Method for forming an extruded billet from a coarse-grained magnesium alloy billet

Abstract

A method of forming an extruded billet from a coarse-grained magnesium alloy billet, the method comprising: Extruding the coarse-grained magnesium alloy billet at temperatures of greater than or equal to 300 °C to less than or equal to 360 °C to form the extruded billet, wherein the coarse-grained magnesium alloy billet has an average grain size of greater than or equal to 800 µm.

Description

INITIATIONThis section contains background information related to the present disclosure that is not necessarily prior art.Light metal components have become an important focus in the manufacture of vehicles, particularly automobiles, where continuous improvement in performance and fuel efficiency is desirable. While conventional steel and other metal alloys provide various performance advantages, including high strength, such materials may be heavy in weight. Light metal components for automotive applications are often made of aluminum and / or magnesium alloys. Such light metals can form load bearing components that are strong and rigid while having good strength and ductility (e.g., elongation). High strength and ductility are particularly important for safety requirements and durability in vehicles such as automobiles.Although magnesium-based alloys are an example of light metals that can be used to form structural members in a vehicle, in practice, the use of magnesium-based alloys may be limited. For example, it is often desirable to reduce the aluminum content of magnesium-based alloys to improve the ductility of the magnesium-based alloys. The reduction of aluminum can have a negative effect on grain refining during casting in such a way that magnesium-based alloys with low aluminum contents often have a coarse grain structure. In certain variations, coarse grain textures may be refined to improve the oscillability using extrusion processes with temperatures greater than or equal to about 380° C. and a high aspect ratio (e.g., greater than or equal to about or equal to about 15). However, for products (e.g., runner) formed by performing forging operations on extruded billet having large diameters (e.g., greater than or equal to about or exactly 200 mm), extrusion ratios are limited (e.g., less than or equal to about or exactly 5). In these cases, the coarse grain microstructure as such cannot be easily refined by conventional extrusion techniques, for example, due to the limited plastic deformation degree and the low grain boundary portions in the original microstructure, thereby limiting the number of sites for dynamic recrystallization (DRX) or nucleation. Accordingly, it would be desirable to develop methods that improve the oscillability of magnesium-based alloys having a coarse microstructure.SUMMARYThe object of the invention is to improve the above-mentioned disadvantages. This object is achieved with the features of claim 1.The present disclosure relates to methods for extruding coarse magnesium alloys into extruded billet.In various aspects, the present disclosure provides a method of forming an extruded billet from a billet comprised of coarse magnesium alloy. The method includes extruding the billet consisting of coarse magnesium alloy at temperatures of less than or equal to about 360° C. to form the billet. The billet made of coarse magnesium alloy may have an average grain size of greater than or equal to about 800 μm.In one aspect, the billet comprised of coarse magnesium alloy may be extruded at temperatures greater than or equal to about 300° C.In one aspect, the billet comprised of coarse magnesium alloy may have a low aluminum content. The billet of coarse magnesium alloy may comprise greater than or equal to about 0.5 wt% to less than or equal to about 3 wt% aluminum.In one aspect, the billet of coarse magnesium alloy may comprise about 2 wt% aluminum.In one aspect, the billet comprised of coarse magnesium alloy may comprise greater than or equal to about 0.3 wt % to less than or equal to about 0.6 wt % manganese.In one aspect, the billet comprised of coarse magnesium alloy may comprise about 0.5 wt % manganese.In one aspect, the billet comprised of coarse magnesium alloy may comprise greater than 0 wt % to less than or equal to about 3 wt % zinc, greater than 0 wt % to less than or equal to about 3 wt % tin, greater than 0 wt % to less than or equal to about 0.5 wt % calcium, and / or greater than 0 wt % to less than or equal to about 5 wt % of the rare earth metals.In one aspect, the billet of coarse magnesium alloy may comprise about 1 wt% zinc.In one aspect, the extruded billet may comprise a plurality of twins having a lens-shaped morphology.In one aspect, the plurality of twins having a lens-shaped morphology may occupy an area fraction greater than or equal to about 20% of