CA3229084A1 - Heat treated aluminum sheets and processes for making - Google Patents

Abstract

Described herein is a continuous heat treatment process for metals, where a strip of a metal, e.g., a heat treatable alloy, is solutionized, rapidly cooled, thermally spiked at elevated temperature, and coiled. The continuous heat treatment process does not involve or need batch aging treatment.

Description

HEAT TREATED ALUMINUM SHEETS AND PROCESSES FOR MAKING
Cross-Reference to Related Application [0001] This application claims the benefit of U.S. Provisional Application No.
63/263,052, filed October 26,2021, which is incorporated herein by reference in its entirety.
Technical Field

[0002] The present disclosure relates to metal processing generally and more specifically to continuous heat treatment processes for metals, where a strip of a heat treatable alloy is solutionized, rapidly cooled, thermally spiked, and coiled.
Background

[0003] Manufacturers of metal articles are faced with the challenge of providing thin gauge materials that have both good formability and high strength after an article has been formed and paint-cured. As one example, the automobile industry requires such products for use in body panels or structural members with reduced weight for improving vehicle economy and fuel efficiency.

[0004] Heat-treatable metals, such as heat-treatable aluminum alloys, can, in some cases, achieve these objectives. Heat-treatable alloys are generally those containing soluble alloying constituents in amounts that exceed their room temperature solubility limits. These alloys can contain hardening elements (e.g., Mg, Si and/or Co) to provide hardening during aging, and potentially other elements, like Fe, Mn and possibly Cr, to control the formability and grain size. Such alloys may develop enhanced properties upon being subjected to working and/or heating, followed by a quenching step. Heat treatment of metals is traditionally performed by precipitation hardening involving the steps of solution heat treatment and aging. In a solution heat treatment process, a metal strip, e.g., an aluminum alloy strip, is solutionized, rapidly cooled and, may or may not be thermally spiked, depending on the product requirements. The purpose of the solutionizing procedure is to take the alloying (solute) elements into solution, which will eventually strengthen the particular alloy. The purpose of the rapid cooling is to lock the solute elements and excess vacancies into the metal (e.g., aluminum) matrix of the metal strip. The purpose of thermal spiking is to ensure that the coil is coiled between 60 C to 110 C and to eliminate the adverse effect of coil storage during which material loses potential strength gain during paint bake of up to 40%. The heat treated metal strip can then undergo an aging procedure.

[0005] As an example, the current process to produce age tempers, requires a batch ageing process where a coil in the T4 temper is heated at 20 C/h to 50 C/h to an elevated temperature ranging from 120 C to 260 C, soaked for >1 hour, and cooled to room temperature. However, the existing thermal treatment and batch aging processes require total cycle times longer than 8 hours plus soak time (>1 hour, often 4-6 hours), added steps and complexity, and precise control over the heat treatment process.
Summary

[0006] The term embodiment and like terms are intended to refer broadly to all of the subject matter of this disclosure and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the claims below. Embodiments of the present disclosure covered herein are defined by the claims below, not this summary. This summary is a high-level overview of various aspects of the disclosure and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this disclosure, any or all drawings and each claim.

[0007] Certain aspects and features of the present disclosure relate to a continuous heat treatment process, where a metal strip is solutionized, rapidly cooled, thermally spiked at an elevated temperature ranging from 120 C to 300 C (e.g., from 200 C to 250 C), and coiled at the rewind located at the end of the continuous line. In some aspects, the continuous heat treatment process and its constituent steps can occur at a particular line speed, for example a line speed of at least 10 meters/min (e.g., at least 40 meters/min;
from 10 meters/min to 100 meters/min, from 40 meters/min to 100 meters/min, or from 10 meters/min to 40 meters/min). In some aspects, the thermal spike treatment can occur in a relatively long reheater furnace, for example a reheater furnace longer than 10 meters. In some aspects, only natural cooling (i.e., no cooling apparatus is used) occurs between thermal spiking and coiling and coiling is carried out in a such a way as to maintain the line speed. In some aspects, the cooling or natural cooling rate after thermal spike treatment is less than 10 C/hour (e.g., less than 2 C/hour) down to ambient temperature, for example.
Therefore, in some aspects, the coiling of the metal strip is performed at a relatively warm temperature, for example at a temperature above 60 C, such as above 110 C, from 70 C to 150 C, from 70 C to 130 C, or from 70 C to 110 C, from 110 C to 150 C, from 110 C to 130 C, or from 110 C to 120 C, for example. In certain aspects, the disclosed process does not include or need a batch aging process to age harden the material.

[0008] The present disclosure is able to produce a product from the disclosed process with thin gauge that has both good formability and high strength using a continuous annealing line without requiring a batch ageing process. The disclosure is particularly beneficial in terms of offering products with tailored combination of properties and hence

9 PCT/US2022/078643 offering the possibility of downgauging or as a potential substitute for 5000 series aluminum alloys supplied in H1X, H2X and H3x tempers.
Detailed Description [0009] Certain aspects and features of the present disclosure relate to a continuous heat treatment process, where a metal strip is solutionized, rapidly cooled, thermally spiked (e.g., by hot air) at an elevated temperature ranging from 120 C to 300 C, coiled, and cooled or naturally cooled (before and/or after coiling), for example at a rate of less than or equal to C/hour, preferably at a rate less than or equal to 2 C/hour. In certain embodiments, the metal strip is a heat treatable alloy, for example, a heat treatable aluminum alloy.

[0010] In certain embodiments, the thermal spike temperature is kept between 120 C
and 300 C (e.g., from about 150 C to 300 C). The use of thermal spike at higher temperature can induce the formation of clusters which act as nuclei to form hardening particles during subsequent coiling and coil cooling.

[0011] The present disclosure improves over existing technology in part by eliminating the batch process altogether by using a reheater furnace to thermally spike a metal strip to a desired temperature at the speed of the line before coiling.
For example, a continuous annealing line can be used without requiring a batch aging process.
The thermally spiked coil in combination with coil cooling provides appropriate conditions for age hardening. The use of thermal spiking and coiling at warm coiling temperatures to tailor a variety of properties is achieved by the present disclosure. The disclosure is particularly beneficial in terms of offering products with tailored combination of properties and hence offering the possibility of downgauging.

[0012] Aspects and features of the present disclosure are described herein with respect to metal strips, such as continuously-cast or uncoiled metal strips, however the present disclosure can also be used with any suitable metal products processed on a continuous annealing line. The aspects and features of the present disclosure can be especially suitable for any metal product having flat surfaces. The aspects and features of the present disclosure can be especially suitable for any metal product having parallel or approximately parallel opposing surfaces (e.g., top and bottom surfaces).
Approximately parallel can include parallel or within 10, 20, 30, 40, 50, 60, 70, 80, 9 , or 10 of parallel, or more.
Definitions and Descriptions

[0013] 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.

[0014] In this description, reference is made to alloys identified by AA
numb ers and other related designations, such as "series" or "7xxx." For an understanding of the number designation system most commonly used in naming and identifying aluminum and its alloys, see "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys" or "Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot," both published by The Aluminum Association.

[0015] 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.

[0016] 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.

[0017] As used herein, a sheet generally refers to an aluminum product having a thickness of less than about 4 mm. For example, a sheet may have a thickness of less than about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, or less than about 0.3 mm (e.g., about 0.2 mm).

