Patent Application
20230243023
This application claims the benefit of Chinese Patent Application No. 202210106864.6 filed on Jan. 28, 2022. The entire disclosure of the application referenced above is incorporated herein by reference.
This section provides background information related to the present disclosure which is not necessarily prior art.
Die casting processes are commonly used to form high volume automobile components. In particular, aluminum alloys are often used to form the structural components in the die casting process because aluminum alloys have many favorable properties, such as high specific strength and excellent corrosion resistance. In addition, outstanding castability of aluminum alloys allows the formation of more complex thin-walled components in die casting process compared to other alloys. Traditionally, aluminum die castings have a limitation on ductility and fracture toughness due to the existence of air entrapment, eutectic silicon particles and a large quantity of coarse Fe-rich intermetallic phases which act as stress raisers in plastic deformations. To satisfy some highly integrated components which require crashworthiness and riveting with steel sheet, such as hinge pillar and shock tower, many technologies have been developed for improving ductility and fracture toughness. For example, complicated T7 heat treatment is commonly applied to modify the morphology of eutectic Si particles from coral-like to spherical for improving fracture toughness. T7 heat treatment includes heating die cast components to elevated temperatures higher than 460° C. and stay for over 30 minutes to spherodize eutectic Si particles followed by air quench. Then ageing heat treatment will be conducted on the obtained components at around 180-230° C. for 30 to 180 minutes to stabilize the mechanical properties. T7 heat treatment requires reduced air entrapment in die cast component, otherwise elevated temperature will induce surface blisters due to underneath porosities. Therefore, super-vacuum die casting process is commonly accompanied with T7 heat treatment.
However, super-vacuum die casting and complicated T7 heat treatment result in high costs and complicated manufacturing. Another strategy to enable the production of die cast components with excellent ductility and fracture toughness is to apply an optimized alloy chemistry with iron reducing to extremely low levels (<0.13% in mass). In the optimized alloy chemistry, manganese in place of iron is applied to improve die-soldering resistance and therefore undesirable coarse Fe-rich intermetallic compounds can be eliminated. However, large amounts of high-purity aluminum must be used resulting in expensive raw materials and high carbon footprints. Additional technologies have been researched to reduce processing costs and carbon footprints without sacrificing mechanical properties.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
In certain aspects, the present disclosure relates to an aluminum alloy component that comprises an aluminum alloy composition. The aluminum alloy composition includes chromium (Cr) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.3 wt. %, manganese (Mn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.4 wt. %, silicon (Si) at a concentration of greater than or equal to about 6.5 wt. % to less than or equal to about 9.5 wt. %, magnesium (Mg) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.35 wt. %, iron (Fe) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.4 wt. %, zinc (Zn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, copper (Cu) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, titanium (Ti) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.2 wt. %, strontium (Sr) at a concentration of greater than or equal to about 0 part per million (ppm) to less than or equal to about 200 ppm, and a balance of the alloy composition being aluminum.
In one aspect, the cast aluminum alloy component has a yield strength of greater than or equal to about 100 MPa, an elongation to fracture of greater than or equal to about 8%, and an equivalent bending angle at (t, mm) thickness of greater than or equal to about 34/√{square root over (t)} degrees.
In one aspect, the cast aluminum alloy component has a yield strength of greater than or equal to about 110 MPa, an elongation to fracture of greater than or equal to about 8%, and an equivalent bending angle at (t, mm) thickness of greater than or equal to about 44/√{square root over (t)} degrees.
In one aspect, a total cumulative amount of the iron (Fe), manganese (Mn), and chromium (Cr) is less than 0.65 wt. %.
In one aspect, a sum of the concentration of iron (Fe), one and a half (1.5) times the concentration of manganese (Mn), and two and seven tenths (2.7) times the concentration of chromium (Cr) is greater than 0.8 wt. %.
In one aspect, the alloy composition includes chromium (Cr) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.3 wt. %, manganese (Mn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, silicon (Si) at a concentration of greater than or equal to about 6.5 wt. % to less than or equal to about 8 wt. %, magnesium (Mg) at a concentration of greater than or equal to about 0.1 wt. % to less than or equal to about 0.3 wt. %, iron (Fe) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.4 wt. %, zinc (Zn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, copper (Cu) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, and a balance of the alloy composition being aluminum
In one aspect, the alloy composition includes chromium (Cr) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.3 wt. %, manganese (Mn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, silicon (Si) at a concentration of greater than or equal to about 8 wt. % to less than or equal to about 9.5 wt. %, magnesium (Mg) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. % iron (Fe) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.4 wt. %, zinc (Zn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, copper (Cu) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, and a balance of the alloy composition being aluminum.
