Patent Application
20240301536
The present disclosure relates to the fields of metallurgy, aluminum alloys, aluminum fabrication, and related fields. In particular, the present disclosure provides novel 5xxx series aluminum alloy variants having improved strength and formability and methods for preparing the same.
There is an increasing demand to provide transportation vehicles with better fuel efficiency to cope with global environmental issues caused by emission gas. To meet these demands, aluminum alloy materials are used instead of conventionally-used steel materials because aluminum alloys are lighter compared to steel. In general, aluminum alloys for producing automotive parts require greater strength and formability to meet increasing demands of manufacturers.
Many aluminum manufacturers use 5xxx series aluminum alloys (i.e., aluminum alloys containing magnesium as its main alloying ingredient) for automotive parts. However, it is difficult to improve the performance of one property of a 5xxx series aluminum (e.g., strength) without decreasing the performance of another property (e.g., formability). Attempts to modify the composition have not been successful primarily because the mechanical properties (e.g., strength and formability) and processability of the aluminum alloys are significantly affected by minor changes to the composition. For example, the composition of the AA5182 alloy is strictly controlled to have a magnesium (Mg) content between 4.0 wt. % and 5.0 wt. %, a manganese (Mn) content between 0.2 wt. % and 0.5 wt. %, a maximum iron (Fe) content of 0.35 wt. %, a maximum silicon (Si) content of 0.2 wt. %, a maximum copper (Cu) content of 0.15 wt. %, and a maximum chromium (Cr) content of 0.1 wt. %. If the Mg content of the AA5182 is increased above 5 wt. % to improve strength and/or formability, the aluminum alloy will be highly susceptible to cracking during the production process. Thus, it is extremely difficult to produce 5xxx series aluminum alloys with higher strength and/or formability using conventional aluminum alloys or methods of production.
Covered embodiments of the present disclosure are defined by the claims, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings and each claim.
Described herein are aluminum alloys that provide higher strength and formability than conventional 5xxx series aluminum alloys. In some embodiments, the present disclosure relates to an aluminum alloy comprising about 0-0.30 wt. % Si, 0.01-0.40 wt. % Fe, 0-1.0 wt. % Cu, 0.01-0.50 wt. % Mn, 5.0-6.0 wt. % Mg, 0-0.20 wt. % Cr, 0-0.30 wt. % Zn, 0-0.25 wt. % Ti, up to 0.15 wt. % of impurities, and Al. In some aspects, the aluminum alloy comprises 0.01-0.20 wt. % Si, 0.01-0.30 wt. % Fe, 0.01-0.90 wt. % Cu, 0.01-0.40 wt. % Mn, 5.1-6.0 wt. % Mg, 0-0.10 wt. % Cr, 0-0.20 wt. % Zn, 0-0.10 wt. % Ti, up to 0.15 wt. % of impurities, and Al. In some aspects, the aluminum alloy comprises 0.01-0.15 wt. % Si, 0.01-0.20 wt. % Fe, 0.05-0.80 wt. % Cu, 0.05-0.30 wt. % Mn, 5.2-6.0 wt. % Mg, 0-0.05 wt. % Cr, 0-0.10 wt. % Zn, 0-0.05 wt. % Ti, up to 0.15 wt. % of impurities, and Al. In some aspects, the aluminum alloy comprises 0.01-0.06 wt. % Si, 0.02-0.15 wt. % Fe, 0.20-0.80 wt. % Cu, 0.05-0.20 wt. % Mn, 5.3-6.0 wt. % Mg, 0.001-0.02 wt. % Cr, 0-0.05 wt. % Zn, 0-0.03 wt. % Ti, up to 0.15 wt. % of impurities, and Al. In some aspects, the aluminum alloy comprises 0.01-0.05 wt. % Si, 0.05-0.11 wt. % Fe, 0.30-0.80 wt. % Cu, 0.05-0.10 wt. % Mn, 5.5-5.9 wt. % Mg, 0.001-0.02 wt. % Cr, 0-0.01 wt. % Zn, 0.001-0.03 wt. % Ti, up to 0.15 wt. % of impurities, and Al. In some aspects, the aluminum alloy comprises at least one of: Mg in an amount from 5.5 wt. % to 6.0 wt. %; and Cu in an amount from 0.30 wt. % to 1.0 wt. %. In some aspects, the aluminum alloy comprises Fe-containing constituents having a particle size of less than 5 microns. In some aspects, a number density of Mg2Si particles in the aluminum alloy microstructure is at least 500/mm2. In some aspects, the aluminum alloy has a yield strength of at least 130 MPa. In some aspects, the aluminum alloy has an ultimate tensile strength of at least 300 MPa. In some aspects, the aluminum alloy has a total elongation of at least 5%.
In some embodiments, the present disclosure relates to a method of producing an aluminum alloy product, comprising: continuously casting an aluminum alloy to form a cast product, wherein the aluminum alloy comprises 0-0.30 wt. % Si, 0.01-0.40 wt. % Fe, 0-1.0 wt. % Cu, 0.01-0.50 wt. % Mn, 5.0-6.0 wt. % Mg, 0-0.20 wt. % Cr, 0-0.30 wt. % Zn, 0-0.25 wt. % Ti, up to 0.15 wt. % of impurities, and Al; optionally flash homogenizing the cast product; hot rolling the cast product to produce a hot rolled product; coiling the hot rolled product; cold rolling the hot rolled product to produce a cold rolled product; and annealing the cold rolled product. In some aspects, the aluminum alloy comprises at least one of: Mg in an amount from 5.5 wt. % to 6.0 wt. %; and Cu in an amount from 0.30 wt. % to 1.0 wt. %. In some aspects, continuously casting comprises a solidification rate of at least 1° C./s to produce the cast product. In some aspects, annealing comprises batch annealing or continuous annealing. In some aspects, flash homogenizing comprises heating the cast product from 400° C. to 600° C. for less than 10 minutes. In some aspects, the method comprises paint baking the cold rolled product after annealing to produce an aluminum alloy product. In some aspects, the yield strength of the aluminum alloy product increases by 5 MPa or greater after paint baking.
Further aspects, objects, and advantages will become apparent upon consideration of the detailed description.
Described herein are novel 5xxx series aluminum alloy variants which exhibit high strength and formability, and methods for preparing the same. Surprisingly, the aluminum alloys described herein exhibit high strength and formability and do not have the same processing issues as conventional 5xxx series aluminum alloys (e.g., cracking during hot rolling), despite having a greater Mg content than conventional 5xxx series aluminum alloys. The aluminum alloys described herein can be produced using a continuous casting process described herein which allows higher amounts of Mg (e.g., greater than 5 wt. %) than other processes for producing 5xxx series aluminum alloys. By incorporating higher levels of Mg and utilizing continuous casting, the aluminum alloys described herein exhibit higher levels of strength and formability without the risk of cracking during the production process. The aluminum alloys and methods of producing aluminum alloys described herein provide superior properties compared to conventional 5xxx series aluminum alloys.
