or equal to about 0.5% by weight; and

[0034] Rare earth metals greater than or equal to about 0% by weight and less than or equal to about 5% by weight.

[0035]

[16] . The method described in

[11] above, wherein the forging assembly comprises a plurality of twin-induced dynamic recrystallized grains.

[0036]

[17] . The method described above

[16] , wherein the twin-induced dynamic recrystallized grains occupy an area fraction of more than or equal to about 20% of the total area of ​​the forging assembly.

[0037]

[18] . The method described above

[16] , wherein the forging component comprises more than or equal to about 20% grain boundaries having an orientation difference of more than or equal to about 60 degrees to less than or equal to about 100 degrees.

[0038]

[19] . A method for forming an extruded billet from a coarse-grained magnesium alloy billet, the method comprising:

[0039] A coarse-grained magnesium alloy billet is moved through an extrusion die at a temperature greater than or equal to about 300°C and less than or equal to about 360°C to form an extruded billet. The coarse-grained magnesium alloy billet contains greater than or equal to about 0.5% by weight and less than or equal to about 3% by weight of aluminum and has an average grain size greater than or equal to about 800 µm. The extruded billet contains a plurality of twins with a lentil-like morphology, the plurality of twins with a lentil-like morphology occupying an area fraction greater than or equal to about 20% of the total area of ​​the extruded billet.

[0040]

[20] . The method described above

[19] , wherein the coarse-grained magnesium alloy further comprises:

[0041] Manganese greater than or equal to about 0.3% by weight and less than or equal to about 0.6% by weight.

[0042]

[21] . The method as described above

[19] , wherein the coarse-grained magnesium alloy further comprises at least one of the following:

[0043] Greater than 0% by weight to less than or equal to about 3% by weight of zinc;

[0044] Tin, greater than 0% by weight to less than or equal to about 3% by weight;

[0045] Calcium greater than 0% by weight to less than or equal to about 0.5% by weight; and

[0046] Rare earth metals greater than 0% by weight to less than or equal to about 5% by weight.

[0047] This disclosure relates to a method for extruding coarse-grained magnesium alloys to form extruded billets.

[0048] In various aspects, this disclosure provides a method for forming an extruded billet from a coarse-grained magnesium alloy billet. The method includes extruding the coarse-grained magnesium alloy billet at a temperature less than or equal to about 360°C to form the billet. The coarse-grained magnesium alloy billet may have an average grain size greater than or equal to about 800 µm.

[0049] In one aspect, the coarse-grained magnesium alloy billet can be extruded at a temperature greater than or equal to about 300°C.

[0050] In one aspect, the coarse-grained magnesium alloy billet may have a low aluminum content. The coarse-grained magnesium alloy billet may include more than or equal to about 0.5% by weight and less than or equal to about 3% by weight of aluminum.

[0051] In one aspect, the coarse-grained magnesium alloy billet may include approximately 2% by weight of aluminum.

[0052] In one aspect, the coarse-grained magnesium alloy billet may include more than or equal to about 0.3% by weight and less than or equal to about 0.6% by weight of manganese.

[0053] In one aspect, the coarse-grained magnesium alloy billet may include approximately 0.5% by weight of manganese.

[0054] In one aspect, the coarse-grained magnesium alloy billet may include at least one of the following: more than 0% by weight to less than or equal to about 3% by weight of zinc, more than 0% by weight to less than or equal to about 3% by weight of tin, more than 0% by weight to less than or equal to about 0.5% by weight of calcium and more than 0% by weight to less than or equal to about 5% by weight of rare earth metals.

[0055] In one aspect, the coarse-grained magnesium alloy billet may include approximately 1% by weight of zinc.

[0056] In one aspect, the extruded preform may include a plurality of twins having a lentil-shaped morphology.

[0057] In one aspect, the plurality of twins having a lentil-like morphology may occupy an area fraction greater than or equal to about 20% of the total area of ​​the extruded preform.

[0058] In one aspect, articles made from the extruded preform may include a plurality of twin-induced dynamic recrystallized grains.

[0059] In one aspect, the twinned dynamically recrystallized grains may occupy an area fraction of more than or equal to about 20% of the total area of ​​the article thus prepared.

[0060] In one aspect, the article thus prepared may include grain boundaries having an orientation difference of more than or equal to about 20% having an orientation difference of more than or equal to about 60 degrees and less than or equal to about 100 degrees.