[0018] As used herein, a foil generally refers to a metal product having a thickness less than about 0.2 mm. For example, a foil may have a thickness of less than about 0.2 mm, less than about 0.15 mm, less than about 0.10 mm, less than about 0.05 mm, less than about 0.04 mm, less than about 0.03 mm, less than about 0.02 mm, or less than about 0.01 mm (e.g., about 0.006 mm).

[0019] As used herein, direct chill (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 capable of withdrawing at the rate of solidification of the liquid metal in the mold, often resulting in a large and relatively thick ingot (e.g., 1 500 mm wide x 500 mm thick x 5 m long). The ingot can be processed, homogenized, hot rolled, cold rolled, may or may not be annealed after hot rolling or before a final cold rolling pass, and/or heat treated, and otherwise finished before being coiled into a metal strip product distributable to a consumer of the metal strip product (e.g., an automotive manufacturing facility).

[0020] 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.
Continuous casting has been desirable in instances where the entire product can be prepared 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.

[0021] 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 0 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 Ti 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.

[0022] 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 3 0 C. As used herein, the meaning of "ambient conditions" or "ambient environment" can include temperatures of about room temperature, relative humidity of from about 20% to about 100%, and barometric pressure of from about 975 millibar (mbar) to about 1050 mb ar. For example, relative humidity can be about 20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, about 40%, about 41%, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50%, about 51%, about 52%, about 53%, about 54%, about 55%, about 56%, about 57%, about 58%, about 59%, about 60%, ab out 61%, about 62%, about 63%, about 64%, about 65%, about 66%, about 67%, about 68%, about 69%, about 70%, about 71%, about 72%, about 73%, about 74%, about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, about 100%, or anywhere in between. For example, barometric pressure can be about 975 mbar, about 980 mbar, about 985 mbar, about 990 mbar, about 995 mbar, about 1000 mbar, about 1005 mbar, about 1010 mbar, about 1015 mbar, about 1020 mbar, about 1025 mbar, about 1030 mbar, about 1035 mbar, about 1040 mbar, about 1045 mbar, about 1050 mbar, or anywhere in between.

[0023] All ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g., 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Unless stated otherwise, the expression "up to" when referring to the compositional amount of an element means that element is optional and includes a zero percent composition of that particular element. Unless stated otherwise, all compositional percentages are in weight percent (wt.%).

[0024] As used herein, the meaning of "a," "an," and "the" includes singular and plural references unless the context clearly dictates otherwise.

[0025] In the present description, aluminum alloy products and their components may be described in terms of their elemental composition in weight percent (wt.%).
In each alloy, the remainder is aluminum, with a maximum wt.% of 0.15% for the sum of all impurities.

[0026] Incidental elements, such as grain refiners and deoxidizers, or other additives may be present in the invention and may add other characteristics on their own without departing from or significantly altering the alloy described herein or the characteristics of the alloy described herein.
Metal strip

[0027] As discussed, the heat treatment processes of the disclosure can be performed on a metal strip, e.g., an aluminum alloy strip. In certain aspects, the metal strip as described herein can be produced from casting a metal, e.g., DC casting or continuously casting a metal. After casting, in certain aspects, homogenizing, hot rolling, and/or cold rolling, and optional annealing after hot rolling or before the final cold rolling, can be performed to produce the metal strip.

[0028] In certain aspects, the metal strip can be a metal sheet, shate, or foil. In certain aspects, the metal strip can be a sheet. For example, in one embodiment, the described process is used to produce a sheet with a gauge from 0.5 mm to 4.5 mm. In some such aspects, the metal strip can be an aluminum alloy sheet, e.g., a heat treatable aluminum alloy sheet. In some aspects, the metal strip can be selected from a 2xxx series, a 6xxx series, or a 7xxx series aluminum alloy sheet. In some aspects, the metal strip is a 2xxx series aluminum alloy sheet. In some aspects, the metal strip is a 6xxx series aluminum alloy sheet. In some aspects, the metal strip is a 7xxx series aluminum alloy sheet. In certain aspects, the metal strip can be a shate. In some aspects, the metal strip can be an aluminum alloy shate, e.g., a heat treatable aluminum alloy shate. In some aspects, the metal strip can be selected from a 2xxx series, a 6xxx series, or a 7xxx series aluminum alloy shate. In some aspects, the metal strip is a 2xxx series aluminum alloy shate. In some aspects, the metal strip is a 6xxx series aluminum alloy shate. In some aspects, the metal strip is a 7xxx series aluminum alloy shate.
In certain aspects, the metal strip can be a foil. In some aspects, the metal strip can be an aluminum alloy foil, e.g., a heat treatable aluminum alloy foil. In some aspects, the metal strip can be selected from a 2xxx series, a 6xxx series, or a 7xxx series aluminum alloy foil.
In some aspects, the metal strip is a 2xxx series aluminum alloy foil. In some aspects, the metal strip is a 6xxx series aluminum alloy foil. In some aspects, the metal strip is a 7xxx series aluminum alloy foil.

[0029] In certain aspects, the alloys exhibit high strength and high deformability. . In some cases, the alloys exhibit an increase in strength after thermal treatment without significant loss of deformability. The properties of the alloys are achieved at least in part due to the methods of processing the alloys to produce the described foils, shates, sheets or other products.

[0030] In some examples, the alloys can have the following elemental composition as provided in Table 1.
Table 1 Element Weight Percentage (wt. %) Cu 0.05 ¨ 1.2 Si 0.6 ¨ 1.5 Mg 0.3 ¨ 1.2 Cr 0.0 ¨ 0.25 Mn 0.0 ¨ 0.35 Fe 0.1 ¨ 0.35 Zr 0.0 ¨ 0.25 Zn 0.0 ¨ 1.0 Ti 0.0 ¨ 0.3 Ni 0.0 ¨ 0.04 0.0 ¨0.05 (each) Impurities 0.0 ¨ 0.15 (total) Al

[0031] In some examples, the alloys can have the following elemental composition as provided in Table 2.
Table 2 Element Weight Percentage (wt. %) Cu 0.6 ¨ 1.2 Si 0.6 ¨ 1.1 Mg 0.7 - 1.2 Cr 0.0 - 0.25 Mn 0.0 - 0.35 Fe 0.1 - 0.3 Zr 0.0 - 0.25 Zn 0.0 - 0.3 Ti 0.0 - 0.10 Ni 0.0 - 0.04 0.0 -0.05 (each) Impurities 0.0 - 0.15 (total) Al In other examples, the alloys can have the following elemental composition as provided in Table 3.
Table 3 Element Weight Percentage (wt. %) Cu 0.7 - 1.0 Si 0.7 - 1.0 Mg 0.8 - 1.1 Cr 0.01 - 0.20 Mn 0.0 - 0.25 Fe 0.16 - 0.26 Zr 0.0 - 0.2 Zn 0.0 - 0.2 Ti 0.01 ¨ 0.07 Ni 0.0 ¨ 0.034 0.0 ¨0.05 (each) Impurities 0.0 ¨ 0.15 (total) Al

