Patent Description:
The present invention relates to cast aluminum alloy products, and products derived therefrom.

The present invention is a cast product as defined in claim <NUM>.

In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the variation of the zinc weight percent is <NUM>% or less between the surface and the thickness center of the aluminum alloy strip.

In one or more embodiments detailed herein, the aluminum alloy strip comprises: (i) <NUM> wt. % to <NUM> wt. % zinc; (ii) <NUM> wt. % to <NUM> wt. % copper; and (iii) <NUM> wt. % to <NUM> wt. % magnesium.

In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip comprises <NUM> wt. % to <NUM> wt. % magnesium.

In one or more embodiments detailed herein, the aluminum alloy strip comprises: <NUM> wt. % to <NUM> wt. % zinc and <NUM> wt. % to <NUM> wt.

The figures constitute a part of this specification and include illustrative embodiments of the present invention and illustrate various objects and features thereof. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components. In addition, any measurements, specifications and the like shown in the figures are intended to be illustrative, and not restrictive.

The present invention will be further explained with reference to the attached drawings, wherein like structures are referred to by like numerals throughout the several views. The drawings shown are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the present invention. Further, some features may be exaggerated to show details of particular components.

Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figures. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely illustrative of the invention that may be embodied in various forms. In addition, each of the examples given in connection with the various embodiments of the invention are intended to be illustrative, and not restrictive.

Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The phrases "in one embodiment" and "in some embodiments" as used herein do not necessarily refer to the same embodiment(s), though they may. Furthermore, the phrases "in another embodiment" and "in some other embodiments" as used herein do not necessarily refer to a different embodiment, although they may. Thus, as described below, various embodiments of the invention may be readily combined, without departing from the scope of the claims.

In addition, as used herein, the term "or" is an inclusive "or" operator, and is equivalent to the term "and/or," unless the context clearly dictates otherwise. The term "based on" is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on.

As used herein, the term "at least one of A, B, or C" and the like, means "only A", "only B", "only C", or "any combination of A, B, and C.

In one or more embodiments detailed herein, the aluminum alloy strip comprises: <NUM> wt. % to <NUM> wt. % zinc and <NUM> wt. % to <NUM> wt.

As used herein, the term "aluminum alloy" means an aluminum metal with soluble elements either in the aluminum lattice or in a phase within aluminum. Elements are added to influence physical properties of the aluminum alloy and performance characteristics.

As used herein, the phrase "7xxx aluminum alloys" and the like means an aluminum alloy selected from 7xxx aluminum alloys registered with the Aluminum Association and unregistered variants of the same.

As used herein, the term "cast product" means a product that has been produced by a casting method such as continuous casting as detailed in <CIT> and <CIT>. In one or more embodiments detailed herein, the term "cast product" includes a product produced from the "cast product". In one or more embodiments, the term "cast product" includes a rolled product produced from the "cast product".

As used herein, the term "variation" of the weight percent of an alloying element in a specified thickness depth of half thickness (T/<NUM>) has units of "%" and is calculated according to the following equation:
<MAT>.

As used herein, the term "centerline segregation" means the enrichment or depletion of alloying elements in a central portion of an aluminum alloy strip. In embodiments, centerline segregation is determined based on a variation of the weight percent of an alloying element in a specified thickness depth of an aluminum alloy strip. In one or more embodiments detailed herein, centerline segregation is determined based on a variation of weight percent of an alloying element of greater than <NUM>% between a surface and a thickness center of the aluminum alloy strip.

As used herein, the "weight percent of an alloying element" in a specified thickness depth is determined using the "macro-segregation procedure" detailed herein.

As used herein, the term "strip" may be of any suitable thickness, and is generally of sheet gauge (<NUM> to <NUM> (<NUM> inch to <NUM> inch)) or thin-plate gauge (<NUM> to <NUM> (<NUM> inch to <NUM> inch)), i.e., has a thickness in the range of from <NUM> to <NUM> (<NUM> inch to <NUM> inch). In one embodiment, the strip has a thickness of at least <NUM> (<NUM> inch). In one embodiment, the strip has a thickness of less than <NUM> (<NUM> inch). In one or more embodiments detailed herein, the strip has a thickness of from <NUM> to <NUM> (<NUM> to <NUM> inches). In one or more embodiments detailed herein, the strip has a thickness of from <NUM> to <NUM> (<NUM> to <NUM> inches).