Conventional AA5182 aluminum alloys for producing automotive parts require a strictly controlled composition to meet the minimum strength requirements while still maintaining formability to produce complex geometries. In general, greater strength is required for aluminum alloys used to produce automotive parts, which has dictated that such automotive parts be fabricated from an aluminum alloy including high amounts of Mg, such as an AA5182 aluminum alloy. However, aluminum alloys having high Mg content are susceptible to cracking. Traditional approaches to reduce cracking mainly focus on ß-phase morphology modification (e.g., continuous to discontinuous) at the grain boundaries by adding some alloying elements which can provide more nucleation sites or form additional particles to interrupt β-phase formation. However, higher quantities of Mg exacerbate cracking and results in an aluminum alloy with significant formability loss.
The novel 5xxx series aluminum alloy variants described herein have an increased amount of Mg content in the aluminum alloy composition, but avoid the cracking problems associated with high Mg aluminum alloys. In particular, the aluminum alloys described herein include a higher amount of Mg, as compared to AA5182 aluminum alloys, and achieve higher strength and formability properties. As described herein, increasing the Mg content and incorporating other alloying elements (e.g., Mn, Cu, Si, etc.) can provide higher strength and formability than 5xxx series aluminum alloys (e.g., AA5182 aluminum alloys). Specifically, a synergistic combination of alloying elements, as further described herein, produces a 5xxx series aluminum alloy variant that exhibits little or no cracking during the production process. By utilizing a continuous casting process, the high Mg content aluminum alloys have higher solidification rates that prevent cracking during the production process. Although increasing the Mg content leads to very high work hardening rates and pile up of dislocations, which can result in edge cracking during cold rolling, this can be controlled by either performing an interannealing step during cold rolling or managing a gentle pass schedule during cold rolling. The high Mg content aluminum alloys described herein have enhanced strength and formability and could replace many existing materials (steels, AA5182 alloys, etc.) in automotive applications.
As used herein, the terms “invention,” “the invention,” “this invention” and “the present invention” are intended to refer broadly to all of the subject matter of this patent application and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below.
In this description, reference is made to alloys identified by aluminum industry designations, such as “series” or “5xxx.” For an understanding of the number designation system most commonly used in naming and identifying aluminum and its alloys, see “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys,” or “Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot,” both published by The Aluminum Association.
As used herein, the meaning of “a,” “an,” or “the” includes singular and plural references unless the context clearly dictates otherwise.
As used herein, a plate generally has a thickness of greater than about 15 mm. For example, a plate may refer to an aluminum product having a thickness of greater than about 15 mm, greater than about 20 mm, greater than about 25 mm, greater than about 30 mm, greater than about 35 mm, greater than about 40 mm, greater than about 45 mm, greater than about 50 mm, or greater than about 100 mm.
As used herein, a shate (also referred to as a sheet plate) generally has a thickness of from about 4 mm to about 15 mm. For example, a shate may have a thickness of about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, or about 15 mm.
As used herein, a sheet generally refers to an aluminum product having a thickness of less than about 4 mm (e.g., less than 3 mm, less than 2 mm, less than 1 mm, less than 0.5 mm, less than 0.3 mm, or less than 0.1 mm). For example, a sheet may have a thickness of about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5, about 0.6 mm about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm, about 1.5 mm, about 1.6 mm, about 1.7 mm, about 1.8 mm, about 1.9 mm, about 2 mm, about 2.1 mm, about 2.2 mm, about 2.3 mm, about 2.4 mm, about 2.5 mm, about 2.6 mm about 2.7 mm, about 2.8 mm, about 2.9 mm, about 3 mm, about 3.1 mm, about 3.2 mm, about 3.3 mm, about 3.4 mm, about 3.5 mm, about 3.6 mm, about 3.7 mm, about 3.8 mm, about 3.9 mm, or about 4 mm.
As used herein, formability refers to the ability of a material to undergo deformation into a desired shape without fracturing, tearing-off, necking, earing, or shaping errors such as wrinkling, spring-back, or galling occurring. In engineering, formability may be classified according to deformation modes. Examples of deformation modes include drawing, stretching, bending, and stretch-flanging.
Reference may be made in this application to alloy temper or condition. For an understanding of the alloy temper descriptions most commonly used, see “American National Standards (ANSI) H35 on Alloy and Temper Designation Systems.” An F condition or temper refers to an aluminum alloy as fabricated. An O condition or temper refers to an aluminum alloy after annealing. An Hxx condition or temper, also referred to herein as an H temper, refers to a non-heat treatable aluminum alloy after cold rolling with or without thermal treatment (e.g., annealing). Suitable H tempers include HX1, HX2, HX3 HX4, HX5, HX6, HX7, HX8, or HX9 tempers. A T1 condition or temper refers to an aluminum alloy cooled from hot working and naturally aged (e.g., at room temperature). A T2 condition or temper refers to an aluminum alloy cooled from hot working, cold worked and naturally aged. A T3 condition or temper refers to an aluminum alloy solution heat treated, cold worked, and naturally aged. A T4 condition or temper refers to an aluminum alloy solution heat treated and naturally aged. A T5 condition or temper refers to an aluminum alloy cooled from hot working and artificially aged (at elevated temperatures). A T6 condition or temper refers to an aluminum alloy solution heat treated and artificially aged. A T7 condition or temper refers to an aluminum alloy solution heat treated and artificially overaged. A T8x condition or temper refers to an aluminum alloy solution heat treated, cold worked, and artificially aged. A T9 condition or temper refers to an aluminum alloy solution heat treated, artificially aged, and cold worked. A W condition or temper refers to an aluminum alloy after solution heat treatment.
As used herein, the meaning of “room temperature” can include a temperature of from about 15° C. to about 30° C., for example about 15° C., about 16° C., about 17° C., about 18° C., about 19° C., about 20° C., about 21° C., about 22° C., about 23° C., about 24° C., about 25° C., about 26° C., about 27° C., about 28° C., about 29° C., or about 30° C.
All ranges disclosed herein are to be understood to encompass both endpoints and any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10.
The following aluminum alloys are described in terms of their elemental composition in weight percentage (wt. %) based on the total weight of the alloy. In certain examples of each alloy, the remainder is aluminum, with a maximum wt. % of 0.15% for the sum of the impurities.