[0061] In various aspects, this disclosure provides a method for forming a forged assembly. The method may include preparing an extruded billet from a lean aluminum-magnesium alloy billet by extruding the billet at a temperature less than or equal to about 360°C to form an extruded billet. The lean aluminum-magnesium alloy billet may have an average grain size greater than or equal to about 800 µm. The extruded billet may be incorporated into the forged assembly.

[0062] In one aspect, the method may further include, after extrusion, moving the extruded billet through a forging die having an opening corresponding to the cross-sectional geometry of the forging assembly.

[0063] In one aspect, the extrusion can be carried out at a temperature greater than or equal to about 300°C.

[0064] In one aspect, the aluminum-depleted magnesium alloy billet may include more than or equal to about 0.5% by weight and less than or equal to about 3% by weight of aluminum.

[0065] In one aspect, the aluminum-magnesium alloy billet may include more than or equal to about 0.3% by weight to less than or equal to about 0.6% by weight of manganese, more than or equal to about 0% by weight to less than or equal to about 3% by weight of zinc, more than or equal to about 0% by weight to less than or equal to about 3% by weight of tin, more than or equal to about 0% by weight to less than or equal to about 0.5% by weight of calcium, and more than or equal to about 0% by weight to less than or equal to about 5% by weight of rare earth metals.

[0066] In one aspect, the extruded preform may include a plurality of twins having a lentil-shaped morphology.

[0067] In one aspect, the plurality of twins having a lentil-like morphology may occupy an area fraction greater than or equal to about 20% of the total area of ​​the extruded preform.

[0068] In one aspect, the forging assembly may include a plurality of twin-induced dynamic recrystallized grains.

[0069] In one aspect, the twin-induced dynamic recrystallized grains may occupy an area fraction greater than or equal to about 20% of the total area of ​​the forging assembly.

[0070] In one aspect, the forging assembly may include grain boundaries having an orientation difference of more than or equal to about 20% having an orientation difference of more than or equal to about 60 degrees to less than or equal to about 100 degrees.

[0071] In various aspects, this disclosure provides a method for forming an extruded billet from a coarse-grained magnesium alloy billet. The method may include moving the coarse-grained magnesium alloy billet through an extrusion die at a temperature greater than or equal to about 300°C and less than or equal to about 360°C to form the billet. The coarse-grained magnesium alloy billet may include greater than or equal to about 0.5 wt% and less than or equal to about 3 wt% aluminum. The coarse-grained magnesium alloy billet may have an average grain size greater than or equal to about 800 µm.

[0072] In one aspect, the extruded preform may include a plurality of twins having a lentil-shaped morphology.

[0073] In one aspect, the plurality of twins having a lentil-like morphology may occupy an area fraction greater than or equal to about 20% of the total area of ​​the extruded preform.

[0074] In one aspect, the extruded preform can be used to prepare articles comprising multiple twin-induced dynamically recrystallized grains.

[0075] In one aspect, the twinned dynamically recrystallized grains may occupy an area fraction of more than or equal to about 20% of the total area of ​​the article thus prepared.

[0076] In one aspect, the article thus prepared may include grain boundaries having an orientation difference of more than or equal to about 20% having an orientation difference of more than or equal to about 60 degrees and less than or equal to about 100 degrees.

[0077] In one aspect, the coarse-grained magnesium alloy billet may further comprise manganese at a concentration greater than or equal to about 0.3% by weight and less than or equal to about 0.6% by weight.

[0078] In one aspect, the coarse-grained magnesium alloy billet may further comprise at least one of the following: more than 0% by weight to less than or equal to about 3% by weight of zinc, more than 0% by weight to less than or equal to about 3% by weight of tin, more than 0% by weight to less than or equal to about 0.5% by weight of calcium, and more than 0% by weight to less than or equal to about 5% by weight of rare earth metals.

[0079] Other applicable areas will become apparent from the description provided herein. The descriptions and specific examples in this overview are intended to be illustrative only and are not intended to limit the scope of this disclosure. Brief description of the attached diagram

[0080] The accompanying drawings described herein are for illustrative purposes only and not for all possible embodiments, and are not intended to limit the scope of this disclosure.

[0081] Figure 1 This is a flowchart illustrating an exemplary method for preparing extruded billets from coarse-grained aluminum-magnesium alloy billets according to various aspects of this disclosure;

[0082] Figure 2 This is a diagram showing the frequency of grain boundary orientation differences in articles prepared from exemplary extruded preforms, wherein exemplary extruded preforms are prepared from coarse-grained magnesium alloy preforms using an extrusion method having a temperature greater than or equal to about or exactly 300°C to less than or equal to about or exactly 360°C, according to various aspects of this disclosure.

