US20190276919A1

US20190276919A1 - ARTIFICIAL AGING PROCESS FOR ALUMINUM-SILICON (AlSi) ALLOYS FOR DIE CAST COMPONENTS

Info

Publication number: US20190276919A1
Application number: US16/348,864
Authority: US
Inventors: Bin Hu; Pan Wang
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2016-12-09
Filing date: 2016-12-09
Publication date: 2019-09-12
Also published as: CN110023524A; DE112016007434T5; WO2018103065A1

Abstract

Provided is a method of heat treating a die cast aluminum alloy component. A die cast component has at least one thin walled region with a thickness of ≤5 mm. The alloy has silicon at ≥6.5 mass % to ≤15.5 mass %, copper at ≥0.1 mass % to ≤3.5 mass %, magnesium at ≤0.5 mass %, manganese at ≤0.6 mass %, and chromium at ≤0.6 mass %. The method includes quenching the die cast component at a cooling rate of ≥ about 100° C./second to a first temperature of less than 50° C. and age hardening by heating the die cast component to a second temperature of ≥ about 150° C. for a predetermined duration of time to facilitate formation of particles of Mg₂Si in an aluminum alloy matrix. The aluminum alloy treated by the method can form lightweight, high strength, high ductility components.

Description

INTRODUCTION

This section provides background information related to the present disclosure which is not necessarily prior art.
The present disclosure pertains to processes for artificially ageing aluminum-based alloys, especially aluminum-based alloys used in high-pressure die casting to form lightweight, high strength, high ductility components.
Aluminum alloys are commonly used for manufacturing components by die-casting, such as, for example, die cast engine blocks and transmission cases in the automobile industry. In particular, aluminum alloys (Al alloys) are often used to die-cast parts with thin walls requiring high strength and high ductility, while also being lightweight. Many common Al alloys used in the automobile industry are die castable and heat treatable. Such die cast aluminum alloys can undergo additional heat treatments to improve strength.
For example, a T5 heat treatment process is typically used for certain aluminum alloys, which involves die casting the alloy, cooling it, and then artificial ageing/age hardening that occurs at an elevated temperature for a predetermined period of time, where the main alloying elements form a eutectic phase during slow solidification. A T6 heat treatment may also be used when the alloy is cast, which typically involves solution heat treating to dissolve soluble phases that form after solidification, and then artificial ageing/age hardening that occurs at an elevated temperature for a predetermined period of time, where the main alloying elements form a eutectic phase during slow solidification. T5 is typically used for thin wall castings, while T6 is typically used for thick wall castings.
The development of new processes for forming die casting aluminum alloys that are strong and ductile, and eliminate process steps and high temperatures during manufacturing are desirable.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
The present disclosure relates to a method of heat treating a die cast aluminum alloy component. In one aspect, such a method includes die casting an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm. The aluminum alloy has silicon at greater than or equal to about 6.5% by mass to less than or equal to about 15.5% by mass of the aluminum alloy, copper at greater than or equal to about 0.1% by mass to less than or equal to about 3.5% by mass of the aluminum alloy, magnesium at less than or equal to about 0.5% by mass of the aluminum alloy, manganese at less than or equal to about 0.6% by mass of the aluminum alloy, and chromium at less than or equal to about 0.6% by mass of the aluminum alloy. The method further includes quenching the die cast component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C. The method may further include age hardening by heating the die cast component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy.
In certain variations, the aluminum alloy further includes iron at less than or equal to about 1.3% by weight, titanium at less than or equal to about 0.15% by mass of the aluminum alloy, strontium at less than or equal to about 0.08% by mass of the aluminum alloy, phosphorus at less than or equal to about 0.003% by weight, and has a balance of aluminum.
In other variations, the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.
In certain other variations, the die cast component has a yield strength of greater than or equal to about 150 MPa.
In certain variations, the die cast component has an ultimate tensile strength of greater than or equal to about 280 MPa.
In yet other variations, the die cast component has a ductility of greater than or equal to about 5%.
In certain variations, the particles of magnesium silicide (Mg₂Si) are substantially homogenously distributed in the matrix of the aluminum alloy of the die cast component.
In other aspects, the present disclosure includes a method of heat treating a die cast aluminum alloy component. The method includes die casting an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm. The aluminum alloy has silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy, copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy, magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy, manganese may be present at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy, and chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy. The method includes quenching the die cast component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C. and age hardening by heating the die cast component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy.
In certain variations, the aluminum alloy further has iron at less than or equal to about 0.25% by weight, titanium at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy, strontium at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy, phosphorus at less than or equal to about 0.003% by weight, and a balance of aluminum.
In other variations, the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.
In certain other variations, the die cast component has a yield strength of greater than or equal to about 150 MPa.
In certain variations, the die cast component has an ultimate tensile strength of greater than or equal to about 280 MPa.
In yet other variations, the die cast component has a ductility of greater than or equal to about 5%.
In certain variations, the particles of magnesium silicide (Mg₂Si) are substantially homogenously distributed in the matrix of the aluminum alloy of the die cast component.
In yet other aspects, the present disclosure provides a method of manufacturing a vehicle component. The method may include die casting the vehicle component with an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm. The aluminum alloy has silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy, copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy, magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy, manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy, chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy, titanium at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy, strontium at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy, iron at less than or equal to about 0.25% by weight, phosphorus at less than or equal to about 0.003% by weight, and a balance aluminum. The method further includes quenching the die cast vehicle component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C. and age hardening by heating the die cast vehicle component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy.
In certain variations, the die cast vehicle component is selected from the group consisting of: pillars, hinge pillars, panels, door panels, door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, storage areas, glove boxes, console boxes, trunks, trunk floors, truck beds, lamp pockets, shock towers, shock tower caps, control arms, suspension components, drive train components, engine mount brackets, transmission mount brackets, alternator brackets, air conditioner compressor brackets, cowl plates, and combinations thereof.
In other variations, the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.
In certain other variations, the die cast component has a yield strength of greater than or equal to about 150 MPa.
In certain variations, the die cast component has an ultimate tensile strength of greater than or equal to about 280 MPa.
In yet other variations, the die cast component has a ductility of greater than or equal to about 5%.
In certain variations, the particles of magnesium silicide (Mg₂Si) are substantially homogenously distributed in the matrix of the aluminum alloy of the die cast component.
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.