Aluminum alloy properties are partially determined by the composition of the aluminum alloys. In certain aspects, the alloy composition may influence or even determine whether the alloy will have properties adequate for a desired application.
The alloys described herein are novel 5xxx series aluminum alloy variants. The alloys exhibit high strength, high formability (e.g., excellent elongation and forming properties), and resistance to cracking during the production process. The properties of the alloy are achieved at least in part due to the elemental composition of the alloy. In some cases, the novel 5xxx series aluminum alloy variants described herein can include a Mg content that is higher than the Mg content of a conventional 5xxx series aluminum alloy and, among other elements, can include one or more of Cu, Mn, and Si in certain amounts, as further described below.
In some examples, an aluminum alloy as described herein can have the following elemental composition as provided in Table 1.
In some examples, the aluminum alloy as described herein can have the following elemental composition as provided in Table 2.
In some examples, the aluminum alloy as described herein can have the following elemental composition as provided in Table 3.
In some examples, the aluminum alloy can have the following elemental composition as provided in Table 4.
In some examples, the aluminum alloy can have the following elemental composition as provided in Table 5.
In some examples, the aluminum alloy described herein includes Si in an amount of from 0% to 0.30% (e.g., from 0% to 0.25%, from 0.01% to 0.20%, from 0.01% to 0.15%, from 0.01% to 0.10%, from 0.01% to 0.06%, or from 0.01% to 0.05%) based on the total weight of the alloy. For example, the alloy can include 0%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, or 0.30% Si. All expressed in wt. %.
In some examples, the aluminum alloy described herein also includes Fe in an amount of from 0.01% to 0.40% (e.g., from 0.01% to 0.25%, from 0.01% to 0.20%, from 0.01% to 0.15%, from 0.02% to 0.11%, or from 0.05% to 0.11%) based on the total weight of the alloy. For example, the alloy can include 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.40% Fe. All expressed in wt. %. The aluminum alloy can include up to 0.40% Fe, and thus can be produced from higher amounts of recycled aluminum alloy.
In some examples, the aluminum alloy described herein includes Cu in an amount of up to 1.0% (e.g., from 0% to 1.0%, from 0.01% to 0.90%, from 0.05% to 0.80%, from 0.20% to 0.80%, or from 0.30% to 0.80%) based on the total weight of the alloy. For example, the alloy can include 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.50%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.60%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.70%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.80%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, 0.90%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%, 0.97%, 0.98%, 0.99%, or 1.0% Cu. All expressed in wt. %. In some cases, an aluminum composition including Cu in the amounts described herein improves the paint bake response of the aluminum alloy. For example, an aluminum with the amounts of Cu described herein exhibits improved strength and formability after paint bake when the aluminum alloy is subjected to continuous annealing. Additionally, the high Cu content increases the ultimate tensile strength which provides a higher work hardening range compared to low Cu content alloys. In some cases, adding Cu to the aluminum alloy composition in amounts greater than 1.0 wt. % may cause cracking during the casting or hot rolling process.
In some examples, the aluminum alloy described herein also includes Mn in an amount of from 0.01% to 0.50% (e.g., 0.01% to 0.40%, from 0.01% to 0.30%, from 0.01% to 0.15%, from 0.05% to 0.30%, from 0.05% to 0.20%, from 0.05% to 0.15%, or from 0.05% to 0.10%) based on the total weight of the alloy. For example, the alloy can include 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.50% Mn. All expressed in wt. %. In some embodiments, an aluminum composition including Mn in the amounts described herein results in excellent n-values (hardening exponent). In some cases, aluminum alloys having a Mn content greater than 0.40 wt. % reduces the n-value due to the solute drag effect and also increases the volume fraction of constituent particles with Fe and Si that results in reduced formability. Thus, the amounts of Mn in the aluminum alloys described herein are finely controlled to prevent loss in formability.
In some examples, the aluminum alloy described herein can include Mg in an amount of from 5.0% to 6.0% (e.g., from 5.1% to 6.0%, from 5.2% to 6.0%, from 5.3% to 6.0%, from 5.4% to 6.0%, from 5.5% to 6.0%, from 5.5% to 5.9%, from 5.6% to 5.9%, or from 5.6% to 5.8%). In some examples, the alloy can include 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, or 6.0% Mg. All expressed in wt. %. In some embodiments, the inclusion of the aforementioned amounts of Mg in the alloys described herein serve as a solid solution strengthening element. As described further below, and as demonstrated in the Examples, aluminum alloys including an Mg content in the amount described herein surprisingly produces an aluminum alloy having excellent strength and formability. In some embodiments, an aluminum composition including less than 5.0 wt. % Mg cannot achieve high strength and/or formability. In some cases, an aluminum composition including greater than 6.0 wt. % Mg (e.g., 6.5 wt. %) results in an aluminum alloy that is very difficult to cold roll and requires multiple inter-annealing steps for rolling, which often results in large amounts of edge cracking during rolling.
In some examples, the aluminum alloy described herein includes Cr in an amount of up to 0.20% (e.g., from 0% to 0.20%, from 0% to 0.10%, from 0% to 0.05%, from 0.001% to 0.05%, from 0.001% to 0.02%, from 0.005% to 0.05%, or from 0.01% to 0.05%) based on the total weight of the alloy. For example, the alloy can include 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.20% Cr. In some embodiments, adding Cr in the aforementioned amounts reduces pitting corrosion and increases strength by solid solution hardening. In some cases, Cr is not present in the alloy (i.e., 0%). All expressed in wt. %.
In some examples, the aluminum alloy described herein includes Zn in an amount of up to 0.30% (e.g., from 0% to 0.25%, from 0% to 0.20%, from 0% to 0.10%, from 0% to 0.05%, from 0.001% to 0.05%, from 0.001% to 0.02%, from 0.005% to 0.05%, or from 0.01% to 0.05%) based on the total weight of the alloy. For example, the alloy can include 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, or 0.30% Zn. In some cases, Zn is not present in the alloy (i.e., 0%). In some cases, excess Zn addition (e.g., above 0.30 wt. %) deteriorates corrosion properties. Thus, the amounts of Zn in the aluminum alloys described herein is limited. All expressed in wt. %.
In some examples, the aluminum alloy described herein can include titanium (Ti) in an amount up to 0.20% (e.g., from 0% to 0.20%, from 0% to 0.10%, from 0% to 0.05%, from 0.001% to 0.05%, from 0.001% to 0.02%, or from 0.005% to 0.05%) based on the total weight of the alloy. For example, the alloy can include 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.20% Ti. In some cases, Ti is not present in the alloy (i.e., 0%). All expressed in wt. %.