[0083] Figure 3 Microscopic images of exemplary extruded billets prepared from coarse-grained magnesium alloy billets using an extrusion method with temperatures greater than or equal to about or exactly 300°C to less than or equal to about or exactly 360°C, according to various aspects of this disclosure; and

[0084] Figure 4 These are microscopic images of exemplary extruded billets prepared from coarse-grained magnesium alloy billets using an extrusion method with a temperature greater than or equal to approximately or exactly 380°C.

[0085] In the various views of the accompanying drawings, the corresponding reference numerals refer to the corresponding components.

[0086] Detailed Explanation

[0087] Exemplary embodiments are provided to make this disclosure thorough and to fully communicate its scope to those skilled in the art. Numerous specific details, such as examples of specific compositions, components, apparatuses, and methods, are set forth to provide a full understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that the specific details are not required, that exemplary embodiments may be embodied in many different forms, and that none of them should be construed as limiting the scope of this disclosure. In some exemplary embodiments, well-known methods, well-known apparatus structures, and well-known technologies are not described in detail.

[0088] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a” and “the” used herein are intended to include the plural forms as well. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of a designated element, component, composition, step, integer, operation, and / or component, but do not exclude the presence or inclusion of one or more other elements, integers, steps, operations, components, and / or combinations thereof. Although the open-ended term “comprising” should be understood as a non-limiting term used to describe and claim protection for the various embodiments described herein, in some respects, the term may be understood as a more restrictive and binding term, such as “consisting of” or “substantially consisting of.” Therefore, for any given embodiment in which compositions, materials, components, elements, components, integers, operations, and / or process steps are listed, this disclosure also expressly includes embodiments consisting of or substantially consisting of these listed compositions, materials, components, components, components, components, integers, operations, and / or process steps. In the case of “consisting of…”, the alternative embodiment does not include any additional compositions, materials, components, elements, elements, integers, operations and / or process steps, while in the case of “essentially composed of…”, such an embodiment does not include any additional compositions, materials, components, elements, elements, integers, operations and / or process steps that materially affect the essential and novel features, but may include any compositions, materials, components, elements, elements, integers, operations and / or process steps that do not materially affect the essential and novel features.

[0089] Any method steps, processes, and operations described herein should not be construed as necessarily requiring them to be performed in the particular order discussed or illustrated, unless expressly specified as such. It should also be understood that additional or alternative steps may be used unless otherwise indicated.

[0090] When a component, element, or layer is mentioned as being “on,” “joined,” “connected,” or “coupled” to another component or layer, it may be directly on, joined, connected, or coupled to the other component, element, or layer, or there may be intermediate elements or layers. Conversely, when an element is mentioned as being “directly on,” “directly joined,” “directly connected,” or “directly coupled” to another component or layer, there are no intermediate elements or layers. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between,” “adjacent” vs. “directly adjacent,” etc.). The term “and / or” as used herein includes any and all combinations of one or more of the related listed items.

[0091] Although the terms first, second, third, etc., may be used herein to describe various steps, elements, components, regions, layers, and / or sections, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise specified. These terms are used only to distinguish one step, element, component, region, layer, or section from another. Unless the context clearly indicates otherwise, terms such as “first,” “second,” and other ordinal terms used herein do not imply order or sequence. Therefore, the first step, element, component, region, layer, or section discussed below may be referred to as the second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0092] For ease of description, spatially or temporally relative terms such as “front,” “back,” “inner,” “outer,” “lower,” “below,” “lower part,” “upper part,” “upper part,” etc., may be used herein to describe the relationship between one element or component and another element or component as shown in the accompanying drawings. Spatially or temporally relative terms are intended to encompass different orientations of the device or system in use or operation other than those depicted in the accompanying drawings.

[0093] Throughout this disclosure, numerical values ​​represent approximate measurements or range limits to include slight deviations from a given value and embodiments that substantially have the listed values ​​as well as embodiments that precisely have the listed values. Except in the detailed embodiments provided at the end, all numerical values ​​of parameters (e.g., quantities or conditions) in this specification (including the appended claims) should be understood to be modified in all cases by the term “about,” regardless of whether “about” actually precedes the numerical value. “About” means that the specified numerical value allows for a certain degree of slight imprecision (closeness to the value; approximate or reasonably close to the value; almost). If the imprecision provided by “about” is not understood in this common sense in the art, “about” as used herein refers at least to variations that may arise from common methods of measuring and using such parameters. For example, “about” may include variations of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some respects, optionally less than or equal to 0.1%.