DRAWINGS

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.

FIG. 1 shows a graph comparing a T5 heat treatment process with a heat treatment process according to certain aspects of the present disclosure showing temperature versus time.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

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.
As used herein, the terms “composition” and “material” are used interchangeably to refer broadly to a substance containing at least the preferred chemical constituents, elements, or compounds, but which may also comprise additional elements, compounds, or substances, including trace amounts of impurities, unless otherwise indicated.
As referred to herein, the word “substantially,” when applied to a characteristic of a composition or method of this disclosure, indicates that there may be slight variation in the characteristic without having a substantial effect on the chemical or physical attributes of the composition or method.
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%.
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.
Aluminum alloys are widely used in vehicles, such as automobiles, motorcycles, boats, tractors, buses, mobile homes, campers, and tanks, and their utilization will continue with efforts to reduce vehicle mass and save space. Methods of processing aluminum alloys according to the present technology form components with reduced mass relative to components made with traditional alloys, such as steel, while maintaining strength and ductility requirements. Aluminum alloys are particularly suitable for use in components of an automobile or other vehicle (e.g., motorcycles, boats), but may also be used in a variety of other industries and applications, including aerospace components, industrial equipment and machinery, farm equipment, heavy machinery, by way of non-limiting example.
For example, aluminum alloys may be used to form die-cast vehicle or automotive components. While exemplary components are illustrated and described throughout the specification, it is understood that the inventive concepts in the present disclosure may also be applied to any structural component capable of being formed of a lightweight metal, including those used in vehicles, like automotive applications including, but not limited to, pillars, such as hinge pillars, panels, including structural panels, door panels, and door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, storage areas, including glove boxes, console boxes, trunks, trunk floors, truck beds, lamp pockets and other components, shock towers, shock tower cap, control arms and other suspension or drive train components, engine mount brackets, transmission mount brackets, alternator brackets, air conditioner compressor brackets, cowl plates, and the like. Specifically, the present disclosure is particularly suitable for any piece of hardware subject to loads or impact (e.g., load bearing).
In various aspects, the present disclosure provides methods for achieving precipitation hardening of die cast aluminum alloys by an artificial aging process. The strengthened aluminum alloys may thus be used in vehicle or automotive applications, by way of non-limiting example. Strengthened aluminum metal components may be load bearing in certain applications for vehicles, in which case they have good strength, stiffness, and ductility (e.g., elongation).
The methods according to certain aspects of the present disclosure can produce high strength, high stiffness, and high ductility thin-wall casting components or parts. The method of producing the aluminum alloy components may be die casting. In a die-casting process, the molten alloy material passes through a die defining one or more orifices or apertures as it enters a mold cavity during the casting process. After passing through the in-gate, runners and gating in the die, the molten metal enters a mold cavity where it solidifies to complete the casting process. The die cast components formed from aluminum alloys enable significant mass reduction relative to conventional metal components, like steel, while providing high strength and good elongation. In certain variations, the cast solid parts form lightweight metal structural components, which have one or more surfaces that are further machined after casting and solidification.
The solidified aluminum alloy forms a solid lightweight metal alloy component having at least one dimension that is considered to be thin, so that thin wall part castings are formed. The at least one dimension may extend across the entire solid lightweight metal alloy component or only in certain regions of particular importance to the structure of the component. A thickness or width of at least one region of the solidified aluminum alloy part may be considered to be thin (e.g., to form a thin wall). In certain aspects, a dimension may be considered to be thin if it is less than or equal to about 5 mm, optionally less than or equal to about 4 mm, optionally less than or equal to about 3 mm, optionally less than or equal to about 2 mm, optionally less than or equal to about 1.75 mm, optionally less than or equal to about 1.5 mm, optionally less than or equal to about 1.25 mm, optionally less than or equal to about 1 mm, optionally less than or equal to about 0.75 mm, and in certain variations, optionally less than or equal to about 0.5 mm. It should be noted that the part may have other dimensions well in excess of 5 mm (such as height and/or length), although the part may have at least one thin region having the dimensions described above.
