Patent Application
20230082861
The present disclosure relates to metallurgy generally and more specifically to the near-surface structure of rolled aluminum alloy products and techniques for improving the mechanical and chemical performance of aluminum alloy products.
During processing of an aluminum alloy product, generation of rolled near-surface microstructures may occur, which may include defects. For example, the defects may be rolled-in oxides, rolled-in oils, transfer cracks, surface cracks, interior cracks, fissures, or high density populations of alloying elements. Defects within the rolled near-surface microstructures may impact the mechanical and chemical performance of the aluminum alloy product. Techniques addressing defects in or associated with rolled near-surface microstructures are lacking.
The term embodiment and like terms are intended to refer broadly to all of the subject matter of this disclosure and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the claims below. Embodiments of the present disclosure covered herein are defined by the claims below, not this summary. This summary is a high-level overview of various aspects of the disclosure and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this disclosure, any or all drawings and each claim.
In an aspect, described are aluminum alloy products. An aluminum alloy product may include or be a rolled aluminum alloy product having a bulk, a first surface region, and a second surface region. The first surface region may include near-surface microstructures (NSMs) having a thickness less than 500 nm. The near-surface microstructures may include one or more defects. The second surface region may be free of near-surface microstructures or substantially free of near-surface microstructures. The second surface region may have a thickness from 1 nm to 2 μm, such as from 1 nm to 5 nm, from 5 nm to 10 nm, from 10 nm to 25 nm, from 25 nm, to 50 nm, from 50 nm to 100 nm, from 100 nm to 250 nm, from 250 nm to 500 nm, from 500 nm to 1 μm, or from 1 μm to 2 μm. The second surface region may include an oxide layer and a micro-grained subsurface structure. In some embodiments, the first surface region and the second surface region may be discontinuous. For example, in some cases, “islands” of the first surface region may form within the second surface region or “islands” of the second surface region may form within the first surface region. In some embodiments, a ratio of the area of the first surface region to the area of the second surface region may be less than 50%. For example, in a 100 μm2 surface area of a rolled aluminum alloy product, at least 51% of the surface area (e.g., 55%, 60%, 65%, 70%, or greater than 75%) may be or include the second surface region. In some cases, only the second surface region may be present within the aluminum alloy product.
In embodiments, the rolled aluminum alloy product may include at least one of a 7xxx series aluminum alloy product, a 6xxx series aluminum alloy product, and a 5xxx series aluminum alloy product. Optionally, the rolled aluminum alloy product may be a hot-rolled aluminum alloy product or a cold-rolled aluminum alloy product. The bulk may include a matrix having grains of an aluminum alloy and the bulk may have a first composition. The first composition may include aluminum and one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese. The one or more alloying elements may be homogenously distributed spatially within the bulk.
The micro-grained subsurface structure may be present between the oxide layer and the bulk, and may have a composition different from or the same as the bulk but may have a thickness of, for example, from 1 nm to 2 μm, and may have a limited number of defects.
The micro-grained subsurface structure may be different from near-surface microstructures that are generated upon creation of the rolled aluminum alloy product (also referred to herein as rolled near-surface microstructures), and, for example, the micro-grained subsurface structure may also be referred to herein as being or comprising modified near-surface microstructures in that it is a sub-surface or near-surface structure that may be generated upon modifying the surface of a rolled aluminum alloy product having rolled near-surface microstructures thereon. The micro-grained sub-surface structure may be devoid or substantially devoid of one or more defects, which may be present in the rolled near-surface microstructures. As used herein, the term substantially devoid refers to an absolute absence of an object or structure within a material or a low amount of an object or structure in the material that does not generally impact the mechanical properties, material properties, or performance of the material. As an example, when an aluminum alloy product is substantially devoid of defects, some defects may be present but those defects may be present at a concentration where defects, on average, are spaced 100 nm or more from another defect. In some cases, where the defects are smaller, the defects may be present at a concentration where the defects on average are spaced much closer together, such as for example 25-50 nm.
As examples, the one or more defects may correspond to or include one or more voids, transfer cracks, or fissures, which may be referred to herein as structural defects. The micro-grained subsurface structure may have a second composition. The second composition may include aluminum and one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese. In some embodiments, a concentration of magnesium in the aluminum alloy may be less than 10 wt. % or a concentration of magnesium and zinc in the aluminum alloy may be less than 20 wt. %, where the ratio of zinc to magnesium in the concentration may be from 0.1 to 10.0. Optionally, a concentration of magnesium in the first composition (i.e., the bulk) is greater than in the second composition (i.e., the micro-grained subsurface structure), a concentration of copper in the first composition is greater than the second composition, or a concentration of zinc in the first composition may be greater than the second composition. The second composition (i.e., the micro-grained subsurface structure) may be substantially devoid of organics, oils, hydrocarbons, soils, inorganic residues, rolled-in oxides, or anodic oxides, which may be referred to herein as compositional defects.
In some embodiments, the second composition (i.e., the micro-grained subsurface structure) may include more defects than the first composition (i.e., the bulk). However, in other embodiments, the second composition may be substantially the same as the first composition. In some instances, the second composition may include a grain structure homogeneity or an alloying element distribution homogeneity different from that of the first composition. In some embodiments, the second composition may include a grain structure that is different from a grain structure of the first composition. For example, the grain structure of the second composition may include aluminum alloy grains having an average diameter of from 10 nm to 500 nm. Optionally, the second composition may include homogenous ultrafine grains, such as having grain sizes or an average grain size of from about 10 nm to about 200 nm, such as from 10 nm to 25 nm, from 25 nm to 50 nm, from 50 nm to 100 nm, from 100 nm to 150 nm, or from 150 nm to 200 nm. The second composition may include or contain precipitates. The precipitates may have an average diameter of from 10 nm to 2 μm, in some examples. In some embodiments, the precipitates may include one or more alloying elements selected from a group including zinc, magnesium, copper, chromium, silicon, iron, and manganese.
The oxide layer on the micro-grained subsurface structure may have a thickness of from 1 nm to 20 nm. The oxide layer may be a native oxide layer, in some examples, or may be thicker than a native oxide layer due to heating that may occur when forming the micro-grained subsurface structure or in subsequent processing. In some embodiments, the aluminum alloy product may further include a silicon-containing layer on the micro-grained subsurface structure or the oxide layer. The silicon-containing layer may modify a portion of bonding sites within the micro-grained subsurface structure. Optionally, a weight percent of aluminum in the second composition may be less than a weight percent of aluminum in the first composition. In some embodiments, the aluminum alloy product with the micro-grained subsurface structure may exhibit a bond durability of from 22 cycles to 100 cycles or more, according to a FLTM BV 101-07 standard test, Stress Durability Test for Adhesive Lap-Sear Bonds (2017), which is hereby incorporated by reference. The bond durability may be at least 22, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, at least 95, or at least 100 cycles.
In another aspect, described are methods of treating aluminum alloy products. A method of this aspect may include providing a rolled aluminum alloy product having a bulk and rolled near-surface microstructures. In some embodiments, the rolled aluminum alloy product may include at least one of a 7xxx series aluminum alloy product, a 6xxx series aluminum alloy product, or a 5xxx series aluminum alloy product. In some embodiments, the rolled aluminum alloy product may be a hot-rolled aluminum alloy product or a cold-rolled aluminum alloy product. The bulk may include a matrix including grains of an aluminum alloy and the bulk may have a first composition. The first composition may include aluminum and one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese. The one or alloying elements may be homogenously distributed spatially within the bulk. The rolled near-surface microstructures may include one or more defects. For example, in some embodiments, the one or more defects may correspond to or include one or more of voids, transfer cracks, or fissures.
The method may also include modifying the rolled near-surface microstructures (i.e., the near-surface microstructures) to generate a first surface region and a second surface region. The first surface region may include rolled near-surface microstructures having a thickness less than 500 nm, which may correspond to a reduction in the thickness of the near-surface microstructures upon modification. The second surface region may be free of the rolled near-surface microstructures. The second surface region may include an oxide layer, such as an oxide having a thickness from 1 nm to 20 nm, and a micro-grained subsurface structure, also referred to herein as modified near-surface microstructures. In some embodiments, the first surface region and the second surface region may be discontinuous. For example, in some cases, “islands” of the first surface region may form within the second surface region, or vice versa. In some embodiments, a ratio of the area of the first surface region to the area of the second surface region may be less than 50%. For example, the ratio of the area of the first surface region to the area of the second surface region may be equal to or less than 40%, equal to or less than 35%, equal to or less than 33%, equal to or less than 30%, equal to or less than 25%, equal to or less than 20%, equal to or less than 15%, equal to or less than 10%, or equal to or less than 5%. In some cases, only the second surface region may be present within the aluminum alloy product.
The micro-grained subsurface structure may be substantially devoid of the one or defects. The micro-grained subsurface structure may be between the oxide layer and the bulk and may have a second composition. The second composition may include aluminum and one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese. In some embodiments, a concentration of magnesium in the aluminum alloy may be less than 10 wt. % or a concentration of magnesium and zinc in the aluminum alloy may be less than 20 wt. %, where the ratio of zinc to magnesium in the concentration may be from 0.1 to 10.0. Optionally, a concentration of magnesium in the first composition may be greater than in the second composition, a concentration of copper in the first composition may be greater than the second composition, or a concentration of zinc in the first composition may be greater than in a second composition. The second composition may be substantially devoid of oils, hydrocarbons, soils, inorganic residues, rolled-in oxides, or anodic oxides. The second composition may include a grain structure that is different from a grain structure of the first composition. For example, the grain structure of the second composition may include aluminum alloy grains having an average diameter of from 10 nm to 500 nm.
In some embodiments, modifying the rolled near-surface microstructures may include consolidating the rolled near-surface microstructures to generate the second composition and eliminate at least a portion of the one or more defects. In some cases, the second composition of the micro-grained subsurface structure may have fewer defects than the rolled near-surface microstructures. Optionally, the second composition may have more defects than the first composition. However, in some embodiments, the second composition may be substantially the same as the first composition. In some instances, the second composition may include a grain structure homogeneity or an alloying element distribution homogeneity different from that of the rolled near-surface microstructures or the first composition.
The second surface region may include a first oxide layer having a thickness of from 1 nm to 20 nm. In some embodiments, the micro-grained subsurface structure may exhibit, or provide to an aluminum alloy product comprising the micro-grained subsurface structure, a bond durability of from 22 cycles to 100 cycles, or more, according to a FLTM BV 101-07 standard test. In some embodiments, modifying the rolled near-surface microstructures may include depositing a silicon-containing layer when generating the micro-grained subsurface structure. The silicon-containing layer may be present on the micro-grained subsurface structure and/or on an oxide layer on or corresponding to part of the micro-grained subsurface structure. The silicon-containing layer may modify a portion of bonding sites within the micro-grained subsurface structure. In some instances, modifying the rolled near-surface microstructures may include coating at least a portion of the micro-grained subsurface structure, and/or an oxide layer thereon, with a silicon-containing material to modify a portion of bonding sites within the micro-grained subsurface structure. Coating may include transferring silicon-containing material from a silicon-containing grit used to modify the rolled near-surface microstructures. Example silicon-containing grit may include a SACO grit. Optionally, modifying the rolled near-surface microstructures to generate the micro-grained subsurface structure may include generating homogenous ultrafine grains.