[0094] In addition, the disclosure of the range includes all values ​​across the entire range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0095] Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0096] This disclosure relates to extruded billets made from coarse-grained aluminum-poor magnesium alloys, particularly from coarse-grained aluminum-poor magnesium alloy billets. The coarse-grained aluminum-poor magnesium alloy billets may have an average grain size greater than or equal to about or exactly 800 µm. The coarse-grained magnesium alloy comprises one or more magnesium alloys. Magnesium alloys according to various aspects of this disclosure include aluminum (Al) and manganese (Mn). In some variations, the magnesium alloy may also include zinc (Zn), tin (Sn), and / or calcium (Ca). In other variations, the magnesium alloy may also include one or more rare earth metals, such as lanthanides and / or yttrium (Y). For example, coarse-grained magnesium alloys may include certain combinations of aluminum, manganese, zinc, tin, calcium, and rare earth metals. An exemplary magnesium alloy may consist essentially of magnesium, aluminum, and manganese. Another exemplary magnesium alloy may consist essentially of magnesium, aluminum, and manganese, and at least one of zinc, tin, calcium, and one or more rare earth metals. In other words, the exemplary magnesium alloy may not include additional compositions, materials, components, elements and / or features that substantially affect the basic and novel characteristics of the exemplary magnesium alloy, but may include any compositions, materials, components, elements and / or features that do not substantially affect the basic and novel characteristics of the exemplary magnesium alloy.

[0097] In some variations, the magnesium alloy may have a low aluminum content. For example, the magnesium alloy may include more than or equal to about or exactly 0.5% by weight to less than or equal to about or exactly 3% by weight of aluminum. The magnesium alloy may include more than or equal to about or exactly 0.5% by weight, optionally more than or equal to about or exactly 0.6% by weight, optionally more than or equal to about or exactly 0.7% by weight, optionally more than or equal to about or exactly 0.8% by weight, optionally more than or equal to about or exactly 0.9% by weight, optionally more than or equal to about or exactly 1% by weight, optionally more than or equal to about or exactly 1.1% by weight, optionally more than or equal to about or exactly 1.2% by weight, optionally more than or equal to about or exactly 1.3% by weight, optionally more than or equal to about or exactly 1.4% by weight, optionally more than or equal to about or exactly 1.5% by weight, optionally more than or equal to about or exactly 1.6% by weight, optionally more than or equal to about or exactly 1.6% by weight. 1.7% by weight, optionally greater than or equal to about or exactly 1.8% by weight, optionally greater than or equal to about or exactly 1.9% by weight, optionally greater than or equal to about or exactly 2.0% by weight, optionally greater than or equal to about or exactly 2.1% by weight, optionally greater than or equal to about or exactly 2.2% by weight, optionally greater than or equal to about or exactly 2.3% by weight, optionally greater than or equal to about or exactly 2.4% by weight, optionally greater than or equal to about or exactly 2.5% by weight, optionally greater than or equal to about or exactly 2.6% by weight, optionally greater than or equal to about or exactly 2.7% by weight, optionally greater than or equal to about or exactly 2.8% by weight, and in some respects, optionally greater than or equal to about or exactly 2.9% by weight of aluminum.The magnesium alloy may comprise less than or equal to approximately or exactly 3% by weight, optionally less than or equal to approximately or exactly 2.9% by weight, optionally less than or equal to approximately or exactly 2.8% by weight, optionally less than or equal to approximately or exactly 2.7% by weight, optionally less than or equal to approximately or exactly 2.6% by weight, optionally less than or equal to approximately or exactly 2.5% by weight, optionally less than or equal to approximately or exactly 2.4% by weight, optionally less than or equal to approximately or exactly 2.3% by weight, optionally less than or equal to approximately or exactly 2.2% by weight, optionally less than or equal to approximately or exactly 2.1% by weight, optionally less than or equal to approximately or exactly 2.0% by weight, optionally less than or equal to approximately or exactly 1.9% by weight, optionally less than or equal to approximately or exactly 3% by weight. 1.8% by weight, optionally less than or equal to about or exactly 1.7% by weight, optionally less than or equal to about or exactly 1.6% by weight, optionally less than or equal to about or exactly 1.5% by weight, optionally less than or equal to about or exactly 1.4% by weight, optionally less than or equal to about or exactly 1.3% by weight, optionally less than or equal to about or exactly 1.2% by weight, optionally less than or equal to about or exactly 1.1% by weight, optionally less than or equal to about or exactly 1% by weight, optionally less than or equal to about or exactly 0.9% by weight, optionally less than or equal to about or exactly 0.8% by weight, optionally less than or equal to about or exactly 0.7% by weight, and in some respects, optionally less than or equal to about or exactly 0.6% by weight of aluminum.