As previously discussed, many die casting aluminum alloys can be heat treated after die casting to improve strength. Heat-treatment strengthening mainly occurs by formation of nano-sized precipitation phase/particles within the matrix. Such precipitation particles in heat treatable aluminum alloys may be formed by a process including a solution heat treatment, where the soluble phases dissolve, followed by an artificial aging process, because mainly alloying elements form as eutectic phases during slow solidification rates. For example, in FIG. 1, temperature 20 versus time 22 is shown. A casting temperature is indicated at 24 and ambient or room temperature at 26. A first heat treatment 30 for strengthening an aluminum alloy in a component having a thin wall is shown as a dotted line. The first heat treatment 30 is representative of a T5 heat treatment temper. The first heat treatment 30 of the aluminum alloy starts at the die casting temperature 24. Then, the aluminum alloy component having a thin wall is slowly cooled until it reaches a second temperature 32 that may be at or slightly above room temperature 26 (shown as above room temperature). Next, the aluminum alloy component is heated in the first heat treatment 30 for artificial aging and age hardening, which occurs at a third elevated temperature 34 for a first predetermined period of time 36. During the artificial aging and age hardening, the main alloying elements form a eutectic phase during slow solidification in the aluminum alloy component having a thin wall.
A second heat treatment 40 for strengthening an aluminum alloy component having a thin wall is shown as a solid line and is one example embodiment of a method according to certain aspects of the present disclosure. After casting at the casting temperature 24, the aluminum alloy component having a thin wall is quenched from an initial quench temperature 42 for rapid cooling to a fourth temperature 44 that is less than or equal to about 50° C. The fourth temperature 44 may be at or slightly above room temperature 26. The quenching can avoid or minimize formation of certain precipitation products, such as Mg₂Si, in certain aluminum alloys. While the initial quench temperature 42 can change depending on the alloy composition, in certain variations, it is greater than or equal to about 425° C. All of the temperatures described herein with respect to treatment of the aluminum alloy may vary depending on the composition of the aluminum alloy, as appreciated by those of skill in the art.
The quenching may be conducted by contacting the alloy with a cooling medium. In certain aspects, the contacting may be achieved by submerging or dipping the aluminum alloy/die cast component into a cooling medium, such as a bath or moving stream of cooling medium, such as water and/or liquid nitrogen. In other aspects, cooling can occur by spraying the aluminum alloy with a cooling medium. In certain aspects, the spray may be pressurized and directed via a nozzle. The cooling medium may be in the form of a gas, a vapor or mist, a liquid, and/or a solid. The cooling medium is directed towards or contacted with the surface of the aluminum alloy component to induce cooling and quenching at a desired cooling rate.
In one example, a cooling rate may greater than or equal to about 100°/C per second. Thus, the quenching process may take the only 3 to 5 seconds, for example, to cool an aluminum alloy from a casting temperature 24 of about 500° C. to room temperature 26.
After cooling to the fourth temperature 44, the second heat treatment 40 involves artificial aging and age hardening by heating the aluminum alloy component, which occurs at a fifth elevated temperature 46 for a second predetermined period of time 48. During the artificial aging and age hardening, the main alloying elements form a eutectic phase during slow solidification to form particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy. Notably the second predetermined period of time 48 is less than the first predetermined period of time 36. Likewise, the third temperature 34 is higher than the fifth temperature 46. Thus, after the quenching process in the second heat treatment 40 process, the artificial aging and age hardening can be conducted at a lower temperature and/or for less time than in a conventional first heat treatment 30 (e.g., T5 heat treatment). As will be appreciated by those of skill in the art, where the temperature is substantially lower in the second heat treatment 40 process, then the second predetermined period 48 may need to be longer. Where the fifth temperature 46 is higher, then the second predetermined period 48 may be much shorter. Thus, the fifth temperature 46 may be the same as the third temperature 34, but this will result in the second predetermined period 48 advantageously being significantly shorter than the first predetermined period 36.