In some embodiments, methods of this aspect may further include subjecting the rolled near-surface microstructures to one or more mechanical alteration processes. Mechanical alteration may include grinding the rolled near-surface microstructures, physically ablating the rolled near-surface microstructures, laser ablating the rolled near-surface microstructures, sand blasting the rolled near-surface microstructures, or polishing the rolled near-surface microstructures. In some cases, physically ablating the rolled near-surface microstructures may include grit-blasting the rolled near-surface microstructures. In some embodiments, mechanical alteration may include subjecting the rolled near-surface microstructures to a first alteration process and subjecting the rolled near-surface microstructures to a second alteration process. Optionally, mechanical alteration may further include subjecting the rolled near-surface microstructures to a third alternation process. In some examples, the first alteration process may include exposing the rolled near-surface microstructures to a first grit, the second alteration process may include exposing the rolled near-surface microstructures to a second grit, and the third alteration process may include exposing the rolled near-surface microstructures to a third grit. The first grit may be coarser than the second grit, and the second grit may be coarser than the third grit.
In some embodiments, modifying the rolled near-surface microstructures may occur during a final gauging of the rolled aluminum alloy product. Optionally, modifying the rolled near-surface microstructures may occur after a hot-rolling process. In some cases, modifying the rolled near-surface microstructures may occur prior to a cold-rolling process. Optionally, modifying the rolled near-surface microstructures may occur before a pretreating process.
In some embodiments, the method may further include subjecting the micro-grained subsurface structure to a pretreatment process. In some instances, the pretreatment process may include etching the micro-grained subsurface structure.
In another aspect, aluminum alloy products are described, such as aluminum alloy products made according to the methods described herein. In yet another aspect, methods are described for making aluminum alloy products as described herein.
Other objects and advantages will be apparent from the following detailed description of non-limiting examples.
The specification makes reference to the following appended figures, in which use of like reference numerals in different figures is intended to illustrate like or analogous components.
Described herein are aluminum alloy products generated by casting and/or rolling processes in which rolled near-surface microstructures of a rolled product are mechanically altered to generate a micro-grained subsurface structure, as well as the processes for generating such products. The rolled near-surface microstructures may occupy a region to a depth into a bulk of the rolled product and may contain one or more defects. The micro-grained subsurface structure may be generated by mechanically altering the rolled-near surface microstructure. The micro-grained subsurface structure may have a composition that is different from a composition of the rolled near-surface microstructures.
Aluminum alloy products may be cast and rolled to generate rolled products having rolled near-surface microstructures. Generation of rolled near-surface microstructures may occur in the subsurface layer of an aluminum alloy product, also known as a “surface layer” or a “Beilby layer.” Defects within the rolled near-surface microstructures may be produced during rolling processes, for example. Exemplary defects include rolled-in oils, rolled-in oxides, voids, fissures, and cracks. For example, the presence of a high density population of amorphous carbon and/or aluminum carbides may be generated from rolling lubricants becoming incorporated into the surface layer of the rolled product during the rolling process. Similarly, a dense population of oxides within the rolled near-surface microstructures may be generated from a combination of the incorporated rolling lubricants and the shear strain produced during the rolling process, which may, for example, result in incorporation of surface oxides within the near-surface microstructures.
The presence of defects within the rolled near-surface microstructures may impact the mechanical and chemical performance of the aluminum alloy product. For example, defects may increase the corrosion sensitivity of the aluminum alloy product or result in poor quality bonding between bonded aluminum alloy products, such as using adhesives or epoxies.
As another example, the existence of oxides and/or voids at or near the boundary between the subsurface layer and the bulk may result in or induce crack propagation. Because voids and oxides at the boundary may provide a preferential crack propagation route between the subsurface layer and the bulk, any stress to the region, either during processing or end use, may result in shearing of the subsurface layer from the bulk. In turn, any cracks propagated within the rolled near-surface microstructures may nucleate new cracks. As secondary cracks may develop from primary cracks, the presence of defects within the near-surface microstructures has damaging chain-reaction potential.
The defects may also cause the rolled near-surface microstructures to have differing mechanical and chemical properties from the bulk. For example, a high density population of oxides within the rolled near-surface microstructures may result in the rolled near-surface microstructures having a relatively low ductility compared to the bulk. This may mean that the rolled near-surface microstructures may deform less than the bulk during processing or use. Differing ductilities may lead to mechanical failures for the aluminum alloy product, such as fracturing, cracking, or even shearing between the rolled near-surface microstructures and the bulk.
Composition and grain structure nonhomogeneity are other defects that may result from the rolling and casting process. In some embodiments, nonhomogeneous elemental distribution (e.g., alloying element distribution) is a concern because it may result in increased corrosion sensitivity for the aluminum alloy product, for example. During aluminum alloy product processing, certain elements may diffuse into the rolled near-surface microstructures of the rolled product faster than other elements. This may lead to certain alloying element populations within the rolled near-surface microstructures having a higher density than populations within the bulk. Additionally, the presence of high density populations of some alloying elements may increase the corrosion sensitivity of the aluminum alloy product. The low activation energy and the presence of defects may cause the diffusion rate of the high density of alloying elements within the rolled near-surface microstructures to be larger than the diffusion rate of the alloying elements within the bulk. This may cause the rolled near-surface microstructures to be reactive. Under corrosive environments, the heightened diffusion rate or presence of the alloying elements near the surface, as well as the presence of other defects within the rolled near-surface microstructures, may lead to more active corrosion propagation conditions.
Mechanically altering the rolled near-surface microstructures may provide numerous advantages, including generating new (modified) near-surface microstructures or a micro-grained subsurface structure having a composition different from the rolled near-surface microstructures. As a specific example, the modified composition of the micro-grained subsurface structure, also referred to herein as the second composition, may be free or substantially free of the defects present in the rolled composition. In some cases, the second composition of the micro-grained subsurface structure may have reduced numbers of defects as compared to the number of defects in the composition of the rolled near-surface microstructures.
Another advantage of generating a micro-grained subsurface structure may be a reduction in corrosion sensitivity. By generating a homogenous elemental distribution within the micro-grained subsurface structure, the reactivity of the subsurface may be controlled (e.g., reduced). Additionally, the micro-grained subsurface structure may be mechanically altered to have suitable mechanical interlocking and cleanliness (e.g., absence of defects) to withstand cyclical or repeated corrosion exposure.
Overall, the mechanical and chemical performance of the aluminum alloy product may be enhanced by mechanically altering the rolled near-surface microstructures in accordance with the discussion herein. Generation of a homogenous elemental distribution and a homogenous grain structure, as well as generating a substantially defect-free near-surface composition, may improve subsequent etching and pretreatment processes, and extend the longevity and utility of the aluminum alloy product. Advantageously, bonding between alloy products having a micro-grained subsurface structure in accordance with the present disclosure may also be more durable than bonding between alloy products having rolled near-surface microstructures.
As used herein, the terms “invention,” “the invention,” “this invention” and “the present invention” are intended to refer broadly to all of the subject matter of this patent application and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below.
In this description, reference is made to alloys identified by AA numbers and other related designations, such as “series” or “7xxx.” For an understanding of the number designation system most commonly used in naming and identifying aluminum and its alloys, see “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” or “Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot,” both published by The Aluminum Association.
As used herein, a plate generally has a thickness of greater than about 15 mm. For example, a plate may refer to an aluminum product having a thickness of greater than about 15 mm, greater than about 20 mm, greater than about 25 mm, greater than about 30 mm, greater than about 35 mm, greater than about 40 mm, greater than about 45 mm, greater than about 50 mm, or greater than about 100 mm.
As used herein, a shate (also referred to as a sheet plate) generally has a thickness of from about 4 mm to about 15 mm. For example, a shate may have a thickness of about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, or about 15 mm.
As used herein, a sheet generally refers to an aluminum product having a thickness of less than about 4 mm. For example, a sheet may have a thickness of less than about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, or less than about 0.3 mm (e.g., about 0.2 mm).
As used herein, terms such as “cast metal product,” “cast product,” “cast aluminum alloy product,” and the like are interchangeable and may refer to a product produced by direct chill casting (including direct chill co-casting) or semi-continuous casting, continuous casting (including, for example, by use of a twin belt caster, a twin roll caster, a block caster, or any other continuous caster), electromagnetic casting, hot top casting, or any other casting method, including the methods disclosed herein.
As used herein, the meaning of “room temperature” can include a temperature of from about 15° C. to about 30° C., for example about 15° C., about 16° C., about 17° C., about 18° C., about 19° C., about 20° C., about 21° C., about 22° C., about 23° C., about 24° C., about 25° C., about 26° C., about 27° C., about 28° C., about 29° C., or about 30° C. As used herein, the meaning of “ambient conditions” can include temperatures of about room temperature, relative humidity of from about 20% to about 100%, and barometric pressure of from about 975 millibar (mbar) to about 1050 mbar. For example, relative humidity can be about 20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, about 40%, about 41%, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50%, about 51%, about 52%, about 53%, about 54%, about 55%, about 56%, about 57%, about 58%, about 59%, about 60%, about 61%, about 62%, about 63%, about 64%, about 65%, about 66%, about 67%, about 68%, about 69%, about 70%, about 71%, about 72%, about 73%, about 74%, about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, about 100%, or anywhere in between. For example, barometric pressure can be about 975 mbar, about 980 mbar, about 985 mbar, about 990 mbar, about 995 mbar, about 1000 mbar, about 1005 mbar, about 1010 mbar, about 1015 mbar, about 1020 mbar, about 1025 mbar, about 1030 mbar, about 1035 mbar, about 1040 mbar, about 1045 mbar, about 1050 mbar, or anywhere in between.
All ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Unless stated otherwise, the expression “up to” when referring to the compositional amount of an element means that element is optional and includes a zero percent composition of that particular element. Unless stated otherwise, all compositional percentages are in weight percent (wt. %).
As used herein, the meaning of “a,” “an,” and “the” includes singular and plural references unless the context clearly dictates otherwise.
In embodiments, the rolled product may be relatively rectangular in cross-section, having a width W and a thickness T, which may be selected based on the application of the aluminum alloy product 100. In various embodiments, the rolled product may have a width W from about 0.1 m to about 10 m, such as from 0.1 m to 1 m, from 1 m to 2 m, from 2 m to 3 m, from 3 m to 5 m, or from 5 m to 10 m. In other embodiments, the rolled product may have a width W within a range from 0.1 m to 0.2 m, from 0.2 m to 0.3 m, from 0.3 m to 0.4 m, or from 0.4 m to 0.5 m. The rolled product may have a thickness T from 0.2 mm to 1 mm, from 1 mm to 4 mm, from 4 mm to 10 mm, from 4 mm to 15 mm, from 15 mm to 25 mm, from 25 mm to 40 mm, from 40 mm to 50 mm, from 50 mm to 100 mm, or, in embodiments, greater than 100 mm. The rolled product may be in the form of a plate, shate, or sheet, for example. It will be appreciated that
The rolled product may include rolled near-surface microstructures 110 and a bulk 120. As described herein, the rolled near-surface microstructures may also be referred to as near-surface microstructures (NSMs). During rolling processes, generation of the rolled near-surface microstructures 110 as part of the rolled product may occur. The rolled near-surface microstructures 110 may occur in a subsurface layer of the rolled product. The subsurface layer, also known as a “surface layer” or a “Beilby layer,” may include a portion of the rolled product that occupies a space from the surface of the rolled product to a depth into the thickness of the rolled product. In embodiments, the rolled product may include more than one surface and/or have more than one subsurface layer. In such embodiments, the rolled near-surface microstructures 110 may occur in each subsurface layer. For example, the rolled product may have a thickness such that two surfaces are generated; one surface on a top of the rolled product and one surface on a bottom of the rolled product, each surface directly opposed to one other. The other four sides or edges of the rolled product that circumferentially extend about the side/edge of the rolled product may not be thick enough or have an area large enough to create a subsurface layer and/or may not be subjected to sufficient rolling processes to generate rolled near-surface microstructures and/or may not be evaluated for near-surface microstructures. In some cases, side edges may be scalped, trimmed, or otherwise removed. In some examples, each of the top and bottom surfaces may have a corresponding subsurface layer. In each of the corresponding subsurface layers, rolled near-surface microstructures 110 may be present. Accordingly, in various embodiments, the rolled product may have more than one surface with rolled near-surface microstructures 110.