[0098] In some variations, the magnesium alloy may include manganese in amounts greater than or equal to about or exactly 0.3% by weight and less than or equal to about or exactly 0.6% by weight. For example, the magnesium alloy may include manganese in amounts greater than or equal to about or exactly 0.3% by weight, optionally greater than or equal to about or exactly 0.35% by weight, optionally greater than or equal to about or exactly 0.4% by weight, optionally greater than or equal to about or exactly 0.45% by weight, optionally greater than or equal to about or exactly 0.5% by weight, and in some aspects, optionally greater than or equal to about or exactly 0.55% by weight. The magnesium alloy may also include manganese in amounts less than or equal to about or exactly 0.6% by weight, optionally less than or equal to about or exactly 0.55% by weight, optionally less than or equal to about or exactly 0.5% by weight, optionally less than or equal to about or exactly 0.45% by weight, optionally less than or equal to about or exactly 0.4% by weight, and in some aspects, optionally less than or equal to about or exactly 0.35% by weight.

[0099] In some variations, the magnesium alloy may include zinc at a concentration greater than or equal to about or exactly 0% by weight and less than or equal to about or exactly 3% by weight. For example, the magnesium alloy may include zinc at a concentration greater than or equal to about or exactly 0% by weight, optionally greater than or equal to about or exactly 0.05% by weight, optionally greater than or equal to about or exactly 0.1% by weight, optionally greater than or equal to about or exactly 0.5% by weight, optionally greater than or equal to about or exactly 1% by weight, optionally greater than or equal to about or exactly 1.5% by weight, optionally greater than or equal to about or exactly 2.0% by weight, and in some aspects, optionally greater than or equal to about or exactly 2.5% by weight. The magnesium alloy may include zinc at a concentration less than or equal to about or exactly 3% by weight, optionally less than or equal to about or exactly 2.5% by weight, optionally less than or equal to about or exactly 2% by weight, optionally less than or equal to about or exactly 1.5% by weight, optionally less than or equal to about or exactly 1% by weight, optionally less than or equal to about or exactly 0.5% by weight, and in some aspects, optionally less than or equal to about or exactly 0.1% by weight.

[0100] In some variations, the magnesium alloy may include tin at a concentration greater than or equal to about or exactly 0% by weight and less than or equal to about or exactly 3% by weight. For example, the magnesium alloy may include tin at a concentration greater than or equal to about or exactly 0% by weight, optionally greater than or equal to about or exactly 0.05% by weight, optionally greater than or equal to about or exactly 0.1% by weight, optionally greater than or equal to about or exactly 0.5% by weight, optionally greater than or equal to about or exactly 1% by weight, optionally greater than or equal to about or exactly 1.5% by weight, optionally greater than or equal to about or exactly 2.0% by weight, and in some aspects, optionally greater than or equal to about or exactly 2.5% by weight. The magnesium alloy may include tin at a concentration less than or equal to about or exactly 3% by weight, optionally less than or equal to about or exactly 2.5% by weight, optionally less than or equal to about or exactly 2% by weight, optionally less than or equal to about or exactly 1.5% by weight, optionally less than or equal to about or exactly 1% by weight, optionally less than or equal to about or exactly 0.5% by weight, and in some aspects, optionally less than or equal to about or exactly 0.1% by weight.

[0101] In some variations, the magnesium alloy may include calcium at a concentration greater than or equal to about or exactly 0% by weight and less than or equal to about or exactly 0.5% by weight. For example, the magnesium alloy may include calcium at a concentration greater than or equal to about or exactly 0% by weight, optionally greater than or equal to about or exactly 0.05% by weight, optionally greater than or equal to about or exactly 0.1% by weight, greater than or equal to about or exactly 0.15% by weight, greater than or equal to about or exactly 0.2% by weight, greater than or equal to about or exactly 0.25% by weight, greater than or equal to about or exactly 0.3% by weight, greater than or equal to about or exactly 0.35% by weight, greater than or equal to about or exactly 0.4% by weight, and in some respects, greater than or equal to about or exactly 0.45% by weight. The magnesium alloy may include less than or equal to about or exactly 0.5% by weight, optionally less than or equal to about or exactly 0.45% by weight, optionally less than or equal to about or exactly 0.4% by weight, optionally less than or equal to about or exactly 0.35% by weight, optionally less than or equal to about or exactly 0.3% by weight, optionally less than or equal to about or exactly 0.25% by weight, optionally less than or equal to about or exactly 0.2% by weight, optionally less than or equal to about or exactly 0.15% by weight, optionally less than or equal to about or exactly 0.1% by weight, and in some respects, optionally less than or equal to about or exactly 0.05% by weight of calcium.