In one aspect, a eutectic silicon phase of the cast aluminum alloy component in an as-cast state includes a coral-like morphology in a three-dimensional space.
In certain aspects, the present disclosure relates to a method for fabricating a cast aluminum component, the method including forming an aluminum melt using greater than or equal to about 40 wt. % of aluminum scrap, adjusting the aluminum melt to form an aluminum alloy composition to form the cast aluminum component, wherein the aluminum alloy composition includes chromium (Cr) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.3 wt. %, manganese (Mn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.4 wt. %, silicon (Si) at a concentration of greater than or equal to about 6.5 wt. % to less than or equal to about 9.5 wt. %, magnesium (Mg) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.35 wt. %, iron (Fe) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.4 wt. %, zinc (Zn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, copper (Cu) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, titanium (Ti) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.2 wt. %, strontium (Sr) at a concentration of greater than or equal to about 0 part per million (ppm) to less than or equal to about 200 ppm, and a balance of the alloy composition being aluminum, and casting the aluminum alloy composition using one of high pressure die casting or semi-solid die casting to form the cast aluminum component.
In one aspect, the method further includes heating the cast aluminum component to at least one temperature greater than or equal to about 100° C. to less than or equal to about 250° C. and for greater than or equal to about 10 minutes to less than or equal to about 300 minutes.
In one aspect, the method further includes heating the cast aluminum component to about 205° C. for about 60 minutes.
In one aspect, the method further includes paint baking the cast aluminum component.
In one aspect, the alloy composition includes chromium (Cr) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.3 wt. %, manganese (Mn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, silicon (Si) at a concentration of greater than or equal to about 6.5 wt. % to less than or equal to about 8 wt. %, magnesium (Mg) at a concentration of greater than or equal to about 0.1 wt. % to less than or equal to about 0.3 wt. %, iron (Fe) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.4 wt. %, zinc (Zn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.2 wt. %, copper (Cu) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, and a balance of the alloy composition being aluminum
In one aspect, the alloy composition includes chromium (Cr) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.3 wt. %, manganese (Mn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, silicon (Si) at a concentration of greater than or equal to about 8 wt. % to less than or equal to about 9.5 wt. %, magnesium (Mg) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. % iron (Fe) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.4 wt. %, zinc (Zn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.2 wt. %, copper (Cu) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, and a balance of the alloy composition being aluminum.
In one aspect, the method generates less than or equal to about 10 tons of carbon dioxide (CO2) emission per 1 ton of the cast aluminum component that is formed.
In certain aspects, the present disclosure relates to a cast aluminum alloy component having a yield strength of greater than or equal to about 100 MPa, an elongation to fracture of greater than or equal to about 8%, and an equivalent bending angle at (t, mm) thickness of greater than or equal to about 34/√(“t”) degrees. The cast aluminum alloy includes an aluminum alloy composition that includes a total cumulative amount of the iron (Fe), manganese (Mn), and chromium (Cr) is less than 0.65 wt. %, and a sum of the concentration of iron (Fe), one and a half (1.5) times the concentration of manganese (Mn), and two and seven tenths (2.7) times the concentration of chromium (Cr) is greater than 0.8 wt. %.
In one aspect, the alloy composition includes chromium (Cr) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.3 wt. %, manganese (Mn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. %, silicon (Si) at a concentration of greater than or equal to about 8 wt. % to less than or equal to about 9.5 wt. %, magnesium (Mg) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.15 wt. % iron (Fe) at a concentration of greater than or equal to about 0.2 wt. % to less than or equal to about 0.4 wt. %, zinc (Zn) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.2 wt. %, copper (Cu) at a concentration of greater than or equal to about 0 wt. % to less than or equal to about 0.5 wt. %, and a balance of the alloy composition being aluminum.
In one aspect, a eutectic silicon phase of the cast aluminum alloy component in an as-cast state includes a coral-like morphology in a three-dimensional space.
In one aspect, the cast aluminum alloy component has been heated to at least one temperature greater than or equal to about 100° C. to less than or equal to about 250° C. and for greater than or equal to about 10 minutes to less than or equal to about 300 minutes
In one aspect, the alloy composition comprises impurities at a concentration of less than exactly or about 0.01 wt. %
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, elements, compositions, steps, integers, operations, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Although the open-ended term “comprising,” is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, in certain aspects, the term may alternatively be understood to instead be a more limiting and restrictive term, such as “consisting of” or “consisting essentially of.” Thus, for any given embodiment reciting compositions, materials, components, elements, features, integers, operations, and/or process steps, the present disclosure also specifically includes embodiments consisting of, or consisting essentially of, such recited compositions, materials, components, elements, features, integers, operations, and/or process steps. In the case of “consisting of,” the alternative embodiment excludes any additional compositions, materials, components, elements, features, integers, operations, and/or process steps, while in the case of “consisting essentially of,” any additional compositions, materials, components, elements, features, integers, operations, and/or process steps that materially affect the basic and novel characteristics are excluded from such an embodiment, but any compositions, materials, components, elements, features, integers, operations, and/or process steps that do not materially affect the basic and novel characteristics can be included in the embodiment.
Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed, unless otherwise indicated.
When a component, element, or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected, or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and/or sections, these steps, elements, components, regions, layers and/or sections should not be limited by these terms, unless otherwise indicated. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer, or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer, or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially or temporally relative terms, such as “before,” “after,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.
Throughout this disclosure, the numerical values represent approximate measures or limits to ranges to encompass minor deviations from the given values and embodiments having about the value mentioned as well as those having exactly the value mentioned. Other than in the working examples provided at the end of the detailed description, all numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. For example, “about” may comprise a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in certain aspects, optionally less than or equal to 0.1%.
Throughout this disclosure, it is to be understood that when a lower limit for a range is not given (e.g., “up to X wt. % element” or “less than X wt. % element”), the lower limit is 0 wt. %, and thus the particular element may not be present in the alloy. However, when it is stated that an element “is present in an amount up to X wt. %”, the lower limit is greater than 0 wt. %, and at least some of the element is present in the alloy.
As used herein, all amounts are weight % (or mass %), unless otherwise indicated, for example volume (vol.) %.
In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges.
Example embodiments will now be described more fully with reference to the accompanying drawings.
Structural assemblies may be used in vehicles to provide structural support and/or mounting locations for other vehicle components. Structural assemblies may include energy-absorbing components that absorb collision energy through controlled deformation. Structural assemblies may be constructed from metal, such as aluminum or steel, and/or polymer composite material components. Metal structural assemblies may absorb energy when elastically and/or plastically deforming without fracture. Lower strength metals may be assembled to additional reinforcement components to achieve a desired strength. Some structural assemblies utilize cross member components to achieve a desired energy absorbing performance, such as in side impact collisions.
The components formed in accordance with certain aspects of the present disclosure are particularly suitable for use in various components of an automobile or other vehicles (e.g., motorcycles, boats, tractors, buses, motorcycles, mobile homes, campers, and tanks), but they may also be used in a variety of other industries and applications, including aerospace components, consumer goods, devices, buildings (e.g., houses, offices, sheds, warehouses), office equipment and furniture, and industrial equipment machinery, agricultural or farm equipment, or heavy machinery, by way of non-limiting example. Non-limiting examples of automotive components include hoods, pillars (e.g., A-pillars, hinge pillars, B-pillars, C-pillars, and the like), panels, including structural panels, door panels, and door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, control arms and other suspension, crush cans, bumpers, structural rails and frames, cross car beams, undercarriage or drive train components, and the like.
In various aspects, the present disclosure provides a component that may be used in a tailored aluminum (Al) alloy chemistry. The Al alloy may include a higher tolerance for iron impurity, and thus for recycled Al scrap. The Al alloy may have high crashworthiness (e.g., yield strength, elongation to fracture, and 3-point bending angle) and rivetability.
Aluminum alloys often include aluminum, alloying elements (e.g., silicon, magnesium and iron), and impurities. In the example embodiments disclosed herein, it has been found that the particular elements in the particular amounts form an alloy (also referred to as an alloy composition) that, after being cast exhibits relatively high strength (e.g., an average yield strength of at least 100 MPa and ultimate tensile strength of at least 230 MPa) and high ductility (e.g., elongation ranging from about 10% to about 18%). In some example embodiments, the alloy may also be exposed to a paint baking process or T5 heat treatment, that, in the final state, exhibits a relatively higher strength (e.g., an average yield strength of at least 120 MPa and ultimate tensile strength of at least 250 MPa) and relatively high ductility (e.g., elongation ranging from about 8% to about 15%). In other words, the as-cast, paint baked, and T5 treated structure of the aluminum alloy has a percent elongation ranging from about 8% to about 18% and a yield strength ranging from about 100 MPa to about 180 MPa. These characteristics are achievable without utilizing super-vacuum and without utilizing a T7 solution-based heat treatment. Without this additional, solution-based heat treatment, the risk of distortion of the structural casting may be reduced, and the cost of production of the structural casting may be reduced.
The example alloys disclosed herein consist essentially of silicon (Si), magnesium (Mg), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), titanium (Ti), strontium (Sr), a balance of aluminum (Al), and inevitable impurities. In some instances, particular element(s) may not be intentionally added to the alloy but may be present in a small amount that equates to an inevitable impurity. For example, phosphorus (P), and zirconium (Zr) are examples of inevitable impurities that may not be added to the alloy on purpose but are present nonetheless. In the examples disclosed herein, the combination of the elements in the specific amounts generates an aluminum alloy that is suitable for casting aluminum components with a lightweight design, and yet with high strength.