In embodiments, the rolled near-surface microstructures 110 may occupy the entire subsurface layer. The rolled near-surface microstructures 110 may occupy a space from the surface of the rolled product to a depth to or into the bulk 120. The depth my be greater than 500 nm. In some cases, the depth may range from 500 nm to 700 nm, from 500 nm to 800 nm, from 200 nm to 800 nm, from 800 nm to 1 μm, from 1 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 15 μm, from 15 μm to 20 μm, or any subranges thereof. In other embodiments, the depth may be less than 500 nm. For example, the depth may range from 50 nm to 100 nm, from 100 nm to 150 nm, from 150 nm to 200 nm, from 200 nm to 250 nm, from 250 nm to 300 nm, from 300 nm to 350 nm, from 350 nm to 400 nm, from 400 nm to 450 nm, from 450 nm to 500 nm, or any subranges thereof.
The rolled product may comprise a 7xxx series aluminum alloy product. Exemplary 7xxx series aluminum alloy products may include AA7011, AA7019, AA7020, AA7021, AA7039, AA7072, AA7075, AA7085, AA7108, AA7108A, AA7015, AA7017, AA7018, AA7019A, AA7024, AA7025, AA7028, AA7030, AA7031, AA7033, AA7035, AA7035A, AA7046, AA7046A, AA7003, AA7004, AA7005, AA7009, AA7010, AA7011, AA7012, AA7014, AA7016, AA7116, AA7122, AA7023, AA7026, AA7029, AA7129, AA7229, AA7032, AA7033, AA7034, AA7036, AA7136, AA7037, AA7040, AA7140, AA7041, AA7049, AA7049A, AA7149, AA7204, AA7249, AA7349, AA7449, AA7050, AA7050A, AA7150, AA7250, AA7055, AA7155, AA7255, AA7056, AA7060, AA7064, AA7065, AA7068, AA7168, AA7175, AA7475, AA7076, AA7178, AA7278, AA7278A, AA7081, AA7181, AA7185, AA7090, AA7093, AA7095, or AA7099 products.
In various embodiments, the rolled product may comprise a 5xxx series aluminum alloy product. For example, the rolled product may comprise a AA5182, AA5183, AA5005, AA5005A, AA5205, AA5305, AA5505, AA5605, AA5006, AA5106, AA5010, AA5110, AA5110A, AA5210, AA5310, AA5016, AA5017, AA5018, AA5018A, AA5019, AA5019A, AA5119, AA5119A, AA5021, AA5022, AA5023, AA5024, AA5026, AA5027, AA5028, AA5040, AA5140, AA5041, AA5042, AA5043, AA5049, AA5149, AA5249, AA5349, AA5449, AA5449A, AA5050, AA5050A, AA5050C, AA5150, AA5051, AA5051A, AA5151, AA5251, AA5251A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A, AA5154B, AA5154C, AA5254, AA5354, AA5454, AA5554, AA5654, AA5654A, AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A, AA5456B, AA5556, AA5556A, AA5556B, AA5556C, AA5257, AA5457, AA5557, AA5657, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA5182, AA5083, AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086, AA5186, AA5087, AA5187, or AA5088 product.
In various embodiments, the rolled product may comprise a 6xxx series aluminum alloy product. For example, the rolled product may comprise a AA6101, AA6101A, AA6101B, AA6201, AA6201A, AA6401, AA6501, AA6002, AA6003, AA6103, AA6005, AA6005A, AA6005B, AA6005C, AA6105, AA6205, AA6305, AA6006, AA6106, AA6206, AA6306, AA6008, AA6009, AA6010, AA6110, AA6110A, AA6011, AA6111, AA6012, AA6012A, AA6013, AA6113, AA6014, AA6015, AA6016, AA6016A, AA6116, AA6018, AA6019, AA6020, AA6021, AA6022, AA6023, AA6024, AA6025, AA6026, AA6027, AA6028, AA6031, AA6032, AA6033, AA6040, AA6041, AA6042, AA6043, AA6151, AA6351, AA6351A, AA6451, AA6951, AA6053, AA6055, AA6056, AA6156, AA6060, AA6160, AA6260, AA6360, AA6460, AA6460B, AA6560, AA6660, AA6061, AA6061A, AA6261, AA6361, AA6162, AA6262, AA6262A, AA6063, AA6063A, AA6463, AA6463A, AA6763, A6963, AA6064, AA6064A, AA6065, AA6066, AA6068, AA6069, AA6070, AA6081, AA6181, AA6181A, AA6082, AA6082A, AA6182, AA6091, or AA6092 product.
While in still other embodiments, the rolled product may comprise a 1xxx series aluminum alloy product, a 2xxx series aluminum alloy product, a 3xxx series aluminum alloy product, a 4xxx series aluminum alloy product, or an 8xxx series aluminum alloy product.
A boundary 115 may exist between the rolled near-surface microstructures 110 and the bulk 120. The boundary 115 may indicate the depth at which a rolled composition of the rolled near-surface microstructures 110 transitions to a composition of the bulk 120, also referred to as a bulk composition or first composition. The boundary 115 may exist at the depth to which the rolled near-surface microstructures 110 occupies into the bulk 120. The boundary 115 may extend parallel or generally parallel to the surface of the rolled product and extend through the entire width or lateral dimension of the rolled product. In some embodiments, the boundary 115 may occur at a discrete depth or may occur over a range of depths. In embodiments, the boundary 115 may be a grain boundary between the rolled near-surface microstructures 110 and the bulk 120. The grain boundary may be the boundary delineating between the two different grain structures of the rolled near-surface microstructures 110 and the bulk 120. For example, the rolled near-surface microstructures 110 may have a nonhomogeneous grain structure, such as a nonuniform distribution of both large and small grain sizes. In contrast, the bulk 120 may have a homogenous (e.g., evenly distributed) grain structure, such as a uniform distribution of grain sizes, which may be large or small. In such an example, the boundary 115 may be the grain boundary between the nonhomogeneous grain structure of the rolled near-surface microstructures 110 and the homogenous grain structure of the bulk 120. In embodiments, the bulk 120, having bulk grain sizes, may occur at a depth from the surface of from 10 μm to 45 μm into the rolled product depending on the alloy and process. In some cases, a homogenous grain structure may mean that a certain percentage of any given volume of the bulk 120 may have the same or approximately the same grain size. For example, a homogeneous grain structure may mean that approximately 70% or more of any given volume of the bulk 120 has approximately the same grain size, such as an average grain size within a range of 5 μm to 50 μm. The differing grain structure homogeneities may be indicated on
As noted above, the rolled near-surface microstructures 110 has a composition, which may be referred to herein as a “rolled composition,” which may include one or more defects 130a-130e (collectively, defects 130). The one or more defects 130 may impact the mechanical and chemical performance of the aluminum alloy product 100. For example, the one or more defects 130 may increase corrosion sensitivity, reduce the bond durability performance, and decrease the tensile and shear strength of the aluminum alloy product 100.
As illustrated in
In embodiments, voids 130b may induce development of the internal cracks 130a and the surface cracks 130d. Weak sites created by the defects 130, such as the voids 130b, may provide more active sites for crack initiation. The voids 130b may include or consist of spaces within the rolled near-surface microstructures 110 that are empty of any solid material. The absence of any solid material may be a result of vapor incorporation into the rolled near-surface microstructures 110 during processing, or may be a result of the mechanical structure and/or the grain composition of the rolled product material.
The one or more defects 130 may also include rolled-in materials 130c. The rolled-in materials 130c may include hot mill pickups, such as rolled-in oxides and/or rolled-in oils, for example. The rolled-in materials 130c may include entrapped oxides and lubricants incorporated into the rolled near-surface microstructures 110 during the rolling process, and optionally other rolled-in impurities. For example, a rolling lubricant may become incorporated in the rolled near-surface microstructures 110 during the rolling of the aluminum alloy product. Entrapped amorphous carbon and/or aluminum carbide in the rolled near-surface microstructures 110 may indicate or correspond to a rolled-in lubricant. Rolled-in oxides may include metal oxides, such as aluminum oxide or magnesium oxide, for example. Metal oxides may be created when metal elements at or near the surface of the rolled product oxidize during processing and then are incorporated into the rolled product.
The presence of the voids 130b and/or the rolled-in materials 130c near the boundary 115 may induce crack propagation. Weak spots at the boundary 115, such as the voids 130b and the rolled-in materials 130c, may provide a crack propagation route between the rolled near-surface microstructures 110 and the bulk 120. As such a route between defects may be a preferential crack propagation route, any stress conditions may induce creation of an internal crack 130a between the rolled near-surface microstructures 110 and the bulk 120. Stress exposure may result in partial or complete shearing of the rolled near-surface microstructures 110 from the bulk 120. Additionally, any internal cracks 130a may nucleate further cracking. Thus, the presence of defects 130 have the potential to create a damaging chain-reaction of defect generation within the rolled near-surface microstructures 110 and possibly into the bulk 120.
In embodiments, the bulk 120 may have a composition referred to herein as a “first composition” that may comprise primarily aluminum and alloying elements 140. Exemplary alloying elements 140 may include zinc, magnesium, copper, chromium, silicon, iron, and/or manganese and may depend on or define a particular alloy. As illustrated in
In various embodiments, one of the defects 130 may include a nonhomogeneous distribution of the alloying elements 140. High density populations 130e of the alloying elements 140 may occur or be generated within the rolled near-surface microstructures 110 during the casting and/or rolling process. Some of the alloying elements 140 may exhibit different diffusion coefficients from one another, resulting in different rates of diffusion for different alloying elements. That is, some of the alloying elements 140 may diffuse at a different rate than another alloying element 140. Thus, during the casting and/or rolling of the rolled product, certain alloying elements may diffuse from the bulk 120 to the surface or into the rolled near-surface microstructures 110 at a faster rate than other elements present within the bulk 120. The faster diffusion rate of certain alloying elements 140 may create an unequal distribution of the alloying elements 140 between the rolled near-surface microstructures 110 and the bulk 120, generating the high density populations 130e of certain alloying elements 140 within the rolled near-surface microstructures 110. For example, in some embodiments, a high density population 130e of zinc may occur within the rolled near-surface microstructures 110 because zinc may have a higher diffusion rate under the processing conditions than other alloying elements, allowing zinc to be preferentially concentrated at the surface. Again, it will be appreciated that the high density populations 130e shown in
Nonhomogeneous distributions of the alloying elements 140, as well as the other defects 130, may impact the chemical performance of the aluminum alloy product 100. For example, the presence of defects 130 within the rolled near-surface microstructures 110 may cause incomplete coverage or patchy pretreatment application. The defects 130 may also interfere with etching pretreatments as the defects 130 and the nonhomogeneous distribution of alloying elements 140 may result in an inconsistent medium for the etching process.
The high density populations 130e may also or alternatively increase the corrosion sensitivity of the aluminum alloy product 100. At or near the surface, the diffusion rate of the alloying elements 140 may increase by one or two fold due to low activation energies, as well as the presence of other defects 130. Thus, the high density populations 130e may propagate reactive pockets or regions within the rolled near-surface microstructures 110 that have the potential to initiate corrosion. Certain aluminum alloy series may be more susceptible to corrosion sensitivity due to the high density populations 130e of the alloying elements 140. For example, 7xxx series aluminum alloys may be more susceptible to creation of high density populations 130e because of its higher alloying element 140 composition. While other aluminum alloy series may comprise 3-4% alloying elements, a 7xxx series aluminum alloy may comprise upwards of 10% alloying elements, for example.