[0102] In some variations, the magnesium alloy may include more than or equal to about or exactly 0% by weight to less than or equal to about or exactly 5% by weight of rare earth metals. For example, the magnesium alloy may include more than or equal to about or exactly 0% by weight, optionally including more than or equal to about or exactly 0.5% by weight, optionally including more than or equal to about or exactly 1% by weight, optionally including more than or equal to about or exactly 1.5% by weight, optionally including more than or equal to about or exactly 2.0% by weight, optionally including more than or equal to about or exactly 2.5% by weight, optionally including more than or equal to about or exactly 3% by weight, optionally including more than or equal to about or exactly 3.5% by weight, optionally including more than or equal to about or exactly 4% by weight, and in some aspects, optionally including more than or equal to about or exactly 4.5% by weight of rare earth metals. The magnesium alloy may include less than or equal to about or exactly 5% by weight, optionally less than or equal to about or exactly 4.5% by weight, optionally less than or equal to about or exactly 4.0% by weight, optionally less than or equal to about or exactly 3.5% by weight, optionally less than or equal to about or exactly 3.0% by weight, optionally less than or equal to about or exactly 2.5% by weight, optionally less than or equal to about or exactly 2.0% by weight, optionally less than or equal to about or exactly 1.5% by weight, optionally less than or equal to about or exactly 1% by weight, and in some respects, optionally less than or equal to about or exactly 0.5% by weight of rare earth metals.

[0103] In each variant, the magnesium alloy includes a balance of magnesium. For example, the magnesium alloy may comprise greater than or equal to about or exactly 85% by weight, optionally greater than or equal to about or exactly 86% by weight, optionally greater than or equal to about or exactly 87% by weight, optionally greater than or equal to about or exactly 88% by weight, optionally greater than or equal to about or exactly 89% by weight, optionally greater than or equal to about or exactly 90% by weight, optionally greater than or equal to about or exactly 91% by weight, optionally greater than or equal to about or exactly 92% by weight, optionally greater than or equal to about or exactly 93% by weight, optionally greater than or equal to about or exactly 94% by weight, optionally greater than or equal to about or exactly 95% by weight, optionally greater than or equal to about or exactly 96% by weight, optionally greater than or equal to about or exactly 97% by weight, or in some respects, optionally greater than or equal to about or exactly 98% by weight of magnesium.

[0104] In each variant, the magnesium alloy may also include trace amounts of other elements that do not materially affect the essential characteristics of the magnesium alloy, for example only, beryllium (Be) and / or strontium (Sr). For instance, the magnesium alloy may include amounts less than or equal to about or exactly 1.5 wt%, optionally less than or equal to about or exactly 1.4 wt%, optionally less than or equal to about or exactly 1.3 wt%, optionally less than or equal to about or exactly 1.2 wt%, optionally less than or equal to about or exactly 1.1 wt%, optionally less than or equal to about or exactly 1.0 wt%, optionally less than or equal to about or exactly 0.9 wt%, optionally less than or equal to about or exactly 0.8 wt%, optionally less than or equal to about or exactly 0.7 wt%, optionally less than or equal to about or exactly 0.6 wt%, optionally less than or equal to about or exactly 0.5 wt%, optionally less than or equal to about or exactly 0.4 wt%, optionally less than or equal to about or exactly 0.3 wt%, optionally less than or equal to about or exactly 0.2 wt%, optionally less than or equal to about or exactly 0.1 wt%, or in some respects, undetectable amounts.