While some examples of inevitable impurities have been mentioned, it is to be understood that other inevitable impurities may be present in these examples of the alloy composition. In other examples, the aluminum alloy composition disclosed herein may consist of silicon (Si), magnesium (Mg), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), titanium (Ti), strontium (Sr), a balance of aluminum (Al), and inevitable impurities, for example, as selected from the group consisting of phosphorus (P), zirconium (Zr), the like, and combinations thereof. In these examples, the alloy composition consists of these metals and semi-metals, without any other metals or semi-metals. Examples of the metals and semi-metals added to the alloy composition disclosed herein are discussed in greater detail below.
In various embodiments, the alloy composition may be as in Table 1, although the disclosure of the inventive concepts is not limited thereto. In various embodiments, the alloy composition of Table 1 may be used to form an aluminum die cast component with an ultimate tensile strength of greater than or equal to exactly or about 250 MPa to less than or equal to exactly or about 300 MPa
The Al alloy composition may comprise silicon (Si) at a concentration of greater than or equal to exactly or about 6.5 wt. % to less than or equal to exactly or about 9.5 wt. %, greater than or equal to exactly or about 6.5 wt. % to less than or equal to exactly or about 8 wt. %, or greater than or equal to exactly or about 8 wt. % to less than or equal to exactly or about 9 wt. %. For example, in various embodiments the Al alloy composition may comprise Si at a concentration of exactly or about 6.5 wt. %, exactly or about 7 wt. %, exactly or about 7.5 wt. %, exactly or about 8 wt. %, exactly or about 8.5 wt. %, or exactly or about 9 wt. %. Silicon may be added to the alloy to reduce the melting temperature of the aluminum and to improve the fluidity of the molten aluminum. The silicon may improve the castability of the alloy, rending it suitable for being cast into dies. Increasing the silicon may deleteriously affect the ductility and fracture toughness as eutectic silicon particles are fragile and may be weakly bonded with the aluminum matrix, and reducing the silicon may deleteriously affect the castability (and thus the composition's suitability for making thin-walled components). To achieve an optimum combination of castability and fracture toughness in the Al—Si die cast alloy, under as-cast, paint baked, or T5 heat treated conditions, Si may be present in a concentration ranging from 6.5 wt. % to 9.5 wt. %. The die cast alloy in an as-cast state may include a coral-like morphology of eutectic silicon in a three-dimensional space.
The Al alloy composition may comprise magnesium (Mg) at a concentration of greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.35 wt. %, greater than or equal to exactly or about 0.1 wt. % to less than or equal to exactly or about 0.3 wt. %, or greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.2 wt. %. For example, in various embodiments the Al alloy composition may comprise Mg at a concentration of exactly or about 0.05 wt. %, exactly or about 0.1 wt. %, exactly or about 0.15 wt. %, exactly or about 0.2 wt. %, exactly or about 0.25 wt. %, exactly or about 0.3 wt. %, or exactly or about 0.35 wt. %. Magnesium addition may improve the strength of alloy under as-cast condition by solid solution strengthening. In addition, magnesium addition may induce strong precipitation strengthening effect after paint baking process and T5 heat treatment, while ductility may be reduced.
The Al alloy composition may comprise chromium (Cr) at a concentration of greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.3 wt. %, or greater than or equal to exactly or about 0.2 wt. % to less than or equal to exactly or about 0.3 wt. %. For example, in various embodiments the Al alloy composition may comprise Cr at a concentration of exactly or about 0.05 wt. %, exactly or about 0.1 wt. %, exactly or about 0.15 wt. %, exactly or about 0.2 wt. %, exactly or about 0.25 wt. %, or exactly or about 0.3 wt. %. Chromium is added to improve die-sticking resistance.
The Al alloy composition may comprise manganese (Mn) at a concentration of greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.4 wt. %, or greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.1 wt. %. For example, in various embodiments the Al alloy composition may comprise Mn at a concentration of exactly or about 0.05 wt. %, exactly or about 0.1 wt. %, exactly or about 0.15 wt. %, exactly or about 0.2 wt. %, exactly or about 0.25 wt. %, exactly or about 0.3 wt. %, exactly or about 0.35 wt. %, or exactly or about 0.4 wt. %. Manganese is another anti-die-sticking element and may be present in various aluminum products available as scrap materials, such as those made of 3xxx aluminum alloys (beverage cans, radiator, etc.) and Al—Si die cast alloys (transmission casing, engine block, etc.). Therefore, Manganese can be easily included when applying a high fraction of scraps in the casting process.