Increased corrosion susceptibility may contribute to poor performance during bonding and/or during bond durability testing. Bond durability testing assesses the strength of bonds created by and/or with the surface (e.g., the near-surface) microstructures of an alloy product. During testing, bonds are created between two aluminum alloy products, such as by an epoxy adhesive. Then, the bonded aluminum alloy products are subjected to strain and/or other conditions. For example, the bonded alloy products may be immersed in a salt solution, subject to humid conditions, or drying conditions. After a series of cycles in one or more conditions, the bonds between the aluminum alloys are evaluated for chemical and mechanical failure. The bond durability performance of an aluminum alloy product may indicate the reactivity and corrosion sensitivity of the product's rolled near-surface microstructures.
Graph 200A includes an x-axis corresponding to a depth into the rolled product. The x-axis origination point, 0 nm, may correspond to the surface of the rolled product. Specifically, 0 nm may correspond to the surface or beginning of the rolled near-surface microstructures 110. The depth into the rolled product may correspond to the thickness of the rolled product. The depth may correspond to a depth into the thickness of the rolled product. In embodiments, the depth may correspond to the entire thickness, while in other embodiments, the depth may correspond to only a portion of the thickness.
Graph 200A also includes a plurality of y-axes corresponding to an intensity of aluminum (e.g., elemental amount present) and an intensity of an alloying element 140 (e.g., elemental amount present) in the rolled product at a given depth into the rolled product. As shown in
Aluminum distribution line 210A on graph 200A depicts an example aluminum elemental profile throughout a depth of the rolled product. The depth may correspond to a thickness of the rolled product. However, in some embodiments, the depth may only correspond to a space occupied by the rolled composition and/or a portion of the first composition. As illustrated, the depth of the rolled product as shown on graph 200A may be 2400 nm (i.e., 2.4 μm). In various embodiments, the depth may be greater than 2400 nm. In other embodiments, the depth may be less than 2400 nm. For example, the depth may be 2000 nm, 1200 nm, or 800 nm. The depth may depend on the section of the rolled product that is being illustrated (e.g., the rolled composition, the thickness of the rolled composition, etc.).
As illustrated in graph 200A, the aluminum concentration 210A in
An alloying element distribution line 220A in
Graph 200B includes an x-axis corresponding to a depth into the rolled product. The x-axis origination point, 0 nm, may correspond to the surface of the rolled product. Specifically, 0 nm may correspond to the surface or beginning of the micro-grained subsurface structure. The depth into the rolled product may correspond to the thickness of the rolled product. The depth may correspond to a depth into the thickness of the rolled product. In embodiments, the depth may correspond to the entire thickness, while in other embodiments, the depth may correspond to only a portion of the thickness.
Graph 200B also includes a plurality of y-axes corresponding to an intensity of aluminum (e.g., elemental amount present) and an intensity of an alloying element 140 (e.g., elemental amount present) in the rolled product at a given depth into the rolled product. As shown in
Aluminum distribution line 210B on graph 200B depicts an example aluminum elemental profile throughout a depth of the rolled product. The depth may correspond to a thickness of the rolled product. However, in some embodiments the depth may only correspond to a space occupied by the second composition and/or a portion of the first composition. As illustrated, the depth of the rolled product as shown on graph 200B may be 2400 nm. In embodiments, the depth may be less than 2400 nm. The depth may depend on the section of the rolled product that is being illustrated (e.g., the second composition, the thickness of the second composition, etc.).
As illustrated in graph 200B, the aluminum concentration 210B in
An alloying element distribution line 220B in
A rolled near-surface microstructure line 235C depicts an example elemental profile of copper within a rolled near-surface microstructure, such as the rolled near-surface microstructures 110. As shown, a low density of copper may be present near the surface of the rolled product. The presence of copper within the rolled product may steadily increase until approximately 1200 nm (1.2 μm) before reaching a constant or approximately constant concentration. The range of 0 to 1200 nm into the rolled product may correspond to the rolled near-surface microstructure. Thus, in exemplary embodiments, a low density population of copper may be present within the rolled near-surface microstructure and then steadily increase to a higher density pollution within the bulk (e.g., bulk 120) of the rolled product.
A rolled near-surface microstructure line 235D depicts an example elemental profile of zinc within a rolled near-surface microstructure, such as the rolled near-surface microstructures 110. As shown, a low density of zinc may be present near the surface of the rolled product. The presence of zinc within the rolled product may steadily increase until approximately 1500 nm (1.5 μm) before reaching a constant or approximately constant concentration. The range of 0 to 1500 nm into the rolled product may correspond to the rolled near-surface microstructure. Thus, in exemplary embodiments, a low density population of zinc may be present within the rolled near-surface microstructure and then steadily increase to a higher density pollution within the bulk (e.g., bulk 120) of the rolled product.
Graph 300A includes an x-axis corresponding to a depth into the rolled product. The x-axis in graph 300A may be the same as the x-axes in graphs 200A and 200B, corresponding to a depth into the rolled product. In embodiments, the depth may correspond to the thickness of the rolled product. In various embodiments, the x-axis origination point, 0 nm, may correspond to the surface of the rolled product. The surface of the rolled product may also be the surface of the rolled near-surface microstructures 110.
Graph 300A also includes a plurality of y-axes. The plurality of y-axes may correspond to an intensity of aluminum and an intensity of the defect. The intensity of both the aluminum and the defect may correspond to the population density or concentration of each of the aluminum and the defect, respectively, present at a given depth of the rolled product. For example, as illustrated in graph 300A by an aluminum distribution line 310A, a lower concentration of aluminum may be present near the surface of the rolled product. However, the concentration of aluminum may increase and reach a steady concentration near a depth of 600 nm into the rolled product. This increasing concentration of aluminum may indicate the presence of the one or more defects 130 near the surface. In other words, the lower concentration of aluminum near the surface of the rolled product may indicate the one or more defects 130 within the rolled near-surface microstructures 110.
A defect distribution line 320A may correspond to a population density or concentration of the defect throughout a depth of a rolled product. The defect may correspond to one or more of the one or more defects 130. For example, the defect may correspond to the rolled-in material 130c, the voids 130b, and/or the internal cracks 130a.
As illustrated by the defect distribution line 320A, a higher concentration of the one or more defects 130 may be present near the surface of the rolled product. The higher concentration of the defect(s) near the surface may correspond to the presence of the defect(s) within the rolled near-surface microstructures 110. The concentration of the defect(s) may decrease further into the depth of the rolled product. At a point, for example around a depth of 600 nm into the rolled product, the defect concentration may reach a lower steady concentration. In embodiments, the point at which the concentration of the defect(s) reaches a steady concentration may correspond to the boundary 115 between the rolled near-surface microstructures 110 and the bulk 120.
In exemplary embodiments, the defect may correspond to a rolled-in material 130c. For example, the defect may correspond to a rolled-in rolling lubricant. In such exemplary embodiments, the defect distribution line 320A may indicate or correspond to a carbon concentration throughout the depth of the rolled product. The high concentration of carbon within the first 600 nm of the rolled product may indicate entrapped rolling lubricant within the rolled near-surface microstructures 110. During the processing of the rolled product, rolling lubricants and other processing material may be incorporated into the rolled near-surface microstructures 110. Thus, near the surface of the rolled product, such as within the rolled near-surface microstructures 110, a higher concentration of the rolled-in materials 130c may be present. However, as the depth continues towards the bulk 120, the concentration of the rolled-in material 130c may decrease until the concentration reaches a lower steady concentration of the first composition, which may be zero for some defects.
Graph 300B includes an x-axis corresponding to a depth into the rolled product. The x-axis in graph 300B may be the same as the x-axis in graph 300A, corresponding to a depth into the rolled product. In embodiments, the depth may correspond to the thickness of the rolled product. In embodiments, the depth may correspond to the thickness of the rolled product. In various embodiments, the x-axis origination point, 0 nm, may correspond to the surface of the rolled product. The surface of the rolled product may also be the surface of the micro-grained subsurface structure.
Graph 300B also includes a plurality of y-axes. The plurality of y-axes may correspond to an intensity of aluminum and an intensity of the defect. The intensity of both the aluminum and the defect may correspond to the population density or concentration of each of the aluminum and the defect, respectively, present at a given depth of the rolled product. For example, as illustrated in graph 300B by an aluminum distribution line 310B, the concentration of the aluminum present near the surface of the rolled product may be same as or similar to the concentration of the aluminum present throughout the depth of the rolled product. As noted above, an increasing concentration of aluminum from the surface of the rolled product towards the bulk 120 may indicate the presence of one or more defects 130 near the surface. Thus, a steady concentration of aluminum between the surface of the rolled product and the bulk 120 may indicate a lack of the one or more defects 130 near the surface.
A defect distribution line 320B (solid line in
Graph 400A includes an x-axis corresponding to a depth into the rolled product. The x-axis may be the same as the x-axes in graphs 200A, 200B, 300A, and 300B. The x-axis may correspond to a depth into the rolled product, starting at an origination point of 0 nm. The origination point of 0 nm may correspond to the surface of the rolled product. The origination point may also correspond to the surface of the rolled near-surface microstructures 110. The x-axis may extend to a depth of 2400 nm. Similar to the discussion with respect to the depth in graph 200A, the depth may correspond to a space occupied by the rolled composition. In various embodiments, the depth may correspond to the thickness of the rolled product. For example, as illustrated in graph 400A, the depth of 2400 nm may correspond to a depth into the bulk 120. However, in other embodiments, the depth may be greater than 2400 nm or may be less than 2400 nm.
Graph 400A also includes a y-axis. The y-axis corresponds to a grain size of the example aluminum alloy product 100 throughout the depth of the rolled product. The grain size may correspond to a crystallization size of the underlying components of the aluminum alloy as the rolled product is created. A grain size distribution line 410A corresponds to the grain size throughout the depth of the rolled product. As illustrated on graph 400A, the grain size near the surface of the rolled product may be larger than the grain size further towards the bulk 120. The grain size may be largest near the surface, within the rolled near-surface microstructures 110, and then may decrease toward the bulk 120 until the grain size reaches a steady small grain size. In embodiments, the grain size may reach a constant size around approximately 600 nm. The point at which the grain size reaches a constant size may correspond to the boundary 115 between the rolled near-surface microstructures 110 and the bulk 120. In some cases, the grain size within the bulk 120 may be larger, ranging from 5 μm to 50 μm. In various embodiments, the grain size may be ultrafine at a certain depth, such as within the bulk 120. For example, the grain size may be from 10 nm to 5 μm in the bulk 120. In some embodiments, a fine-grained layer below the oxide layer may form having ultrafine grains. In other embodiments, the grain size may be small within the rolled near-surface microstructures 110 but be larger further towards the bulk 120.
The one or more defects 130 present within the rolled near-surface microstructures 110 may also impact the chemical performance of the aluminum alloy product 100. Specifically, the high density populations 130e of the alloying element 140 may increase the corrosion sensitivity of the aluminum alloy product 100. As discussed above, the high density populations 130e may increase the corrosion propensity of aluminum alloy product 100, in part, because the alloying elements 140 making up the high density populations 130e may diffuse faster than adjacent elements or compounds, or the alloying elements 140 may be more reactive than adjacent elements or compounds. In turn, the high density populations 130e may create reactive pockets within the rolled near-surface microstructures 110 that may lead to favorable corrosion propagation conditions.