Optionally, the aluminum alloys described herein can further include other minor elements, sometimes referred to as impurities, in amounts of 0.05% or below, 0.04% or below, 0.03% or below, 0.02% or below, or 0.01% or below. These impurities may include, but are not limited to V, Ni, Hf, Zr, Sc, Sn, Ga, Ca, Bi, Na, Pb, or combinations thereof. Accordingly, V, Ni, Hf, Zr, Sc, Sn, Ga, Ca, Bi, Na, or Pb may be present in alloys in amounts of 0.05% or below, 0.04% or below, 0.03% or below, 0.02% or below, or 0.01% or below. The sum of all impurities does not exceed 0.15% (e.g., 0.1%). In some examples, the aluminum alloy can include up to 0.15 wt. % to improve corrosion resistance. All expressed in wt. %. The remaining percentage of each alloy can be aluminum.
The aluminum alloys described herein exhibit excellent properties when produced according to the methods described herein. In some embodiments, the aluminum alloys described herein exhibit improved properties compared to conventional 5xxx series aluminum alloys when produced according to a continuous casting process described herein in combination with batch annealing after cold rolling. In some embodiments, the aluminum alloys described herein exhibit improved properties compared to conventional 5xxx series aluminum alloys when produced according to a continuous casting process described herein in combination with continuous annealing after cold rolling. The processing steps significantly improve the strength and formability properties of the aluminum alloy.
In some examples, an aluminum alloy product produced from the aluminum alloys described herein can have a yield strength of about 130 MPa or greater. For example, an aluminum alloy product produced from the aluminum alloys described herein can have a yield strength of 130 MPa or greater, 135 MPa or greater, 140 MPa or greater, 145 MPa or greater, 150 MPa or greater, 155 MPa or greater, 160 MPa or greater, 165 MPa or greater, 170 MPa or greater, 175 MPa or greater, or 180 MPa or greater. In some cases, the yield strength is from about 130 MPa to about 250 MPa (e.g., from about 135 MPa to about 200 MPa, from about 140 MPa to 190 MPa, or from about 145 MPa to about 180 MPa), or anywhere in between. The aluminum alloy products described herein can exhibit the yield strengths as described herein when measured in a longitudinal (L) direction, a transverse (T) direction, and/or in a diagonal (D) direction, each respective to the rolling direction.
In some examples, an aluminum alloy product produced from the aluminum alloys described herein can have an ultimate tensile strength of about 300 MPa or greater. For example, an aluminum alloy product produced from the aluminum alloys described herein can have a yield strength of 300 MPa or greater, 305 MPa or greater, 310 MPa or greater, 315 MPa or greater, 320 MPa or greater, 325 MPa or greater, 330 MPa or greater, 335 MPa or greater, 340 MPa or greater, 345 MPa or greater, or 350 MPa or greater. In some cases, the ultimate tensile strength is from about 300 MPa to about 500 MPa (e.g., from about 305 MPa to about 450 MPa, from about 310 MPa to about 400 MPa, or from about 315 MPa to about 350 MPa), or anywhere in between. The aluminum alloy products described herein can exhibit the ultimate tensile strength as described herein when measured in a longitudinal (L) direction, a transverse (T) direction, and/or in a diagonal (D) direction, each respective to the rolling direction.
The aluminum alloy products produced from the aluminum alloys described herein also exhibit an increase in yield strength after paint baking. For example, an aluminum alloy product produced from the aluminum alloys described herein, after a simulated paint bake cycle, exhibit an increased yield strength of 2 MPa or greater, 4 MPa or greater, 5 MPa or greater, 10 MPa or greater, 15 MPa or greater, 20 MPa or greater, or 25 MPa or greater. In some embodiments, an aluminum alloy product produced from the aluminum alloys described herein exhibit an increased yield strength from 2 MPa to 100 MPa, e.g., from 5 MPa to 90 MPa, from 10 MPa to 80 MPa, from 20 MPa to 75 MPa, from 25 MPa to 60 MPa, from 30 MPa to 50 MPa, or from 35 MPa to 45 MPa. The aluminum alloy products described herein can exhibit the improved yield strength as described herein when measured in a longitudinal (L) direction, a transverse (T) direction, and/or in a diagonal (D) direction, each respective to the rolling direction. In some aspects, the simulated paint bake cycle may include heating the aluminum alloy product to 185° C. for about 20 minutes.
The aluminum alloys described herein produced according to the methods described herein also exhibit high formability. The high formability can be measured, for example, by measuring total elongation or uniform elongation. ISO/EN A80 is one standard that can be used for testing the total elongation. ISO/EN Ag is one standard that can be used for testing the uniform elongation. In some examples, an aluminum alloy product produced from the aluminum alloys described herein can have a total elongation (A80) of at least about 5% and up to about 30%. For example, an aluminum alloy product produced from the aluminum alloys described herein can have a total elongation of about 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, or anywhere in between. The aluminum alloy products described herein can exhibit the total elongations as described herein when measured in a longitudinal (L) direction, a transverse (T) direction, and/or in a diagonal (D) direction, each respective to the rolling direction.
In some examples, an aluminum alloy product produced from the aluminum alloys described herein can have a uniform elongation (Ag) of at least about 5% and up to about 30%. For example, an aluminum alloy product produced from the aluminum alloys described herein can have a uniform elongation of about 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, or anywhere in between. The aluminum alloy products described herein can exhibit the uniform elongation as described herein when measured in a longitudinal (L) direction, a transverse (T) direction, and/or in a diagonal (D) direction, each respective to the rolling direction.
Another way to measure formability is the r-value (also known as the Lankford coefficient), the plastic strain ratio during a tensile test. The r-value is a measurement of the deep-drawability of a sheet metal (i.e., the resistance of a material to thinning or thickening when put into tension or compression). The r-value can be measured according to ASTM E517 (2020). In some embodiments, an aluminum alloy product produced from the aluminum alloys described herein can have an r-value in any direction or all directions (longitudinal (L), diagonal (D), and/or transverse (T)) of at least about 0.45, e.g., at least about 0.50, at least about 0.55, at least about 0.60, at least about 0.65, at least about 0.70, or at least about 0.75. In some embodiments, an aluminum alloy product produced from the aluminum alloys described herein can have an r-value in any direction or all directions from 0.45 to 0.95, e.g., from 0.50 to 0.95, from 0.55 to 0.90, from 0.60 to 0.90, from 0.65 to 0.85, or from 0.70 to 0.85.