the total area of the extruded billet.In one aspect, an article made from the extruded billet may comprise a plurality of twin-induced dynamic recrystallization grains.In one aspect, the twin-induced dynamic recrystallization grains may occupy an area ratio greater than or equal to about 20% of the total area of the article in the manufactured state.In one aspect, the article when manufactured may comprise greater than or equal to about 20% boundaries with misalignment from greater than or equal to about 60 degrees to less than or equal to about 100 degrees.In various aspects, the present disclosure provides a method of forming a forged part. The method may include forming an extruded billet from a billet consisting of low aluminum magnesium alloy by extruding the billet consisting of low aluminum magnesium alloy at temperatures less than or equal to about 360° C. to form the extruded billet. The billet made of low-aluminum magnesium alloy may have an average grain size of greater than or equal to about 800 μm. The extruded billet may be integrated into the forging.In one aspect, the method may further include, after the extrusion, moving the extruded billet through a forging die having an opening corresponding to the cross-sectional geometry of the forged part.In one aspect, the extrusion may be performed at temperatures greater than or equal to about 300° C.In one aspect, the billet comprised of low aluminum magnesium alloy may comprise greater than or equal to about 0.5 wt % to less than or equal to about 3 wt % aluminum.In one aspect, the billet comprised of low aluminum magnesium alloy may comprise greater than or equal to about 0.3% to less than or equal to about 0.6% manganese, greater than or equal to about 0% to less than or equal to about 3% zinc, greater than or equal to about 0% to less than or equal to about 3% tin, greater than or equal to about 0% to less than or equal to about 0.5% calcium, and greater than or equal to about 0% to less than or equal to about 5% rare earth metals by weight.In one aspect, the extruded billet may comprise a plurality of twins having a lens-shaped morphology.In one aspect, the plurality of twins having a lens-shaped morphology may occupy an area fraction greater than or equal to about 20% of the total area of the extruded billet.In one aspect, the forging may include a plurality of twin-induced dynamic recrystallization grains.In one aspect, the twin-induced dynamic recrystallization grains may occupy an area fraction greater than or equal to about 20% of the total area of the forging.In one aspect, the forging may include greater than or equal to about 20% limits with misalignment from greater than or equal to about 60 degrees to less than or equal to about 100 degrees.In various aspects, the present disclosure provides a method of forming an extruded billet from a billet comprised of coarse magnesium alloy. The method may include moving the billet consisting of coarse magnesium alloy through an extrusion die at temperatures from greater than or equal to about 300° C. to less than or equal to about 360° C. to form the billet. The billet of coarse magnesium alloy may comprise greater than or equal to about 0.5 wt% to less than or equal to about 3 wt% aluminum. The billet made of coarse magnesium alloy may have an average grain size of greater than or equal to about 800 μm.In one aspect, the extruded billet may comprise a plurality of twins having a lens-shaped morphology.In one aspect, the plurality of twins having a lens-shaped morphology may occupy an area fraction greater than or equal to about 20% of the total area of the extruded billet.In one aspect, the extruded billet can be used to produce an article comprising a plurality of twin-induced dynamic recrystallization grains.In one aspect, the twin-induced dynamic recrystallization grains may occupy an area ratio greater than or equal to about 20% of the total area of the article in the manufactured state.In one aspect, the article when manufactured may comprise greater than or equal to about 20% boundaries with misalignment from greater than or equal to about 60 degrees to less than or equal to about 100 degrees.In one aspect, the billet of coarse magnesium alloy may further comprise greater than or equal to about 0.3% to less than or equal to about 0.6% by weight manganese.In one aspect, the billet comprised of coarse magnesium alloy may comprise greater than 0 wt % to less than or equal to about 3 wt % zinc, greater than 0 wt % to less than or equal to about 3 wt % tin, greater than 0 wt % to less than or equal to about 0.5 wt % calcium, and / or greater than 0 wt % to less than or equal to about 5 wt % of the rare earth metals.Further areas of applicability will become apparent from the description herein. The description and specific examples in this summary are for illustrative purposes