Heat-treated aluminum sheets and their manufacturing process

Abstract

A continuous heat treatment process of metal is disclosed herein, in which a strip of metal, for example, a heat-treatable alloy, is solution-treated, rapidly cooled, then heat-spikened at an elevated temperature and coiled. The continuous heat treatment process does not include or require batch aging treatment.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 263,052 filed on October 26, 2021, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present disclosure generally relates to metalworking, and more specifically to a continuous heat treatment process of metal in which a strip of heat-treatable alloy is solutionized, rapidly cooled, thermally spiked, and coiled. Background Technology

[0005] Manufacturers of metal articles face the challenge of providing thin-gauge materials that possess both excellent formability and high strength after the article is formed and the paint is cured. For example, the automotive industry requires such products for use in weight-reduced body panels or structural members to improve vehicle economy and fuel efficiency.

[0006] Heat-treatable metals, such as heat-treatable aluminum alloys, can achieve these objectives in some cases. Heat-treatable alloys are generally alloys containing an amount of soluble alloying elements that exceeds the room-temperature solubility limit. These alloys may contain hardening elements (e.g., Mg, Si, and / or Co) to provide hardening during aging, as well as other potential elements such as Fe, Mn, and Cr to control formability and grain size. These alloys can exhibit enhanced properties if subjected to a quenching step following processing and / or heating. Heat treatment of metals is traditionally performed by precipitation hardening, which involves solution heat treatment and an aging step. In the solution heat treatment process, a metal strip, for example, an aluminum alloy strip, is solution-treated and rapidly cooled; depending on product requirements, it may or may not be thermally spiked. The purpose of the solution treatment procedure is to introduce alloying (solute) elements into a solution to ultimately strengthen a specific alloy. The purpose of rapid cooling is to immobilize the solute elements and excess voids into the metal (e.g., aluminum) matrix of the metal strip. The purpose of heat spiking is to ensure that the coil is coiled between 60°C and 110°C, thereby eliminating the adverse effects of coil storage, where the material can lose up to 40% of its strength increase during paint baking. The heat-treated metal strip can then undergo an aging process.

[0007] For example, in the current process for producing aging temper, the coil of T4 temper is heated at a rate of 20°C / h to 50°C / h and then raised to a temperature in the range of 120°C to 260°C. It requires a batch aging process in which the body is cooled at room temperature after immersion for a period of time. However, existing heat treatment and batch aging processes require a total cycle time longer than 8 hours and an immersion time ( Precise control of the heat treatment process is required due to the added steps and complexity, time (often 4 to 6 hours), and added steps. means of solving the problem

[0008] The terms "Examples" and similar terms are intended to refer broadly to all subject matter of this disclosure and the claims below. Statements containing such terms should be understood as not limiting the subject matter described herein or the meaning or scope of the claims below. The embodiments of this disclosure covered herein are defined by the claims below, not by this summary. This summary is a high-level overview of the various aspects of this disclosure and introduces some of the concepts further described in the detailed description sections below. This summary is not intended to identify the principal or essential features of the claimed subject matter, nor is it intended to be used separately to determine the scope of the claimed subject matter. Subject matter should be understood by referring to the full specification of this disclosure, some or all of the drawings, and the appropriate parts of each claim.

[0009] Specific embodiments and features of the present invention relate to a continuous heat treatment process in which a metal strip is solution-treated, rapidly cooled, heat-spikeped at an elevated temperature in the range of 120°C to 300°C (e.g., 200°C to 250°C), and coiled at a re-winding position located at the end of a continuous line. In some embodiments, the continuous heat treatment process and its constituent steps may occur at a specific line speed, e.g., at least 10 meters / min (e.g., at least 40 meters / min; 10 meters / min to 100 meters / min, 40 meters / min to 100 meters / min, or 10 meters / min to 40 meters / min). In some embodiments, the heat-spike treatment may occur in a relatively long reheating furnace, e.g., a reheating furnace longer than 10 meters. In some embodiments, only natural cooling (i.e., no cooling device is used) occurs between the heat-spike and coiling, and coiling is performed in such a manner that the line speed is maintained. In some embodiments, the cooling or natural cooling rate after the thermal spike treatment is, for example, less than 10°C / hour to ambient temperature (e.g., less than 2°C / hour). Accordingly, in some embodiments, the coiling of the metal strip is performed at a relatively warm temperature, for example, 60°C or higher, such as 110°C or higher, 70°C to 150°C, 70°C to 130°C, or 70°C to 110°C, 110°C to 150°C, 110°C to 130°C, or 110°C to 120°C. In certain embodiments, the disclosed process does not include or require a batch aging process for age-hardening the material.

[0010] The present disclosure allows for the production of a product from the disclosed process having a thin gauge with both excellent formability and high strength using a continuous annealing line without requiring a batch aging process. The present disclosure is particularly beneficial as a potential substitute for 5000 series aluminum alloys supplied in H1X, H2X, and H3x tempers, or by providing a product with a customized combination of properties, thereby offering the possibility of downgassing. Specific details for implementing the invention

[0011] Specific aspects and features of the present disclosure relate to a continuous heat treatment process in which a metal strip is solution-treated, rapidly cooled, thermally spiked (e.g., by hot air) at an elevated temperature in the range of 120°C to 300°C, coiled, and cooled or naturally cooled (before and / or after coiling) at a rate of, for example, 5°C / hour or less, preferably 2°C / hour or less. In specific embodiments, the metal strip is a heat-treatable alloy, for example, a heat-treatable aluminum alloy.

[0012] In certain embodiments, the thermal spike temperature is maintained at 120°C to 300°C (e.g., about 150°C to 300°C). Using the thermal spike at a higher temperature can induce the formation of clusters that act as nuclei for forming hardened particles during subsequent coiling and coil cooling.

[0013] The present disclosure partially improves existing technology by completely eliminating the batch process by using a reheater furnace to thermally spike a metal strip to a desired temperature at line speed prior to coiling. For example, a continuous annealing line can be used without a batch aging process. Thermally spiked coils combined with coil cooling provide conditions suitable for age hardening. Using thermal spikes and coiling at warm coiling temperatures to adjust various properties is achieved by the present disclosure. The present disclosure is particularly beneficial in that it provides products with customized combinations of properties and, accordingly, offers the possibility of downgassing.

[0014] Although the embodiments and features of the present disclosure are described herein in relation to metal strips, such as metal strips that are not continuously cast or coiled, the present disclosure may also be used with any suitable metal product processed in a continuous annealing line. The embodiments and features of the present disclosure may be particularly suitable for any metal product having a flat surface. The embodiments and features of the present disclosure may be particularly suitable for any metal product having parallel or approximately parallel opposing surfaces (e.g., upper and lower surfaces). Approximately parallel may include parallel or parallel within 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, or 10° or more.

[0015] Definition and explanation

[0016] As used herein, the terms “invention,” “the above invention,” “such invention,” and “the present invention” are intended to refer broadly to all subjects of this patent application and the claims below. Descriptions containing these terms should be understood as not limiting the subjects described herein or the meaning or scope of the claims below.

[0017] In this description, alloys identified by AA numbers and other related designations such as "series" or "7xxx" are referred to. To understand the numbering system most commonly used to name and identify aluminum and its alloys, refer to the "International Alloy Designation and Chemical Composition Restrictions for Forged Aluminum and Forged Aluminum Alloys" and the "Aluminum Association Register of Alloy Designation and Chemical Composition Restrictions for Aluminum Alloys in Casting and Ingot Forms," ​​both published by the Aluminum Association.

[0018] As used in this specification, the plate generally has a thickness greater than about 15 mm. For example, the plate may mean an aluminum product with a thickness 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.

[0019] As used herein, the shate (also called a sheet plate) generally has a thickness of about 4 mm to about 15 mm. For example, the 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.

[0020] As used herein, a sheet generally refers to an aluminum product having a thickness of less than about 4 mm. For example, the thickness of the sheet may be less than about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, or less than about 0.3 mm (e.g., about 0.2 mm).

[0021] As used herein, foil generally refers to a metal product having a thickness of about 0.2 mm or less. For example, the thickness of the foil may be about 0.2 mm or less, about 0.15 mm or less, about 0.10 mm or less, about 0.05 mm or less, about 0.04 mm or less, about 0.03 mm or less, about 0.02 mm or less, or about 0.01 mm or less (e.g., about 0.006 mm).

[0022] As used herein, direct cooling (DC) and continuous casting are two methods of casting solid metal from liquid metal. In DC casting, liquid metal is poured into a mold having a retractable false bottom that can be withdrawn at the solidification rate of the liquid metal within the mold, and often a large and relatively thick ingot (e.g., 1500 mm wide x 500 mm thick x 5 m long) is produced. The ingot may be processed, homogenized, hot-rolled, or cold-rolled, and may or may not be annealed after hot-rolling or before passing through final cold-rolling and / or before heat treatment, and may be finished before being coiled into metal strip products that can be distributed to consumers (e.g., automotive manufacturing facilities).