Graph 400B includes an x-axis corresponding to a depth into the rolled product. The x-axis may be the same as the x-axis in graph 400A. The x-axis may correspond to a depth into the rolled product, starting at an origination point of 0 nm. The origination point of 0 nm may correspond to the surface of the rolled product. The origination point may also correspond to the surface of the micro-grained subsurface structure. The x-axis may extend to a depth of 2400 nm. Similar to the depth in graphs 200B and 300B, the depth may correspond to a space occupied by the second composition. In various embodiments, the depth may correspond to the thickness of the rolled product. For example, as illustrated in graph 400B, the depth of 2400 nm may correspond to a depth into the bulk 120. However, in other embodiments, the depth may be greater than 2400 nm or may be less than 2400 nm.
Graph 400B also includes a y-axis. Similar to graph 400A, the y-axis may correspond to a grain size of the aluminum alloy product 100 throughout the depth of the rolled product. The grain size may correspond to a crystallization size of the underlying components of the aluminum alloy as the rolled product is created. A grain size distribution line 410B corresponds to the grain size throughout the depth of the rolled product. As illustrated in graph 400B, the grain size near the surface of the rolled product may be substantially the same as or similar to the grain size further towards the bulk 120. In embodiments, the grain size may be a fine grain size throughout the micro-grained subsurface structure and the bulk 120. In some cases, the grain size may be ultrafine throughout the depth. For example, the grain size may be from 10 nm to 5 μm at the surface of the rolled product and throughout the bulk 120. In other embodiments, the grain size may be a larger grain size throughout the micro-grained subsurface structure and the bulk 120, such as larger than a grain size of the rolled near-surface microstructures 110.
The one or more defects 130 and differing grain sizes discussed above within the rolled near-surface microstructures 110 may impact the mechanical performance of the aluminum alloy product 100. For example, the presence of rolled-in materials 130c or other defects within the rolled near-surface microstructures 110 may cause the rolled near-surface microstructures 110 to have a different ductility than the bulk 120. Differing ductilities between the rolled near-surface microstructures 110 and the bulk 120 may result in mechanical failures as the rolled near-surface microstructures 110 may deform less than the bulk 120.
In embodiments, mechanical altering of the rolled near-surface microstructures may include modifying the rolled near-surface microstructures to generate a first surface region and a second surface region. The first surface region may be or include the rolled near-surface microstructures having a thickness less than 500 nm. For example, the rolled near-surface microstructures in the first surface region may have a thickness of from 400 nm to 500 nm, from 300 nm to 400 nm, from 200 nm to 300 nm, from 100 nm to 200 nm, from 50 nm to 100 nm, from 10 nm to 50 nm, or from 1 nm to 10 nm. In some cases, the first surface region may be substantially free of the rolled near-surface microstructures such that only trace amounts of the rolled near-surface microstructures are present.
The second surface region may be free or substantially free of the near-surface microstructures. The second surface region may include an oxide layer. The oxide layer may have a thickness from 1 nm to 20 nm. For example, the oxide layer may range from 1 nm to 15 nm, from 1 nm to 10 nm, from 1 nm to 5 nm, or from 1 nm to 2 nm. In some cases, the second surface region may be free or substantially free of the oxide layer. A micro-grained subsurface structure, may be present between the oxide layer and the bulk. The micro-grained subsurface structure may have a thickness from 1 nm to 2 μm. For example, the micro-grained subsurface structure may have a thickness from 1 nm to 1 μm, from 10 nm to 800 nm, from 50 nm to 800 nm, from 100 nm to 800 nm, from 100 nm to 500 nm or from 100 nm to 400 nm.
In some embodiments, the first surface region and the second surface region may both be present after mechanical alteration of the rolled near-surface microstructures. The first surface region and the second surface region may be present at a ratio of 50% or less of the first surface region to the second surface region. For example, a ratio of an area of the first surface region to an area of the second surface region may be 40% or less, 30% or less, 20% or less, 15% or less, 10% or less, 5% or less, or 1% or less. In some cases, the first surface region may not be present after mechanical altering of the rolled near-surface microstructures. In some embodiments, the first surface region and the second surface region may be discontinuous. For example, the second surface region may form “islands” or pockets within the first surface region.
In various embodiments, the mechanical altering of the rolled near-surface microstructures may include creating a new layer of modified near-surface microstructures, referred to herein as a micro-grained subsurface structure. For example, mechanical altering the rolled near-surface microstructures may generate the first surface region containing the micro-grained subsurface structure. The new layer of micro-grained subsurface structure may comprise material from the rolled near-surface microstructures and/or material from the bulk and, in some cases, may optionally include material provided during the mechanical alteration process. As illustrated in
The composition of the rolled near-surface microstructures 510 may comprise one or more defects 530, which may be the same as or different from the one or more defects 130. The one or more defects 530 may include surface cracks 530d, interior cracks 530a, voids 530b, rolled-in material 530c, and/or high density populations 530e of alloying elements 540. As such, the one or more defects 530 may include a nonhomogeneous distribution of the alloying elements 540 and a nonhomogeneous distribution of grain size and structure within the rolled near-surface microstructures 510. In contrast to the rolled near-surface microstructures 510, the bulk 520 may have a first composition comprising minimal to no defects. The first composition may comprise a homogenous distribution of the alloying elements 540, as illustrated, and may comprise a homogenous distribution of grain size and structure. Although the homogenous distribution of alloying elements 540 is depicted as an array in the bulk 520 in
At
In some embodiments, a top layer 512a may be generated on the micro-grained subsurface structure 512. The top layer 512a may optionally be or include an oxide layer. Such an oxide layer may be an engineered oxide layer, which may have a particular thickness, composition, and structure which may allow for strong bonding with an adhesive, such as an epoxy adhesive.
In some embodiments, the top layer 512a may be or comprise a silicon-containing layer. The silicon-containing layer may modify a portion of bonding sites on the surface of or within the rolled near-surface microstructures 510. As noted above, the rolled near-surface microstructures 510 may include one or more defects 530, such as transfer cracks, voids, or fissures. By depositing the silicon-containing layer onto the rolled near-surface microstructures 510, one or more of the defects 530 within the rolled composition of the rolled near-surface microstructures 510 may be addressed such to form a second composition having fewer defects 530 than the rolled composition of the rolled near-surface microstructures 510.
To deposit the silicon-containing layer onto the rolled near-surface microstructures 510, a silicon-containing material, such as grit 555 embodied as a silicon-containing grit may be used. In embodiments, depositing the silicon-containing layer onto the rolled near-surface microstructures 510 or a portion of the rolled near-surface microstructures 510 may include grit blasting the rolled near-surface microstructures 510 with the silicon-containing grit. For example, a silicon-containing grit may be coated or treated with a silicon-containing material and be configured to transfer the silicon-containing material to a surface, such as the surface of the rolled near-surface microstructures 510, upon impingement. That is, when the grit 555 impacts the rolled near-surface microstructures 510, the thermal, mechanical, and kinetic energy of the impact may cause or induce the transfer of the silicon-containing material coating the grit 555 to the rolled near-surface microstructures 510. For example, when the grit 555 impacts the surface, local thermal transients may be generated, causing the silicon-containing material to deposit onto the surface. The energy generated from the individual impacts of each grit 555 particle may cause the natural oxide of the aluminum to be disrupted such that the silicon-containing material contacts and binds to both the oxide and the metal present at the surface. During a mechanical alteration process or treatment of the aluminum alloy product, a complex, amorphous silicon-containing film may form on the surface of the rolled product, generating the silicon-containing layer within, on top of, or as part of the micro-grained subsurface structure 512. In embodiments, the silicon-containing material may be ionized such to have a positive or negative charge. In such embodiments, the ionized state of the silicon-containing material may cause the silicon-containing material to have an affinity for the rolled near-surface microstructures 510. Thus, upon impact of the grit 555 with the rolled near-surface microstructures 510, the grit 555 may transfer silicon to the rolled near-surface microstructures 510 due, in part, to the ionic charge of the silicon-containing material.
As noted above, the grit 555 may be treated or coated with a silicon-containing compound that contains the silicon-containing material for transfer to the rolled near-surface microstructures 510. For example, the grit 555 may be treated with a silicon oxide (e.g., SiOx such as SiO, SiO2, SiO3, SiO4), silane, hexamethyldisiloxane (HMDSO), tetramethylsilane (TMS), tetraethoxysilane (TEOS), triethoxysilane, N-sec-butyl(trimethylsilyl)amine, 1,3-diethyl-1,1,3,3,tetramethyldisilazane, methylsilane, pentamethyldisilane, tetraethylsilane, tetramethyldisilane, or any other suitable organosilicon compound. In embodiments, the silicon-containing grit 555 may also include additional materials, such as adhesion promotors, corrosion inhibitors, aesthetic dopants, coupling agents, an antimicrobial agent, or the like, or any combination thereof. An exemplary grit 555 may include or comprise a SACO grit.
The silicon-containing material may modify a portion of the bonding sites within the rolled near-surface microstructures 510. The rolled near-surface microstructures 510 may have bonding sites that are not readily available or receptive to bonding. For example, the one or more defects 530 may reduce or impede the bonding sites or the bonding sites may be occupied with undesirable materials. To improve the bonding sites, the silicon-containing material may cause the bonding sites to open and be available for bonding. For example, the silicon-containing material may impart a desired ionic charge or change the electrochemical or mechanical structure of the bonding sites such to improve and facilitate bonding at the bonding sites. In embodiments, the impingement of the grit 555 may improve the bonding sites. For example, the impact of the grit 555 may consolidate the rolled near-surface microstructures 510 or remove undesirable material occupying a portion of the bonding sites.
Mechanically altering the rolled near-surface microstructures to have or generate a micro-grained subsurface structure is useful for improving the overall mechanical and chemical performance of the aluminum alloy product. In part, the improved mechanical and chemical performance of the aluminum alloy product may be due to the removal or alteration of the one or more defects.
As shown in
As noted with reference to the aluminum alloy product 100 and 500, high density populations 630e of the alloying element 640 may be present within the rolled near-surface microstructures 610. Within the bulk 620, the alloying element 640 may be homogenously distributed, meaning that, in any given volume of the bulk 620, the same or generally the same concentration of the alloying element 640 may be present. In
In contrast, the alloying element 640 may not be homogenously distributed within the rolled near-surface microstructures 610. As illustrated in
To alter the rolled composition of the rolled near-surface microstructures 610 to a more desirable composition, the rolled near-surface microstructures 610 may be mechanically altered during the processing of the aluminum alloy product 600. For example, the rolled near-surface microstructures 610 may be mechanically altered at any stage before the aluminum alloy product 600 undergoes any pretreatment processes. In various embodiments, the rolled near-surface microstructures 610 may be mechanically altered after a hot-rolling process is performed or after a cold-rolling process is performed. In other embodiments, the rolled near-surface microstructures 610 may be mechanically altered during a final gauging process of the aluminum alloy product 600.
The aluminum alloy product 600 may be treated according to one or more methods disclosed herein. For example, the method of treating an aluminum alloy product may include providing a rolled product having a bulk and rolled near-surface microstructures, wherein the rolled near-surface microstructures have a rolled composition comprising one or more defects. For example, the one or more defects may include at least one of rolled-in oxides, rolled-in oils, transfer cracks, voids, fissures, nonuniform bonding sites, or alloying elements nonhomogeneity. The method may also include mechanically altering the rolled near-surface microstructures to generate a micro-grained subsurface structure having a second composition that is different from the rolled composition. In some cases, the rolled near-surface microstructures may occupy a space to a depth into the bulk. In other embodiments, the second composition may include fewer defects than the rolled composition but more defects than a first composition of the bulk. For example, the second composition may be substantially the same as a first composition of the bulk or the second composition may be substantially free of the one or more defects. Additionally, the second composition may include grain structure homogeneity and an alloying element distribution homogeneity.