[0032] In one example, an aluminum alloy can have the following elemental composition as provided in Table 4. In certain aspects, the alloy is used to prepare aluminum foils and sheets.
Table 4 Element Weight Percentage (wt. %) Cu 0.75 ¨0.9 Si 0.75 ¨0.9 Mg 0.85 ¨ 1.0 Cr 0.05 ¨ 0.18 Mn 0.05 ¨ 0.18 Fe 0.16 ¨ 0.26 Zr 0.0 ¨ 0.15 Zn 0 ¨ 0.15 Ti 0.012 ¨ 0.05 Ni 0.0 ¨ 0.034 0.0 ¨0.05 (each) Impurities 0.0 ¨ 0.15 (total) Al

[0033] In certain examples, the disclosed alloy includes copper (Cu) in an amount from about 0.05% to about 1.2% (e.g., from about 0.1% to about 1.2%, from about 0.2 %
to about 1.1 %, from about 0.3 % to about 1.0 %, from about 0.4 % to about 1.0 %, from about 0.6% to about 1.1 %, from about 0.65% to about 0.9%, from about 0.7 % to about 1.0 or from about 0.6 % to about 0.7%) based on the total weight of the alloy. For example, the alloys can include 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 %, about 0.36%, about 0.37 %, about 0.38 %, about 0.39 %, about 0.4 %, about 0.41 %, about 0.42 %, about 0.43 %, about 0.44%, about 0.45 %, about 0.46 %, about 0.47 %, about 0.48 %, about 0.49%, about 0.5%, about 0.51 %, about 0.52%, about 0.53%, about 0.54 %, about 0.55%, about 0.56 %, about 0.57 %, about 0.58 %, about 0.59 %, 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 0.9 %, 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%, about or about 1.1%
Cu. All expressed in wt. %.

[0034] In certain examples, the disclosed alloy includes silicon (Si) in an amount from about 0.6 % to about 1.5 % (e.g., from about 0.7 % to about 1.3 %, from about 0.8 % to about 1.2 %, from about 0.9% to about 1.1 %, from about 0.6 % to about 0.9%, from about 0.9% to about 1.1 %, or from about 1.0% to about 1.1 %) based on the total weight of the alloy. For example, the alloys can include 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 %, ab out 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%, 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% Si. All expressed in wt. %.

[0035] In certain examples, the disclosed alloy includes magnesium (Mg) in an amount from about 0.3 % to about 1.3 % (e.g., from about 0.4 % to about 1.25 %, from about 0.5 % to about 1.2 %, from about 0.7 % to about 1.1 %, from about 0.8 % to about 1.25%, from about 1.1 % to about 1.25%, from about 1.1 % to about 1.2 %, from about 1.0% to about 1.2 %, from about 1.05 % to about 1.3 %, or from about 1.15% to about 1.3 %) based on the total weight of the alloy. For example, the alloys can include 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 %, 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 % Mg. All expressed in wt. %.

[0036] In certain aspects, the alloy includes chromium (Cr) in an amount up to about 0.25 % (e.g., from about 0 % to about 0.25 %, from about 0.03 % to about 0.06 %, from about 0.03 % to about 0.19 %, or from about 0.06 % to about 0.1 %) based on the total weight of the alloy. For example, the alloy can include 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%, about 0.028 %, about 0.029 %, about 0.03 %, about 0.031 %, about 0.032 %, about 0.033%, about 0.034 %, about 0.035 %, about 0.036%, about 0.037%, about 0.038 %, about 0.039%, about 0.04 %, about 0.041%, about 0.042 %, about 0.043 %, about 0.044 %, about 0.045%, about 0.046 %, about 0.047 %, about 0.048%, about 0.049%, about 0.05 %, about 0.051%, about 0.052 %, about 0.053 %, about 0.054 %, about 0.055 %, about 0.056 %, about 0.057 %, about 0.058 %, about 0.059 %, about 0.06 %, about 0.061 %, about 0.062 %, ab out 0.063%, about 0.064 %, about 0.065 %, about 0.066 %, about 0.067%, about 0.068 %, about 0.069%, about 0.07 %, about 0.071%, about 0.072 %, about 0.073 %, about 0.074 %, about 0.075%, about 0.076 %, about 0.077 %, about 0.078%, about 0.079%, about 0.08 %, about 0.081 %, about 0.082 %, about 0.083 %, about 0.084 %, about 0.085 %, about 0.086 %, about 0.087 %, about 0.088 %, about 0.089 %, about 0.09 %, about 0.091 %, about 0.092 %, ab out 0.093%, about 0.094 %, about 0.095 %, about 0.096%, about 0.097%, about 0.098 %, about 0.099 %, 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 %, or about 0.25 % Cr. All expressed in wt. %. In some cases, Cr is not present in the alloy (i.e., 0 %). In some examples, Cr can control grain structure and prevent grain growth and recrystallization. Higher amounts of Cr can provide a higher formability and improved b endability in aged temper.

[0037] In certain examples, the alloy can include manganese (Mn) in an amount up to about 0.35 % (e.g., from about 0 % to about 0.35 %, from about 0.05 % to about 0.18 %, from about 0.1 % to about 0.35 %, or from about 0.1% to about 0.3 %) b ased on the total weight of the alloy. For example, the alloy can include 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%, about 0.028%, about 0.029 %, about 0.03 %, about 0.031 %, about 0.032 %, about 0.033%, about 0.034 %, about 0.035 %, about 0.036%, about 0.037%, about 0.038 %, about 0.039%, about 0.04 %, about 0.041%, about 0.042 %, about 0.043 %, about 0.044 %, about 0.045%, about 0.046%, about 0.047 %, about 0.048%, about 0.049%, about 0.05 %, about 0.051%, about 0.052 %, about 0.053 %, about 0.054 %, about 0.055 %, about 0.056 %, about 0.057%, about 0.058%, about 0.059 %, about 0.06 %, about 0.061 %, about 0.062 %, about 0.063%, about 0.064 %, about 0.065 %, about 0.066%, about 0.067%, about 0.068 %, about 0.069%, about 0.07 %, about 0.071%, about 0.072 %, about 0.073 %, about 0.074 %, about 0.075%, about 0.076%, about 0.077 %, about 0.078%, about 0.079%, about 0.08 %, about 0.081%, about 0.082 %, about 0.083 %, about 0.084 %, about 0.085 %, about 0.086 %, about 0.087%, about 0.088%, about 0.089 %, about 0.09 %, about 0.091 %, about 0.092 %, about 0.093%, about 0.094 %, about 0.095 %, about 0.096%, about 0.097%, about 0.098 %, about 0.099 %, 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 %, or about 0.35% Mn. In some cases, Mn is not present in the alloy (i.e., 0%).
All expressed in wt. %.

[0038] In certain aspects, the alloy also includes iron (Fe) in an amount from about 0.1 % to about 0.35 % (e.g., from about 0.1 % to about 0.3 %, from about 0.1 %
to about 0.25 %, from about 0.18 % to about 0.25%, from about 0.2 % to about 0.21%, or from about 0.15 % to about 0.22 %) based on the total weight of the alloy. For example, the alloy can include 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 % Fe. In some cases, Fe is not present in the alloy (i.e., 0 %). All expressed in wt. %.