[0023] Continuous casting involves continuously injecting molten metal into a casting cavity defined between a pair of moving opposing casting surfaces and withdrawing a form of the cast metal (e.g., a metal strip) from the exit of the casting cavity. Continuous casting was preferred when the entire product could be manufactured in a single, fully coupled processing line. Such a fully coupled processing line involves matching or "coupling" the speed of the continuous casting equipment to the speed of the downstream processing equipment.

[0024] In this application, alloy tempers or conditions may be referred to. To understand the most commonly used descriptions of alloy tempers, refer to "ANSI H35 for the alloy and temper designation system." F condition or temper refers to a manufactured aluminum alloy. O condition or temper refers to an aluminum alloy after annealing. Hxx condition or temper, also referred to herein as H temper, refers to an aluminum alloy that is non-heat treatable after cold rolling, with or without heat treatment (e.g., annealing). Suitable H tempers include HX1, HX2, HX3, HX4, HX5, HX6, HX7, HX8, or HX9 tempers. T1 condition or temper refers to an aluminum alloy that has been cooled from hot working and naturally aged (e.g., at room temperature). T2 condition or temper refers to an aluminum alloy that has been cooled during hot working, cold working, and natural aging processes. Condition or temper T3 refers to aluminum alloys that have undergone solution treatment, cold working, and natural aging. Condition or temper T4 refers to aluminum alloys that have undergone solution heat treatment and natural aging. Condition or temper T5 refers to aluminum alloys that have been cooled from hot working and artificially aged (at high temperatures). Condition or temper T6 refers to aluminum alloys that have undergone solution heat treatment and artificial aging. Condition or temper T7 refers to aluminum alloys that have undergone solution heat treatment and artificial over-aging. Condition or temper T8x refers to aluminum alloys that have undergone solution treatment, cold working, and artificial aging. Condition or temper T9 refers to aluminum alloys that have undergone solution treatment, artificial aging, and cold working. Condition or temper W refers to aluminum alloys after solution heat treatment.

[0025] As used herein, the meaning of “room temperature” may include a temperature of about 15°C to about 30°C, for example, about 15°C, about 16°C, about 17°C, about 18°C, about 19°C, about 20°C, about 21°C, about 22°C, about 23°C, about 24°C, about 25°C, about 26°C, about 27°C, about 28°C, about 29°C, or about 30°C. As used herein, the meaning of “ambient conditions” or “ambient environment” may include a temperature of approximately room temperature, a relative humidity of about 20% to about 100%, and an atmospheric pressure of about 975 millibars (mbar) to about 1050 mbar. For example, relative humidity is approximately 20%, approximately 21%, approximately 22%, approximately 23%, approximately 24%, approximately 25%, approximately 26%, approximately 27%, approximately 28%, approximately 29%, approximately 30%, approximately 31%, approximately 32%, approximately 33%, approximately 34%, approximately 35%, approximately 36%, approximately 37%, approximately 38%, approximately 39%, approximately 40%, approximately 41%, approximately 42%, approximately 43%, approximately 44%, approximately 45%, approximately 46%, approximately 47%, approximately 48%, approximately 49%, approximately 50%, approximately 51%, approximately 52%, approximately 53%, approximately 54%, approximately 55%, approximately 56%, approximately 57%, approximately 58%, approximately 59%, approx. 60%, approx. 61%, approx. 62%, approx. 63%, approx. 64%, approx. 65%, approx. 66%, approx. 67%, approx. 68%, approx. 69%, approx. 70%, approx. 71%, approx. 72%, approx. 73%, approx. 74%, approx. 75%, approx. 76%, approx. 77%, approx. 78%, approx. 79%, approx. 80%, approx. 81%, approx. 82%, approx. 83%, approx. 84%, approx. 85%, approx. 86%, approx. 87%, approx. 88%, approx. 89%, approx. 90%, approx. 91%, approx. 92%, approx. 93%, approx. 94%, approx. 95%, approx. 96%, approx. 97%, approx. 98%, approx. 99%, approx. It can be 100%, or any value in between.For example, the atmospheric pressure may be about 975 mbar, about 980 mbar, about 985 mbar, about 990 mbar, about 995 mbar, about 1000 mbar, about 1005 mbar, about 1010 mbar, about 1015 mbar, about 1020 mbar, about 1025 mbar, about 1030 mbar, about 1035 mbar, about 1040 mbar, about 1045 mbar, about 1050 mbar, or any value in between.

[0026] All ranges disclosed herein should be understood to include any and all sub-ranges contained therein. For example, a specified range of “1 to 10” should be considered to include all sub-ranges between (inclusive of) a minimum value of 1 and a maximum value of 10; that is, all sub-ranges starting with a minimum value of 1 or greater, such as 1 to 6.1, for example, and all sub-ranges ending with a maximum value of 10 or less, such as 5.5 to 10, for example. Unless otherwise specified, when referring to the composition amount of an element, the expression “maximum” means that the element is optional and that the composition of that specific element is 0%. Unless otherwise specified, all composition percentages are in weight % (wt.%).

[0027] As used herein, the meaning of the singular terms (“a,” “an,” and “the”) includes singular and plural references unless otherwise specified in the context.

[0028] In this description, aluminum alloy products and their components may be described in terms of elemental composition in weight percent (wt.%). In each alloy, the remainder is aluminum and has a maximum wt.% of 0.15% of the total sum of all impurities.

[0029] Incidental elements or other additives, such as grain refiners and deoxidizers, may be present in the present invention and may add other properties themselves without deviating from or significantly altering the properties of the alloy described herein or the alloy described herein.

[0030] metal strip

[0031] As discussed, the heat treatment process of the present disclosure may be performed on a metal strip, for example, an aluminum alloy strip. In certain embodiments, the metal strip described herein may be produced from metal casting, for example, DC casting or continuous metal casting. After casting, in certain embodiments, homogenization, hot rolling and / or cold rolling, and optional annealing after hot rolling or before final cold rolling may be performed to produce the metal strip.

[0032] In certain embodiments, the metal strip may be a metal sheet, shade, or foil. In certain embodiments, the metal strip may be a sheet. For example, in one embodiment, the described process is used to produce sheets having a gauge from 0.5 mm to 4.5 mm. In some of these embodiments, the metal strip may be an aluminum alloy sheet, for example, a heat-treatable aluminum alloy sheet. In some embodiments, the metal strip may be selected from 2xxx series, 6xxx series, or 7xxx series aluminum alloy sheets. In some embodiments, the metal strip is a 2xxx series aluminum alloy sheet. In some embodiments, the metal strip is a 6xxx series aluminum alloy sheet. In some embodiments, the metal strip is a 7xxx series aluminum alloy sheet. In certain embodiments, the metal strip may be a shade. In some embodiments, the metal strip may be an aluminum alloy shade, for example, a heat-treatable aluminum alloy shade. In some embodiments, the metal strip may be selected from 2xxx series, 6xxx series, or 7xxx series aluminum alloy sheets. In some embodiments, the metal strip is a 2xxx series aluminum alloy sheet. In some embodiments, the metal strip is a 6xxx series aluminum alloy sheet. In some embodiments, the metal strip is a 7xxx series aluminum alloy sheet. In certain embodiments, the metal strip may be a foil. In some embodiments, the metal strip may be an aluminum alloy foil, for example, a heat-treatable aluminum alloy foil. In some embodiments, the metal strip may be selected from 2xxx series, 6xxx series, or 7xxx series aluminum alloy foils. In some embodiments, the metal strip is a 2xxx series aluminum alloy foil. In some embodiments, the metal strip is a 6xxx series aluminum alloy foil. In some embodiments, the metal strip is a 7xxx series aluminum alloy foil.

[0033] In certain embodiments, the alloy exhibits high strength and high deformability. In some cases, the strength increases after heat treatment without significant loss of the alloy's deformability. The properties of the alloy are achieved at least partially due to the method of processing the alloy to produce the described foils, shades, sheets, or other products.

[0034] In some embodiments, the alloy may have the following elemental composition as provided in Table 1.

[0035]

[0036] In some examples, the alloy may have the following elemental composition as provided in Table 2.

[0037]

[0038] In another example, the alloy may have the following elemental composition as provided in Table 3.

[0039]

[0040] In one example, the aluminum alloy may have the following elemental composition as provided in Table 4. In certain embodiments, the alloy is used to manufacture aluminum foils and sheets.