The Al alloy composition may comprise iron (Fe) at a concentration of greater than or equal to exactly or about 0.2 wt. % to less than or equal to exactly or about 0.4 wt. %. For example, in various embodiments the Al alloy composition may comprise Fe at a concentration of exactly or about 0.2 wt. %, exactly or about 0.25 wt. %, exactly or about 0.3 wt. %, exactly or about 0.35 wt. %, or exactly or about 0.4 wt. %. Iron is one of the impurities which is difficult to eliminate from recycled aluminum scrap, especially when considering a cost-efficient approach. In general, the price of recycled aluminum scraps in the market decreases with increasing iron content. As such, greater amounts of iron concentrations in a composition that has desired mechanical properties may improve the amount of scrap material inclusion, improving material costs, energy requirements (e.g., carbon footprint), and logistics of producing an aluminum alloy. Further, iron may help resist die soldering, however iron may undermine ductility and fracture toughness.
The Al alloy composition may comprise copper (Cu) at a concentration of greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.5 wt. %, or greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.1 wt. %. For example, in various embodiments the Al alloy composition may comprise Cu at a concentration of exactly or about 0.01 wt. %, exactly or about 0.5 wt. %, exactly or about 0.1 wt. %, exactly or about 0.15 wt. %, exactly or about 0.2 wt. %, exactly or about 0.25 wt. %, exactly or about 0.3 wt. %, exactly or about 0.35 wt. %, exactly or about 0.4 wt. %, exactly or about 0.45 wt. %, or exactly or about 0.5 wt. %. Copper may have a minor impact on mechanical properties when its content is below 0.5 wt. %. Copper may be undesirable as it will reduce corrosion resistance, however, copper may not be completely eliminated from recycled aluminum scraps due to the ubiquity of copper in typical scrap from aluminum products which use copper to, for example, enhance thermal stability.
The Al alloy composition may comprise zinc (Zn) at a concentration of greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.2 wt. %, or greater than or equal to exactly or about 0.1 wt. % to less than or equal to exactly or about 0.2 wt. %, or greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.1 wt. %. For example, in various embodiments the Al alloy composition may comprise Zn at a concentration of exactly or about 0.01 wt. %, exactly or about 0.05 wt. %, exactly or about 0.1 wt. %, exactly or about 0.15 wt. %, or exactly or about 0.2 wt. %. Similar to copper, when zinc addition is below 0.2 wt. %, impacts on castability and mechanical properties may be minor. The 0.2 wt. % tolerance set in example embodiments of the aluminum alloy composition may allow for more inclusion of recycled aluminum (e.g., scrap aluminum).
The Al alloy composition may comprise titanium (Ti) at a concentration of greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.2 wt. %. For example, in various embodiments the Al alloy composition may comprise Ti at a concentration of exactly or about 0.01 wt. %, exactly or about 0.05 wt. %, exactly or about 0.1 wt. %, exactly or about 0.15 wt. %, or exactly or about 0.2 wt. %. Titanium may be added as a grain refiner to improve the control of the grain growth of the molten aluminum during the die casting process. Controlling the grain growth can improve the ductility of the casting and can also reduce the risk of hot cracking of the casting.
The Al alloy composition may comprise strontium (Sr) at a concentration of greater than or equal to exactly or about 0 ppm to less than or equal to exactly or about 200 ppm. For example, in various embodiments the Al alloy composition may comprise Sr at a concentration of exactly or about 0 ppm, exactly or about 50 ppm, exactly or about 100 ppm, exactly or about 150 ppm, or exactly or about 200 ppm. Strontium may be beneficial for mitigating die soldering issue. However, a concentration of strontium over 200 ppm may induce increased porosity volume in the die cast component such that mechanical properties may no longer be suitable.
The remainder of the aluminum alloy composition includes a balance of aluminum and inevitable impurities. In some examples, at least some of the aluminum starting material used to form the aluminum in the aluminum alloy composition may be an at least substantially pure aluminum substance (e.g., 99.9% pure aluminum with less than 0.1 wt. % of impurities). The impurities present in the aluminum starting material may include vanadium, phosphorus, and/or zirconium. The impurities present in the aluminum starting material may also or alternatively include iron, manganese, chromium, silicon, or the like. In some examples, at least a portion of the aluminum starting material used to form the aluminum in the aluminum alloy composition may come from scrap aluminum. That is, a portion (e.g., exactly or about 10%, exactly or about 15%, exactly or about 20%, exactly or about 25%, exactly or about 30%, exactly or about 35%, exactly or about 40%, exactly or about 45%, or exactly or about 50%) of the starting aluminum melt for the aluminum alloy composition may be scrap aluminum.