[0039] In certain aspects, the alloy includes zirconium (Zr) in an amount up to about 0.25 % (e.g., from about 0 % to about 0.2 %, from about 0.01 % to about 0.25 %, from about 0.01 % to about 0.15 %, from about 0.01 % to about 0.1 %, or from about 0.02 %
to about 0.09 %) based on the total weight of the alloy. For example, the alloy can include 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 0.21 %, about 0.22%, about 0.23%, about 0.24 %, or about 0.25 Zr. In certain aspects, Zr is not present in the alloy (i.e., 0 %).
All expressed in wt. %. In some examples, Zr can control grain structure and prevent grain growth and recrystallization. Higher amounts of Zr can provide a higher formability and improved bendability as well in T4 and aged temper.

[0040] In certain aspects, the alloy described herein includes zinc (Zn) in an amount up to about 1.0% (e.g., from about 0% to about 1.0%, from about 0.001% to about 0.3 %, from about 0.005 % to about 0.09%, from about 0.004 % to about 0.3 %, from about 0.03 %
to about 0.2%, or from about 0.06% to about 0.1 %)based on the total weight of the alloy.
For example, the alloy can include 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 %, about 0.028 %, about 0.029%, 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 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 %, about 0.36%, about 0.37 %, about 0.38 %, about 0.39 %, about 0.4 %, about 0.41 %, about 0.42 %, about 0.43 %, about 0.44 %, about 0.45 %, about 0.46 %, about 0.47%, about 0.48 %, about 0.49 %, about 0.50 %, about 0.51 %, ab out 0.52 %, about 0.53 %, about 0.54%, about 0.55%, about 0.56 %, about 0.57 %, about 0.58 %, about 0.59 %, 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 %, ab out 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% Zn. In some cases, Zn is not present in the alloy (i.e., 0 %). All expressed in wt. %. In certain aspects, Zn can benefit forming, including bending and the reduction of bending anisotropy in foil, sheet, and s h ate products.

[0041] In certain aspects, the alloy includes titanium (Ti) in an amount of up to about 0.3 % (e.g., from about 0% to about 0.3 %, from about 0.01 % to about 0.25%, from 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 can include 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 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 %
Ti. In certain aspects, Ti is not present in the alloy (i.e., 0 %). All expressed in wt. %.

[0042] In certain aspects, the alloy includes nickel (Ni) in an amount up to about 0.04 % (e.g., from 0 % to about 0.02 %, from about 0.01 % to about 0.03 %, from about 0.03 % to about 0.04 %) based on the total weight of the alloy. For example, the alloy can include 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 0.035 %, about 0.036%, about 0.037 %, about 0.038%, about 0.039 %, or about 0.04 % Ni. In certain aspects, Ni is not present in the alloy (i.e., 0 %). All expressed in wt. %.

[0043] Optionally, the alloy compositions can further include other minor elements, sometimes referred to as impurities, in amounts of about 0.05 % or below, about 0.04 % or below, about 0.03% or below, about 0.02% or below, or about 0.01% or below each. These impurities may include, but are not limited to, V, Ga, Ca, Hf, Sr, Sc, Sn, or combinations thereof. Accordingly, V, Ga, Ca, Hf, Sr, Sc, or Sn may be present in an alloy in amounts of about 0.05 % or below, about 0.04 % or below, about 0.03 % or below, about 0.02 % or below, or about 0.01 % or below. In certain aspects, the sum of all impurities does not exceed about 0.15 % (e.g., 0.1 %). All expressed in wt. %. In certain aspects, the remaining percentage of the alloy is aluminum.
Continuous Heat Treatment Process

[0044] Certain aspects and features of the present disclosure relate to a continuous heat treatment process, where a metal strip is solutionized, rapidly cooled, thermally spiked at an elevated temperature (for example, at a temperature ranging from 120 C to 300 C), and coiled, as described below. In certain embodiments, the metal strip is a heat treatable alloy, for example, 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 only naturally cooled before or after coiling. In some embodiments, the coil can be cooled (e.g, using a cooling fan(s)) after coiling at the end of the continuous heat treatment process. In certain embodiments, the metal strip itself can be prepared from scalping, homogenizing, hot rolling, optionally batch annealing, and cold rolling a cast ingot.

[0045] 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 greater than 5 meters/min, e.g., greater than 10 meters/min, greater than 20 meters/min, greater than 25 meters/min, greater than 30 meters/min, greater than 40 meters/min, greater than 50 meters/min, greater than 60 meters/min, greater than 70 meters/min, greater than 80 meters/min, greater than 90 meters/min, greater than 100 meters/min, from 10 meters/min to 100 meters/min, from 20 meters/min to 80 meters/min, from 30 meters/min to 70 meters/min, or from 40 meters/min to 60 meters/min.
Solutionizing

[0046] Solutionizing can put into solution (e.g., aluminum solid solution) the desired amount of alloying elements that are present in a particular alloy. In some aspects, the solutionizing step can comprise heating the metal strip (e.g., plate, shate, sheet, or foil) from room temperature to a temperature of from about 400 C to about 590 C (e.g., from about 450 C to about 575 C, from about 400 C to about 525 C, from about 450 C
to about 510 C, from about 520 C to about 590 C, from about 520 C to about 580 C, from about 520 C to about 560 C, from about 530 C to about 570 C, from about 545 C to about 575 C, from about 550 C to about 570 C, from about 555 C to about 565 C, from about 540 C to about 560 C, from about 540 C to about 575 C, from about 560 C to about 580 C, from about 550 C to about 575 C, about 540 C, about 550 C, about 560 C, or about 570 C).

[0047] In certain embodiments, the strip can soak at the temperature for a period of time. In certain aspects, the strip is allowed to soak for a time (e.g., up to approximately 5 minutes, from about 10 seconds to about 5 minutes inclusively, from about 1 second to about 3 minutes, or from about 5 seconds to about 5 minutes). For example, the strip can be soaked at the temperature (e.g., from 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, or less than 150 seconds, or less than 5 minutes, or anywhere in between.

[0048] In certain aspects, the solutionizing can be carried out in a continuous process, e.g., a continuous heat treatment line. In some embodiments, the continuous process (e.g., continuous heat treatment line) can have a specific line speed.

[0049] In certain aspects, the solutionizing step is performed on a metal strip immediately after a hot rolling step and/or a cold rolling step. In other aspects, the solutionizing step is performed on a metal strip after (e.g., >48 hour after) a hot rolling step and/or a cold rolling step. In certain aspects, the solutionizing step is performed after an annealing and cold rolling step.
Rapid Cooling

[0050] Without being bound by theory, in order to lock the solute elements and.
excess vacancies into the metal (e.g., aluminum) matrix of the metal strip, the metal strip can be cooled very rapidly. Thus, in some aspects, after solutionizing, the metal strip can be rapidly cooled to reduce the temperature of the metal strip. In some aspects, the transfer time from the solutionizing furnace into the cooling medium is very short (e.g., less than I s, less than 2 s, less than 3 s, less than 5 s, less than 10 s, less than 15 s, less than 20 s, less than 25 s, less than 30 s, less than 35 s, less than 40 s, less than 45 s, less than 50 s, less than 55 s, less than I min, less than 2 min, less than 3 min, less than 4 min, less than 5 min, or less than 10 min). The time for transfer of the solutionized metal begins from the moment .that the furnace door begins to open and goes to the point at which the aluminum alloy is completely immersed and submerged. If the transfer time exceeds the prescribed time limit, incomp I ete solutionizing can occur, which means nonuniform metallurgical and mechanical conditions of the particular alloy.