According to certain embodiments of the present disclosure, the method of treating an aluminum alloy product, such as the aluminum alloy product 600, may include grinding the rolled near-surface microstructures, laser ablating the rolled near-surface microstructures, sand blasting the rolled near-surface microstructures, and/or polishing the rolled near-surface microstructures. In some embodiments, mechanically altering the rolled near-surface microstructures may include physically ablating the rolled near-surface microstructures. For example, physically ablating the rolled near-surface microstructures may include grit-blasting the rolled near-surface microstructures. While in still other embodiments, mechanically altering the rolled near-surface microstructures may include compressing the rolled near-surface microstructures to a controlled depth. For example, compressing the rolled near-surface microstructures may include shot peening the near-surface microstructures to the controlled depth. Mechanically altering the second composition may also include generating homogenous ultrafine grains.
The method of mechanically altering the rolled near-surface microstructures may also include subjecting the rolled near-surface microstructures to a first alteration process and then subjecting the rolled near-surface microstructures to a second alteration process. In certain embodiments, mechanically altering may further include subjecting the rolled near-surface microstructures to a third alteration process. For example, the first alteration process may include exposing the rolled near-surface microstructures to a first grit, the second alteration process may include exposing the rolled near-surface microstructures to a second grit, and the third alteration process may include exposing the rolled near-surface microstructures to a third grit. In some examples, the first grit is coarser than the second grit and the second grit is coarser than the third grit.
The method of treating an aluminum alloy product as disclosed herein may include mechanically altering the rolled near-surface microstructures during a final gauging of the rolled product. However, in other embodiments, the mechanically altering the rolled near-surface microstructures may occur after a hot-rolling process and/or prior to a cold-rolling process. In some embodiments, mechanically altering the rolled near-surface microstructures may occur before pretreating the rolled product. The method may further include pretreating the rolled product. For example, the method may include pretreating the rolled product by etching the rolled product.
The rolled product subjected to mechanically altering via the methods disclosed herein may comprise at least one of a 7xxx series aluminum alloy product, a 6xxx series aluminum alloy product, or a 5xxx series aluminum alloy product. In various embodiments, the rolled product may be a hot-rolled product or a cold-rolled product.
An aluminum alloy product according to the methods and techniques disclosed herein may include a rolled product having a bulk and a micro-grained subsurface structure, wherein the rolled product initially has rolled near-surface microstructures having a rolled composition including one or more defects that is modified to mechanically alter the rolled near-surface microstructures to generate the micro-grained subsurface structure having a second composition that is different from the rolled composition. The one or more defects may include at least one of rolled-in oxides, voids, transfer cracks, fissures, nonuniform bonding sites, or alloying elements nonhomogeneity. The rolled near-surface microstructures may occupy a space to a depth into the bulk. In various embodiments, the second composition may include few defects than the rolled composition but more defects than the first composition. For example, the second composition may be substantially the same as a first composition of the bulk or the second composition may be substantially free of the one or more defects. The second composition may include grain structure homogeneity and alloying element distribution homogeneity. For example, the second composition may include homogenous ultrafine grains.
In various embodiments, the rolled product may include at least one of a 7xxx series aluminum alloy product, a 6xxx series aluminum alloy product, and a 5xxx series aluminum alloy product. The rolled product may be a hot-rolled product or a cold-rolled product. In certain cases, the aluminum alloy product may be made according to any of the methods disclosed herein.
As illustrated in
As illustrated in
The abrasive surfaces may be rotated or ground against the rolled near-surface microstructures 610 to remove material and/or redistribute the rolled composition. In various embodiments, the abrasive surfaces may be on a flat surface or a surface parallel to the surface of the aluminum alloy product 600. Instead of rotating to grind the surface, the abrasive surface may be agitated back and forth to achieve a desired friction between the abrasive surface and the rolled near-surface microstructures 610. The amount of friction applied during the grinding of the surface may be proportional to the amount of the rolled near-surface microstructures 610 to be altered. For example, a higher friction applied to the surface may correspond to a higher rate of alteration to the rolled near-surface microstructures 610. Various different grit sizes of the abrasive surface on grinding elements 650 may be used for grinding the surface, with the grit size optionally decreasing with successive grindings applied by grinding elements 650. A larger grit size may be desirable to start with to achieve a more robust grinding or friction effect, while smaller grit sizes may be desirable for subsequent grindings to alter the surface less and less and to generate a desirable micro-grained subsurface structure 612.
As noted above, the rolled near-surface microstructures 610 may occupy a space from the surface of the rolled product to a depth into the bulk 620. For example, the depth may be greater than 500 nm. However, in other embodiments, the depth may be less than 500 nm. The depth may range from 200 nm to 400 nm, from 300 nm to 500 nm, from 400 nm to 600 nm, from 200 nm to 600 nm, from 500 nm to 700 nm, from 500 nm to 800 nm, or from 200 nm to 800 nm, from 800 nm to 1 μm, from 1 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 15 μm, or from 15 μm to 20 μm. During the mechanical alteration, the rolled near-surface microstructures 610, a portion of the depth, may be altered. In embodiments, a portion of the depth may be mechanically altered. For example, if the depth of the near-surface microstructures 610 is 10 μm, then the portion of the depth mechanically altered may be the first 5 μm of the rolled near-surface microstructures 610. The portion of the depth mechanically altered may range from 50 nm to 100 nm, from 100 nm to 200, from 200 nm to 400 nm, from 300 nm to 500 nm, from 400 nm to 600 nm, from 200 nm to 600 nm, from 500 nm to 700 nm, from 500 nm to 800 nm, from 200 nm to 800 nm, from 800 nm to 1 μm, from 1 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 15 μm, or from 15 μm to 20 μm, depending on the overall depth. In some embodiments, the entire depth corresponding to the rolled near-surface microstructures 610 may be altered.
A micro-grained subsurface structure 612 may be achieved by mechanically altering the rolled near-surface microstructures 610 as described above. As shown in
As shown in
The second composition of the micro-grained subsurface structure 612 may also include a homogeneous grain structure. Grain structure homogeneity may provide that the grain size throughout the micro-grained subsurface structure 612 is the same or within a standard deviation of the bulk 620, for example. In various embodiments, grain structure homogeneity may correspond to the grain structure homogeneity of the micro-grained subsurface structure 612 being the same as the grain structure homogeneity of the bulk 620. For example, after the rolled near-surface microstructures 610 is mechanically altered and the micro-grained subsurface structure is generated, the grain structure of the micro-grained subsurface structure 612 may include an ultrafine grain structure matching that of (or similar to) the ultrafine grain structure within the first composition. In other embodiments, however, an ultrafine grain structure may be created within the micro-grained subsurface structure 612 while the bulk 620 contains a larger homogenous grain structure. In some cases, the grain structure of the micro-grained subsurface structure 612 may include aluminum alloy grains having an average diameter of from 10 nm to 500 nm. Although not shown in
The rolled near-surface microstructures 700 may include one or more defects 730. The one or more defects 730 may be the same as or different from the one or more defects 130, 530, or the one or more defects 630, as described herein. In embodiments, the one or more defects 730 may include internal cracks 730a, surface cracks 730d, voids 730b, rolled-in materials 730c, and/or high density populations 730e of alloying elements 740. As illustrated, the distribution of the alloying element 740 within the rolled near-surface microstructures 710 may be nonhomogeneous, resulting in pockets of high density populations 730e and pockets of minimal alloying element 740. Similar to the first compositions discussed with respect to the bulk 120, the bulk 520, or the bulk 620, the first composition of the bulk 720 may provide a homogeneous distribution of the alloying element 740. Between the first composition of the bulk 720 and the rolled composition of the rolled near-surface microstructures 710 may optionally be a boundary 715. The boundary 715 may be the same as or different from the boundary 115, the boundary 515, or the boundary 615.
At
Mechanically altering the rolled near-surface microstructures 710 may include one or more ablation devices 750. The one or more ablation devices 750 may include components for ablating the rolled near-surface microstructures 710. In an exemplary embodiment, physically ablating the rolled near-surface microstructures 710 may include sand blasting the surface. In such an embodiment, the ablation devices 750 may be grit blasting devices. The ablation devices 750 may be configured to blast grit 755 at the rolled near-surface microstructures 710. In embodiments where the ablation devices 750 may be sand blasting devices, the grit 755 may include sand, glass, or other silicate based grit. The size and composition of the grit 755 may depend on the application of the aluminum alloy product 700 and/or the desired extent of mechanical alteration to the rolled near-surface microstructures 710. It may be desirable, for some embodiments, to subject the surface to ablation using grit blasting with grit of various sizes, such as with multiple successive grit blasting applications of different grit sizes. For example, a larger grit size may be desirable to start with to achieve a more robust modification effect, while smaller grit sizes may be desirable for subsequent grit blasting to alter the surface less and less and to create a desirable micro-grained subsurface structure 712.
In exemplary embodiments where mechanically altering the rolled near-surface microstructures 710 includes shot peening the surface, then the ablation devices 750 may comprise peening devices. Exemplary shot peening methods may include physical shot peening, ultrasonic peening, wet peening, and laser peening. In the case of physical shot peening, the ablation devices 750 may include peening devices configured to propel the shot at the rolled near-surface microstructures 710 with sufficient force to achieve the mechanical alteration. In embodiments, the mechanical alteration may include compressing the rolled near-surface microstructures 710 to create plastic deformation within the outermost layer of the rolled product. Shot peening may be preferred over abrasive mechanical alteration in applications where less material removal is desired. Since shot peening compresses the rolled near-surface microstructures 710 instead of removing particles and material from the rolled near-surface microstructures 710, shot peening may be a preferred means of mechanically altering the rolled near-surface microstructures 710 in certain applications.
The micro-grained subsurface structure 712 may be generated by mechanically altering the rolled near-surface microstructures 710 as described above. The newly generated micro-grained subsurface structure 712 may be a thin surface layer. In embodiments, the micro-grained subsurface structure 712 may be from 1 nm to 2 μm. For example, the micro-grained subsurface structure 712 may be from 25 nm to 50 nm thick, from 50 nm to 100 nm thick, from 50 nm to 200 thick, from 50 nm to 300 nm thick, from 50 nm to 400 nm thick, from 50 nm to 500 nm thick, from 50 nm to 100 nm thick, from 100 nm to 200 nm thick, from 100 nm to 400 nm thick, from 100 nm to 500 nm, from 500 nm to 1 μm, from 800 nm to 2 μm, or from 1 μm to 2 μm thick.
The micro-grained subsurface structure 712 may comprise a second composition that is free or substantially free of the one or more defects 730. As noted above, substantially free of the one or more defects 730 may provide that the micro-grained subsurface structure 712 functions the same as though the second composition were free of the one or more defects. In embodiments, when the micro-grained subsurface structure 712 is substantially free of the one or more defects 730, any defects 730 present may not impact the mechanical or chemical performance of the aluminum alloy product 700. The second composition of the micro-grained subsurface structure 712 may be different than a rolled composition of the rolled near-surface microstructures 710. In various embodiments, the second composition may be between the rolled composition and a first composition of the bulk 720. In exemplary embodiments, the second composition may be the same or substantially the same as the first composition.