The Al alloy composition may comprise inevitable impurities at a concentration of greater than or equal to exactly or about 0 wt. % to less than or equal to exactly or about 0.15 wt. %. For example, in various embodiments the Al alloy composition may comprise impurities at a concentration of less than exactly or about 0.001 wt. %, less than exactly or about 0.01 wt. %, less than exactly or about 0.05 wt. %, or less than exactly or about 0.15 wt. %.
In one example embodiment, the Al alloy composition consists essentially of Si, Mg, Cr, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. In another embodiment, the alloy composition consists of Si, Mg, Cr, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %.
In one example embodiment, the Al alloy composition consists essentially of Si, Cr, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. In another embodiment, the alloy composition consists of Si, Cr, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %.
In one embodiment, the Al alloy composition consists essentially of Si, Mg, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. In another embodiment, the alloy composition consists of Si, Mg, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %.
In one embodiment, the Al alloy composition consists essentially of Si, Mg, Cr, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. In another embodiment, the alloy composition consists of Si, Mg, Cr, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %.
In one embodiment, the Al alloy composition consists essentially of Si, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. In another embodiment, the alloy composition consists of Si, Mn, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %.
In one embodiment, the Al alloy composition consists essentially of Si, Cr, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. In another embodiment, the alloy composition consists of Si, Cr, Fe, Cu, Zn, Ti, Sr, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %.
In one embodiment, the Al alloy composition consists essentially of Si, Mg, Cr, Mn, Fe, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. In another embodiment, the alloy composition consists of Si, Mg, Cr, Mn, Fe, Al, and any impurities cumulatively present at less than or equal to about 0.5 weight %. That is, the Al alloy composition may not include Cu, Zn, Ti, and Sr, or the Al alloy composition may include one or more of Cu, Zn, Ti, and Sr as described above.
Iron is insoluble in aluminum in the solid state and may form a variety of iron-rich intermetallic phases. As a result, iron may have a great adverse impact on the final mechanical properties of an Al alloy. The iron-rich intermetallic compounds in a plate morphology may form crack planes, and thus lower toughness, ductility, and fatigue resistance. Additionally, the iron-rich intermetallic compounds may act as a crack initiator and provide a lower resistance crack path. Morphologies may be a block, script, or needle shape in 2-dimensional (2D) section and play an important role in affecting mechanical properties. The script or block shape may be preferable by reducing stress concentrations at tip. Therefore, iron content should be strictly controlled to control and/or reduce the volume of iron-rich intermetallic compounds, if high ductility and fracture toughness are needed.
However, a minimum content of iron has previously been required in die cast alloys as the iron can significantly mitigate or resolve die sticking issues. Solidified aluminum can stick to the steel die used in casting under high pressure, which results in die soldering. In high pressure die casting process, iron from the steel die may diffuse into the aluminum melt and combine with the aluminum to form a Fe-rich intermetallic layer on the die. Solidified aluminum may be strongly bonded onto the formed Fe-rich intermetallic layer via eutectic reaction. When die soldering occurs, the surface finish of the resulting part (i.e., casting, structural body) may be destroyed when ejected from the die, and the die life may be reduced as well. Casting foundry experience is that over 0.8 wt. % of iron addition can significantly improve die-sticking resistance of aluminum die cast alloy as this may impede the formation of a Fe-rich intermetallic layer on steel die.
Manganese may also contribute to the reduction in the amount of dissolved iron in the molten aluminum, and may also reduce the amount of iron-rich intermetallic compounds that form as a result of the molten aluminum reacting with the dissolved iron. Chromium, as an alternative element to impede die sticking, disrupts the eutectic reaction in solidification which bonds solidified aluminum to the formed Fe-rich intermetallic layer on steel die. Additionally, manganese and chromium together may have a stronger anti-die-sticking effect than iron alone. For examples, only 0.45 wt. % manganese addition or 0.25 wt. % chromium addition may be used in place of 0.8 wt. % iron addition in Al—Si die cast alloys. Therefore, with the combined addition of manganese and chromium, iron content can be reduced without sacrificing die-sticking resistance. Further, manganese and chromium together may alter the morphology of iron-rich intermetallic compounds to the script-shape or block-shape, thereby improving fracture toughness.
In some example embodiments, an anti-die-sticking factor (ADSF) is used to balance the iron, manganese, and chromium contents. The combination of the Fe wt. %, one and half (1.5) times the Mn wt. % and two and seven tenths (2.7) times the Ct wt. % may be used to calculate the ADSF of an Al alloy. In some example embodiments, the Al alloy composition of Table 1 may have an ADSF of 0.8 or greater for acceptable anti-die-sticking performance. An ADSF of less than 0.8 may lead to the surface finish of the resulting part (i.e., casting, structural body) being destroyed when ejected from the die, and the die life may be reduced as well.