[0105] In various aspects, this disclosure provides a method for forming an extruded billet from a coarse-grained low-aluminum magnesium alloy, particularly from a coarse-grained low-aluminum magnesium alloy billet. The method includes, for example, extruding the coarse-grained magnesium alloy billet at a temperature greater than or equal to about or exactly 300°C and less than or equal to about or exactly 360°C. For example, the coarse-grained magnesium alloy billet can be extruded at a temperature greater than or equal to about or exactly 300°C, optionally greater than or equal to about or exactly 305°C, greater than or equal to about or exactly 310°C, greater than or equal to about or exactly 315°C, greater than or equal to about or exactly 320°C, greater than or equal to about or exactly 325°C, greater than or equal to about or exactly 330°C, greater than or equal to about or exactly 335°C, greater than or equal to about or exactly 340°C, greater than or equal to about or exactly 345°C, greater than or equal to about or exactly 350°C, and in some aspects, optionally greater than or equal to about or exactly 355°C. Coarse-grained magnesium alloy billets can be extruded at temperatures less than or equal to approximately or exactly 360°C, optionally less than or equal to approximately or exactly 355°C, optionally less than or equal to approximately or exactly 350°C, optionally less than or equal to approximately or exactly 345°C, optionally less than or equal to approximately or exactly 340°C, optionally less than or equal to approximately or exactly 335°C, optionally less than or equal to approximately or exactly 330°C, optionally less than or equal to approximately or exactly 325°C, optionally less than or equal to approximately or exactly 320°C, optionally less than or equal to approximately or exactly 315°C, optionally less than or equal to approximately or exactly 310°C, and in some respects, optionally less than or equal to approximately or exactly 305°C. As those skilled in the art will recognize, extrusion is a process of passing metal in a flowable form through a defined area, such as a die, to form an intermediate billet with a standard shape or cross-section, while forging is a high-pressure process that involves, for example, moving an intermediate billet through a die to form a final, complex three-dimensional forged assembly or part.

[0106] like Figure 1 As shown, an exemplary method 100 for forming an extruded billet from a coarse-grained low-aluminum-magnesium alloy billet may include heating the coarse-grained low-aluminum-magnesium alloy billet 120 to a temperature greater than or equal to about or exactly 300°C and less than or equal to about or exactly 360°C, and extruding 130 the heated coarse-grained low-aluminum-magnesium alloy billet to form the extruded billet. In some variations, extrusion 130 may be performed at a ram speed greater than or equal to about or exactly 0.5 mm / s and less than or equal to about or exactly 3 mm / s. In some variations, extrusion 130 may have an extrusion ratio greater than or equal to about or exactly 2 and less than or equal to about 5.

[0107] Due to the low-temperature extrusion process, the extruded billet can each have multiple lentil-shaped twins within the magnesium matrix defining the billet. In subsequent forging processes, the twin morphology can be transformed so that the microstructure of the resulting magnesium article includes twin-induced dynamically recrystallized grains. The twin morphology can occupy an area fraction greater than or equal to about or exactly 20% of the total area of ​​the extruded billet prepared according to various aspects of this disclosure. In some variations, the lentil-shaped twins can have a grain boundary orientation difference greater than or equal to about or exactly 60 degrees and less than or equal to about 100 degrees. Figure 2 As shown, where x-axis 202 represents the misorientation angle in degrees and y-axis 204 represents the frequency, the fraction of grain boundaries with misorientation between 60 and 100 degrees constitutes more than or equal to about or exactly 20% of all grain boundaries. In each variant, twins formed in the extruded billet can act as nucleation sites for the dynamic recrystallization of fine grains during subsequent forging processes.

[0108] In various aspects, method 100 may include a low-aluminum magnesium alloy billet forming a coarse-grained 110 grain. The low-aluminum magnesium alloy forming the 110 coarse-grained 110 grain may include casting methods, such as using a direct-chill casting process and / or a semi-continuous casting process. In each variant, the extruded billet may have an average diameter greater than or equal to about or exactly 200 mm, and in some variants, optionally greater than or equal to about or exactly 300 mm.

[0109] Figure 3 These are microscopic images of exemplary extruded preforms prepared using an extrusion process at temperatures greater than or equal to approximately or exactly 300°C to less than or equal to approximately or exactly 360°C, showing the presence of multiple lentil-shaped twins. For comparison only. Figure 4 These are microscopic images of an exemplary extruded preform prepared using an extrusion method at a temperature greater than or equal to approximately or exactly 380°C. In this case, the white arrows identify the dynamic recrystallization of fine grains. In this case, the area fraction of dynamic recrystallization of the fine grains is less than or equal to approximately or exactly 10%.

[0110] Billets extruded from coarse-grained, low-aluminum-content magnesium alloys are particularly suitable for forming components for automobiles or other vehicles (e.g., motorcycles, boats, tractors, buses, motorhomes, campervans, and tanks), but they can also be used in a variety of other industries and applications, including aerospace components, consumer products, devices, buildings (e.g., homes, offices, sheds, warehouses), office equipment and furniture, industrial equipment machinery, agricultural or farm equipment, or heavy machinery, as non-limiting examples. Non-limiting examples of automotive components or articles of manufacture include hoods, pillars (e.g., A-pillars, hinge pillars, B-pillars, C-pillars, etc.), panels including structural panels, door panels and door assemblies, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, levers and other suspension components, crush cans, bumpers, structural rails and frames, crossbeams, undercarriage, or drivetrain components, etc.