The n value, or the strain hardening exponent, gives an indication of how much the material hardens or becomes stronger when plastically deformed. The n-value can be measured according to ASTM E646 (2020). The n-value measured over a strain range from 10% to 20% is indicated as n (10-20). For instance, an aluminum alloy product produced from the aluminum alloys described herein can have an n (10-20) value in any individual direction or in all directions (longitudinal (L), diagonal (D), and/or transverse (T)) of at least about 0.10, e.g., at least about 0.15, at least about 0.20, at least about 0.25, or at least about 0.30. In some embodiments, an aluminum alloy product produced from the aluminum alloys described herein can have an n-value in any direction or all directions from 0.10 to 0.50, e.g., from 0.15 to 0.45, from 0.20 to 0.40, from 0.25 to 0.40, from 0.30 to 0.40, or from 0.30 to 0.35.
The aluminum alloys described herein when produced according to the methods described herein possess a particle distribution that results in improved mechanical properties. For example, the aluminum alloys described herein include higher amounts of Mg (e.g., from 5.0 wt. % to 6.0 wt. %) and/or Cu (e.g., from 0.3 wt. % up to 1.0 wt. %) than conventional 5xxx series aluminum alloys. Despite having higher amounts of Mg and/or Cu, the constituents formed with Fe did not substantially increase compared to AA5182 alloys. As shown in
In some embodiments, the aluminum alloys described herein when produced according to the methods described herein include Fe-containing constituents having a particle size less than 10 microns, e.g., less than 9 microns, less than 8 microns, less than 7 microns, less than 6 microns, less than 5 microns, or less than 4 microns. In some embodiments, the aluminum alloys described herein when produced according to the methods described herein include Fe-containing constituents having a particle size from 0.01 to 10 microns, e.g., from 0.01 to 10 microns, from 0.01 to 10 microns, from 0.05 to 8 microns, from 0.1 to 6 microns, from 0.2 to 5 microns, or from 0.2 to 4.5 microns.
The amounts and size of Fe-containing constituent particles in the aluminum alloys described herein result in improved formability and corrosion resistance properties. Fe-containing constituent particles typically serve as crack initiation sites, which results in damage to the aluminum alloys when subjected to deformation. Additionally, large Fe-containing constituent particles result in higher corrosion potential and poor corrosion performance. Advantageously, the low amounts and small size of the Fe-containing constituent particles of the aluminum alloys described herein are favorable for both forming and corrosion resistance.
The aluminum alloys described herein, when produced according to the methods described herein, exhibit an increased Mg2Si content compared to AA5182 alloy. The Mg and Si combine as Mg2Si, imparting a considerable strength improvement after age-hardening.
In some embodiments, the aluminum alloys described herein when produced according to the methods described herein include Mg2Si particles having a particle size less than 10 microns, e.g., less than 9 microns, less than 8 microns, less than 7 microns, less than 6 microns, less than 5 microns, or less than 4 microns. In some embodiments, the aluminum alloys described herein when produced according to the methods described herein include Mg2Si particles having a particle size from 0.01 to 10 microns, e.g., from 0.01 to 10 microns, from 0.01 to 10 microns, from 0.05 to 8 microns, from 0.1 to 6 microns, from 0.2 to 5 microns, or from 0.2 to 4.5 microns.
In some embodiments, the aluminum alloys described herein when produced according to the methods described herein includes a peak area fraction of Mg2Si particles greater than 0.013%, e.g., greater than 0.013%, greater than 0.015%, greater than 0.018%, greater than 0.020%, greater than 0.021%, or greater than 0.025%. In some embodiments, the aluminum alloys described herein when produced according to the methods described herein includes a peak area fraction of Mg2Si particles from 0.013% to 0.030%, e.g., from 0.014% to 0.028%, from 0.015% to 0.025%, from 0.018% to 0.024%, or from 0.020% to 0.024%.
In some embodiments, the aluminum alloys described herein when produced according to the methods described herein includes a number density of Mg2Si particles greater than 300/mm2%, e.g., greater than 325/mm2, greater than 350/mm2, greater than 375/mm2, greater than 400/mm2, greater than 425/mm2, greater than 450/mm2, greater than 475/mm2, or greater than 500/mm2. In some embodiments, the aluminum alloys described herein when produced according to the methods described herein includes a number density of Mg2Si particles from 300/mm2 to 600/mm2, e.g., from 325/mm2 to 575/mm2, from 350/mm2 to 550/mm2, from 375/mm2 to 525/mm2, or from 400/mm2 to 525/mm2. In some embodiments, the total number density (overall number density) of Mg2Si particles is less than 3000/mm2.
The Mg2Si particles dissolve during high temperature annealing (e.g., continuous annealing) for solid solution strengthening. The Mg2Si particles will form strengthening precipitates during paint bake for extra strength improvement. The Fe-containing constituent particles and the Mg2Si particles act as heterogeneous nucleation sites during annealing and produce fine grain orientation/random texture for better formability.
In certain aspects, the disclosed alloy composition is a product of a disclosed method. Without intending to limit the disclosure, aluminum alloy properties are partially determined by the formation of microstructures during the alloy's preparation. In certain aspects, the method of preparation for an alloy composition may influence or even determine whether the alloy will have properties adequate for a desired application. In some embodiments, the aluminum alloys described herein can be produced by continuous casting, optional flash homogenization, hot rolling, coiling, cold rolling, and annealing.
In some embodiments, the method may include continuously casting a metal strip. The method for casting the metal strip can be any suitable continuous casting process. However, surprisingly desirable results have been achieved using a continuous casting process, such as the continuous casting process described in U.S. Pat. No. 10,913,107 entitled “METAL CASTING AND ROLLING LINE,” the disclosure of which is hereby incorporated by reference in its entirety. Following casting, the method comprises flash homogenizing the metal strip prior to hot rolling. The flash homogenization temperature and duration of hot rolling are finely controlled to preserve a large grain size and high strength for the aluminum alloy. The metal strip can be flash homogenized at a temperature from 400° C. to 500° C. in a furnace at a suitable heating rate, followed by maintaining the temperature (“soak” or “soaking”) for short period of time (e.g., up to 10 minutes). Following flash homogenization, the metal strip is hot rolled at a hot rolling temperature from 300° C. to 500° C. to produce a hot rolled product. The hot rolled product can be coil cooled. After coiling, the hot rolled product is cold rolled in a number of cold rolling passes to produce a cold rolled product. The cold rolled product can optionally be coiled. In some embodiments, the cold rolled product is batch annealed or continuously annealed to produce an aluminum alloy product.