only and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGSThe drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. FIG. 1 shows a flow diagram illustrating an example method of manufacturing an extruded billet from a billet consisting of coarse-grained, low-aluminum magnesium alloy, in accordance with various aspects of the present disclosure. FIG. 2 is a graphical illustration illustrating the frequency of boundary misalignment for an article made from an exemplary extruded billet, wherein the extruded billet is made from a billet made from coarse magnesium alloy using an extrusion process at temperatures of greater than or equal to about or exactly 300° C. to less than or equal to about or exactly 360° C., in accordance with various aspects of the present disclosure. FIG. 3 shows a micrograph of an example extruded billet made from a billet made of coarse magnesium alloy using an extrusion process at temperatures of greater than or equal to about or exactly 300° C. to less than or equal to about or exactly 360° C., in accordance with various aspects of the present disclosure. FIG. 4 is a microscopic photograph of an exemplary extruded billet formed from a billet of coarse magnesium alloy using a solvent selected from the group consisting of:This is accomplished by an extrusion process at temperatures greater than or equal to about or exactly 380° C.Corresponding reference numerals designate corresponding parts throughout the several views of the drawings.DETAILED DESCRIPTIONAs example configurations are provided, this is a thorough disclosure that will fully convey scope to those skilled in the art. Numerous specific details are set forth, such as examples of specific compositions, components, devices, and methods, in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be used, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, device structures, and technologies are not described in detail.The terminology used herein is for describing particular exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" may also include the plural forms unless the context clearly indicates otherwise. The terms "comprise," "comprising," "include," and "have" are inclusive and therefore specify the presence of stated features, elements, compositions, steps, integers, operations, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.Although the open term "comprising" is to be understood as a non-limiting term that serves to describe and claim various embodiments set forth herein, in certain aspects, the term may alternatively be understood as a more limiting and restrictive term, such as "consisting of" or "consisting essentially of.". Therefore, for any given configuration specifying compositions, materials, components, elements, features, integers, operations, and / or method steps, the present disclosure expressly also encompasses configurations consisting of or consisting essentially of such specified compositions, materials, components, elements, features, integers, operations, and / or method steps. In the case of "consisting of", the alternative embodiment excludes any additional compositions, materials, components, elements, features, integers, operations, and / or process steps, while in the case of "consisting essentially of", any additional compositions, materials, components, elements, features, integers, operations, and / or process steps that significantly impact the basic and novel characteristics are excluded from such an embodiment, but any compositions, materials, components, elements, features, integers, operations, and / or process steps that do not significantly impact the basic and novel characteristics may be included in the embodiment.All method steps, processes, and operations described herein are not to be construed as necessarily requiring execution in the particular order discussed or illustrated, unless expressly characterized as the order of execution. It will also be appreciated that additional or alternative steps may be employed, unless otherwise indicated.When a component, element, or layer is referred to as being "on" or "engaged to" another element or layer, or as being "connected" or "coupled" to or the same, it may be directly on or engaged to or connected to or coupled to the other component, element, or layer, or intervening elements or layers may be present. On the other hand, when an element is referred to as being "directly on" or "directly engaged to" another element or layer, or as being "directly connected" or "directly coupled" to or the same, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent," or "adjacent" versus "directly adjacent" or "directly adjacent," etc.). As used herein, the term "and / or" includes any combination of one or more of the associated listed items.