In certain aspects, the fifth temperature 46 is greater than or equal to about 150° C., which facilitates formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy. In certain variations, the fifth temperature 46 may be greater than or equal to about 155° C. to less than or equal to about 220° C. The present disclosure thus provides methods of artificial aging for achieving precipitation hardening by in die cast aluminum alloys.
In certain aspects, the present methods of heat treating select aluminum alloys after casting to form thin wall components can create solid aluminum alloy metal components or parts having a substantially uniform microstructure (e.g., eliminating segregation and bands). Further, more solute and alloying ingredients can be distributed in the metal matrix. In traditional high pressure die-casting processes, concentration of alloying ingredients with the metal is not necessarily uniform, as inhomogeneity may occur. However, in certain aspects, the aluminum alloy components or parts formed in accordance with the methods of the present disclosure may have a homogenous and substantially uniform composition, where concentration of ingredients is homogenously distributed throughout. In such variations, the aluminum alloy component may have a substantially uniform microstructure, meaning that the microstructure is substantially the same microstructure, composition, grain boundaries, and grain sizes throughout the region or solid phase. Such a microstructure results in higher ductility and higher strength in the cast part. In certain aspects, the magnesium silicide (Mg₂Si) may be substantially homogeneously distributed throughout the matrix of the aluminum alloy of the die cast component.
As noted above, the selection of alloys in accordance with the principles of the present disclosure can form solid lightweight aluminum alloy metal components or parts having superior strength and ductility (e.g., elongation). The methods of the present disclosure are particularly suitable for use with high or medium ductility die cast aluminum alloy components. In certain aspects, the methods of the present disclosure include artificial aging for achieving precipitation hardening of die cast aluminum alloys to provide about 40 MPa to about 50 MPa of improvement in yield strength, meanwhile not significantly reducing or sacrificing ductility. Thus, a cast solid aluminum alloy component formed in accordance with certain aspects of the present disclosure may have a percentage of elongation of greater than or equal about 5%. In certain aspects, a percentage of elongation may optionally be greater than or equal to about 6%, and in certain variations, optionally greater than or equal to about 7%.
A high strength cast solid aluminum alloy component may have a yield strength of greater than or equal to 150 MPa. In certain variations, a high strength cast aluminum alloy component has a yield strength of greater than or equal to about 175 MPa, optionally greater than or equal to about 200 MPa, and in certain variations, optionally greater than or equal to about 225 MPa.
In other aspects, a high strength cast solid aluminum alloy component may have an ultimate tensile strength of greater than or equal to about 175 MPa, optionally greater than or equal to about 200 MPa, optionally greater than or equal to about 225 MPa, optionally greater than or equal to about 250 MPa, optionally greater than or equal to about 275 MPa, and in certain variations optionally greater than or equal to about 280 MPa.
The present methods are particularly advantageous with specific aluminum alloys that are heat treatable. In one variation, the aluminum alloy comprises silicon (Si) at greater than or equal to about 6.5% by mass to less than or equal to about 15.5% by mass of the aluminum alloy, copper (Cu) at greater than or equal to about 0.1% by mass to less than or equal to about 3.5% by mass of the aluminum alloy, magnesium (Mg) at less than or equal to about 0.5% by mass of the aluminum alloy, manganese (Mn) at less than or equal to about 0.6% by mass of the aluminum alloy, and/or chromium (Cr) at less than or equal to about 0.6% by mass of the aluminum alloy. In certain aspects, the aluminum alloy may further comprise iron (Fe) at less than or equal to about 1.3% by weight, titanium (Ti) at less than or equal to about 0.15% by mass of the aluminum alloy, strontium (Sr) at less than or equal to about 0.08% by mass of the aluminum alloy, and/or phosphorus (P) at less than or equal to about 0.003% by weight. In any of these alloy compositions, the balance is aluminum. Further, impurities are cumulatively present at less than or equal to about 0.1% by mass of the aluminum alloy. Such a composition is represented in Table 1.