The alloys described herein can be cast into a metal article (e.g., metal strip) using a continuous casting (CC) process. Continuous casting involves continuously injecting molten metal into a casting cavity defined between a pair of moving opposed casting surfaces and withdrawing a cast metal form (e.g., a metal strip) from the exit of the casting cavity. Surprisingly, beneficial results can be achieved by intentionally decoupling the casting process from the hot rolling process in a continuous casting and rolling system. By decoupling the continuous casting process from the hot rolling process, the casting speed and the rolling speed no longer need to be closely matched. Rather, the casting speed can be selected to produce desired characteristics in the metal strip, and the rolling speed can be selected based on the requirements and limitations of the rolling equipment. In a decoupled continuous casting and rolling system, the continuous casting device can cast a metal strip that is immediately or shortly thereafter coiled into an intermediate, or transfer, coil. The intermediate coil can be stored or immediately brought to the rolling equipment. At the rolling equipment, the intermediate coil can be uncoiled, allowing the metal strip to pass through the rolling equipment to be hot rolled and otherwise processed. The end result of the hot rolling process is a metal strip that can have the characteristics desired for a particular customer. In some cases, the metal strip can be coiled and distributed, such as to an automotive plant capable of forming automotive parts from the metal strip. In some cases, the metal strip can be heated at various points after being initially cast in the continuous casting process (e.g., by the continuous caster), however the metal strip will remain below a solidus temperature of the metal strip.
The casting device can be any suitable continuous casting device. However, surprisingly desirable results have been achieved using a belt casting device, such as the belt casting device described in U.S. Pat. No. 6,755,236 entitled “BELT-COOLING AND GUIDING MEANS FOR CONTINUOUS BELT CASTING OF METAL STRIP,” the disclosure of which is hereby incorporated by reference in its entirety. In some cases, especially desirable results can be achieved by using a belt casting device having belts made from a metal having a high thermal conductivity, such as copper. The belt casting device can include belts made from a metal having a thermal conductivity of at least 250, 300, 325, 350, 375, or 400 watts per meter per Kelvin at casting temperatures, although metals having other values of thermal conductivity may be used. The casting device can cast a metal strip at any suitable thickness, however desirable results have been achieved at thicknesses of approximately 5 mm to 50 mm.
In some cases, the casting device can be configured to provide fast solidification (e.g., quickly solidifying at rates of at or more than about 10 times faster than standard DC casting solidification, such as at least at or about 1° C./s, at least at or about 10° C./s, or at least at or about 100° C./s) and fast cooling (e.g., quickly cooling at rates of at least at or about 1° C./s, at least at or about 10° C./s, or at least at or about 100° C./s) of the metal strip, which can facilitate improved microstructure in the final metal strip. In some cases, the solidification rate can be at or above 100 times the solidification rate of traditional DC casting. Fast solidification can result in a unique microstructure, including a unique distribution of dispersoid-forming elements very evenly distributed throughout the solidified aluminum matrix. Fast cooling this metal strip, such as immediately quenching the metal strip as it exits the casting device, or shortly thereafter, can facilitate locking the dispersoid-forming elements in solid solution. The resultant metal strip can be then supersaturated with dispersoid-forming elements. The supersaturated metal strip can then be coiled into an intermediate coil for further processing in the decoupled casting and rolling system. In some cases, the desired dispersoid-forming elements include Mn, Cr, V, and/or Zr. This metal strip that is supersaturated with dispersoid-forming elements can, when reheated, very quickly induce the precipitation of evenly distributed and desirably-sized dispersoids.
In some cases, fast solidification and fast cooling can be performed singularly by a casting device. The casting device can be of sufficient length and have sufficient heat removal characteristics to produce a metal strip supersaturated in dispersoid-forming elements. In some cases, the casting device can be of sufficient length and have sufficient heat removal characteristics to reduce the temperature of the cast metal strip to at or below 250° C., 240° C., 230° C., 220° C., 210° C., or 200° C., although other values may be used. Generally, such a casting device would have to either occupy significant space or operate at slow casting speeds. In some cases, where a smaller and faster casting device is desired, the metal strip can be quenched immediately after exiting the casting device or soon thereafter. One or more nozzles can be positioned downstream of the casting device to reduce the temperature of the metal strip to at or below 250° C., 240° C., 230° C., 220° C., 210° C., 200° C., 175° C., 150° C., 125° C., or 100° C., although other values may be used. The quench can occur sufficiently fast or quickly to lock the dispersoid-forming elements in a supersaturated metal strip.
The metal strip can then be subjected to further processing steps. Optionally, the further processing steps can be used to prepare sheets. Such processing steps include, but are not limited to, an optional flash homogenization step, a hot rolling step, a cold rolling step, and an annealing step. The processing steps are described below in relation to a metal strip. However, the processing steps can also be used for a cast slab or strip, using modifications as known to those of skill in the art.
Optionally, if a homogenization step is performed, a metal strip prepared from the alloy compositions described herein may be heated to a homogenization temperature, such as a temperature ranging from about 400° C. to 600° C. For example, the metal strip can be heated to a temperature of about 400° C., 410° C., 420° C., 430° C., 440° C., 450° C., 460° C., 470° C., 480° C., 490° C., 500° C., 510° C., 520° C., 530° C., 540° C., or 550° C. In some cases, the metal strip can be flash homogenized. Flash homogenization can include heating the metal strip to a temperature above 500° C. (e.g., from 500° C. to 570° C., from 520° C. to 560° C., or at or approximately 560° C.) for a relatively short period of time (e.g., approximately 1 minute to 10 minutes, such as 30 second, 45 seconds, 1 minutes, 1.5 minutes, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes, or any range in between). This heating can occur between the continuous caster and the optional initial coiling, and more specifically between the continuous caster and the hot rolling stand prior to coiling, or between that hot rolling stand and coiling. This flash homogenization can help reduce the aspect ratio of the Fe-containing particles and can also reduce the size of these particles. In some cases, flash homogenization (e.g., at 570° C. for about 2 minutes) can successfully achieve beneficial spheroidization and/or refinement of Fe-containing particles that would otherwise require extensive homogenization at higher temperatures.
In some cases, an optional soaking furnace (e.g., a tunnel furnace) can be positioned downstream of the continuous belt caster near the exit of the continuous belt caster to perform flash homogenization. The use of a soaking furnace can facilitate achieving a uniform temperature profile across the lateral width of the metal strip. Additionally, the soaking furnace can flash homogenize the metal strip, which can prepare the metal strip for improved breakup of Fe-containing particles during hot rolling.