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 may be used only to distinguish one step, element, component, region, layer, or portion from another step, element, component, region, layer, or portion. Terms such as "first," "second," and other numerical terms, when used herein, do not imply a sequence or order unless the context clearly indicates that. Thus, a first step, element, component, region, layer, or portion discussed below could be referred to as a second step, element, component, region, layer, or portion without departing from the teachings of the example embodiments.Spatially or temporally relative terms such as "before," "after," "inner," "outer," "below," "under," "lower," "over," "upper," and the like may be used herein for convenience to describe the relationship of an element or feature to one or more other elements or features as illustrated in the figures. Spatially or temporally relative terms may be intended to include different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.Throughout this disclosure, the numerical values represent approximate dimensions or limits for ranges to include minor deviations from the stated values and configurations that have approximately the stated value, as well as those values that have exactly the stated value. Unlike the working examples at the end of the detailed description, all numerical values of parameters (e.g., amounts or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term "about", regardless of whether or not "about" actually appears before the numerical value. "About" means that the numerical value indicated permits slight imprecision (with some approximation to the accuracy of the value, about or rather close to the value, fast). Where the imprecision given by "about" is not otherwise understood by this common meaning in the art, then "about" as used herein means at least modifications that may result from common methods of measuring and using such parameters. For example, "about" may comprise a deviation 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 certain aspects, optionally less than or equal to 0.1%.Moreover, the disclosure of ranges includes the disclosure of all values and further divided ranges within the entire range, including the endpoints and the sub-ranges indicated for the ranges.Exemplary embodiments will now be described in more detail with reference to the accompanying drawings.The present disclosure relates to extruded billet made from coarse-grained, low-aluminum magnesium alloys, and more particularly, billet made from coarse-grained, low-aluminum magnesium alloys. Billet made of coarse-grained, low-aluminum magnesium alloys can have an average grain size greater than or equal to about or exactly 800 μm. The coarse magnesium alloys include one or more magnesium alloys. Magnesium alloys according to various aspects of the present disclosure include aluminum (Al) and manganese (Mn). In certain variations, the magnesium alloys may also include zinc (Zn), tin (Sn), and / or calcium (Ca). In still other variations, the magnesium alloys may also include rare earth metals such as one or more of the lanthanide series elements and / or yttrium (Y). The coarse magnesium alloys may include, for example, certain combinations of aluminum, manganese, zinc, tin, calcium, and rare earth metals. A magnesium alloy can consist, for example, essentially of magnesium, aluminum and manganese. Another exemplary magnesium alloy may consist essentially of magnesium, aluminum and manganese, but also of at least one of the metals zinc, tin, calcium and one or more rare earth metals. That is, additional compositions, materials, constituents, elements, and / or features that substantially affect the basic and novel characteristics of the exemplary magnesium alloy may be omitted from the exemplary magnesium alloys, but any compositions, materials, constituents, elements, and / or features that do not substantially affect the basic and novel characteristics of the exemplary magnesium alloy may be included.In certain variations, the magnesium alloys may have a low aluminum content. The magnesium alloys may comprise, for example, greater than or equal to about or exactly 0.5 wt % to less than or equal to about or exactly 3 wt % aluminum. The magnesium alloys may be greater than or equal to about or exactly 0.5 wt %, optionally greater than or equal to about or exactly 0.6 wt %, optionally greater than or equal to about or exactly 0.7 wt %, optionally greater than or equal to about or exactly 0.8 wt %, optionally greater than or equal to about or exactly 0.9 wt %, optionally greater than or equal to about or exactly 1 wt %, optionally greater than or equal to about or exactly 1.1 wt %, optionally greater than or equal to about or exactly 1.2 wt %, optionally greater than or equal to about or exactly 1.3 wt %, optionally greater than or equal to about or exactly 1.4 wt %, optionally greater