Similar to the micro-grained subsurface structure 512 and 612 discussed above, the second composition of the micro-grained subsurface structure 712 may comprise a homogeneous distribution of the alloying elements 740. Exemplary alloying elements 740 may include zinc, manganese, magnesium, copper, chromium, silicon, and/or iron. As illustrated in
In an exemplary embodiment, the mechanical altering of the rolled near-surface microstructures may include a multi-alteration process. A multi-alteration process may be a preferential means of mechanically altering rolled near-surface microstructures. During mechanical alteration of rolled near-surface microstructures, a disturbed layer may be generated. The disturbed layer may be a layer generated near the surface of the rolled near-surface microstructures that becomes deformed due to the mechanical alteration process. To minimize potential for generating the disturbed layer, a multi-alteration process may be employed. As illustrated in
As illustrated in
To achieve a desired second composition, the rolled near-surface microstructures 810 may be mechanically altered. Starting at
Each alteration process, the first alteration process in
By using differing grits 855a, 855b, and 855c, the rolled near-surface microstructures 810 may be mechanically altered to achieve a desired second composition. For example, the coarser grit 855a may be used first to alter the surface cracks 830d and the voids 830b. However, the coarser grit 855a may generate a disturbed layer having rough, undesirable features. As part of the disturbed layer, high density populations 830e of the alloying elements 840 may be present, along with uneven grain structure within the rolled near-surface microstructures 810. To achieve a smooth, uniform grain structure in the rolled near-surface microstructures 810, the grit 855b and then the fine grit 855c may be used subsequent to the coarser grit 855a. The grits 855b and 855c may alter the disturbed layer and create a smooth, defect-free micro-grained subsurface structure 812. As noted above, the micro-grained subsurface structure 812 may be free or substantially free of the one or more defects 830. Although not shown in
In various embodiments, different types of mechanical alteration may be used at each alteration process. For example, the first alteration process may include shot peening the rolled near-surface microstructures 810. The second alteration process may include grinding the rolled near-surface microstructures 810 with abrasive rollers. The third alteration process may include sand blasting the rolled near-surface microstructures 810 with a fine grit 855. Any combination of the mechanical alterations discussed herein may be used to create the micro-grained subsurface structure 812.
In exemplary embodiments, each alteration process may optionally use a 10-pound load force of the grit 855. Each alteration process may optionally last for two minutes. In various embodiments, each alteration process may last for more than two minutes or for less than two minutes. In various embodiments, each alteration process may use a load greater than 10-pounds or less than 10-pounds. The length and load applied during each alteration process may depend on the micro-grained subsurface structure 812 desired.
At
Following mechanical alteration, the resultant product can be processed by any suitable means. Optionally, the processing steps can be used to prepare sheets, for example. Such processing steps include, but are not limited to, homogenization, hot-rolling, cold-rolling, solution heat treatment, and an optional pre-aging step. Mechanically altered products can be processed and made into products such as sheets, plates, or other suitable products.
The metal products described herein can be used in automotive applications and other transportation applications, including aircraft and railway applications, or any other desired application. For example, the disclosed metal products can be used to prepare automotive structural parts, such as bumpers, side beams, roof beams, cross beams, pillar reinforcements (e.g., A-pillars, B-pillars, and C-pillars), inner panels, outer panels, side panels, inner hoods, outer hoods, or trunk lid panels. The metal products and methods described herein can also be used in aircraft or railway vehicle applications, to prepare, for example, external and internal panels.
The metal products and methods described herein can also be used in electronics applications. For example, the metal products and methods described herein can be used to prepare housings for electronic devices, including mobile phones and tablet computers. In some examples, the metal products can be used to prepare housings for the outer casing of mobile phones (e.g., smart phones), tablet bottom chassis, and other portable electronics.
Non-limiting exemplary 1xxx aluminum alloys for use in the products, systems, and methods described herein can include AA1100, AA1100A, AA1200, AA1200A, AA1300, AA1110, AA1120, AA1230, AA1230A, AA1235, AA1435, AA1145, AA1345, AA1445, AA1150, AA1350, AA1350A, AA1450, AA1370, AA1275, AA1185, AA1285, AA1385, AA1188, AA1190, AA1290, AA1193, AA1198, or AA1199.
Non-limiting exemplary 2xxx series aluminum alloys for use in the products, systems, and methods described herein can include AA2001, A2002, AA2004, AA2005, AA2006, AA2007, AA2007A, AA2007B, AA2008, AA2009, AA2010, AA2011, AA2011A, AA2111, AA2111A, AA2111B, AA2012, AA2013, AA2014, AA2014A, AA2214, AA2015, AA2016, AA2017, AA2017A, AA2117, AA2018, AA2218, AA2618, AA2618A, AA2219, AA2319, AA2419, AA2519, AA2021, AA2022, AA2023, AA2024, AA2024A, AA2124, AA2224, AA2224A, AA2324, AA2424, AA2524, AA2624, AA2724, AA2824, AA2025, AA2026, AA2027, AA2028, AA2028A, AA2028B, AA2028C, AA2029, AA2030, AA2031, AA2032, AA2034, AA2036, AA2037, AA2038, AA2039, AA2139, AA2040, AA2041, AA2044, AA2045, AA2050, AA2055, AA2056, AA2060, AA2065, AA2070, AA2076, AA2090, AA2091, AA2094, AA2095, AA2195, AA2295, AA2196, AA2296, AA2097, AA2197, AA2297, AA2397, AA2098, AA2198, AA2099, or AA2199.
Non-limiting exemplary 3xxx series aluminum alloys for use in the products, systems, and methods described herein can include AA3002, AA3102, AA3003, AA3103, AA3103A, AA3103B, AA3203, AA3403, AA3004, AA3004A, AA3104, AA3204, AA3304, AA3005, AA3005A, AA3105, AA3105A, AA3105B, AA3007, AA3107, AA3207, AA3207A, AA3307, AA3009, AA3010, AA3110, AA3011, AA3012, AA3012A, AA3013, AA3014, AA3015, AA3016, AA3017, AA3019, AA3020, AA3021, AA3025, AA3026, AA3030, AA3130, or AA3065.
Non-limiting exemplary 4xxx series aluminum alloys for use in the products, systems, and methods described herein can include AA4004, AA4104, AA4006, AA4007, AA4008, AA4009, AA4010, AA4013, AA4014, AA4015, AA4015A, AA4115, AA4016, AA4017, AA4018, AA4019, AA4020, AA4021, AA4026, AA4032, AA4043, AA4043A, AA4143, AA4343, AA4643, AA4943, AA4044, AA4045, AA4145, AA4145A, AA4046, AA4047, AA4047A, or AA4147.
Non-limiting exemplary 5xxx series aluminum alloys for use in the products, systems, and methods described herein can include AA5182, AA5183, AA5005, AA5005A, AA5205, AA5305, AA5505, AA5605, AA5006, AA5106, AA5010, AA5110, AA5110A, AA5210, AA5310, AA5016, AA5017, AA5018, AA5018A, AA5019, AA5019A, AA5119, AA5119A, AA5021, AA5022, AA5023, AA5024, AA5026, AA5027, AA5028, AA5040, AA5140, AA5041, AA5042, AA5043, AA5049, AA5149, AA5249, AA5349, AA5449, AA5449A, AA5050, AA5050A, AA5050C, AA5150, AA5051, AA5051A, AA5151, AA5251, AA5251A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A, AA5154B, AA5154C, AA5254, AA5354, AA5454, AA5554, AA5654, AA5654A, AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A, AA5456B, AA5556, AA5556A, AA5556B, AA5556C, AA5257, AA5457, AA5557, AA5657, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA5182, AA5083, AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086, AA5186, AA5087, AA5187, or AA5088.
Non-limiting exemplary 6xxx series aluminum alloys for use in the products, systems, and methods described herein can include AA6101, AA6101A, AA6101B, AA6201, AA6201A, AA6401, AA6501, AA6002, AA6003, AA6103, AA6005, AA6005A, AA6005B, AA6005C, AA6105, AA6205, AA6305, AA6006, AA6106, AA6206, AA6306, AA6008, AA6009, AA6010, AA6110, AA6110A, AA6011, AA6111, AA6012, AA6012A, AA6013, AA6113, AA6014, AA6015, AA6016, AA6016A, AA6116, AA6018, AA6019, AA6020, AA6021, AA6022, AA6023, AA6024, AA6025, AA6026, AA6027, AA6028, AA6031, AA6032, AA6033, AA6040, AA6041, AA6042, AA6043, AA6151, AA6351, AA6351A, AA6451, AA6951, AA6053, AA6055, AA6056, AA6156, AA6060, AA6160, AA6260, AA6360, AA6460, AA6460B, AA6560, AA6660, AA6061, AA6061A, AA6261, AA6361, AA6162, AA6262, AA6262A, AA6063, AA6063A, AA6463, AA6463A, AA6763, A6963, AA6064, AA6064A, AA6065, AA6066, AA6068, AA6069, AA6070, AA6081, AA6181, AA6181A, AA6082, AA6082A, AA6182, AA6091, or AA6092.
Non-limiting exemplary 7xxx series aluminum alloys for use in the products, systems, and methods described herein can include AA7011, AA7019, AA7020, AA7021, AA7039, AA7072, AA7075, AA7085, AA7108, AA7108A, AA7015, AA7017, AA7018, AA7019A, AA7024, AA7025, AA7028, AA7030, AA7031, AA7033, AA7035, AA7035A, AA7046, AA7046A, AA7003, AA7004, AA7005, AA7009, AA7010, AA7011, AA7012, AA7014, AA7016, AA7116, AA7122, AA7023, AA7026, AA7029, AA7129, AA7229, AA7032, AA7033, AA7034, AA7036, AA7136, AA7037, AA7040, AA7140, AA7041, AA7049, AA7049A, AA7149, AA7204, AA7249, AA7349, AA7449, AA7050, AA7050A, AA7150, AA7250, AA7055, AA7155, AA7255, AA7056, AA7060, AA7064, AA7065, AA7068, AA7168, AA7175, AA7475, AA7076, AA7178, AA7278, AA7278A, AA7081, AA7181, AA7185, AA7090, AA7093, AA7095, or AA7099.
Non-limiting exemplary 8xxx series aluminum alloys for use in the products, systems, and methods described herein can include AA8005, AA8006, AA8007, AA8008, AA8010, AA8011, AA8011A, AA8111, AA8211, AA8112, AA8014, AA8015, AA8016, AA8017, AA8018, AA8019, AA8021, AA8021A, AA8021B, AA8022, AA8023, AA8024, AA8025, AA8026, AA8030, AA8130, AA8040, AA8050, AA8150, AA8076, AA8076A, AA8176, AA8077, AA8177, AA8079, AA8090, AA8091, or AA8093.
The examples disclosed herein will serve to further illustrate aspects of the invention without, at the same time, however, constituting any limitation thereof. On the contrary, it is to be clearly understood that resort may be had to various embodiments, modifications and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without departing from the spirit of the invention. The examples and embodiments described herein may also make use of conventional procedures, unless otherwise stated. Some of the procedures are described herein for illustrative purposes.
The following Table 1 provides exemplary results showing the improved bond durability performance of various aluminum alloy products that have been mechanically altered to generate a micro-grained subsurface structure. The bond durability results for aluminum alloy products maintaining rolled near-surface microstructures and not undergoing mechanical alteration are provided in Table 1 for comparison.
For the results in Table 1, Sample 1 comprises a 7075 aluminum alloy product that is mechanically altered using physical abrasion. Sample 1 is mechanically altered using an abrasive surface to generate a micro-grained subsurface structure. Similarly, Sample 2 comprises another 7xxx series aluminum alloy product that is mechanically altered using a similar abrasive surface, such as S702. Samples 3 and 4 comprise 7075 aluminum alloy products. Samples 5, 6, and 7 comprise additional 7xxx aluminum alloy products. Samples 3, 4, 5, 6, and 7 all have mill finishes. None of Samples 3-7 are mechanically altered and instead, retain rolled near-surface microstructures.