As used herein, "surface" means a top surface or a bottom surface of the cast product.

As used herein, "thickness center" means a depth of half the total thickness of the cast product or half thickness (t/<NUM>).

In one or more embodiments detailed herein, the aluminum alloy strip may include at least one of <NUM> wt. % to <NUM> wt. % copper and <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy may include 7xxx (zinc based) aluminum alloys.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % magnesium.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % manganese. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % manganese. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % manganese. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % manganese. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % manganese.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % chromium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % chromium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % chromium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % chromium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % chromium.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium. In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium.

In one or more embodiments detailed herein, the aluminum alloy strip has <NUM> wt. % to <NUM> wt. % zirconium.

In one or more embodiments detailed herein, the aluminum alloy strip is free of at least one of copper, magnesium, manganese, chromium, or zirconium.

In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% or less.

In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent is <NUM>% to <NUM>% between a surface and a thickness center of the aluminum alloy strip.

In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%. In one or more embodiments detailed herein, a variation of the zinc weight percent between a surface and a thickness center of the aluminum alloy strip is <NUM>% to <NUM>%.

In one or more embodiments detailed herein, the aluminum alloy has a zinc weight percent of <NUM>% to <NUM>% or any other weight percent range detailed herein and does not exhibit centerline segregation.

In embodiments, the casting of the aluminum alloy strip detailed herein may be accomplished via a continuous casting apparatus capable of producing continuously cast products that are solidified at high solidification rates. One example of a continuous casting apparatus capable of achieving the above-described solidification rates is the apparatus described in <CIT> and <CIT>. In one or more embodiments detailed herein, the aluminum alloy strip is continuously cast using the Micromill™ process described in <CIT> and<CIT>.

In embodiments, as illustrated in <FIG>, a molten aluminum alloy metal M may be stored in a hopper H (or tundish) and delivered through a feed tip T, in a direction B, to a pair of rolls R<NUM> and R<NUM>, having respective roll surfaces D<NUM> and D<NUM>, which are each rotated in respective directions A<NUM> and A<NUM>, to produce a solid cast product S. In one or more embodiments detailed herein, gaps G<NUM> and G<NUM> may be maintained between the feed tip T and respective rolls R<NUM> and R<NUM> as small as possible to prevent molten metal from leaking out, and to minimize the exposure of the molten metal to the atmosphere, while maintaining a separation between the feed tip T and rolls R<NUM> and R<NUM>. A plane L through the centerline of the rolls R<NUM> and R<NUM> passes through a region of minimum clearance between the rolls R<NUM> and R<NUM> referred to as the roll nip N.

In one or more embodiments detailed herein, during casting, the molten metal M directly contacts the cooled rolls R<NUM> and R<NUM> at regions <NUM> and <NUM>, respectively. Upon contact with the rolls R<NUM> and R<NUM>, the metal M begins to cool and solidify. The cooling metal produces an upper shell <NUM> of solidified metal adjacent the roll R<NUM> and a lower shell <NUM> of solidified metal adjacent to the roll R<NUM>. The thickness of the shells <NUM> and <NUM> increases as the metal M advances towards the nip N. Large dendrites <NUM> of solidified metal (not shown to scale) may be produced at the interfaces between each of the upper and lower shells <NUM> and <NUM> and the molten metal M. The large dendrites <NUM> may be broken and dragged into a center portion <NUM> of the slower moving flow of the molten metal M and may be carried in the direction of arrows C<NUM> and C<NUM>. The dragging action of the flow can cause the large dendrites <NUM> to be broken further into smaller dendrites <NUM> (not shown to scale). In the central portion <NUM> upstream of the nip N referred to as a region <NUM>, the metal M is semi-solid and may include a solid component (the solidified small dendrites <NUM>) and a molten metal component. The metal M in the region <NUM> may have a mushy consistency due in part to the dispersion of the small dendrites <NUM> therein. At the location of the nip N, some of the molten metal may be squeezed backwards in a direction opposite to the arrows C<NUM> and C<NUM>. The forward rotation of the rolls R<NUM> and R<NUM> at the nip N advances substantially only the solid portion of the metal (the upper and lower shells <NUM> and <NUM> and the small dendrites <NUM> in the central portion <NUM>) while forcing molten metal in the central portion <NUM> upstream from the nip N such that the metal may be completely solid as it leaves the point of the nip N. In this manner and in one or more embodiments detailed herein, a freeze front of metal may be formed at the nip N. Downstream of the nip N, the central portion <NUM> may be a solid central portion, <NUM> containing the small dendrites <NUM> sandwiched between the upper shell <NUM> and the lower shell <NUM>. In the central portion, <NUM>, the small dendrites <NUM> may be <NUM> microns to <NUM> microns in size and have a generally globular shape. The three portions, of the upper and lower shells <NUM> and <NUM> and the solidified central portion <NUM>, constitute a single, solid cast product (S in <FIG> and element <NUM> in <FIG>). Thus, the aluminum alloy cast product <NUM> may include a first portion of an aluminum alloy and a second portion of the aluminum alloy (corresponding to the shells <NUM> and <NUM>) with an intermediate portion (the solidified central portion18) therebetween. The solid central portion <NUM> may constitute <NUM> percent to <NUM> percent of the total thickness of the cast product <NUM>.