than or equal to about or exactly 1.5 wt %, optionally greater than or equal to about or exactly 1.6 wt %, optionally greater than or equal to about or exactly 1.7 wt %, optionally greater than or equal to about or exactly 1.8 wt %, optionally greater than or equal to about or equal to about 1.9 wt %, optionally greater than or equal to about or equal to about 2.0 wt %, optionally greater than or equal to about or equal to about 2.1 wt %, optionally greater than or equal to about or equal to about 2.2 wt %, optionally greater than or equal to about or equal to about 2.3 wt %, optionally greater than or equal to about or equal to about 2.4 wt %, optionally greater than or equal to about or equal to about 2.5 wt %, optionally greater than or equal to about 2.6 wt %, optionally greater than or equal to about or equal to about 2.7 wt %, optionally greater than or equal to about or equal to about 2.8 wt %, and in certain aspects optionally greater than or equal to about or equal to about 2.9 wt % aluminum. The magnesium alloys may be less than or equal to about or exactly 3 wt %, optionally less than or equal to about or exactly 2.9 wt %, optionally less than or equal to about or exactly 2.8 wt %, optionally less than or equal to about or exactly 2.7 wt %, optionally less than or equal to about or exactly 2.6 wt %, optionally less than or equal to about or exactly 2.5 wt %, optionally less than or equal to about or exactly 2.4 wt %, optionally less than or equal to about or exactly 2.3 wt %, optionally less than or equal to about or exactly 2.2 wt %, optionally less than or equal to about or exactly 2.1 wt %, optionally less than or equal to about or exactly 2.0 wt %, optionally less than or equal to about or exactly 1.9 wt %, optionally less than or equal to about or exactly 1.8 wt %, optionally less than or equal to about or exactly 1.7 wt %, optionally less than or equal to about or exactly 1.6 wt %, optionally 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 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 %, and in certain aspects optionally less than or equal to about or exactly 0.6 wt %.In certain variations, the magnesium alloys may comprise greater than or equal to about or exactly 0.3 wt % to less than or equal to about or exactly 0.6 wt % manganese. For example, the magnesium alloys may comprise greater than or equal to about or exactly 0.3 wt %, optionally greater than or equal to about or exactly 0.35 wt %, optionally greater than or equal to about or exactly 0.4 wt %, optionally greater than or equal to about or exactly 0.45 wt %, optionally greater than or equal to about or exactly 0.5 wt %, and in certain aspects, optionally greater than or equal to about or exactly 0.55 wt % manganese. The magnesium alloys may comprise less than or equal to about or exactly 0.6 wt %, optionally less than or equal to about or exactly 0.55 wt %, optionally less than or equal to about or exactly 0.5 wt %, optionally less than or equal to about or exactly 0.45 wt %, optionally less than or equal to about or exactly 0.4 wt %, and in certain aspects optionally less than or equal to about or exactly 0.35 wt % manganese.In certain variations, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt % to less than or equal to about or exactly 3 wt % zinc. For example, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt %, optionally greater than or equal to about or exactly 0.05 wt %, optionally greater than or equal to about or exactly 0.1 wt %, optionally greater than or equal to about or exactly 0.5 wt %, optionally greater than or equal to about or exactly 1 wt %, optionally greater than or equal to about or exactly 1.5 wt %, optionally greater than or equal to about or exactly 2.0 wt %, and in certain aspects, optionally greater than or equal to about or exactly 2.5 wt % zinc. The magnesium alloys may comprise less than or equal to about or exactly 3 wt %, optionally less than or equal to about or exactly 2.5 wt %, optionally less than or equal to about or exactly 2 wt %, optionally less than or equal to about or exactly 1.5 wt %, optionally less than or equal to about or exactly 1 wt %, optionally less than or equal to about or exactly 0.5 wt %, and in certain aspects optionally less than or equal to about or exactly 0.1 wt % zinc.In certain variations, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt % to less than or equal to about or exactly 3 wt % tin. For example, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt %, optionally greater than or equal to about or exactly 0.05 wt %, optionally greater than or equal to about or exactly 0.1 wt %, optionally greater than or equal to about or exactly 0.5 wt %, optionally greater than or equal to about or exactly 1 wt %, optionally greater than or equal to about or exactly 1.5 wt %, optionally greater than or equal to about or exactly 