The metal strip, or optionally the homogenized metal strip if a homogenization step is performed, can be subjected to a hot rolling step to produce a hot rolled product. In some cases, the metal strip cast from the continuous caster can be rolled (e.g., hot rolled) prior to coiling. The rolling prior to coiling can be at a large reduction of thickness, such as at least 30% or more typically between 50% and 75%. Especially useful results have been found when the continuously cast metal strip is rolled with a single hot rolling stand prior to coiling, although additional stands can be used in some cases. In some cases, this high-reduction (e.g., greater than 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or 75% reduction in thickness) hot rolling after continuous casting can help break up Fe-containing particles in the metal strip, among other benefits. In some embodiments, hot rolling can be performed at a temperature of from about 300° C. to about 500° C. (e.g., about 300° C., about 310° C., about 320° C., about 330° C., about 340° C., about 350° C., about 360° C., about 370° C., about 380° C., about 390° C., about 400° C., about 410° C., about 420° C., about 430° C., about 440° C., about 450° C., about 460° C., about 470° C., about 480° C., about 490° C., or about 500° C.).
In some cases, the combination of flash homogenization and hot rolling after continuous casting, as described herein, can be especially useful for refining (e.g., breaking up) Fe-containing particles. The hot rolled product can be cool coiled after hot rolling. The hot rolled product can be cool coiled at a temperature ranging from about 200° C. to 400° C. In some embodiments, the hot rolled product is coil cooled for ease of cold rolling as well as to modify grain and crystallographic texture of the aluminum alloy. For example, the hot rolled product can be coiled at a temperature of about 200° C. (e.g., about 210° C., about 220° C., about 230° C., about 240° C., about 250° C., about 260° C., about 270° C., about 280° C., about 290° C., about 300° C., about 310° C., about 320° C., about 330° C., about 340° C., about 350° C., about 360° C., about 370° C., about 380° C., about 390° C., or about 400° C.).
Optionally, one or more cold rolling steps can then be performed to result in a cold rolled product. The hot rolled product can be uncoiled using an uncoiler. The uncoiled hot rolled product can be cold rolled in a cold rolling stand. The hot rolled product can be cold rolled using cold rolling mills into thinner products, such as a cold rolled sheet. The cold rolling can be performed to result in a final gauge thickness that represents a gauge reduction of greater than 50% (e.g., greater than 55%, greater than 60%, greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, or greater than 90% reduction) as compared to a gauge prior to the start of cold rolling. In some embodiments, the cold rolling step may include one or more cold rolling steps to achieve the desired gauge thickness reduction. Optionally, the process for producing the aluminum alloy can include an interannealing step (e.g., between one or more cold rolling steps). In some cases, the cold rolled product can be coiled after cold rolling.
The cold rolled product can be annealed after cold rolling. The annealing process can be batch annealing or continuous annealing.
In some embodiments, batch annealing can be performed after cold rolling. In some cases, the batch-annealing step can be performed at a peak metal temperature of from about 300° C. to about 450° C. (e.g., about 310° C., about 320° C., about 330° C., about 340° C., about 350° C., about 360° C., about 370° C., about 380° C., about 390° C., about 400° C., about 410° C., about 420° C., about 430° C., about 440° C., or about 450° C.). In some cases, the heating rate in the batch-annealing step can be about 10° C./h to about 100° C./h (e.g., from about 20° C./h to about 90° C./h, from about 30° C./h to about 85° C./h, from about 40° C./h to about 80° C./h, from about 50° C./h to about 75° C./h, from about 30° C./h to about 80° C./h, from about 40° C./h to about 70° C./h, or from about 50° C./h to about 60° C./h). In some cases, the cold rolled product is allowed to soak for up to about 5 hours during the batch-annealing step (e.g., from about 30 minutes to about 4 hours, from about 45 minutes to about 3 hours, or from about 1 hour to about 2 hours, inclusively). For example, the cold rolled product can be soaked at a temperature of from about 300° C. to about 450° C. for about 20 minutes, about 30 minutes, about 45 minutes, about 1 hour, about 1.5 hours, about 2 hours, about 3 hours, about 4 hours, about 5 hours, or anywhere in between. In one example, the cold rolling product is heated to a temperature from about 350° C. to about 400° C. at a heating rate from about 50° C./h to about 75° C./h, soaked from about 1 hour seconds to about 2 hours, and is cooled at a cooling rate from about 5° C./h to about 30° C./h.
In some embodiments, continuous annealing can be performed after cold rolling. In some cases, the continuous-annealing step can be performed at a peak metal temperature of from about 400° C. to about 600° C. (e.g., about 410° C., about 420° C., about 430° C., about 440° C., about 450° C., about 460° C., about 470° C., about 480° C., about 490° C., about 500° C., about 510° C., about 520° C., about 530° C., about 540° C., about 550° C., about 560° C., about 570° C., about 580° C., about 590° C., or about 600° C.). In some cases, the heating rate in the continuous-annealing step can be about 0.1° C./s to about 30° C./s (e.g., from about 0.2° C./s to about 28° C./s, from about 0.3° C./s to about 28° C./s, from about 0.4° C./s to about 25° C./s, from about 0.5° C./s to about 20° C./s, from about 0.8° C./s to about 18° C./s, from about 1° C./s to about 15° C./s, or from about 2° C./s to about 10° C./s). In some cases, the cold rolled product is allowed to soak for up to about 1 minute during the continuous-annealing step (e.g., 0 seconds, 5 seconds, 10 seconds, or 30 seconds). In one example, the cold rolling product is heated to a temperature from about 400° C. to about 600° C. at a heating rate from about 0.5° C./s to about 20° C./s, soaked from about 0 seconds to about 5 seconds, and is cooled at a cooling rate from about 5° C./s to about 200° C./s.
The aluminum alloy products described herein can be used in automotive applications and other transportation applications, including aircraft and railway applications. For example, the disclosed aluminum alloy products can be used to prepare automotive structural parts, such as bumpers, side beams, roof beams, cross beams, pillar reinforcements (e.g., A-pillars, B-pillars, and C-pillars), inner panels, outer panels, side panels, inner hoods, outer hoods, or trunk lid panels. The aluminum alloy products and methods described herein can also be used in aircraft or railway vehicle applications, to prepare, for example, external and internal panels.
The aluminum alloy products and methods described herein can also be used in electronics applications. For example, the aluminum alloy products and methods described herein can be used to prepare housings for electronic devices, including mobile phones and tablet computers. In some examples, the aluminum alloy products can be used to prepare housings for the outer casing of mobile phones (e.g., smart phones), tablet bottom chassis, and other portable electronics.