TABLE 1

Si	Fe		Mg	Mn	Cr	Ti	Sr
(%	(%	Cu	(%	(%	(%	(%	(%	P
by	by	(% by	by	by	by	by	by	(% by
mass)	mass)	mass)	mass)	mass)	mass)	mass)	mass)	mass)	Balance

Alloy	6.5-15.5	<1.3	0.1-3.5	<0.5	<0.6	<0.6	<0.15	<0.08	<0.003	Al

In another variation, the aluminum alloy comprises silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy, copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy, magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy, chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy, and/or manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy. In certain aspects, the aluminum alloy may further comprise iron (Fe) at less than or equal to about 0.25% by weight, titanium (Ti) at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy, strontium (Sr) at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy, and/or phosphorus (P) at less than or equal to about 0.003% by weight. In any of these alloy compositions, the balance is aluminum. Further, impurities are cumulatively present at less than or equal to about 0.1% by mass of the aluminum alloy. Such a composition is represented in Table 2.

TABLE 2

Si		Cu	Mg	Mn	Cr	Ti	Sr
(%	Fe	(%	(%	(%	(%	(%	(%	P
by	(% by	by	by	by	by	by	by	(% by
mass)	mass)	mass)	mass)	mass)	mass)	mass)	mass)	mass)	Balance

Alloy	8.5-10.5	<0.25	0.8-1.5	0.1-0.5	0.4-0.6	0.1-0.6	0.05-0.1	<0.08	<0.003	Al

In certain variations, the present disclosure contemplates a method of heat treating a die cast aluminum alloy component. The method includes die casting an aluminum alloy to form a die cast component having at least one thin walled region. In certain aspects, the think walled region may have a thickness of less than or equal to about 5 mm. The aluminum alloy may be any of those described above that are heat treatable. In certain aspects, the aluminum alloy includes silicon at greater than or equal to about 6.5% by mass to less than or equal to about 15.5% by mass of the aluminum alloy, copper at greater than or equal to about 0.1% by mass to less than or equal to about 3.5% by mass of the aluminum alloy, magnesium at less than or equal to about 0.5% by mass of the aluminum alloy, and manganese at less than or equal to about 0.6% by mass of the aluminum alloy.
The method may further include quenching the die cast component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C. Then, the die cast component can be age hardened by heating the die cast component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy.
In certain aspects, the aluminum alloy further includes iron at less than or equal to about 1.3% by weight, titanium at less than or equal to about 0.15% by mass of the aluminum alloy, strontium at less than or equal to about 0.08% by mass of the aluminum alloy, phosphorus at less than or equal to about 0.003% by weight, and a balance of aluminum.
In certain other aspects, the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.
In other aspects, the die cast component has a yield strength of greater than or equal to about 150 MPa.
In certain other aspects, the die cast component may have an ultimate tensile strength of greater than or equal to about 280 MPa.
In yet other aspects, the die cast component has a ductility or elongation of greater than or equal to about 5%.
In certain aspects, the particles of magnesium silicide (Mg₂Si) are substantially homogenously distributed in the matrix of the aluminum alloy of the die cast component. The method includes die casting an aluminum alloy to form a die cast component having at least one thin walled region. In certain aspects, the think walled region may have a thickness of less than or equal to about 5 mm. The aluminum alloy may be any of those described above that are heat treatable. In certain aspects, the aluminum alloy includes silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy, copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy, magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy, chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy, and manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy.
The method may also include quenching the die cast component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C. and age hardening by heating the die cast component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy.
In certain aspects, the aluminum alloy further includes iron at less than or equal to about 0.25% by weight, titanium at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy, strontium at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy, phosphorus at less than or equal to about 0.003% by weight, and a balance of aluminum.
In certain other aspects, the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.
In other aspects, the die cast component has a yield strength of greater than or equal to about 150 MPa.
In certain other aspects, the die cast component may have an ultimate tensile strength of greater than or equal to about 280 MPa.
In yet other aspects, the die cast component has a ductility or elongation of greater than or equal to about 5%.
In certain other aspects, the present disclosure contemplates a method of manufacturing a vehicle component. The method may include die casting the vehicle component with an aluminum alloy to form a die cast component having at least one thin walled region. In certain aspects, the thin walled region has a thickness of less than or equal to about 5 mm. The aluminum alloy may be any of those described previously above. In one variation, the aluminum alloy may include silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy, copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy, magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy, manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy, chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy, titanium at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy, strontium at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy, iron at less than or equal to about 0.25% by weight, phosphorus at less than or equal to about 0.003% by weight, and a balance aluminum.
In certain aspects, the die cast vehicle component is selected from the group consisting of pillars, hinge pillars, panels, door panels, door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, storage areas, glove boxes, console boxes, trunks, trunk floors, truck beds, lamp pockets, shock towers, shock tower caps, control arms, suspension components, drive train components, engine mount brackets, transmission mount brackets, alternator brackets, air conditioner compressor brackets, cowl plates, and combinations thereof.
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.