[0041]

[0042] In certain embodiments, the disclosed alloy contains copper (Cu) in an amount of about 0.05% to about 1.2% (e.g., about 0.1% to about 1.2%, about 0.2% to about 1.1%, about 0.3% to about 1.0%, about 0.4% to about 1.0%, about 0.6% to about 1.1%, about 0.65% to about 0.9%, about 0.7% to about 1.0%, or about 0.6% to about 0.7%) based on the total weight of the alloy. For example, the alloy is about 0.05%, about 0.06%, about 0.07%, about 0.08%, about 0.09%, about 0.1%, about 0.11%, about 0.12%, about 0.13%, about 0.14%, about 0.15%, about 0.16%, about 0.17%, about 0.18%, about 0.19%, about 0.2%, about 0.21%, about 0.22%, about 0.23%, about 0.24%, about 0.25%, about 0.26%, about 0.27%, about 0.28%, about 0.29%, about 0.3%, about 0.31%, about 0.32%, about 0.33%, about 0.34%, about 0.35%, approx. 0.36%, approx. 0.37%, approx. 0.38%, approx. 0.39%, approx. 0.4%, approx. 0.41%, approx. 0.42%, approx. 0.43%, approx. 0.44%, approx. 0.45%, approx. 0.46%, approx. 0.47%, approx. 0.48%, approx. 0.49%, approx. 0.5%, approx. 0.51%, approx. 0.52%, approx. 0.53%, approx. 0.54%, approx. 0.55%, approx. 0.56%, approx. 0.57%, approx. 0.58%, approx. 0.59%, approx. 0.6%, approx. 0.61%, approx. 0.62%, approx. 0.63%, approx. 0.64%, approx. 0.65%, approx. 0.66%, approx. 0.67%, approx. 0.68%, approx. 0.69%, approx. 0.7%, approx. 0.71%, approx. 0.72%, approx. 0.73%, approx. 0.74%, approx. 0.75%, approx. 0.76%, approx. 0.77%, approx. 0.78%, approx. 0.79%, approx. 0.8%, approx. 0.81%, approx. 0.82%, approx. 0.83%, approx. 0.84%, approx. 0.85%, approx. 0.86%, approx. 0.87%, approx. 0.88%, approx. 0.89%, approx. 0.It may contain 9%, about 0.91%, about 0.92%, about 0.93%, about 0.94%, about 0.95%, about 0.96%, about 0.97%, about 0.98%, about 0.99%, about 1.0%, about 1.01%, about 1.02%, about 1.03%, about 1.04%, about 1.05%, about 1.06%, about 1.07%, about 1.08%, about 1.09%, or about 1.1% of Cu. All are expressed in wt. %.

[0043] In certain embodiments, the disclosed alloy contains silicon (Si) in an amount of about 0.6% to about 1.5% (e.g., about 0.7% to about 1.3%, about 0.8% to about 1.2%, about 0.9% to about 1.1%, about 0.6% to about 0.9%, about 0.9% to about 1.1%, or about 1.0% to about 1.1%) based on the total weight of the alloy. For example, the alloy is about 0.6%, about 0.61%, about 0.62%, about 0.63%, about 0.64%, about 0.65%, about 0.66%, about 0.67%, about 0.68%, about 0.69%, about 0.7%, about 0.71%, about 0.72%, about 0.73%, about 0.74%, about 0.75%, about 0.76%, about 0.77%, about 0.78%, about 0.79%, about 0.8%, about 0.81%, about 0.82%, about 0.83%, about 0.84%, about 0.85%, about 0.86%, about 0.87%, about 0.88%, about 0.89%, about It may contain 0.9%, approximately 0.91%, approximately 0.92%, approximately 0.93%, approximately 0.94%, approximately 0.95%, approximately 0.96%, approximately 0.97%, approximately 0.98%, approximately 0.99%, approximately 1.0%, approximately 1.01%, approximately 1.02%, approximately 1.03%, approximately 1.04%, approximately 1.05%, approximately 1.06%, approximately 1.07%, approximately 1.08%, approximately 1.09%, or approximately 1.1% of Si. All are expressed in wt. %.

[0044] In certain embodiments, the disclosed alloy contains magnesium (Mg) in an amount of about 0.3% to about 1.3% (e.g., about 0.4% to about 1.25%, about 0.5% to about 1.2%, about 0.7% to about 1.1%, about 0.8% to about 1.25%, about 1.1% to about 1.25%, about 1.1% to about 1.2%, about 1.0% to about 1.2%, about 1.05% to about 1.3%, or about 1.15% to about 1.3%) based on the total weight of the alloy. For example, the alloy is about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.71%, about 0.72%, about 0.73%, about 0.74%, about 0.75%, about 0.76%, about 0.77%, about 0.78%, about 0.79%, about 0.8%, about 0.81%, about 0.82%, about 0.83%, about 0.84%, about 0.85%, about 0.86%, about 0.87%, about 0.88%, about 0.89%, about 0.9%, about 0.91%, about 0.92%, about 0.93%, about 0.94%, about 0.95%, about 0.96%, It may contain about 0.97%, about 0.98%, about 0.99%, about 1.0%, about 1.01%, about 1.02%, about 1.03%, about 1.04%, about 1.05%, about 1.06%, about 1.07%, about 1.08%, about 1.09%, about 1.1%, about 1.11%, about 1.12%, about 1.13%, about 1.14%, about 1.15%, about 1.16%, about 1.17%, about 1.18%, about 1.19%, or about 1.2% of Mg. All are expressed in wt. %.

[0045] In a specific embodiment, the alloy contains chromium (Cr) in an amount of up to about 0.25% (e.g., about 0% to about 0.25%, about 0.03% to about 0.06%, about 0.03% to about 0.19%, or about 0.06% to about 0.1%) based on the total weight of the alloy. For example, the alloy is about 0.001%, about 0.002%, about 0.003%, about 0.004%, about 0.005%, about 0.006%, about 0.007%, about 0.008%, about 0.059%, about 0.01%, about 0.011%, about 0.012%, about 0.013%, about 0.014%, about 0.015%, about 0.016%, about 0.017%, about 0.018%, about 0.019%, about 0.02%, about 0.021%, about 0.022%, about 0.023%, about 0.024%, about 0.025%, about 0.026%, about 0.027%, Approx. 0.028%, Approx. 0.029%, Approx. 0.03%, Approx. 0.031%, Approx. 0.032%, Approx. 0.033%, Approx. 0.034%, Approx. 0.035%, Approx. 0.036%, Approx. 0.037%, Approx. 0.038%, Approx. 0.039%, Approx. 0.04%, Approx. 0.041%, Approx. 0.042%, Approx. 0.043%, Approx. 0.044%, Approx. 0.045%, Approx. 0.046%, Approx. 0.047%, Approx. 0.048%, Approx. 0.049%, Approx. 0.05%, Approx. 0.051%, Approx. 0.052%, Approx. 0.053%, Approx. 0.054%, Approx. 0.055%, approx. 0.056%, approx. 0.057%, approx. 0.058%, approx. 0.059%, approx. 0.06%, approx. 0.061%, approx. 0.062%, approx. 0.063%, approx. 0.064%, approx. 0.065%, approx. 0.066%, approx. 0.067%, approx. 0.068%, approx. 0.069%, approx. 0.07%, approx. 0.071%, approx. 0.072%, approx. 0.073%, approx. 0.074%, approx. 0.075%, approx. 0.076%, approx. 0.077%, approx. 0.078%, approx. 0.079%, approx. 0.08%, approx. 0.081%, approx. 0.082%, approximately 0.083%, approximately 0.084%, approximately 0.085%, approximately 0.0.86%, approx. 0.087%, approx. 0.088%, approx. 0.089%, approx. 0.09%, approx. 0.091%, approx. 0.092%, approx. 0.093%, approx. 0.094%, approx. 0.095%, approx. 0.096%, approx. 0.097%, approx. 0.098%, approx. 0.099%, approx. 0.1%, approx. 0.11%, approx. 0.12%, approx. 0.13%, approx. 0.14%, approx. 0.15%, approx. 0.16%, approx. 0.17%, approx. 0.18%, approx. 0.19%, approx. 0.2%, approx. 0.21%, approx. 0.22%, approx. 0.23%, approx. 0.24%, or approx. It may contain 0.25% Cr. All are expressed in wt. %. In some cases, Cr is not present in the alloy (i.e., 0%). In some examples, Cr can control the grain structure and prevent grain growth and recrystallization. Higher Cr content can provide higher formability and improved bendability at aging temper.