Alloys 1-3 are exemplary alloys produced according to methods described below. Alloy A is a conventional AA5182 aluminum alloy which is currently employed in automotive body parts.
Alloys 1-3, as shown in Table 6, were continuously cast into metal strips based on the methods described herein. The metal strips were flash homogenized in a tunnel furnace operating at a temperature from 400° C. to 500° C. The metal strips were hot rolled in a hot mill stand resulting in hot rolled products having a gauge thickness reduction from 40% to 80%. The hot rolled products were coil cooled to a temperature of about 350° C. The hot rolled products were uncoiled and cold rolled in a cold mill stand resulting in cold rolled products having a gauge thickness reduction greater than 50%. The cold rolled products were coiled. The cold rolled products were subjected to batch annealing or continuous annealing to produce a final aluminum alloy product. Alloy A was direct chill cast or continuously cast.
The strength properties of the exemplary alloys and comparative alloy were determined. Specifically, the alloys were subjected to yield strength and ultimate tensile strength tests.
Alloys 1-3 and Alloy A were tested to determine the impact of paint baking on the tensile properties of the aluminum alloy.
The formability properties of the exemplary alloys and comparative alloy were determined. Specifically, the alloys were subjected to uniform elongation, total elongation, r-value, and n-value tests to determine the formability of the exemplary alloys and comparative alloy.
The aluminum alloys produced according to the methods described herein exhibited a microstructure that provided the properties described herein.
Illustration 1 is an aluminum alloy comprising 0-0.30 wt. % Si, 0.01-0.40 wt. % Fe, 0-1.0 wt. % Cu, 0.01-0.50 wt. % Mn, 5.0-6.0 wt. % Mg, 0-0.20 wt. % Cr, 0-0.30 wt. % Zn, 0-0.25 wt. % Ti, up to 0.15 wt. % of impurities, and Al.
Illustration 2 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy comprises 0.01-0.20 wt. % Si, 0.01-0.30 wt. % Fe, 0.01-0.90 wt. % Cu, 0.01-0.40 wt. % Mn, 5.1-6.0 wt. % Mg, 0-0.10 wt. % Cr, 0-0.20 wt. % Zn, 0-0.20 wt. % Ti, up to 0.15 wt. % of impurities, and Al.
Illustration 3 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy comprises 0.01-0.15 wt. % Si, 0.01-0.20 wt. % Fe, 0.05-0.80 wt. % Cu, 0.05-0.30 wt. % Mn, 5.2-6.0 wt. % Mg, 0-0.05 wt. % Cr, 0-0.10 wt. % Zn, 0-0.10 wt. % Ti, up to 0.15 wt. % of impurities, and Al.
Illustration 4 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy comprises 0.01-0.06 wt. % Si, 0.02-0.15 wt. % Fe, 0.20-0.80 wt. % Cu, 0.05-0.20 wt. % Mn, 5.3-6.0 wt. % Mg, 0.001-0.02 wt. % Cr, 0-0.05 wt. % Zn, 0-0.03 wt. % Ti, up to 0.15 wt. % of impurities, and Al.
Illustration 5 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy comprises 0.01-0.05 wt. % Si, 0.05-0.11 wt. % Fe, 0.30-0.80 wt. % Cu, 0.05-0.10 wt. % Mn, 5.5-5.9 wt. % Mg, 0.001-0.02 wt. % Cr, 0-0.01 wt. % Zn, 0.001-0.03 wt. % Ti, up to 0.15 wt. % of impurities, and Al.
Illustration 6 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy comprises at least one of: Mg in an amount from 5.5 wt. % to 6.0 wt. %; and Cu in an amount from 0.30 wt. % to 1.0 wt. %.
Illustration 7 is the aluminum alloy of any preceding or subsequent illustration, wherein a particle size of Fe-containing constituents is less than 5 microns.
Illustration 8 is the aluminum alloy of any preceding or subsequent illustration, wherein a number density of Mg2Si particles in the aluminum alloy microstructure is at least 500/mm2.
Illustration 9 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy has a yield strength of at least 130 MPa.
Illustration 10 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy has an ultimate tensile strength of at least 300 MPa.
Illustration 11 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy has a total elongation of at least 5%.
Illustration 12 is an aluminum alloy product comprising an aluminum alloy of any preceding or subsequent illustration.
Illustration 13 is the aluminum alloy product of any preceding or subsequent illustration, wherein the aluminum alloy product is produced by continuous casting, flash homogenization, hot rolling, and cold rolling.
Illustration 14 is a method of producing an aluminum alloy product, comprising: continuously casting an aluminum alloy to form a cast product, wherein the aluminum alloy comprises 0-0.30 wt. % Si, 0.01-0.40 wt. % Fe, 0-1.0 wt. % Cu, 0.01-0.50 wt. % Mn, 5.0-6.0 wt. % Mg, 0-0.20 wt. % Cr, 0-0.30 wt. % Zn, 0-0.25 wt. % Ti, up to 0.15 wt. % of impurities, and Al; optionally flash homogenizing the cast product; hot rolling the cast product to produce a hot rolled product; coiling the hot rolled product; cold rolling the hot rolled product to produce a cold rolled product; and annealing the cold rolled product.
Illustration 15 is the method of any preceding or subsequent illustration, wherein the aluminum alloy comprises at least one of: Mg in an amount from 5.5 wt. % to 6.0 wt. %; and Cu in an amount from 0.30 wt. % to 1.0 wt. %.
Illustration 16 is the method of any preceding or subsequent illustration, wherein continuously casting comprises a solidification rate of at least 1° C./s to produce the cast product.
Illustration 17 is the method of any preceding or subsequent illustration, wherein annealing comprises batch annealing or continuous annealing.
Illustration 18 is the method of any preceding or subsequent illustration, wherein flash homogenizing comprises heating the cast product from 400° C. to 600° C. for less than 10 minutes.
Illustration 19 is the method of any preceding or subsequent illustration, further comprising paint baking the cold rolled product after annealing to produce an aluminum alloy product.
Illustration 20 is the method of any preceding or subsequent illustration, wherein the yield strength of the aluminum alloy product increases by 5 MPa or greater after paint baking.
All patents, publications, and abstracts cited above are incorporated herein by reference in their entireties. Various embodiments of the invention have been described in fulfillment of the various objectives of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptions thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention as defined in the following claims.
This application claims the benefit of and priority to U.S. Provisional Application No. 63/160,198, filed Mar. 12, 2021, which is incorporated herein by reference in its entirety for all intents and purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/070250 | 1/19/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63160198 | Mar 2021 | US |