[0051] In certain aspects, after solutionizing, the metal strip can be cooled at a rate that can vary between about 1 C/s to 400 C/s in a rapid cooling step that is based on the selected gauge. For example, the rapid cooling rate can be from about 50 C/s to about 3 75 C/s, from about 60 C/s to about 375 C/s, from about 70 C/s to about 350 C/s, from about 80 C/s to about 325 C/s, from about 90 C/s to about 300 C/s, from about 100 C/s to about 275 C/s, from about 125 C/s to about 250 C/s, from about 150 C/s to about 225 C/s, from about 175 C/s to about 200 C/s, from about 10 C/s to about 125 C/s, or from about 20 C/s to about 125 C/s. In some aspects, the metal strip can 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, from about 20 C to about 80 C, from about 20 C to about 70 C , from about 20 C to about 60 C, from about 25 C to about 5 0 C, from about 25 C to about 40 C, to about 20 C, to about 25 C, to about 30 C, to about 35 C, to about 40 C, to about 45 C, or to about 50 C.

[0052] In certain aspects, the metal strip can be rapidly cooled with a liquid (e.g., water) and/or a gas or another selected cooling medium. In certain aspects, the metal strip is rapidly cooled with air. In certain aspects, the metal strip can be rapidly cooled with water.
Thermal spiking

[0053] The metal strip can be subjected to a thermal spike treatment at elevated temperature. As described herein, using thermal spike temperatures higher than those previously disclosed in the art helped achieve the unexpected benefits of the present disclosure. In some aspects, the thermal spike temperature (i.e., the peak temperature that the metal strip is exposed to, not necessarily the temperature of the metal strip itself) is in the range of from about 100 C to about 300 C, e.g., from about 120 C to about 300 C, from about 150 C to about 300 C, from about 170 C to about 280 C, from about 180 C to about 270 C, from about 190 C to about 260 C, from about 200 C to about 250 C, from about 210 C to about 250 C, from about 220 C to about 250 C, from 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. In some aspects, the metal strip itself reaches to within 100 C
of the thermal spike temperature, e.g., 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, or within 1 C.

[0054] In some aspects, the thermal spike treatment occurs after solutionizing and air cooling the metal strip. In some aspects, the thermal spike treatment can occur at the same processing line speed as the solutionizing and rapid cooling, e.g., as part of a continuous heat treatment process.

[0055] Conventional 6XXX materials in T4 or T4P tempers contain large number of fine metastable clusters and zones uniformly distributed throughout a metal matrix. In the conventional process, during the paint cure, some fine unstable clusters/zones re-dissolve in the metal matrix, while other improve the 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 thermal spiking between 150 and 320 C, (for example, in a long reheater furnace) e.g., between about 150 and 300 C, between about 180 and 300 C, or between about 150 and 225 C, followed by coiling and coil cooling forms some of the clusters and zones and enhances the precipitation process during coil cooling.

[0056] The period of time for which the temperature is maintained at the peak thermal spike temperature may range from zero to any time that is practical in the circumstances. In some aspects, the thermal spike treatment occurs at the speed of the processing line of the continuous heat treatment process (for example in a long furnace). For example, the speed of the processing line and the speed of the thermal spike treatment can occur at a speed of from about 1 meter/min to about 120 meters/min, e.g., from about 2 meters/min to about 110 meters/min, from about 5 meters/min to about 100 meters/min, from about 10 meters/min to about 600 meters/min, from about 20 meters/min to about 500 meters/min, from about 25 meters/min to about 500 meters/min, from about 30 meters/min to about 400 meters/min, from about 40 meters/min to about 350 meters/min, from about 50 meters/min to about 300 meters/min, or from about 100 meters/min to about 250 meters/min. In practice, the period is usually from zero up to about 5 minutes, e.g., from about 1 sec to about 5 min, from about 2 sec to about 4 min, from about 3 sec to about 3 min, from about 5 sec to about 2 min, from about 7 sec to about 1 min, or from about 10 sec to about 30 sec.

[0057] In some aspects, the thermal spike treatment is carried out at a heating rate of (i.e., the temperature of the metal strip increases at a rate) about 1 C/min to about 50 C/s (e.g., from about 1 C/s to about 40 C/s, from about 2 C/s to about 40 C/s, from about 3 C/s to about 35 C/s, from about 3 C/s to about 30 C/s, from about 5 C/s to about 30 C/s, from about 10 C/s to about 25 C/s, or from about 2 C/s to about 10 C/s).

[0058] In some aspects, the thermal spike treatment is performed in a reheater furnace, e.g., a continuous reheater furnace. In some aspects, the thermal spike treatment is performed in a long reheater furnace. For example, the furnace can have an effective length of (i.e., a length that 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, or at least 100 meters. Without limiting the disclosure, this may allow for an increased line speed and/or thermal spike time.
Aging

[0059] In some aspects, the metal strip does not undergo an aging process. In some aspects, the thermal spike of the metal strip in combination with coiling of the metal strip and/or cooling of the metal strip can take the place of age hardening.
Cooling

[0060] In some aspects, the metal strip can be cooled after the thermal spike treatment. In some aspects, this cooling can occur after coiling. In other aspects, this cooling can occur before coiling. And in some aspects, cooling can occur before and/or after coiling.
For example, in some aspects, the metal strip can be air cooled, e.g., using at least one fan. In some aspects, the metal strip is only naturally cooled (for example, during the passage of the strip between the thermal spike treatment and coiling), meaning that there is no apparatus or process used to cool the metal strip prior to coiling. For example, the metal strip might only be exposed to the ambient conditions (e.g., at the line speed of the continuous heat treatment process) prior to coiling. In some aspects, the metal strip is only naturally cooled after coiling. As described herein, naturally cooling (e.g. only exposure to the ambient conditions prior to cooling) does not fall within the term "cooling" or "cooled" as used previously in the art. In some aspects, the cooling or natural cooling can be carried out until the metal strip reaches ambient temperature.

[0061] In some aspects, the metal strip and/or the coiled metal strip can be cooled or naturally cooled at a rate of less than or equal to about 60 C/hour (e.g., less than or equal to about 50 C/hour, less than or equal to about 40 C/hour, less than or equal to about 30 C/hour, less than or equal to about 20 C/hour, less than or equal to about 10 C/hour, less than or equal to about 5 C/hour, less than or equal to about 3 C/hour, less than or equal to about 2.5 C/hour, less than or equal to about 2 C/hour, less than or equal to about 1.5 C/hour, less than or equal to about 1 C/hour, or less than or equal to about 0.8 C/hour).
Methods of Preparing the Metal Strip

[0062] In certain aspects, the disclosed metal (e.g., alloy) strip compositions are products of disclosed methods. Without limiting the disclosure, alloy properties, such as 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.