[0046] In certain examples, the alloy may contain manganese (Mn) in an amount of up to about 0.35% (e.g., about 0% to about 0.35%, about 0.05% to about 0.18%, about 0.1% to about 0.35%, or about 0.1% to about 0.3%) based on the total weight of the alloy. For example, the alloy is about 0.001%, about 0.002%, about 0.003%, about 0.004%, about 0.005%, about 0.006%, about 0.007%, about 0.008%, about 0.059%, about 0.01%, about 0.011%, about 0.012%, about 0.013%, about 0.014%, about 0.015%, about 0.016%, about 0.017%, about 0.018%, about 0.019%, about 0.02%, about 0.021%, about 0.022%, about 0.023%, about 0.024%, about 0.025%, about 0.026%, about 0.027%, Approx. 0.028%, Approx. 0.029%, Approx. 0.03%, Approx. 0.031%, Approx. 0.032%, Approx. 0.033%, Approx. 0.034%, Approx. 0.035%, Approx. 0.036%, Approx. 0.037%, Approx. 0.038%, Approx. 0.039%, Approx. 0.04%, Approx. 0.041%, Approx. 0.042%, Approx. 0.043%, Approx. 0.044%, Approx. 0.045%, Approx. 0.046%, Approx. 0.047%, Approx. 0.048%, Approx. 0.049%, Approx. 0.05%, Approx. 0.051%, Approx. 0.052%, Approx. 0.053%, Approx. 0.054%, Approx. 0.055%, approx. 0.056%, approx. 0.057%, approx. 0.058%, approx. 0.059%, approx. 0.06%, approx. 0.061%, approx. 0.062%, approx. 0.063%, approx. 0.064%, approx. 0.065%, approx. 0.066%, approx. 0.067%, approx. 0.068%, approx. 0.069%, approx. 0.07%, approx. 0.071%, approx. 0.072%, approx. 0.073%, approx. 0.074%, approx. 0.075%, approx. 0.076%, approx. 0.077%, approx. 0.078%, approx. 0.079%, approx. 0.08%, approx. 0.081%, approx. 0.082%, approximately 0.083%, approximately 0.084%, approximately 0.0.85%, approx. 0.086%, approx. 0.087%, approx. 0.088%, approx. 0.089%, approx. 0.09%, approx. 0.091%, approx. 0.092%, approx. 0.093%, approx. 0.094%, approx. 0.095%, approx. 0.096%, approx. 0.097%, approx. 0.098%, approx. 0.099%, approx. 0.1%, approx. 0.11%, approx. 0.12%, approx. 0.13%, approx. 0.14%, approx. 0.15%, approx. 0.16%, approx. 0.17%, approx. 0.18%, approx. 0.19%, approx. 0.2%, approx. 0.21%, approx. 0.22%, approx. 0.23%, approx. It may contain 0.24%, about 0.25%, about 0.26%, about 0.27%, about 0.28%, about 0.29%, about 0.3%, about 0.31%, about 0.32%, about 0.33%, about 0.34%, or about 0.35% of Mn. In some cases, Mn is not present in the alloy (i.e., 0%). All are expressed in wt. %.

[0047] In certain embodiments, the alloy also contains iron (Fe) in an amount of about 0.1% to about 0.35% (e.g., about 0.1% to about 0.3%, about 0.1% to about 0.25%, about 0.18% to about 0.25%, about 0.2% to about 0.21%, or about 0.15% to about 0.22%) based on the total weight of the alloy. For example, the alloy may contain about 0.1%, about 0.11%, about 0.12%, about 0.13%, about 0.14%, about 0.15%, about 0.16%, about 0.17%, about 0.18%, about 0.19%, about 0.2%, about 0.21%, about 0.22%, about 0.23%, about 0.24%, about 0.25%, about 0.26%, about 0.27%, about 0.28%, about 0.29%, or about 0.30% of Fe. In some cases, Fe is not present in the alloy (i.e., 0%). All are expressed in wt. %.

[0048] In a specific embodiment, the alloy contains zirconium (Zr) in an amount of up to about 0.25% (e.g., about 0% to about 0.2%, about 0.01% to about 0.25%, about 0.01% to about 0.15%, about 0.01% to about 0.1%, or about 0.02% to about 0.09%) based on the total weight of the alloy. For example, the alloy is about 0.001%, about 0.002%, about 0.003%, about 0.004%, about 0.005%, about 0.006%, about 0.007%, about 0.008%, about 0.009%, about 0.01%, about 0.02%, about 0.03%, about 0.04%, about 0.05%, about 0.06%, about 0.07%, about 0.08%, about 0.09%, about 0.1%, about 0.11%, about 0.12%, about 0.13%, about 0.14%, about 0.15%, about 0.16%, about 0.17%, about 0.18%, about 0.19%, about 0.2%, about It may contain 0.21%, about 0.22%, about 0.23%, about 0.24%, or about 0.25% of Zr. In certain embodiments, Zr is not present in the alloy (i.e., 0%). All are expressed in wt. %. In some examples, Zr can control the crystal structure and prevent crystal growth and recrystallization. A larger amount of Zr can provide higher formability and improved bendability even at T4 and aging tempers.

[0049] In certain embodiments, the alloy described herein contains zinc (Zn) in an amount of up to about 1.0% (e.g., about 0% to about 1.0%, about 0.001% to about 0.3%, about 0.005% to about 0.09%, about 0.004% to about 0.3%, about 0.03% to about 0.2%, or about 0.06% to about 0.1%) based on the total weight of the alloy. For example, the alloy is about 0.001%, about 0.002%, about 0.003%, about 0.004%, about 0.005%, about 0.006%, about 0.007%, about 0.008%, about 0.009%, about 0.01%, about 0.011%, about 0.012%, about 0.013%, about 0.014%, about 0.015%, about 0.016%, about 0.017%, about 0.018%, about 0.019%, about 0.02%, about 0.021%, about 0.022%, about 0.023%, about 0.024%, about 0.025%, about 0.026%, about 0.027%, Approx. 0.028%, Approx. 0.029%, Approx. 0.03%, Approx. 0.04%, Approx. 0.05%, Approx. 0.06%, Approx. 0.07%, Approx. 0.08%, Approx. 0.09%, Approx. 0.1%, Approx. 0.11%, Approx. 0.12%, Approx. 0.13%, Approx. 0.14%, Approx. 0.15%, Approx. 0.16%, Approx. 0.17%, Approx. 0.18%, Approx. 0.19%, Approx. 0.2%, Approx. 0.21%, Approx. 0.22%, Approx. 0.23%, Approx. 0.24%, Approx. 0.25%, Approx. 0.26%, Approx. 0.27%, Approx. 0.28%, Approx. 0.29%, Approx. 0.3%, Approx. 0.31%, approx. 0.32%, approx. 0.33%, approx. 0.34%, approx. 0.35%, approx. 0.36%, approx. 0.37%, approx. 0.38%, approx. 0.39%, approx. 0.4%, approx. 0.41%, approx. 0.42%, approx. 0.43%, approx. 0.44%, approx. 0.45%, approx. 0.46%, approx. 0.47%, approx. 0.48%, approx. 0.49%, approx. 0.50%, approx. 0.51%, approx. 0.52%, approx. 0.53%, approx. 0.54%, approx. 0.55%, approx. 0.56%, approx. 0.57%, approx. 0.58%, approx. 0.59%, approx. 0.6%, approx. 0.61%, approx. 0.62%, approx. 0.63%, approx. 0.64%, approx. 0.65%, approx. 0.66%, approx. 0.67%, approx. 0.68%, approx. 0.69%, approx. 0.7%, approx. 0.71%, approx. 0.72%, approx. 0.73%, approx. 0.74%, approx. 0.75%, approx. 0.76%, approx. 0.77%, approx. 0.78%, approx. 0.79%, approx. 0.8%, approx. 0.81%, approx. 0.82%, approx. 0.83%, approx. 0.84%, approx. 0.85%, approx. 0.86%, approx. 0.87%, approx. 0.88%, approx. 0.89%, approx. It may contain 0.90%, about 0.91%, about 0.92%, about 0.93%, about 0.94%, about 0.95%, about 0.96%, about 0.97%, about 0.98%, about 0.99%, or about 1.0% of Zn. In some cases, Zn is not present in the alloy (i.e., 0%). All are expressed in wt. %. In certain embodiments, Zn can provide advantages in forming, including bending and reduction of bend anisotropy in foil, sheet, and sheet products.

[0050] In certain aspects, the alloy contains titanium (Ti) in an amount of up to about 0.3% (e.g., about 0% to about 0.3%, about 0.01% to about 0.25%, about 0.05% to about 0.2%, or up to about 0.1%) based on the total weight of the alloy. For example, the alloy is about 0.01%, about 0.011%, about 0.012%, about 0.013%, about 0.014%, about 0.015%, about 0.016%, about 0.017%, about 0.018%, about 0.019%, about 0.02%, about 0.025%, about 0.03%, about 0.035%, about 0.04%, about 0.045%, about 0.05%, about 0.055%, 0.06%, about 0.065%, about 0.07%, about 0.075%, about 0.08%, about 0.085%, about 0.09%, about 0.095%, about 0.1%, about 0.11%, about It may contain 0.12%, about 0.13%, about 0.14%, about 0.15%, about 0.16%, about 0.17%, about 0.18%, about 0.19%, about 0.2%, about 0.21%, about 0.22%, about 0.23%, about 0.24%, about 0.25%, about 0.26%, about 0.27%, about 0.28%, about 0.29%, or about 0.3% of Ti. In certain embodiments, Ti is not present in the alloy (i.e., 0%). All are expressed in wt. %.