The rolls R<NUM> and R<NUM> may serve as heat sinks for the heat of the molten metal M. In one embodiment, heat may be transferred from the molten metal M to the rolls R<NUM> and R<NUM> in a uniform manner to ensure uniformity in the surface of the cast product <NUM>. Surfaces D<NUM> and D<NUM> of the respective rolls R<NUM> and R<NUM> may be made from steel, copper, nickel, or other suitable material and may be textured and may include surface irregularities (not shown) which may contact the molten metal M.

The control, maintenance and selection of the appropriate speed of the rolls R<NUM> and R<NUM> may impact the ability to continuously cast products. The roll speed determines the speed that the molten metal M advances towards the nip N. If the speed is too slow, the large dendrites <NUM> will not experience sufficient forces to become entrained in the central portion <NUM> and break into the small dendrites <NUM>. In one or more embodiments detailed herein, the roll speed may be selected such that a freeze front, or point of complete solidification, of the molten metal M may form at the nip N. Accordingly, the present casting apparatus and methods may be suited for operation at high speeds such as those ranging from <NUM> to <NUM> (<NUM> to <NUM> feet) per minute; alternatively from <NUM> to <NUM> (<NUM> to <NUM> feet) per minute; alternatively from <NUM> to <NUM> (<NUM> to <NUM> feet) per minute; alternatively from <NUM> to <NUM> (<NUM> to <NUM> feet) per minute; and alternatively from <NUM> to <NUM> (<NUM> to <NUM> feet) per minute. The linear rate per unit area that molten aluminum is delivered to the rolls R<NUM> and R<NUM> may be less than the speed of the rolls R<NUM> and R<NUM> or about one quarter of the roll speed.

Continuous casting of aluminum alloys according to the present disclosure may be achieved by initially selecting the desired dimension of the nip N corresponding to the desired gauge of the cast product S. The speed of the rolls R<NUM> and R<NUM> may be increased to a desired production rate or to a speed which is less than the speed which causes the roll separating force increases to a level which indicates that rolling is occurring between the rolls R<NUM> and R<NUM>. Casting at the rates contemplated by an embodiment of the present invention (i.e. <NUM> to <NUM> (<NUM> to <NUM> feet) per minute) solidifies the aluminum alloy cast product about <NUM> times faster than aluminum alloy cast as an ingot cast and improves the properties of the cast product over aluminum alloys cast as an ingot. The rate at which the molten metal is cooled may be selected to achieve rapid solidification of the outer regions of the metal. Indeed, the cooling of the outer regions of metal may occur at a rate of at least <NUM> degrees Celsius per second.

The continuous cast strip may be of any suitable thickness, and is generally of sheet gauge (<NUM> to <NUM> (<NUM> inch to <NUM> inch)) or thin-plate gauge (<NUM> to <NUM> (<NUM> inch to <NUM> inch)), i.e., has a thickness in the range of from <NUM> to <NUM> (<NUM> inch to <NUM> inch). In one embodiment, the strip has a thickness of at least <NUM> (<NUM> inch). In one embodiment, the strip has a thickness of less than <NUM> (<NUM> inch).

Samples are first mounted and polished in Lucite using standard metallographic preparation techniques for aluminum. An Electron Probe Micro Analyzer ("EPMA") is used to profile the distribution of the alloying elements across a thickness to show the macro-segregation of the alloying elements.

EPMA line scans are set with an initial spot of <NUM> micrometers diameter about <NUM> micrometers from the sample surface moving in the thickness direction until the other surface is reached. The defocused beam spots are calculated to maintain a <NUM> micrometer separation to provide <NUM>% overlap between points.