[0063] The metal (e.g., alloy) strip described herein can be cast into ingots using a casting method. For example, the casting process can comprise a Direct Chill (DC) casting process. In another example, the casting process can comprise a continuous casting process.
The cast ingot can then be subjected to further processing steps. In one non-limiting example, the processing method includes scalping, homogenization, hot rolling, optional batch annealing, and cold rolling, prior to the aforementioned solutionizing, rapid cooling, thermal spike treatment, and coiling and subsequent cooling (e.g., fan cooling after coiling).
Homogenization

[0064] In some aspects, the homogenization step can involve a one-step homogenization or a two-step homogenization. In one example of the homogenization step, a one-step homogenization is performed where an ingot prepared from an alloy composition described herein is heated to attain 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 can be heated to a temperature of from about 520 C to about 580 C, from about 530 C to about 575 C, from about 535 C to about 570 C, from about 540 C to about 565 C, from about 545 C to about 560 C, from about 530 C to about 560 C, or from about 550 C to about 580 C . In some cases, the heating rate to the peak metal temperature can 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 can be from about 10 C/min to about 100 C/m in (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, from about 20 C/min to about 90 C/min, from about 30 C/min to about 80 C/min, from about 40 C/min to about 70 C/min, or from about 50 C/min to about 60 C/min).

[0065] The ingot is then allowed to soak (i.e., held at the indicated temperature) for a period of time. According to one non-limiting example, the ingot is allowed to soak for up to about 8 hours (e.g., from about 5 seconds to 8 hours, or from about 30 minutes to about 8 hours, inclusively). For example, the ingot can be soaked 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 anywhere in between.

[0066] In another example of the homogenization step, a two-step homogenization is performed where an ingot prepared from an alloy composition described herein is heated to attain a first temperature of about, or at least about, 480 C to about 520 C. For example, the ingot can be heated to a first temperature of about 480 C, 490 C, 500 C, 510 C, or 520 C.
In certain aspects, the heating rate to the first temperature can be from 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, from about 20 C/min to about 90 C/min, from about 30 C/min to about 80 C/min, from about 40 C/min to about 70 C/min, or from about 50 C/min to about 60 C/min). In other aspects, the heating rate to the first temperature can be from 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, from about 20 C/ hour to about 90 C/ hour, from about 30 C/ hour to about 80 C/

hour, from about 40 C/ hour to about 70 C/hour, or from about 50 C/ hour to about 60 C/
hour).

[0067] The ingot is then allowed to soak for a period of time. In certain cases, the ingot is allowed to soak for up to about 6 hours (e.g., from 5 seconds to 6 hours, or from 30 minutes to 6 hours, inclusively). For example, the ingot can be soaked at a temperature of from about 480 C to about 520 C for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours, or anywhere in between.

[0068] In the second step of the two-step homogenization process, the ingot can be further heated from the first temperature to a second temperature of greater than about 520 C
(e.g., greater than 520 C, greater than 530 C, greater than 540 C, greater than 550 C, greater than 560 C, greater than 570 C, or greater than 580 C). For example, the ingot can be heated to a second temperature of from about 520 C to about 580 C, from about 530 C
to about 575 C, from about 535 C to about 570 C, from about 540 C to about 565 C, from about 545 C to about 560 C, from about 530 C to about 560 C, or from about 550 C to about 580 C. The heating rate to the second temperature can be from about 10 C/min to about 100 C/min (e.g., from about 20 C/min to about 90 C/min, from about 30 C/min to about 80 C/min, from about 10 C/min to about 90 C/min, from about 10 C/min to about 70 C/min, from about 10 C/min to about 60 C/min, from about 40 C/min to about 70 C/min, or from about 50 C/min to about 60 C/min).

[0069] In other aspects, the heating rate to the second temperature can be from about C/hour to about 100 C/hour (e.g., from about 10 C/ hour to about 90 C/
hour, from about 10 C/ hour to about 70 C/hour, from about 10 C/ hour to about 60 C/
hour, from about 20 C/ hour to about 90 C/hour, from about 30 C/ hour to about 80 C/
hour, from about 40 C/ hour to about 70 C/hour, or from about 50 C/ hour to about 60 C/hour).

[0070] The ingot is then allowed to soak for a period of time. In certain cases, the ingot is allowed to soak for up to about 6 hours (e.g., from 5 seconds to 6 hours, or from 30 minutes to 6 hours, inclusively). For example, the ingot can be soaked at a temperature of from about 520 C to about 580 C for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours, or anywhere in between.
Hot Rolling

[0071] In some aspects, following the homogenization step, a hot rolling step can be performed. In certain cases, the ingots are laid down and hot-rolled with an entry temperature range of about 380 C to about 540 C. For example, the entry temperature can 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 can range from about 230 C to about 420 C
(e.g., from about 330 C to about 370 C). For example, the hot roll exit temperature can be about 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 can be combined with any of the above entry temperatures.

[0072] In certain cases, the ingot can be hot rolled to an about 2 mm to about 15 mm thick gauge (e.g., from about 5 mm to about 12 mm thick gauge), which is referred to as a shate. For example, the ingot can be hot rolled to an about 4 mm thick gauge, about 5 mm thick gauge, about 6 mm thick gauge, about 7 mm thick gauge, about 8 mm thick gauge, about 9 mm thick gauge, about 10 mm thick gauge, about 11 mm thick gauge, about 12 mm thick gauge, about 13 mm thick gauge, about 14 mm thick gauge, or about 15 mm thick gauge. In certain cases, the ingot can be hot rolled to a gauge greater than 15 mm thick (i.e., a plate). In other cases, the ingot can be hot rolled to a gauge less than 4 mm (i.e., a sheet).

The hot rolled coil can be batch annealed in some cases before cold rolling in some aspects. It is also possible in certain embodiments that the annealing is carried out after a first cold pass or a second cold pass, before the final cold pass.
Cold Rolling

[0073] In some aspects, a cold rolling step can be performed following the hot rolling step. In certain aspects, the rolled product from the hot rolling step can be cold rolled to a sheet (e.g., below approximately 4.0 mm). In certain aspects, 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 aspects, the alloy is cold rolled to about 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 about 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, or 3.0 mm.

[0074] Aspects of the above process can be used to produce metal strips as described.
Further, as discussed, the metal strips can be processed using the disclosed continuous heat treatment processes to produce a heat treated article. In some aspects, the entire process to produce a metal strip and heat treat the metal strip is continuous. The metal strip can be then be subjected to the described heat treatment process.
Examples

[0075] These illustrative examples are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional features and examples with reference to the drawings in which like numerals indicate like elements, and directional descriptions are used to describe the illustrative embodiments but, like the illustrative embodiments, should not be used to limit the present disclosure. The elem ents included in the illustrations herein may not be drawn to scale.

[0076] Example 1

[0077] A direct chill 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 was scalped, homogenized, hot and cold rolled to a final 0.9 mm gauge. The cold rolled strip of coil (Example 1) was solution heat treated between 540 C and 575 C, rapidly cooled to below 50 C, and thermally spiked in a furnace set at 220 C in a continuous process where strip is travelling at 60 meters/min before coiling. There was no intentional (i.e., only natural) cooling in between thermal spiking and coiling at the end of the process. The strip was sampled before coiling at a flying shear location of the line and after cooling on a finishing line.

[0078] The samples taken before and after the coiling were tested after 6 days of continuous anneal solution heat treatment ("CASH") using ASTM samples in as-is and paint bake conditions (2 + 20 min @185 C - referred to as T8X). Table 5 shows that the transverse yield strength of the sheet sample taken at the flying shear and before coiling exhibit 117 and 229 MPa in the as-is and paint bake tempers respectively, and they are only marginally higher than typical values expected from this alloy. However, the yield strengths (YS) values are higher in both tempers in the coil cooled samples, which is very surprising as traditional products without thermal spiking and coiled at similar temperatures do not exhibit such high properties. Such products are generally produced by subjecting a coil in the T4 temper to a separate batch ageing heat treatment. Without being bound by theory, it is believed that the disclosed thermal spiking process accelerates the age hardening process during coil cooling.