[0051] In a specific embodiment, the alloy contains nickel (Ni) in an amount of up to about 0.04% (e.g., 0% to about 0.02%, about 0.01% to about 0.03%, about 0.03% to about 0.04%) based on the total weight of the alloy. For example, the alloy is about 0.001%, about 0.005%, about 0.01%, about 0.011%, about 0.012%, about 0.013%, about 0.014%, about 0.015%, about 0.016%, about 0.017%, about 0.018%, about 0.019%, about 0.02%, about 0.021%, about 0.022%, about 0.023%, about 0.024%, about 0.025%, about 0.026%, about 0.027%, about 0.028%, about 0.029%, about 0.03%, about 0.031%, about 0.032%, about 0.033%, about 0.034%, about It may contain 0.035%, about 0.036%, about 0.037%, about 0.038%, about 0.039%, or about 0.04% of Ni. In certain embodiments, Ni is not present in the alloy (i.e., 0%). All are expressed in wt. %.

[0052] Optionally, the alloy composition may additionally contain other trace elements, sometimes referred to as impurities, in amounts of about 0.05% or less, about 0.04% or less, about 0.03% or less, about 0.02% or less, or about 0.01% or less, respectively. These impurities may include, but are not limited to, V, Ga, Ca, Hf, Sr, Sc, Sn, or combinations thereof. Thus, V, Ga, Ca, Hf, Sr, Sc, and Sn may be present in the alloy in amounts of about 0.05% or less, about 0.04% or less, about 0.03% or less, about 0.02% or less, or about 0.01% or less. In certain embodiments, the sum of all impurities does not exceed about 0.15% (e.g., 0.1%). All are expressed in wt. %. In certain embodiments, the remainder of the alloy is aluminum.

[0053] Continuous heat treatment process

[0054] Specific embodiments and features of the present invention relate to a continuous heat treatment process in which a metal strip is solution-treated and rapidly cooled, and then thermally spiked and coiled at a high temperature (e.g., a temperature in the range of 120°C to 300°C) as described below. In certain embodiments, the metal strip is a heat-treatable alloy, e.g., a heat-treatable aluminum alloy. In certain embodiments, the thermally spiked metal strip is cooled before or after coiling. In certain embodiments, the thermally spiked metal strip is cooled naturally only before or after coiling. In some embodiments, the coil may be cooled after coiling at the end of the continuous heat treatment process (e.g., using cooling fan(s)). In certain embodiments, the metal strip itself may be produced from scalping, homogenization, hot rolling, optionally batch annealing, and cold rolling of a cast ingot.

[0055] The continuous heat treatment process can be operated at a specific line speed. For example, the continuous heat treatment process can be operated at a line speed of 5 meters / min or more, e.g., 10 meters / min or more, 20 meters / min or more, 25 meters / min or more, 30 meters / min or more, 40 meters / min or more, 50 meters / min or more, 60 meters / min or more, 70 meters / min or more, 80 meters / min or more, 90 meters / min or more, 100 meters / min or more, 10 meters / min to 100 meters / min, 20 meters / min to 80 meters / min, 30 meters / min to 70 meters / min, or 40 meters / min to 60 meters / min.

[0056] Solution

[0057] Solution treatment allows a desired amount of alloying elements present in a specific alloy to be added to a solution (e.g., an aluminum solid solution). In some embodiments, the dissolving step comprises dissolving a metal strip (e.g., plate, shade, sheet, or foil) at room temperature to about 400°C to about 590°C (e.g., about 450°C to about 575°C, about 400°C to about 525°C, about 450°C to about 510°C, about 520°C to about 590°C, about 520°C to about 580°C, about 520°C to about 560°C, about 530°C to about 570°C, about 545°C to about 575°C, about 550°C to about 570°C, about 555°C to about 565°C, about 540°C to about 560°C, about 540°C to about 575°C, about It may include heating to a temperature of 560°C to about 580°C, about 550°C to about 575°C, about 540°C, about 550°C, about 560°C, or about 570°C.

[0058] In certain embodiments, the strip may be immersed in the corresponding temperature for a period of time. In certain embodiments, it is permitted to immerse the strip briefly (e.g., up to about 5 minutes, from about 10 seconds to about 5 minutes, from about 1 second to about 3 minutes, or from about 5 seconds to about 5 minutes). For example, the strip may be immersed at a suitable temperature (e.g., about 525°C to about 590°C) for less than 20 seconds, less than 25 seconds, less than 30 seconds, less than 35 seconds, less than 40 seconds, less than 45 seconds, less than 50 seconds, less than 55 seconds, less than 60 seconds, less than 65 seconds, less than 70 seconds, less than 75 seconds, less than 80 seconds, less than 85 seconds, less than 90 seconds, less than 95 seconds, less than 100 seconds, less than 105 seconds, less than 110 seconds, less than 115 seconds, less than 120 seconds, less than 125 seconds, less than 130 seconds, less than 135 seconds, less than 140 seconds, less than 145 seconds, less than 150 seconds, or less than 5 minutes or any value in between.

[0059] In certain embodiments, solution treatment may be performed in a continuous process, for example, in a continuous heat treatment line. In some embodiments, the continuous process (e.g., a continuous heat treatment line) may have a specific line speed.

[0060] In a specific embodiment, the solution treatment step is performed on the metal strip immediately after the hot rolling step and / or the cold rolling step. In another embodiment, the solution treatment step is performed on the metal strip after the hot rolling step and / or the cold rolling step (e.g., after > 48 hours). In a specific embodiment, the solution treatment step is performed after the annealing and cold rolling steps.

[0061] Rapid cooling

[0062] Without being bound by theory, the metal strip can be cooled very rapidly to fix solute elements and excess voids in the metal (e.g., aluminum) matrix of the metal strip. Thus, in some embodiments, after solution treatment, the metal strip can be rapidly cooled to lower the temperature of the metal strip. In some embodiments, the transfer time from the solution treatment furnace to the cooling medium is very short (e.g., less than 1 second, less than 2 seconds, less than 3 seconds, less than 5 seconds, less than 10 seconds, less than 15 seconds, less than 20 seconds, less than 25 seconds, less than 30 seconds, less than 35 seconds, less than 40 seconds, less than 45 seconds, less than 50 seconds, less than 55 seconds, less than 1 minute, less than 2 minutes, less than 3 minutes, less than 4 minutes, less than 5 minutes, less than 10 minutes). The transfer time of the solution-treated metal begins from the moment the furnace door starts to open and proceeds until the point where the aluminum alloy is completely submerged and immersed. If the transfer time exceeds the specified time limit, incomplete solution treatment may occur, which implies non-uniform metallurgical and mechanical conditions of the specific alloy.

[0063] In a specific embodiment, after solution treatment, the metal strip may be cooled at a rate that can vary between about 1°C / s and 400°C / s in a rapid cooling step based on a selected gauge. For example, the rapid cooling rate may be about 50°C / s to about 375°C / s, about 60°C / s to about 375°C / s, about 70°C / s to about 350°C / s, about 80°C / s to about 325°C / s, about 90°C / s to about 300°C / s, about 100°C / s to about 275°C / s, about 125°C / s to about 250°C / s, about 150°C / s to about 225°C / s, about 175°C / s to about 200°C / s, about 10°C / s to about 125°C / s, or about 20°C / s to about 125°C / s. In some embodiments, the metal strip may be rapidly cooled to a temperature of less than 100°C, e.g., less than 90°C, less than 80°C, less than 70°C, less than 60°C, less than 50°C, less than 45°C, less than 40°C, less than 35°C, less than 30°C, less than 25°C, less than 20°C, less than 15°C, about 20°C to about 80°C, about 20°C to about 70°C, about 20°C to about 60°C, about 25°C to about 50°C, about 25°C to about 40°C, up to about 20°C, up to about 25°C, up to about 30°C, up to about 35°C, about 40°C, about 45°C, or up to about 50°C.

[0064] In certain embodiments, the metal strip may be rapidly cooled using a liquid (e.g., water) and / or gas or other selected cooling medium. In certain embodiments, the metal strip is rapidly cooled with air. In certain embodiments, the metal strip may be rapidly cooled with water.

[0065] Thermal spikes

[0066] Metal strips may be subjected to thermal spike treatment at elevated temperatures. As described herein, using a thermal spike temperature higher than that previously disclosed in the art has helped to achieve unexpected benefits of the present disclosure. In some embodiments, the thermal spike temperature (i.e., the highest temperature to which the metal strip is exposed, which does not necessarily have to be the temperature of the metal strip itself) may be in the range of about 100°C to about 300°C, e.g., about 120°C to about 300°C, about 150°C to about 300°C, about 170°C to about 280°C, about 180°C to about 270°C, about 190°C to about 260°C, about 200°C to about 250°C, about 210°C to about 250°C, about 220°C to about 250°C, about 220°C to about 240°C, about 200°C, about 210°C, about 220°C, about 230°C, about 240°C, or about 250°C. There is. In some embodiments, the metal strip itself reaches a thermal spike temperature within 100°C, for example, within 90°C, within 80°C, within 70°C, within 60°C, within 50°C, within 40°C, within 30°C, within 20°C, within 10°C, within 5°C, and within 1°C.