Claims

What is claimed is:

1. A method of heat treating a die cast aluminum alloy component, the method comprising:

die casting an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm, the aluminum alloy comprising:

silicon at greater than or equal to about 6.5% by mass to less than or equal to about 15.5% by mass of the aluminum alloy;

copper at greater than or equal to about 0.1% by mass to less than or equal to about 3.5% by mass of the aluminum alloy;

chromium at less than or equal to about 0.6% by mass of the aluminum alloy;

magnesium at less than or equal to about 0.5% by mass of the aluminum alloy; and

manganese at less than or equal to about 0.6% by mass of the aluminum alloy;

quenching the die cast component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C.; and

age hardening by heating the die cast component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy.

2. The method of claim 1, wherein the aluminum alloy further comprises:

iron at less than or equal to about 1.3% by weight;

titanium at less than or equal to about 0.15% by mass of the aluminum alloy;

strontium at less than or equal to about 0.08% by mass of the aluminum alloy;

phosphorus at less than or equal to about 0.003% by weight; and has

a balance of aluminum.

3. The method of claim 1, wherein the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.

4. The method of claim 1, wherein the die cast component has a yield strength of greater than or equal to about 150 MPa.

5. The method of claim 1, wherein the die cast component has an ultimate tensile strength of greater than or equal to about 280 MPa.

6. The method of claim 1, wherein the die cast component has a ductility of greater than or equal to about 5%.

7. The method of claim 1, wherein the particles of magnesium silicide (Mg₂Si) are substantially homogenously distributed in the matrix of the aluminum alloy of the die cast component.

8. A method of heat treating a die cast aluminum alloy component, the method comprising:

silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy;

copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy;

magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy;

manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy; and

chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy; and

9. The method of claim 8, wherein the aluminum alloy further comprises:

iron at less than or equal to about 0.25% by weight;

titanium at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy;

strontium at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy;

phosphorus at less than or equal to about 0.003% by weight; and has

a balance of aluminum.

10. The method of claim 8, wherein the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.

11. The method of claim 8, wherein the die cast component has a yield strength of greater than or equal to about 150 MPa.

12. The method of claim 8, wherein the die cast component has an ultimate tensile strength of greater than or equal to about 280 MPa.

13. The method of claim 8, wherein the die cast component has a ductility of greater than or equal to about 5%.

14. The method of claim 8, wherein the particles of magnesium silicide (Mg₂Si) are substantially homogenously distributed in a matrix of the aluminum alloy.

15. A method of manufacturing a vehicle component, the method comprising:

die casting the vehicle component with an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm, wherein the aluminum alloy comprises:

manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy;

chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy;

iron at less than or equal to about 0.25% by weight;

phosphorus at less than or equal to about 0.003% by weight; and

a balance aluminum;

quenching the die cast vehicle component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C.; and

age hardening by heating the die cast vehicle component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg₂Si) in a matrix of the aluminum alloy.

16. The method of claim 15, wherein the vehicle component is selected from the group consisting of: pillars, hinge pillars, panels, door panels, door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, storage areas, glove boxes, console boxes, trunks, trunk floors, truck beds, lamp pockets, shock towers, shock tower caps, control arms, suspension components, drive train components, engine mount brackets, transmission mount brackets, alternator brackets, air conditioner compressor brackets, cowl plates, and combinations thereof.

17. The method of claim 15, wherein the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C.

18. The method of claim 15, wherein the die cast component has a yield strength of greater than or equal to about 150 MPa.

19. The method of claim 15, wherein the die cast component has a ductility of greater than or equal to about 5%.

20. The method of claim 15, wherein the particles of magnesium silicide (Mg₂Si) are substantially homogenously distributed in a matrix of the aluminum alloy.