2.0 wt %, and in certain aspects, optionally greater than or equal to about or exactly 2.5 wt % tin. The magnesium alloys may comprise less than or equal to about or exactly 3 wt %, optionally less than or equal to about or exactly 2.5 wt %, optionally less than or equal to about or exactly 2 wt %, optionally less than or equal to about or exactly 1.5 wt %, optionally less than or equal to about or exactly 1 wt %, optionally less than or equal to about or exactly 0.5 wt %, and in certain aspects optionally less than or equal to about or exactly 0.1 wt % tin.In certain variations, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt % to less than or equal to about or exactly 0.5 wt % calcium. For example, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt %, optionally greater than or equal to about or exactly 0.05 wt %, optionally greater than or equal to about or exactly 0.1 wt %, greater than or equal to about or exactly 0.15 wt %, greater than or equal to about or exactly 0.2 wt %, greater than or equal to about or exactly 0.25 wt %, greater than or equal to about or exactly 0.3 wt %, greater than or equal to about or exactly 0.35 wt %, greater than or equal to about or exactly 0.4 wt %, and in certain aspects greater than or equal to about or exactly 0.45 wt % calcium. The magnesium alloys may comprise less than or equal to about or exactly 0.5 wt %, optionally less than or equal to about or exactly 0.45 wt %, optionally less than or equal to about or exactly 0.4 wt %, optionally less than or equal to about or exactly 0.35 wt %, optionally less than or equal to about or exactly 0.3 wt %, optionally less than or equal to about or exactly 0.25 wt %, optionally less than or equal to about or exactly 0.2 wt %, optionally less than or equal to about or exactly 0.15 wt %, optionally less than or equal to about or exactly 0.1 wt %, and in certain aspects optionally less than or equal to about or exactly 0.05 wt % calcium.In certain variations, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt % to less than or equal to about or exactly 5 wt % of the rare earth metals. For example, the magnesium alloys may comprise greater than or equal to about or exactly 0 wt %, optionally greater than or equal to about or exactly 0.5 wt %, optionally greater than or equal to about or exactly 1 wt %, optionally greater than or equal to about or exactly 1.5 wt %, optionally greater than or equal to about or exactly 2.0 wt %, optionally greater than or equal to about or exactly 2.5 wt %, optionally greater than or equal to about or exactly 3 wt %, optionally greater than or equal to about or exactly 3.5 wt %, optionally greater than or equal to about or exactly 4 wt %, and in certain aspects optionally greater than or equal to about or exactly 4.5 wt % of the rare earth metals. The magnesium alloys may comprise less than or equal to about or exactly 5 wt %, optionally less than or equal to about or exactly 4.5 wt %, optionally less than or equal to about or exactly 4.0 wt %, optionally less than or equal to about or exactly 3.5 wt %, optionally less than or equal to about or exactly 3.0 wt %, optionally less than or equal to about or exactly 2.5 wt %, optionally less than or equal to about or exactly 2.0 wt %, optionally less than or equal to about or exactly 1.5 wt %, optionally less than or equal to about or exactly 1 wt %, and in certain aspects optionally less than or equal to about or exactly 0.5 wt % of the rare earth metals.In each variation, the magnesium alloys comprise a balance of magnesium. For example, the magnesium alloys may comprise greater than or equal to about or exactly 85 wt %, optionally greater than or equal to about or exactly 86 wt %, optionally greater than or equal to about or exactly 87 wt %, optionally greater than or equal to about or exactly 88 wt %, optionally greater than or equal to about or exactly 89 wt %, optionally greater than or equal to about or exactly 90 wt %, optionally greater than or equal to about or exactly 91 wt %, optionally greater than or equal to about or exactly 92 wt %, optionally greater than or equal to about or exactly 93 wt %, optionally greater than or equal to about or exactly 94 wt %, optionally greater than or equal to about or exactly 95 wt %, optionally greater than or equal to about or exactly 96 wt %, optionally greater than or equal to about or exactly 97 wt %, and in certain aspects optionally greater than or equal to about or exactly 98 wt % magnesium.In any variation, the magnesium alloys may also include traces of other elements, such as, for example, beryllium (Be) and / or strontium (Sr), which do not substantially affect the basic characteristics of the magnesium alloys. For example, the magnesium alloys may be 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 %, and in certain aspects, amounts that are not detectable.In various