[0079] Table 5: Transverse Tensile Properties of Coil Example 1 Condition Temper Yield Strength UTS EIT (%) (Mp a) (Mp a) Before Coil T4 117 237 24.4 Cooling T8X 229 296 18.9 After Coil T4 237 322 20.4 Cooling T8X 308 347 14.9 Note: T8X is 2 % + 20 min at 185 C

[0080] Examples 2-5

[0081] Direct chilled cast ingots of four different alloys, with the compositions shown in Table 6, were scalped, homogenized, hot and cold rolled to the final gauge.
The cold rolled strip of coil as in Example 1 was solution heat treated between 540 C and 575 C, rapidly cooled to below 50 C and thermally spiked in a furnace set 250 C in a continuous process where strip is travelling at 60 meters/min before coiling at the end of the line. The strip was sampled before coiling at flying shear location of the line and after cooling on a finishing line.

[0082] Table 6: Compositions of Examples 2-5 in wt. %
Alloys Al Si Fe Cu Mn Mg Cr Ti 2 98.3 0.59 0.21 0.12 0.09 0.62 0.01 0.03 3 98.1 0.81 0.24 0.09 0.08 0.62 0.03 0.02 4 98.1 1.05 0.22 0.02 0.14 0.44 0.00 0.03 98.0 0.80 0.25 0.09 0.08 0.65 0.01 0.03

[0083] Samples of Examples 2-5 taken before and after the coiling were tested after a few days of cash using ASTM samples in as-is and T8X (2%+20min @185 C) conditions, except for coil Example 3 which was tested using JIS sample and paint bake temper of (2%+20min @170 C). Table 7 summarizes the tensile properties of the Example 2-5 samples taken at the flying shear and the finishing line. Table 7 shows that all four alloys exhibit significantly higher strengths in coil cooled sample as opposed to the flying shear samples before coil cooling confirming the results of Example 1.

[0084] Table 7: Transverse Tensile Properties of Examples 2-5 Thermally Spiked at Alloys Ga (mm) Condition Temper YS Mpa UTS Mpa EIT%
2 1 Before coil T4 97 203 26.5 cooling T8X 190 255 18.4 After coil T4 133 233 23.9 cooling T8X 251 303 18.1 3 1.4 Before coil T4 115 227 24.3 cooling T8X 222 282 19.0 After coil T4 212 290 18.4 cooling T8X 11111111" "1111111111111111I
4 0.95 Before coil T4 99 218 27.0 cooling T8X 216 280 20.8 After coil T4 198 286 22.1 cooling T8X 269 313 18.3 0.95 Before coil T4 100 220 26.3 cooling T8X 232 294 17.1 After coil T4 ............260.......................3.3Ø......................1.8:.7.......
....
cooling T8X
Note: T8X is 2% plus 20 min at 185 C

[0085] Examples 6-8

[0086] Like Examples 2-5, three cold rolled coils of Alloy Ex. 4 were solutionized in a continuous heat treatment line and thermally spiked ranging from 200 and 250 C and, with no intentional cooling (i.e., only natural air cooling) after thermal spiking, coiling at the end of the line. The samples of Examples 6-8 obtained from before coiling at the flying shear and coiled from the finishing line were tested using the ASTM samples in both as-is and T8X
tempers. The results of this trial as summarized in Table 8 show that the thermally spiked and coil cooled samples exhibit higher strengths compared to the flying shear samples, confirming the effects of thermal spiking and the results of previous examples.

[0087] The same coils for Examples 6-8, listed in Table 8, were re-solutionized the same way as the first time but with reheater set in auto mode, 100 C and 150 0C, respectively. The results from the resolution coils are summarized in Table 9, which shows that an increase in thermal spiking temperature results in higher strengths but the extent of the increase is lower than those seen at >200 C. As shown in these results, the thermal spiking temperature has significant impact on the strength of the coil cooled samples.
This observation shows that with proper choice of alloy and thermal temperatures, it is possible to produce different combination of tensile properties without the requirement of an additional batch ageing process.

[0088] Table 8: Transverse Tensile Properties Thermally Spiked Alloy Ex.
4 Coils Examples 6-8 Alloys Coil Cooling Temper YS (Mpa) UTS (Mpa) EIT %
6 200 Before T4 104 214 24.3 After T8X 208 271 14.6 Before T4 150 242 19.3 After T8X 257 311 19.3 7 250 Before T4 92 207 27.0 After T8X 201 267 19.3 Before T4 190 279 22.6 After T8X 257 303 19.0 8 250 Before T4 97 211 25.5 After T8X 218 283 19.7 Before T4 k k After T8X 268 314 19.1 Notes: T8X is 2% plus 20 min @ 185 C

[0089] Table 9: Transverse Tensile Properties of Coils of Examples 6-8 and Resolutionized and Thermally Spiked at Lower Temperatures Alloys Spike Coil Cooling Temper Yield St. UTS (Mpa) EIT %
Temp (C) (Mpa) 6 Normal Before T4 112 236 29.3 After T4 111 232 28.6 T8X 202 270 19.6 7 100 Before T4 108 229 28.4 After T4 101 221 27.9 T8X 226 287 19.8 8 150 Before T4 111 238 26.3 After T4 110 228 26.4 T8X 238 299 20.3 Notes: T8X is 2% plus 20 min @185 C

[0090] Examples 9-10

[0091] The objective of this trial was to twofold: first, examine the effects of heating rate during thermal spiking via change in the line speeds (52 m/min vs 41 m/min) on the strength of AA6111 coils and, second, compare tensile properties of AA6111 with typical 5xxx alloys supplied in H3X tempers.

[0092] A pair of 2mm 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 solutionized between 520 to 560 C, rapidly cooled below 50 C, thermally spiked in a furnace at 250 C before coiling at the end of the continuous process. Coils of Examples 9 and 10 were heat treated at 52 meter/min and 41 meter/min, respectively. The samples obtained from each coil on a finishing line and tested using the ASTM samples in both as-is and T8X tempers. The results of this trial are summarized in Table 10. Both coils processed at two line speeds show very similar properties in both T4 and T8X tempers, suggesting no major effect on the tensile properties from change in line speeds ranging from 41 m/min to 52 m/min strip speed. The higher strengths in T4 temper potentially could be used for structural parts offering downgauging possibility or eliminate postformed heat treatments.

[0093] Table 10: Transverse Tensile Properties of 2 mm gauge AA6111 Coils Examples 9 and 10 Solutionized and Thermally Spiked before coiling Line Yield UTS
Alloys Speed Temper Strength (mp EIT (%) (m/min) (Mpa)

[0094] Table 11: Typical properties of Commonly Used 5xxx Alloys in Different

[0095] Tempers AA Alloys Temper Yield Strength UTS (Mpa) Total Elongation (Mpa) (A)

[0096] Table 11 summarizes typical ASTM tensile properties of commonly used 5xxx alloys. The YS, UTS and total elongations values range from 190 to 290 MPa and 230 and 325 MPa and 7 to 16%, respectively. The YS of AA6111 coils in Table 10 is close to 5086-H34 with significantly higher total elongation. This suggest that AA6111 material produced by the process described herein could replace 5086-H34 product while offering better total elongation. The same alloy could be produced with lower strengths by thermal spiking at lower temperatures to match strengths of other AA5xxx products. Different combinations of strength could also be achieved by changing alloy chemistries along with other process variables.