[0111] In various aspects, this disclosure provides methods for forming articles or components from extruded preforms. For example, an exemplary method of forming a component includes forging the extruded preform. In some variations, forging may include moving the extruded preform through a die having an opening or slit that matches the cross-sectional geometry of the component, so that the forged component exiting the die has a cross-sectional geometry. In some variations, the die may have a first half-die and a second half-die that together define the opening. The first half-die and the second half-die may be configured to apply pressure to the extruded preform. For example, a pressure greater than or equal to about or exactly 50 kN to less than or equal to about or exactly 150 kN may be applied to the extruded preform. In some variations, forging may be performed by pushing the extruded preform through the die at a stamping speed greater than or equal to about or exactly 1 mm / s to less than or equal to about or exactly 15 mm / s. Forging may be performed at a temperature greater than or equal to about or exactly 350°C to less than or equal to about or exactly 450°C. In some variations, as those skilled in the art will recognize, the method may include one or more flow forming processes following the forging process.

[0112] The above description of the provided embodiments is for illustrative purposes only. It is not intended to be exhaustive or limiting of this disclosure. Elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable and applicable to selected embodiments, if applicable, even if not explicitly shown or described. They can also be changed in many ways. Such changes should not be considered a departure from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A method for forming an extruded billet from a coarse-grained magnesium alloy billet, the method comprising: A coarse-grained magnesium alloy billet is extruded at a temperature of 305-345°C to form an extruded billet, wherein the coarse-grained magnesium alloy billet has an average grain size greater than 800 µm. The extruded preform contains multiple twins with a lentil-shaped morphology, and The twin-induced dynamic recrystallized grains occupy an area fraction of 20% or more of the total area of ​​the billet.

2. The method of claim 1, wherein the coarse-grained magnesium alloy billet has a low aluminum content and contains more than or equal to 1.5% by weight and less than or equal to 3% by weight of aluminum.

3. The method of claim 2, wherein the coarse-grained magnesium alloy billet contains 2% by weight of aluminum.

4. The method of claim 2, wherein the coarse-grained magnesium alloy billet further comprises more than or equal to 0.3% by weight and less than or equal to 0.6% by weight of manganese.

5. The method of claim 4, wherein the coarse-grained magnesium alloy billet contains 0.5% by weight of manganese.

6. The method of claim 2, wherein the coarse-grained magnesium alloy billet further comprises at least one of the following: Zinc, greater than 0% by weight and less than or equal to 3% by weight; Tin, greater than 0% by weight and less than or equal to 3% by weight; Calcium greater than 0.5% by weight and less than or equal to 0.5% by weight; and Rare earth metals, greater than 0% by weight and less than or equal to 5% by weight.

7. The method of claim 6, wherein the coarse-grained magnesium alloy billet contains 1% by weight of zinc.

8. A method of forming a forged component, the method comprising: An extruded billet is prepared from a coarse-grained magnesium alloy billet having an average grain size greater than 800 µm by extruding the coarse-grained magnesium alloy billet at a temperature of 305-345°C, wherein the extruded billet is incorporated into a forging assembly. The forging assembly comprises multiple twin-induced dynamically recrystallized grains, and The twin-induced dynamic recrystallized grains occupy an area fraction of greater than or equal to 20% of the total area of ​​the forging assembly.

9. The method of claim 8, wherein the method further comprises: After extrusion, the extruded billet is moved through a forging die with an opening corresponding to the cross-sectional geometry of the forging assembly.

10. The method of claim 8, wherein the coarse-grained magnesium alloy billet has a low aluminum content and contains more than or equal to 1.5% by weight and less than or equal to 3% by weight of aluminum.

11. The method of claim 8, wherein the coarse-grained magnesium alloy billet comprises: Manganese, greater than or equal to 0.3% by weight and less than or equal to 0.6% by weight; Zinc, greater than or equal to 0% by weight and less than or equal to 3% by weight; Tin with a weight percentage greater than or equal to 0% and less than or equal to 3%; Calcium greater than or equal to 0% by weight and less than or equal to 0.5% by weight; and Rare earth metals ranging from 0% to 5% by weight.

12. The method of claim 8, wherein the forging component comprises more than or equal to 20% grain boundaries having an orientation difference of more than or equal to 60 degrees and less than or equal to 100 degrees.

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