aspects, the present disclosure provides methods for forming extruded billet from coarse-grained, low-aluminum magnesium alloys, and more particularly, billet consisting of coarse-grained, low-aluminum magnesium alloys. The methods include, for example, extruding the coarse magnesium alloy billet at temperatures of greater than or equal to about or exactly 300° C. to less than or equal to about or exactly 360° C. For example, the coarse magnesium alloy billet may be extruded at temperatures of 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 315° C., greater than or equal to about or exactly 350° C., greater than or equal to about or exactly 350° 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, In some aspects, the extrusion may be greater than or equal to about 350° C. and, in some aspects, optionally greater than or equal to about 355° C. The billet consisting of coarse magnesium alloy can be extruded at temperatures of less than or equal to about or exactly 360° C., optionally less than or equal to about or exactly 355° C., optionally less than or equal to about or exactly 350° C., optionally less than or equal to about or exactly 345° C., optionally less than or equal to about or exactly 340° C., optionally less than or equal to about or exactly 335° C., optionally less than or equal to about or exactly 325° C., optionally less than or equal to about or exactly 32° C., optionally less than or equal to about or exactly 315° C., optionally less than or equal to about or exactly 315° C., and in certain aspects optionally less than or equal to about or exactly 305° C. As those skilled in the art will appreciate, extrusion is a process in which metal in flowable form is passed through a confined region, e.g., a die, to form an intermediate billet having a standard shape or cross-section, while forging is a high pressure process, including, for example, moving the intermediate billet through a die to form a final complex three-dimensional forging or piece.As illustrated in FIG. 1, an example method 100 of forming an extruded billet from a coarse-grained, low-aluminum magnesium alloy billet may include heating 120 the coarse-grained, low-aluminum magnesium alloy billet to a temperature of greater than or equal to about or exactly 300° C. to less than or exactly 360° C., and extruding 130 the heated coarse-grained, low-aluminum magnesium alloy billet to form the extruded billet. In certain modifications, the extrusion 130 may be performed at a ram speed of greater than or equal to about or exactly 0.5 mm / s to less than or exactly 3 mm / s. In certain variations, the extruder 130 may have an extrusion ratio of greater than or equal to about or exactly 2 to less than or equal to about 5.As a result of the low temperature extrusion process, the extruded billet may each have a plurality of twins of lenticular morphology within the magnesium matrix defining the extruded billet. In the subsequent forging processes, the twin morphologies may be transformed such that the microstructure of the formed magnesium article comprises twin-induced dynamic recrystallization grains. The twin morphologies may occupy an area fraction greater than or equal to about or exactly 20% of the total area of the extruded billet produced in accordance with various aspects of the present disclosure. In certain variations, the twins with lens-shaped morphology may have a boundary misalignment that is greater than or equal to about 60 degrees to less than or equal to about 100 degrees. As illustrated in FIG. 2, where the x-axis 202 represents the angle of misalignment in degrees and the y-axis 204 represents the frequency, a fraction of boundaries with misalignment between 60 degrees and 100 degrees may be greater than or equal to about or exactly 20% of all boundaries. In any variation, the twins formed in the extruded billet can serve as a nucleation site for the dynamic recrystallization of fine grains in subsequent forging processes.In various aspects, the method 100 may include forming 110 the billet from coarse-grained, low-aluminum magnesium alloy. Forming 110 the coarse-grained, low-aluminum magnesium alloy may comprise a casting method, e.g. using a direct permanent mold casting method and / or a semi-continuous casting method. In any variation, the extruded billet may have an average diameter greater than or equal to about or exactly 200 mm, and in certain variations, optionally greater than or equal to about or exactly 300 mm.FIG. 3 shows a micrograph of an example extruded billet produced using an extrusion process at temperatures of greater than or equal to about or exactly 300° C. to less than or equal to about or exactly 360° C., wherein the plurality of twins have a lens-shaped morphology. For comparison only, FIG. 4 shows a micrograph of an exemplary extruded billet produced using an extrusion