All samples are subjected to a bond durability test. During this test, each sample is made of two pieces of aluminum alloy product, prepared and treated using the same conditions, that are bonded together via six bonding sites. Next, each sample is subjected to a variety of test conditions. For example, the test conditions may include one or more of immersion in a salt solution, exposure to humid conditions, exposure to dry conditions, or application of force inducing stress or strain. Each sample is subjected to numerous cycles of these test conditions. The number of cycles a sample is subjected to is either the number of cycles to reach mechanical failure or 60 cycles, the maximum number of cycles used in this particular test. Mechanical failure includes bond failure, a break in the metal product or a break in the adhesive.
As evident by Table 1, Samples 1 and 2 performed substantially better than the non-altered Samples 3, 4, 5, 6, and 7. Samples 1 and 2 comprising the micro-grained subsurface structure lasted 60 cycles of the Bond Durability test with all six bonds intact. In contrast, the five mill finished samples comprising rolled near-surface microstructures all experienced mechanical failure to all bonds within 10 cycles.
Images 920, 940, and 950 shown distribution of various elements through the cross-section of the aluminum alloy product sample. Image 920 provides a distribution of aluminum through the aluminum alloy product sample. As shown, aluminum density is highest throughout the bulk 912 and is substantially homogenous throughout the cross-sectional depth of the bulk 912. Image 940 provides a distribution of zinc through the aluminum alloy product sample. As shown, the population of zinc is higher within the bulk 912 than in other areas of the aluminum alloy product sample. Image 950 provides a distribution of chromium through the aluminum alloy product sample. As shown, chromium presence is higher in the bulk 912 with higher density populations present in the bulk 912.
In some areas, the surface region of the aluminum alloy product sample may be devoid or substantially devoid of the micro-grained subsurface structure 1010. One such area is depicted in
The area percentage of yellow to blue surface regions for each sample is evaluated to determine the ratio of the first surface region to the second surface region. Images 1110 include color mapping for a sample 1112 and a sample 1114. Samples 1112 and 1114 are samples of the first aluminum alloy material which have a mill finish. As shown, the surface area of the sample 1112 comprises 47% of the first surface region and 53% of the second surface region. As shown, the surface area of the sample 1114 comprises 54.3% of the first surface region and 45.7% of the second surface region. The increased surface percentage of the first surface region indicates a prominence of near-surface microstructures containing defects. This may correspond to a lower bond durability of the first aluminum alloy material.
Images 1120 include color mapping for a sample 1122 and a sample 1124. Samples 1122 and 1124 are samples of the second aluminum alloy material which have been mechanically altered according to techniques and methods herein. As shown, the surface area of the sample 1122 comprises 32.3% of the first surface region and 67.7% of the second surface region. As shown, the surface area of the sample 1124 comprises 22.4% of the first surface region and 77.6% of the second surface region. For sample 1122 and 1124 the surface percentage of the first surface region decreased compared to samples 1112 and 1114, indicating a decrease in near-surface microstructures containing one or more defects. This may correspond to a higher bond durability of the second aluminum alloy material.
As used below, any reference to a series of illustrations is to be understood as a reference to each of those examples disjunctively (e.g., “Illustrations 1-4” is to be understood as “Illustrations 1, 2, 3, or 4”).
Illustration 1 is an aluminum alloy product, comprising: a bulk, wherein the bulk comprises a bulk grain structure including grains of an aluminum alloy, the aluminum alloy comprising: aluminum; and one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese; a first surface region including a near-surface microstructure (NSM) of a thickness less than 500 nm; a second surface region free of the NSM, wherein the second surface region comprises an oxide layer; and a micro-grained subsurface structure present between the oxide layer and the bulk, wherein the micro-grained subsurface structure: has a thickness from 1 nm to 2 μm; is devoid or substantially devoid of one or more compositional defects, wherein the one or more compositional defects comprise organics, oils, hydrocarbons, soils, inorganic residues, rolled-in oxides, or anodic oxides; and comprises a grain structure that is different from the bulk grain structure, wherein the grain structure comprises aluminum alloy grains having an average diameter of from 10 nm to 500 nm.
Illustration 2 is the aluminum alloy product of any previous or subsequent illustration, wherein the oxide layer has a thickness from 1 nm to 20 nm.
Illustration 3 is the aluminum alloy product of any previous or subsequent illustration, wherein the oxide layer has an average thickness of 10 nm and a standard deviation of 5 nm.
Illustration 4 is the aluminum alloy product of any previous or subsequent illustration, wherein the oxide layer is devoid or substantially devoid of one or more defects.
Illustration 5 is the aluminum alloy product of any previous or subsequent illustration, wherein the NSM comprises one or more compositional defects, wherein the one or more compositional defects comprise organics, oils, hydrocarbons, soils, inorganic residues, rolled-in oxides, or anodic oxides.
Illustration 6 is the aluminum alloy product of any previous or subsequent illustration, wherein a ratio of the first surface region to the second surface region is less than 50%.
Illustration 7 is the aluminum alloy product of any previous or subsequent illustration, wherein the first surface region and the second surface region are discontinuous.
Illustration 8 is the aluminum alloy product of any previous or subsequent illustration, wherein the micro-grained subsurface structure further comprises precipitates having an average diameter of from 10 nm to 2 μm, wherein the precipitates comprise one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese.
Illustration 9 is the aluminum alloy product of any previous or subsequent illustration, further comprising a silicon-containing layer on the micro-grained subsurface structure, wherein the silicon-containing layer modifies a portion of bonding sites within the micro-grained subsurface structure.
Illustration 10 is the aluminum alloy product of any previous or subsequent illustration, wherein a weight percent of aluminum in the micro-grained subsurface structure is less than a weight percent of aluminum in the bulk.
Illustration 11 is the aluminum alloy product of any previous or subsequent illustration, exhibiting a bond durability of from 22 cycles to 100 cycles, or more, according to a FLTM BV 101-07 standard test.
Illustration 12 is the aluminum alloy product of any previous or subsequent illustration, wherein a concentration of magnesium and zinc in the aluminum alloy is less than 20 wt. %, wherein a ratio of zinc to magnesium in the concentration is from 0.1 to 10.0.
Illustration 13 is the aluminum alloy product of any previous or subsequent illustration, wherein a concentration of magnesium in the bulk is greater than in the micro-grained subsurface structure, wherein a concentration of copper in the bulk is greater than in the micro-grained subsurface structure, or wherein a concentration of zinc in the bulk is greater than in the micro-grained subsurface structure.
Illustration 14 is the aluminum alloy product of any previous or subsequent illustration, wherein the micro-grained subsurface structure comprises more structural defects than the bulk, wherein structural defects correspond to or comprise voids, transfer cracks, or fissures.
Illustration 15 is the aluminum alloy product of any previous or subsequent illustration, wherein the micro-grained subsurface structure is substantially the same as the bulk.
Illustration 16 is the aluminum alloy product of any previous or subsequent illustration, wherein the micro-grained subsurface structure comprises a grain structure homogeneity or an alloying element distribution homogeneity different from that of the bulk.
Illustration 17 is a method of treating an aluminum alloy product, comprising: providing a rolled aluminum alloy product comprising: a bulk, wherein the bulk comprises a bulk grain structure including grains of an aluminum alloy, the aluminum alloy comprising: aluminum; and one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese; and a near-surface microstructure (NSM) having a thickness of greater than 500 nm; modifying the NSM to generate: a first surface region including a near-surface microstructure (NSM) of a thickness less than 500 nm; a second surface region free of the NSM, wherein the second surface region comprises an oxide layer; and a micro-grained subsurface structure between the oxide layer and the bulk, wherein the micro-grained subsurface structure: has a thickness from 1 nm to 2 μm; is devoid or substantially devoid of one or more compositional defects, wherein the one or more compositional defects comprise organics, oils, hydrocarbons, soils, inorganic residues, rolled-in oxides, or anodic oxides; and comprises a grain structure that is different from the bulk grain structure, wherein the grain structure comprises aluminum alloy grains having an average diameter of from 10 nm to 500 nm.
Illustration 18 is the method of any previous or subsequent illustration, wherein the oxide layer has a thickness from 1 nm to 20 nm.
Illustration 19 is the method of any previous or subsequent illustration, wherein the oxide layer has an average thickness of 10 nm and a standard deviation of 5 nm.
Illustration 20 is the method of any previous or subsequent illustration, wherein the oxide layer is devoid or substantially devoid of one or more defects.
Illustration 21 is the method of any previous or subsequent illustration, wherein the NSM comprises one or more compositional defects, wherein the one or more compositional defects comprise organics, oils, hydrocarbons, soils, inorganic residues, rolled-in oxides, or anodic oxides.
Illustration 22 is the method of any previous or subsequent illustration, wherein a ratio of the first surface region to the second surface region is less than 50%.
Illustration 23 is the method of any previous or subsequent illustration, wherein the first surface region and the second surface region are discontinuous.
Illustration 24 is the method of any previous or subsequent illustration, wherein the micro-grained subsurface structure further comprises precipitates having an average diameter of from 10 nm to 2 μm, wherein the precipitates comprise one or more alloying elements selected from the group consisting of zinc, magnesium, copper, chromium, silicon, iron, and manganese.
Illustration 25 is the method of any previous or subsequent illustration, wherein a concentration of magnesium and zinc in the aluminum alloy is less than 20 wt. %, wherein a ratio of zinc to magnesium in the concentration is from 0.1 to 10.0.
Illustration 26 is the method of any previous or subsequent illustration, wherein a weight percent of aluminum in the micro-grained subsurface structure is less than a weight percent of aluminum in the bulk.
Illustration 27 is the method of any previous or subsequent illustration, wherein a concentration of magnesium in the bulk is greater than in the micro-grained subsurface structure, wherein a concentration of copper in the bulk is greater than in the micro-grained subsurface structure, or wherein a concentration of zinc in the bulk is greater than in the micro-grained subsurface structure.
Illustration 28 is the method of any previous or subsequent illustration, wherein the micro-grained subsurface structure provides a bond durability of from 22 cycles to 100 cycles, or more, according to a FLTM BV 101-07 standard test.
Illustration 29 is the method of any previous or subsequent illustration, wherein the micro-grained subsurface structure has fewer structural defects than the NSM and more structural defects than the bulk, wherein structural defects correspond to or comprise voids, transfer cracks, or fissures.
Illustration 30 is the method of any previous or subsequent illustration, wherein modifying the NSM comprises depositing a silicon-containing layer when generating the micro-grained subsurface structure or coating at least a portion of the micro-grained subsurface structure with a silicon-containing layer, wherein the silicon-containing layer modifies a portion of bonding sites within the micro-grained subsurface structure.
Illustration 31 is the method of any previous or subsequent illustration, wherein modifying comprises subjecting the NSM to mechanical alteration, wherein the mechanical alteration comprises one or more of: grinding the NSM, physically ablating the NSM; grit-blasting the NSM; laser ablating the NSM; sand blasting the NSM; or polishing the NSM.
All patents, publications and abstracts cited above are incorporated herein by reference in their entirety. The foregoing description of the embodiments, including illustrated embodiments, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or limiting to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art.
This application claims the benefit of and priority to U.S. Provisional Application No. 62/978,767, filed on Feb. 19, 2020, U.S. Provisional Application No. 62/984,555, filed on Mar. 3, 2020, and U.S. Provisional Application No. 62/993,365, filed on Mar. 23, 2020, which are hereby incorporated by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/018501 | 2/18/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62978767 | Feb 2020 | US | |
| 62984555 | Mar 2020 | US | |
| 62993365 | Mar 2020 | US |