[0067] In some embodiments, the thermal spike treatment occurs after the metal strip is solution-treated and air-cooled. In some embodiments, the thermal spike treatment may occur, for example, as part of a continuous heat treatment process, at the same processing line speed as the solution treatment and rapid cooling.

[0068] Conventional 6XXX materials of T4 or T4P temper contain a large number of fine metastable clusters and zones uniformly distributed throughout the metal matrix. In conventional processes, during paint curing, some fine unstable clusters / zones are redissolved into the metal matrix, while others improve material strength due to age hardening. The process described herein allows the alloy material to exhibit an enhanced aging response (hardness response). Without being bound by theory, it is believed that coiling and coil cooling following a thermal spike between 150 and 320°C (e.g., in a long reheating furnace), for example, about 150 to 300°C, about 180 to 300°C, or about 150 to 225°C, forms some clusters and zones and enhances the precipitation process during coil cooling.

[0069] The duration during which the temperature is maintained at the peak heat spike temperature may vary from 0 to any practical time depending on the situation. In some embodiments, heat spike processing occurs at the processing line speed of a continuous heat processing process (e.g., in a long furnace). For example, the processing line speed and heat spike processing speed may occur at a speed of about 1 meter / min to about 120 meters / min, for example, about 2 meters / min to about 110 meters / min, about 5 meters / min to about 100 meters / min, about 10 meters / min to about 600 meters / min, about 20 meters / min to about 500 meters / min, about 25 meters / min to about 500 meters / min, about 30 meters / min to about 400 meters / min, about 40 meters / min to about 350 meters / min, about 50 meters / min to about 300 meters / min, or about 100 meters / min to about 250 meters / min. In fact, this period is usually 0 to 5 minutes at most, for example, about 1 second to about 5 minutes, about 2 seconds to about 4 minutes, about 3 seconds to about 3 minutes, about 5 seconds to about 2 minutes, about 7 seconds to about 1 minute, or about 10 seconds to about 30 seconds.

[0070] In some embodiments, the thermal spike treatment is performed at a heating rate of about 1°C / min to about 50°C / s (i.e., the temperature of the metal strip increases at a constant rate) (e.g., about 1°C / s to about 40°C / s, about 2°C / s to about 40°C / s, about 3°C / s to about 35°C / s, about 3°C / s to about 30°C / s, about 5°C / s to about 30°C / s, about 10°C / s to about 25°C / s, or about 2°C / s to about 10°C / s).

[0071] In some embodiments, the heat spike treatment is performed in a reheating furnace, e.g., a continuous reheating furnace. In some embodiments, the heat spike treatment is performed in a long reheating furnace. For example, the furnace may have an effective length (i.e., the length at which the metal strip is heated in a continuous process) of at least 10 meters, e.g., at least 20 meters, at least 25 meters, at least 30 meters, at least 40 meters, at least 50 meters, at least 60 meters, at least 70 meters, at least 80 meters, at least 90 meters, and at least 100 meters. Without limiting the present disclosure, this may allow for increased line speeds and / or heat spike times.

[0072] prescription

[0073] In some embodiments, the metal strip does not undergo an aging process. In some embodiments, thermal spikes of the metal strip combined with coiling and / or cooling of the metal strip may substitute for age hardening.

[0074] cooling

[0075] In some embodiments, the metal strip may be cooled after the heat spike treatment. In some embodiments, such cooling may occur after coiling. In other embodiments, such cooling may occur before coiling. And in some embodiments, cooling may occur before and / or after coiling. For example, in some embodiments, the metal strip may be air-cooled, for example, using at least one fan. In some embodiments, the metal strip is cooled only naturally (for example, during the passage of the strip between the heat spike treatment and coiling), which means that there is no device or process used to cool the metal strip before coiling. For example, the metal strip may be exposed only to ambient conditions (for example, at the line speed of a continuous heat treatment process) before coiling. In some embodiments, the metal strip is cooled naturally only after coiling. As described herein, natural cooling (for example, exposure only to ambient conditions before cooling) does not fall under the terms "cooling" or "cooled" as previously used in the art. In some embodiments, cooling or natural cooling may be performed until the metal strip reaches ambient temperature.

[0076] In some embodiments, the metal strip and / or coiled metal strip may be cooled at a rate of about 60°C / hour or less or naturally cooled (e.g., about 50°C / hour or less, about 40°C / hour or less, about 30°C / hour or less, about 20°C / hour or less, about 10°C / hour or less, about 5°C / hour or less, about 3°C / hour or less, about 2.5°C / hour or less, about 2°C / hour or less, about 1.5°C / hour or less, about 1°C / hour or less, or about 0.8°C / hour or less).

[0077] Method for manufacturing metal strips

[0078] In certain embodiments, the disclosed metal (e.g., alloy) strip composition is the product of the disclosed method. Without limiting the present disclosure, alloy properties, such as aluminum alloy properties, are partially determined by the formation of a microstructure during the manufacture of the alloy. In certain embodiments, the method of manufacturing the alloy composition may influence or even determine whether the alloy will have properties suitable for a desired application.

[0079] The metal (e.g., alloy) strips described herein may be cast into ingots using a casting method. For example, the casting process may include a direct cooling (DC) casting process. In other examples, the casting process may include a continuous casting process. The cast ingots may undergo additional processing steps. In one example that is not limited, the processing method includes scalping, homogenization, hot rolling, selective batch annealing and cold rolling, rapid cooling, heat spike treatment and coiling, and subsequent cooling (e.g., fan cooling after coiling) prior to the aforementioned solution treatment.

[0080] Homogenization

[0081] In some embodiments, the homogenization step may include one-step homogenization or two-step homogenization. In one example of the homogenization step, one-step homogenization is performed by heating an ingot made from the alloy composition described herein to achieve a peak metal temperature (PMT) of about or at least about 500°C (e.g., at least 520°C, at least 530°C, at least 540°C, at least 550°C, at least 560°C, at least 570°C, or at least 580°C). For example, the ingot may be heated to a temperature of about 520°C to about 580°C, about 530°C to about 575°C, about 535°C to about 570°C, about 540°C to about 565°C, about 545°C to about 560°C, about 530°C to about 560°C, or about 550°C to about 580°C. In some cases, the heating rate to the peak metal temperature may be about 100°C / hour or less, 75°C / hour or less, 50°C / hour or less, 40°C / hour or less, 30°C / hour or less, 25°C / hour or less, 20°C / hour or less, 15°C / hour or less, or 10°C / hour or less. In other cases, the heating rate to the peak metal temperature may be about 10°C / min to about 100°C / min (e.g., about 10°C / min to about 90°C / min, about 10°C / min to about 70°C / min, about 10°C / min to about 60°C / min, about 20°C / min to about 90°C / min, about 30°C / min to about 80°C / min, about 40°C / min to about 70°C / min, or about 50°C / min to about 60°C / min).

[0082] Then, the ingot is allowed to be immersed for a certain period of time (i.e., maintained at the indicated temperature). According to one non-limiting example, the ingot is allowed to be immersed for up to about 8 hours (e.g., from about 5 seconds to 8 hours, or from about 30 minutes to about 8 hours). For example, the ingot may be immersed at a temperature of at least 500°C for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or any value in between.

[0083] In another example of a homogenization step, a two-step homogenization is performed by heating an ingot made from the alloy composition described herein to achieve a first temperature of about or at least about 480°C to about 520°C. For example, the ingot may be heated to a first temperature of about 480°C, 490°C, 500°C, 510°C, or 520°C. In a specific embodiment, the heating rate to the first temperature may be about 10°C / min to about 100°C / min (e.g., about 10°C / min to about 90°C / min, about 10°C / min to about 70°C / min, about 10°C / min to about 60°C / min, about 20°C / min to about 90°C / min, about 30°C / min to about 80°C / min, about 40°C / min to about 70°C / min, or about 50°C / min to about 60°C / min). In another embodiment, the heating rate to the first temperature may be about 10°C / hour to about 100°C / hour (e.g., about 10°C / hour to about 90°C / hour, about 10°C / hour to about 70°C / hour, about 10°C / hour to about 60°C / hour, about 20°C / hour to about 90°C / hour, about 30°C / hour to about 80°C / hour, about 40°C / hour to about 70°C / hour, or about 50°C / hour to about 60°C / hour).