process at temperatures greater than or equal to about or exactly 380° C. The white arrows in this case indicate the dynamic recrystallization of fine grains. In this case, the area ratio of the dynamic fine grain recrystallization is less than or equal to about or exactly 10%.Studs extruded from low aluminum content coarse magnesium alloys are particularly suitable for the manufacture of structural parts for automobiles or other vehicles (e.g., motor cycles, boats, tractors, buses, motor cycles, recreational vehicles, recreational vehicles and tanks), but can also be used in a variety of other industries and applications, for example (not limiting), including aerospace components, consumer goods, equipment, buildings (e.g., houses, offices, scales, warehouses), office equipment and furniture, and industrial equipment machines, agricultural equipment, agricultural machinery or heavy machinery. Non-limiting examples of parts or articles in motor vehicles include hood panels, pillars (e.g., A-pillars, hinge pillars, B-pillars, C-pillars, and the like), body parts including structural body parts, door panels and door components, interior floors, floor panels, roofs, exterior surfaces, under-floor protection, wheels, suspension arms and other suspensions, crush cans, bumpers, structural rails and frames, cross beams, chassis or drive components, and the like.In various aspects, the present disclosure provides methods for forming articles or components from extruded billet. For example, a method of forming components includes forging the extruded billet. In certain modifications, forging may include moving the extruded billet through a die having an opening or slot corresponding to the cross-sectional geometry of the component such that the forging exiting the die has the cross-sectional geometry. In certain modifications, the die may include first and second halves that together form the opening. The first half and the second half may be configured to apply a pressure to the extruded billet. For example, a pressure of 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 billet. In certain modifications, forging may be performed by forcing the extruded billet through the die at a ram speed of 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 temperatures of greater than or equal to about or exactly 350° C. to less than or equal to about or exactly 450° C. In certain modifications, the method may include one or more swaging processes following the swaging process, as will be appreciated by those skilled in the art.The foregoing description of the embodiments is illustrative and illustrative. It does not claim to be exhaustive or to limit the disclosure. Individual elements or features of a particular configuration are generally not limited to that particular configuration, but are optionally interchangeable and may be used in a selected configuration, although not specifically shown or described. They can also be modified in many ways. Such modifications are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

A method of forming an extruded billet from a coarse magnesium alloy billet, the method comprising: extruding the coarse magnesium alloy billet at temperatures of greater than or equal to 300°C to less than or equal to 360°C to form the extruded billet, wherein the coarse magnesium alloy billet has an average grain size of greater than or equal to 800 μm.The method of claim 1, wherein the billet consisting of coarse magnesium alloy has a low aluminum content and comprises greater than or equal to 1.5 wt% to less than or equal to 3 wt% aluminum.The method of claim 2, wherein the billet consisting of coarse magnesium alloy comprises 2 wt% aluminum.The method of claim 2, wherein the billet consisting of coarse magnesium alloy further comprises greater than or equal to 0.3 wt% to less than or equal to 0.6 wt% manganese.The method of claim 4, wherein the billet consisting of coarse magnesium alloy comprises 0.5 wt% manganese.The method of claim 2, wherein the coarse magnesium alloy billet further comprises at least one of greater than 0 wt% to less than or equal to 3 wt% zinc, greater than 0 wt% to less than or equal to 3 wt% tin, greater than 0 wt% to less than or equal to 0.5 wt% calcium, and greater than 0 wt% to less than or equal to 5 wt% of the rare earth metals.The method of claim 6, wherein the coarse magnesium alloy comprises 1% by weight zinc.The method of claim 1, wherein the billet comprises a plurality of twin-induced dynamic recrystallization grains.The method of claim 1, wherein the extruded billet comprises a plurality of twins having a lens-shaped morphology.The method of claim 9, wherein the twin-induced dynamic recrystallization grains occupy an area fraction greater than or equal to 20% of the total area of the billet.

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