In some example embodiments, the ADSF has been considered to include an amount of iron to improve the ability of the Al alloy composition to include recycled aluminum scraps. As a result, the Al alloy composition of Table 1 with an ADSF of greater than 0.8 may be able to use greater amounts of scrap aluminum metals while reducing manufacturing processes, for example, heat treatments, aluminum purity requirements, atmospheric conditions (e.g., vacuum process versus ambient conditions).
The volume of iron-rich intermetallic particles in the as-cast microstructure has great impact on fracture toughness and ductility and therefore should be controlled in to guarantee excellent crashworthiness and rivetability. The volume of iron-rich intermetallic particles is determined by the content of iron, manganese and chromium and may be determined by thermodynamic computational methods. In the Al—Si die cast alloys which can be riveted with/to steel sheets without applying super-vacuum die casting processes and/or T7 heat treatments, iron content is strictly limited below 0.15 wt. % to control the volume of iron-rich intermetallic particles below 1.4%. 1.4% is therefore set as the upper limit for the volume of iron-rich intermetallic compounds in some example embodiments. The contents of iron, manganese and chromium in some example embodiments of the aluminum alloy compositions are designed based on thermodynamic calculation results shown in
Al alloy compositions according to various aspects of the present disclosure and those of a T7 heat-treated composition are shown in Table 2 below. This table is provided for comparison purposes and may not reflect all the acceptable characteristic ranges for the Al alloy composition provided herein.
The 0.2% Proof Stress is the stress where after unloading, the specimen has a permanent elongation of 0.2%. The 0.2% Proof Stress may also be referred to as a yield strength. UTS is the maximum stress a material can withstand while under stress (e.g., being stretched or pulled) before breaking. Elongation percentage is the length at which a material breaks under stress (e.g., being stretched or pulled). A T7 heat treatment includes heating the casting at about 460° C. for 1 hour followed by air quench and then aging at 230° C. for a 3 hour.
In operation 57, the cast aluminum alloy component may undergo a heat treatment. The heat treatment may be operation 571, a T5 heat treatment including artificially aging the cast Al alloy at exactly or about 205° C. for 60 minutes, or operation 572, paint baking the cast aluminum alloy component, although other methods may be used, and the inventive concepts are not limited thereto. Paint baking may be the heat treatment a cast component undergoes during paint drying/baking during automobile manufacture, in which the cast component undergoes multiple cycles at elevated temperatures (e.g., 80° C. to 200° C.) at different times. In some example embodiments, a paint baking treatment may include 4 cycles at greater than or equal to about 100° C., each cycle holding the elevated temperature for greater than or equal to about 20 minutes to less than or equal to 60 minutes. In some example embodiments a paint baking treatment may include about 20 minutes at about 190° C., return to ambient temperature, about 35 minutes at about 110° C., return to ambient temperature, about 20 minutes at about 165° C., return to ambient temperature, and about 20 minutes at about 145° C. One of ordinary skill in the art would recognize that a paint baking treatment will vary based on the different paint material and other concerns. Operation 57 is an optional operation and in some example embodiments, the cast aluminum alloy component may not undergo a heat treatment. The method 50 may generate less than or equal to about 10 tons of carbon dioxide (CO2) emission per 1 ton of the article that is formed.
Al alloy compositions according to various aspects of the present disclosure and those of a Comparative Example 2 are shown in Table 3 below. This table is provided for comparison purposes and may not reflect all the acceptable characteristic ranges for the Al alloy composition provided herein.
The Example 2, in an as-cast state, may have a 0.2% Proof Stress of 110.7±3.7 MPa, a UTS of 262.8±4.8 MPa, an elongation percentage of 13.1±1.5%, and a bending angle of 32.2±1.7. The Example 2, after a T5 heat treatment, may have a 0.2% Proof Stress of 142.6±3.9 MPa, a UTS of 262.6±4.9 MPa, an elongation percentage of 11.4±1.2%, and a bending angle of 22.7±1.4. The Comparative Example 2, in an as-cast state, may have a 0.2% Proof Stress of 116.7±3.5 MPa, a UTS of 275.4±4.2 MPa, an elongation percentage of 13.0±1.0%, and a bending angle of 29.1±0.7. The Comparative Example 2, after a T5 heat treatment, may have a 0.2% Proof Stress of 162.3±3.3 MPa, a UTS of 278.4±4.4 MPa, an elongation percentage of 10.4±0.8%, and a bending angle of 19.7±0.9. Example 2 and Comparative Example 2 have similar mechanical properties with Example 2 having improved material tolerances, for example greater tolerance for scrap inclusion. As such, Example 2 may greatly improve the carbon footprint of die casting aluminum by requiring less primary aluminum which is from electrolytic reduction of alumina which is energy intensive and may release abundant greenhouse gases. Aluminum scrap can be used to replace at least a portion (e.g., about 50%) of the primary aluminum for Example 2.