[0084] Next, the ingot is allowed to be immersed for a certain period of time. In some cases, the ingot is allowed to be immersed for up to about 6 hours (e.g., from 5 seconds to 6 hours, or from 30 minutes to 6 hours). For example, the ingot may be immersed at a temperature of about 480°C to about 520°C for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or any time in between.

[0085] In the second step of the two-step homogenization process, the ingot may be further heated from the first temperature to a second temperature of about 520°C (e.g., over 520°C, over 530°C, over 540°C, over 550°C, over 560°C, over 570°C, or over 580°C). For example, the ingot may be heated to a second temperature of about 520°C to about 580°C, about 530°C to about 575°C, about 535°C to about 570°C, about 540°C to about 565°C, about 545°C to about 560°C, about 530°C to about 560°C, or about 550°C to about 580°C. The heating rate to the second temperature may be about 10°C / min to about 100°C / min (e.g., about 20°C / min to about 90°C / min, about 30°C / min to about 80°C / min, about 10°C / min to about 90°C / min, about 10°C / min to about 70°C / min, about 10°C / min to about 60°C / min, about 40°C / min to about 70°C / min, or about 50°C / min to about 60°C / min).

[0086] In another embodiment, the heating rate to the second temperature may be about 10°C / hour to about 100°C / hour (e.g., about 10°C / hour to about 90°C / hour, about 10°C / hour to about 70°C / hour, about 10°C / hour to about 60°C / hour, about 20°C / hour to about 90°C / hour, about 30°C / hour to about 80°C / hour, about 40°C / hour to about 70°C / hour, or about 50°C / hour to about 60°C / hour).

[0087] Next, the ingot is allowed to be immersed for a certain period of time. In some cases, the ingot is allowed to be immersed for up to about 6 hours (e.g., from 5 seconds to 6 hours, or from 30 minutes to 6 hours). For example, the ingot may be immersed at a temperature of about 520°C to about 580°C for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or any time in between.

[0088] Hot rolling

[0089] In some embodiments, a hot rolling step may be performed after the homogenization step. In some cases, the ingot is placed and hot rolled in an entry temperature range of about 380°C to about 540°C. For example, the entry temperature may be, for example, about 505°C, 510°C, 515°C, 520°C, 525°C, 530°C, 535°C, or 540°C. In certain cases, the hot roll exit temperature may be in the range of about 230°C to about 420°C (for example, about 330°C to about 370°C). For example, the hot roll exit temperature may be approximately 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, 360°C, 365°C, 370°C, 375°C, or 380°C and may be combined with one of the above entry temperatures.

[0090] In some cases, the ingot may be hot-rolled to a thickness gauge of about 2 mm to about 15 mm (e.g., about 5 mm to about 12 mm thickness gauge), referred to as a sheet. For example, the ingot may be hot-rolled to a thickness gauge 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. In some cases, the ingot may be hot-rolled to a thickness greater than 15 mm (i.e., a plate). In other cases, the ingot may be hot-rolled to a thickness of less than 4 mm (i.e., a sheet). In some embodiments, the hot-rolled coil may be batch-annealed prior to cold-rolling. In certain embodiments, annealing may be performed after the first or second cold pass and before the final cold pass.

[0091] Cold rolling

[0092] In some embodiments, the cold rolling step may be performed after the hot rolling step. In certain embodiments, the product rolled from the hot rolling step may be cold rolled to become a sheet (e.g., approximately less than 4.0 mm). In certain embodiments, the rolled product is cold rolled to a thickness of 0.6 mm to 1.0 mm, 1.0 mm to 3.0 mm, or 3.0 mm to 4.0 mm. In certain embodiments, the alloy is cold rolled to a thickness of approximately 3.5 mm or less, 3 mm or less, 2.5 mm or less, 2 mm or less, 1.5 mm or less, or 1 mm or less. For example, the rolled product can be cold-rolled to a thickness of about 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, or up to 3.0mm.

[0093] An embodiment of the above process can be used to produce a metal strip as described. Additionally, as discussed, the metal strip can be processed using the disclosed continuous heat treatment process to produce a heat-treated article. In some embodiments, the entire process of producing the metal strip and heat-treating the metal strip is continuous. Then, the heat treatment process described for the metal strip can be applied.

[0094] example

[0095] These exemplary examples are provided to introduce the reader to the general subject matter discussed in this specification and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional features and examples with reference to drawings in which similar numbers represent similar elements, and directional descriptions are used to describe exemplary embodiments but, like exemplary embodiments, should not be used to limit the content of this disclosure. Elements included in the drawings of this document may not be drawn in proportion.

[0096] Example 1

[0097] A direct-cooled cast ingot of an alloy containing 0.62 wt.% Mg, 0.75 wt.% Si, 0.21 wt.% Cu, 0.13 wt.% Mn, 0.2 wt.% Fe, and 0.02 wt.% Ti is scalped, homogenized, hot-rolled, and cold-rolled to produce a final 0.9 mm gauge. The cold-rolled strip of the coil (Example 1) is solution-treated between 540°C and 575°C in a continuous process where the strip moves at a speed of 60 m / min prior to coiling, then quenched to 50°C or lower, and heat-spikemed in a furnace set at 220°C. At the end of the process, there was no intentional cooling (i.e., natural cooling only) between the heat spike and coiling. The strip was sampled at the flying shear position of the line before coiling and after cooling at the finishing line.

[0098] Samples taken before and after coiling were tested after 6 days of continuous annealing solution treatment ("CASH") using ASTM samples under as-is paint baking conditions (2% + 20 min @ 185°C - designated as T8X). Table 5 shows that the transverse yield strength of sheet samples taken before flying shear and coiling is 117 and 229 MPa at the current state and paint baking tempers, respectively, which is slightly higher than the typical values ​​expected for this alloy. However, the yield strength (YS) values ​​were higher for both tempers of the coil-cooled samples, which is quite surprising given that existing products coiled at similar temperatures without thermal spikes do not exhibit such high characteristics. Such products are typically produced by coiling at a T4 temper through separate batch aging heat treatment. Without being bound by theory, the initiated thermal spike process is believed to accelerate the age hardening process during coil cooling.

[0099]

[0100] Examples 2 to 5

[0101] Direct-cooled cast ingots of four different alloys having the compositions shown in Table 6 were scalped, homogenized, and hot- and cold-rolled to make final gauge. Cold-rolled coil strips, such as those in Example 1, were solution-heat-treated between 540°C and 575°C in a continuous process moving at a speed of 60 m / min before being coiled at the end of the line, then rapidly cooled to 50°C or lower, and then heat-spiketed in a furnace set at 250°C. The strips were sampled at the flying shear position of the line before being coiled and after cooling at the finishing line.

[0102]

[0103] Samples of Examples 2 through 5, taken before and after coiling, were tested a few days after cache using ASTM samples under as-is and T8X conditions (2% + 20 min @ 185°C), with the exception of coil Example 3, which was tested using JIS samples and paint baking temper (2% + 20 min @ 170°C). Table 7 summarizes the tensile properties of samples of Examples 2 through 5 taken at the flying shear and finish lines. Table 7 confirms the results of Example 1 by showing that all four alloys exhibit significantly higher strength in the coil-cooled samples compared to the flying shear samples before coil cooling.

[0104]

[0105] Examples 6 to 8

[0106] As with Examples 2 through 5, three cold-rolled coils of Alloy Example 4 were solution-treated in a continuous heat treatment line, heat-spiked in the range of 200 to 250°C, and coiled at the end of the line without intentional cooling (i.e., natural air cooling only) after heat spiking. Samples of Examples 6 through 8, obtained before coiling in flying shear and coiled at the finish line, were tested using ASTM samples in both as-is and T8X temper. The results of this experiment, summarized in Table 8, show that the heat-spiked and coil-cooled samples exhibit higher strength compared to the flying shear samples, confirming the effect of heat spiking and the results of the previous examples.

[0107] The same coils for Examples 6 through 8 listed in Table 8 were melted in the same manner as the initial melting, but the reheaters were set to automatic mode, 100°C, and 150°C, respectively. The results for the re-solvent coils are summarized in Table 9, which shows that strength increases with increasing thermal spike temperature, but the degree of increase is lower than that observed at >200°C. As can be seen from these results, the thermal spike temperature has a significant effect on the strength of the coil-cooled samples. This observation demonstrates that by appropriately selecting the alloy and thermal temperature, various combinations of tensile properties can be produced without an additional batch aging process.

[0108]

[0109]

[0110] Examples 9 to 10

[0111] The purpose of this experiment was twofold: first, to investigate the effect of heating rate during a heat spike on the strength of AA6111 coils through changes in line speed (52 m / min vs. 41 m / min), and second, to compare the tensile properties of AA6111 with those of a common 5xxx alloy supplied with H3X temper.