[0097] The thermally spiked AA6xxx does not exhibit any major natural ageing. The characteristics together with comparable strengths and total elongations offers a very attractive alternative to 5xxx products where high formability are required.

[0098] Example 11

[0099] A direct chilled cast ingot 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 was scalped, homogenized, hot and cold rolled to a final 2.3 mm gauge. The cold rolled strip of coil was solution heat treated between 525 C, rapidly cooled to below 50 C, and thermally spiked in a furnace to heat up strip to about 190 C in a continuous process and rewound in a coil wide sidewall temperature of about 135 C. The line speed was modulated between 17 to 20 meters/min to ensure strip temperature at the exit of the furnace close to 190 C. There was no intentional cooling in between thermal spiking and coiling at the end of the process. The coil temperature decreased from 135 C to 85 C at about 2.8 C/h and further cooling to ambient would be less than 2 C/hour. The coil was sampled after 5 days of the heat treatment and tested using ASTM samples in as-is and different paint bake tempers.

[00100] Table 12 shows the average transverse ASTM tensile properties of the sheet sample taken from the coil cooled samples. The yield strength (YS) and ultimate tensile strength (UTS) of the coil cooled sample are 277 and 344 Mpa respectively with a 17% total elongation value. These properties are significantly different from AA6111 coils normally produced with coiling temperatures below 100 C, typically exhibiting 125 Mpa YS, 230 1ViPa UTS, and 24% total elongation. The properties of the coil are characteristic of aged tempers obtained close to 50 h of ageing at 140 C. Without being bound by theory, the thermal spiking is accelerating the hardening process during coil cooling. The alloy shows marginal increase in strength if aged at elevated temperatures with and without prestrain s as shown in Table 12. The thermal spiking process produces coils with strength at relatively short ageing times and better elongations than expected from a typical batch annealing process with less than 14% elongation.

[00101] Table 12: Transverse Tensile Properties of Example 11 (AA6111) Temper Yield Strength (Mpa) UTS (Mpa) Total Elongation (%) 20 min @ 180 C 286 330 13 2% + 20 min @ 180 C 301 336 17 30 min 225 C 285 329 14 [0100] The foregoing description of the embodiments, including illustrated embodiments, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or limiting to the precise forms disclosed.
Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art.
[0101] As used below, any reference to a series of embodiments is to be understood as a reference to each of those embodiments disjunctively (e.g., "Embodiments 1-4" is to be understood as "Embodiments 1, 2, 3, or 4").

[0102]
Embodiment 1 is a process for producing a heat treated aluminum alloy comprising 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 temperature from 150 C
to 300 C
continuously at the line speed to produce a thermally spiked metal strip; and coiling the thermally spiked metal strip to produce a coiled metal strip.

[0103]
Embodiment 2 is the process of Embodiment 1, further comprising cooling the thermally spiked metal strip after thermally spiking.

[0104]
Embodiment 3 is the process of any of the embodiments, wherein cooling the thermally spiked metal strip comprises air cooling the thermally spiked metal strip.

[0105]
Embodiment 4 is the process of Embodiment 1, wherein only natural cooling occurs of the thermally spiked metal strip occurs between thermal spiking and coiling.

[0106]
Embodiment 5 is the process of any of the embodiments, wherein coiling the thermally spiked metal strip is carried out continuously at the end of a continuous line.

[0107]
Embodiment 6 is the process of any of the embodiments, wherein the cooling of the thermally spiked metal strip is at a rate of less than 10 C/hour.

[0108]
Embodiment 7 is the process of any of the embodiments, wherein the cooling of the thermally spiked metal strip is at a rate of less than 2 C/hour.

[0109]
Embodiment 8 is the process of any of the embodiments, wherein the coiling of the thermally spiked metal strip is at a temperature of 70 C to 130 C.

[0110] Embodiment 9 is the process of any of the embodiments, wherein the coiling of the thermally spiked metal strip is performed at a temperature above 60 C.

[0111] Embodiment 10 is the process of any of the embodiments, wherein the line speed is at least 10 meters/min.

[0112] Embodiment 11 is the process of any of the embodiments, wherein the line speed is from 10 meters/min to 120 meters/min.

[0113] Embodiment 12 is the process of any of the embodiments, wherein the thermal spike temperature is from 150 C to 280 C.

[0114] Embodiment 13 is the process of any of the embodiments, wherein the thermal spike temperature is from 200 C to 250 C.

[0115] Embodiment 14 is the process of any of the embodiments, wherein casting a metal strip comprises continuous casting.

[0116] Embodiment 15 is the process of any of the embodiments, wherein casting a metal strip comprises Direct Chill (DC casting).

[0117] Embodiment 16 is the process of any of the embodiments, further comprising homogenizing, hot rolling, and cold rolling the metal strip after casting and before solutionizing.

[0118] Embodiment 17 is the process of any of the embodiments, wherein thermally spiking the cooled metal strip is carried out in a reheater furnace with a length of at least 12 meters.

[0119] Embodiment 18 is the process of any of the embodiments, wherein the solutionizing temperature is from about 480 C to about 590 C.

[0120] Embodiment 19 is the process of any of the embodiments, wherein air cooling the solutionized metal strip comprises cooling the solutionized metal strip to less than 50 C.

[0121] Embodiment 20 is a heat treated metal strip formed from the process of any of the embodiments.

Claims (15)

Claims What is claimed is:

1. A process for producing a heat treated aluminum alloy comprising:
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 temperature from 150 C to 320 C
continuously at the line speed to produce a thermally spiked metal strip;
and coiling the thermally spiked metal strip to produce a coiled metal strip.

2. The process of claim 1, further comprising cooling the coiled metal strip.

3. The process of claim 2, wherein cooling the coiled metal strip comprises air cooling the thermally spiked metal strip.

4. The process of claim 1, wherein only natural cooling occurs of the thermally spiked metal strip occurs between thermal spiking and coiling.

5. The process of claim 1, wherein coiling the thermally spiked metal strip is carried out continuously at the end of a continuous line.

6. The process of claim 2, wherein the cooling of the coiled metal strip is at a rate of less than or equal to 10 C/hour.

7. The process of claim 1, wherein the coiling of the thermally spiked metal strip is at a temperature of 110 C to 160 C.

8. The process of claim 1, wherein the line speed is at least 10 meters/min.

9. The process of claim 1, wherein the line speed is from 10 meters/min to meters/min.

10. The process of claim 1, wherein the thermal spike temperature is from 150 C to 300 C.

11. The process of claim 1, further comprising homogenizing, hot rolling, and cold rolling the metal strip before solutionizing.

12. The process of claim 1, wherein thermally spiking the cooled metal strip is carried out in a reheater furnace with a length of at least 12 meters.

13. The process of claim 1, wherein the solutioniiing temperature is from about 480 C to about 590 C.

14. The process of claim 1, wherein air cooling the solutionized metal strip comprises cooling the solutionized metal strip to less than 50 C.

15. A heat treated metal strip formed from the process of claim 1.