Bending angles here refers to the angle at the maximum load based on the VDA238-100 bending test (sample size of 60 mm×60 mm×3 mm; punch radius of 0.4 mm). A T5 heat treatment includes artificially aging the cast Al alloy at 205° C. for 60 minutes.
In various embodiments, a die-casting of the Al alloy composition according to Table 1 may have a yield strength of greater than or equal to exactly or about 100-140 MPa in as-cast state and 120-210 MPa after a paint baking or T5 heat treatment.
In various embodiments, a die-casting of the Al alloy composition according to Table 1 may have a UTS of greater than or equal to exactly or about 230-270 MPa in as-cast state and 250-310 MPa after a paint baking or T5 heat treatment.
In various embodiments, a die-casting of the Al alloy composition according to Table 1 may have an elongation to fracture of greater than or equal to exactly or about 5%, greater than or equal to exactly or about 6%, greater than or equal to exactly or about 8%, greater than or equal to exactly or about 10%, greater than or equal to exactly or about 12%, greater than or equal to exactly or about 14%, greater than or equal to exactly or about 16%, greater than or equal to exactly or about 18%, greater than or equal to exactly or about 20%, greater than or equal to exactly or about 22%, greater than or equal to exactly or about 24%, greater than or equal to exactly or about 26%, greater than or equal to exactly or about 28%, greater than or equal to exactly or about 30%, greater than or equal to exactly or about 32%, or greater than or equal to exactly or about 34% in an as-cast state. In various embodiments, a die-casting of the Al alloy composition according to Table 1 may have an elongation to fracture of greater than or equal to exactly or about 5%, greater than or equal to exactly or about 6%, greater than or equal to exactly or about 7%, greater than or equal to exactly or about 8%, greater than or equal to exactly or about 10%, greater than or equal to exactly or about 12%, greater than or equal to exactly or about 14%, greater than or equal to exactly or about 16%, greater than or equal to exactly or about 18%, or greater than or equal to exactly or about 20% after a T5 heat treatment.
In various embodiments, a die-casting of the Al alloy composition according to Table 1 may have an equivalent bending angle based on the VDA238-100 bending test greater than or equal to exactly or about 34/√{square root over (t)}° (t is thickness of plate sample), of greater than or equal to exactly or about 12°, of greater than or equal to exactly or about 14°, of greater than or equal to exactly or about 16°, of greater than or equal to exactly or about 18°, of greater than or equal to exactly or about 20°, of greater than or equal to exactly or about 22°, of greater than or equal to exactly or about 24°, of greater than or equal to exactly or about 26°, of greater than or equal to exactly or about 28°, or of greater than or equal to exactly or about 30° in an as cast-state. In various embodiments, a die-casting of the Al alloy composition according to Table 1 may have a 3-point bending angle at greater than or equal to 3 mm of greater than or equal to exactly or about 10°, of greater than or equal to exactly or about 12°, of greater than or equal to exactly or about 14°, of greater than or equal to exactly or about 16°, of greater than or equal to exactly or about 18°, of greater than or equal to exactly or about 20°, of greater than or equal to exactly or about 22°, or of greater than or equal to exactly or about 24° after a T5 heat treatment. For example, an equivalent bending angle based on the VDA238-100 bending test for a sample with a thickness of 3 mm, the test result would be approximately 19.63.
To decrease costs, and reduce the carbon footprint, associated with using primary aluminum prepared, for example, using electrolytic reduction process, select aluminum scrap can be used to replace at least a portion (e.g., about 50%) of the primary aluminum. Aluminum scrap includes production aluminum scrap, as well as post-consumer aluminum scrap. Production aluminum scrap refers to aluminum scrap, such as trimmings and machining chips, that remain following various manufacturing processes. Post-consumer aluminum scrap refers to end-of life aluminum products (e.g., used beverage cans). Production aluminum scrap is often limited. Thus, it is desirable to effectively utilize post-consumer aluminum scrap. However, the amount of post-consumer aluminum scrap is often limited by its iron content, which is generally greater than about 0.15 wt. %, and often, greater than about 0.20 wt. %.
Forming the aluminum alloy ingot according to some example embodiments may result in a reduction of at least about 40%, at least about 70%, or at least about 90% of CO2 equivalents relative to a corresponding method performed with a primary Al alloy and without post-consumer Al scrap. In some aspects, the method generates about 10 tons, about 5 tons, or about 3 tons CO2 per 1 ton of the alloy composition.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210106864.6 | Jan 2022 | CN | national |