[0112] A pair of 2 mm gauge cold-rolled coils (Examples 9 and 10) of AA6111 alloy containing 0.76 wt.% Cu, 0.74 wt.% Mg, 0.66 wt.% Si, 0.27 wt.% Fe, and 0.74 wt.% Mn were solution-treated between 520 and 560°C, rapidly cooled to 50°C or lower, and hot-spike in a furnace at 250°C before being coiled at the end of the continuous process. The coils of Examples 9 and 10 were heat-treated at speeds of 52 meters / min and 41 meters / min, respectively. Samples obtained from each coil of the finishing line were tested as is and using ASTM samples at T8X temper. The results of this experiment are summarized in Table 10. Two coils processed at two different line speeds exhibit very similar properties for both T4 and T8X tempers, indicating that variations in line speed within the strip speed range of 41 m / min to 52 m / min do not significantly affect tensile properties. The higher strength of the T4 temper can potentially be used in structural parts that provide downgassing possibilities or eliminate post-forming heat treatment.

[0113]

[0114]

[0115] Table 11 summarizes the typical ASTM tensile properties of commonly used 5xxx alloys. The ranges for YS, UTS, and total elongation values ​​are 190 to 290 MPa, 230 to 325 MPa, and 7 to 16%, respectively. The YS of the AA6111 coil in Table 10 is close to that of 5086-H34, which has a significantly higher total elongation. This suggests that AA6111 material produced by the process described herein can replace 5086-H34 products while providing better total elongation. The same alloy can be produced at lower strengths through thermal spiking at lower temperatures to match the strength of other AA5xxx products. Various strength combinations can also be obtained by changing the alloy chemistry along with other process variables.

[0116] Thermally spiked AA6xxx does not exhibit any major natural aging. Along with similar strength and total elongation, these characteristics provide a very attractive alternative to 5xxx products requiring high formability.

[0117] Example 11

[0118] Direct-cooled cast ingots of AA6111 alloy containing 0.69 wt.% Mg, 0.57 wt.% Si, 0.51 wt.% Cu, 0.19 wt.% Mn, 0.23 wt.% Fe, and 0.01 wt.% Ti were scalped, homogenized, and hot- and cold-rolled to produce a final 2.3 mm gauge. The cold-rolled coil strips were solution-heat-treated at 525°C, rapidly cooled to below 50°C, heat-spikeped into a furnace to heat the strips to approximately 190°C in a continuous process, and re-rolled at a coil-wide sidewall temperature of approximately 135°C. The line speed was controlled to 17 to 20 meters / min to ensure the strip temperature at the furnace exit was close to 190°C. At the end of the process, there was no intentional cooling between the heat spike and coiling. The coil temperature was reduced from 135°C to 85°C at approximately 2.8°C / h, and additional cooling to the surroundings was less than 2°C / h. The coil was sampled 5 days after heat treatment, and ASTM samples were used as is and tested with various paint baking tempers.

[0119] Table 12 shows the average transverse ASTM tensile properties of sheet samples taken from coil-cooled samples. The yield strength (YS) and ultimate tensile strength (UTS) of the coil-cooled samples are 277 and 344 MPa, respectively, with a total elongation value of 17%. These properties differ significantly from AA6111 coils typically produced at coiling temperatures below 100°C, which generally exhibit a YS of 125 MPa, a UTS of 230 MPa, and a total elongation of 24%. The characteristics of the coils are typical of tempers aged at 140°C for nearly 50 hours. Without being bound by theory, thermal spikes accelerate the hardening process during coil cooling. As shown in Table 12, the alloy was found to exhibit a slight increase in strength when aged at high temperatures with or without prior deformation. The thermal spike process produces coils with strength at better elongation and relatively shorter aging times than expected from a typical batch annealing process with an elongation of less than 14%.

[0120]

[0121] The foregoing description of the embodiments, including the exemplified examples, is provided for illustrative and illustrative purposes only and is not intended to encompass or limit the exact forms disclosed. Various modifications, applications, and uses thereof will be apparent to those skilled in the art.

[0122] As used below, any reference to a series of embodiments should be understood separately as a reference to each of these embodiments (e.g., “Examples 1 through 4” should be understood as “Examples 1, 2, 3 or 4”).

[0123] Example 1 is a process for manufacturing a heat-treated aluminum alloy, comprising the steps of: casting a metal strip; solution-treating the cast metal strip at a line speed to produce a solution-treated metal strip; air-cooling the solution-treated metal strip to produce a cooled metal strip; continuously heat-spiking the cooled metal strip at a line speed at a temperature of 150°C to 300°C to produce a heat-spiked metal strip; and coiling the heat-spiked metal strip to produce a coiled metal strip.

[0124] Example 2 is the process of Example 1, and further includes the step of cooling the heat-spikeped metal strip after heat spiking.

[0125] Example 3 is a process of any one of the examples, wherein the step of cooling a heat-spikeped metal strip includes the step of air-cooling the heat-spikeped metal strip.

[0126] Example 4 is the process of Example 1, where only natural cooling of the heat-spikeped metal strip occurs between the heat spike and the coiling.

[0127] Example 5 is a process of any one of the examples, wherein the step of coiling a heat-spikeped metal strip is performed continuously at the end of a continuous line.

[0128] Example 6 is a process of any one of the examples, in which the cooling rate of the heat-spikeped metal strip is less than 10°C / hour.

[0129] Example 7 is a process of any one of the examples, in which the cooling rate of the heat-spikeped metal strip is less than 2°C / hour.

[0130] Example 8 is a process of any one of the examples, and the coiling temperature of the heat-spikeped metal strip is 70°C to 130°C.

[0131] Example 9 is a process of any one of the examples, wherein the coiling of the heat-spikeped metal strip is performed at a temperature of 60°C or higher.

[0132] Example 10 is a process of any one of the examples, and the line speed is at least 10 meters / min.

[0133] Example 11 is a process of any one of the examples, and the line speed is 10 meters / min to 120 meters / min.

[0134] Example 12 is a process of any one of the examples, and the heat spike temperature is 150°C to 280°C.

[0135] Example 13 is a process of any one of the examples, and the heat spike temperature is 200°C to 250°C.

[0136] Example 14 is a process among the examples, wherein the metal strip casting includes continuous casting.

[0137] Example 15 is a process among the examples in which metal strip casting includes direct cooling (DC casting).

[0138] Example 16 further includes the steps of homogenizing, hot rolling, and cold rolling the metal strip after casting and before solution treatment as a process of any one of the examples.

[0139] Example 17 is a process of any one of the examples in which the thermal spiking of the cooled metal strip is performed in a reheating furnace at least 12 meters long.

[0140] Example 18 is a process of any one of the examples, and the solution temperature is about 480°C to about 590°C.

[0141] Example 19 is a process of any one of the examples, wherein air cooling includes cooling the solution-treated metal strip to less than 50°C.

[0142] Example 20 is a heat-treated metal strip formed by the process of any example.

Claims

Claim 1 A method for manufacturing a heat-treated 6xxx aluminum alloy comprises the steps of: casting a metal strip; solutionizing the cast metal strip at a line speed to produce a solutionized metal strip; air cooling the solutionized metal strip to produce a cooled metal strip; thermally spiking the cooled metal strip at a line speed at a temperature of 150°C to 320°C to produce a thermally spiked metal strip; and coiling the thermally spiked metal strip to produce a coiled metal strip, wherein the coiling of the thermally spiked metal strip is performed at a temperature of 110°C to 160°C. Claim 2 A method according to claim 1, further comprising the step of cooling the coiled metal strip. Claim 3 In paragraph 2, the step of cooling the coiled metal strip comprises the step of air-cooling the heat-spikeped metal strip. Claim 4 A method according to claim 1, wherein only natural cooling of the heat-spikeped metal strip occurs between the heat spiking and the coiling. Claim 5 A method according to claim 1, wherein the step of coiling the heat-spikeped metal strip is performed continuously at the end of a continuous line. Claim 6 A method according to paragraph 2, wherein the cooling of the coiled metal strip is performed at a rate of 10°C / hour or less. Claim 7 delete Claim 8 A method according to claim 1, wherein the line speed is 10 meters / min or more. Claim 9 A method according to claim 1, wherein the line speed is 10 meters / min to 120 meters / min. Claim 10 The method of claim 1, wherein the heat spike temperature is 150°C to 300°C. Claim 11 A method according to claim 1, further comprising the steps of homogenizing, hot rolling, and cold rolling the metal strip before solution treatment. Claim 12 A method according to claim 1, wherein the step of heat-spiking the cooled metal strip is performed in a reheater furnace having a length of at least 12 meters. Claim 13 A method according to claim 1, wherein the solution temperature is 480°C to 590°C. Claim 14 A method according to claim 1, wherein the step of air-cooling the solution-treated metal strip comprises the step of cooling the solution-treated metal strip to less than 50°C. Claim 15 A heat-treated metal strip formed by the method of claim 1.

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