A JEOL JXA 8530F Field Emission Electron Probe Microanalyzer Hyperprobe with <NUM> Wave dispersive spectrometers and JEOL SDD-EDS are used to gather the data. The operating conditions are:.

The wave dispersive spectrometer (WDS) crystal and spectrometers are used as detailed in the Table <NUM>.

A background measurement is collected every <NUM> spots for <NUM> seconds on positive and negative background locations. Elements measured are quantitatively analyzed using the JEOL quant ZAF analysis package for metals with atomic number correction by Philibert-Tixier method and flourescence excitation correction by Reed method.

Alternately, the concentration of alloying elements through depth of a sample was determined using a quantometer consistent with the method used to analyze the samples from <CIT>.

Samples are first mounted and polished in Lucite using standard metallographic preparation techniques for aluminum. An EPMA is used to profile the distribution of the alloying elements across a thickness to show the micro-segregation of the alloying elements.

EPMA line scans are set with a focused spot moving with a <NUM> micrometer step across several grains to provide overlapping points through multiple grains.

Aluminum alloy samples were cast using the apparatus detailed in <CIT> at a speed of <NUM> (<NUM> feet) per minute to <NUM> (<NUM> feet) per minute and had a final thickness detailed in the tables below. The average weight percentages of the zinc, magnesium and copper from the surface to <NUM>,<NUM> micrometers thickness depth in each sample was determined using either the "macro-segregation" procedure detailed herein or via quantometer. Table <NUM> below shows the average weight percentages of zinc, copper and magnesium from surface to a thickness depth of <NUM>,<NUM> micrometers in each of the cast samples and the method used to determine the weight percentages in each sample:.

Table <NUM> below shows the variation of zinc weight percentages in each of the samples from surface to a thickness depth of <NUM>,<NUM> micrometers:.

The average weight percentages of the zinc, magnesium and copper from the surface to the thickness center in each sample were determined using either the "macro-segregation" procedure detailed herein or via quantometer. Table <NUM> below shows the average weight percentages of zinc, copper and magnesium from surface to a thickness center in each of the cast samples and the method used to determine the weight percentages in each sample:.

Table <NUM> below shows the variation of zinc weight percentages in each of the samples from surface to a thickness center in each sample:.

The data generated for each sample is plotted in <FIG>. A comparison the weight percentages of the zinc, magnesium and copper through thickness of a direct chill cast prior art product and a continuously cast prior art product of <CIT> are also included as <FIG> for comparison.

As shown in <FIG> and the tables above, the inventors surprisingly found that the variation of the zinc weight percent between a surface and a thickness depth of <NUM>,<NUM> micrometers in samples <NUM>-<NUM> is less than <NUM>%. Moreover, the variation of the zinc weight percent between a surface and a thickness depth of <NUM>,<NUM> micrometers of sample <NUM> is greater than <NUM>%. Similarly, based on visual inspection of <FIG>, the variation of the zinc weight percent between a surface and a thickness depth of <NUM>,<NUM> micrometers in the direct chill cast prior art product and the continuously cast prior art product is greater than <NUM>%.

As shown in <FIG> and the tables above, the inventors surprisingly found that the variation of the zinc weight percent between a surface and a thickness center in samples <NUM>-<NUM> according to the present invention is less than <NUM>%. Moreover, based on visual inspection of <FIG>, the variation of the zinc weight percent between a surface and a thickness center of the direct chill cast prior art product and the continuously cast prior art product is greater than <NUM>%.

The weight percentages of the zinc, magnesium and copper across grains from the surface to <NUM> micrometers thickness depth in sample <NUM> was determined using the "micro-segregation" procedure detailed herein. The data is presented in <FIG>. For comparison, the weight percentages of the zinc, magnesium and copper across grains through thickness for a direct chill cast prior art product are shown in <FIG>. As shown in <FIG>, the inventors surprisingly found that the weight percent of the primary alloying elements Zn, Cu and Mg were substantially uniform across the grains within the matrix with an increase in the weight percent of the alloying elements at the positions of second phase particles at grain boundaries and within the grains.

<FIG> shows the structure of sample <NUM>. The structure of samples of aluminum alloys having average zinc contents of <NUM>% and <NUM>% cast using the apparatus detailed in <CIT> at a speed of <NUM> (<NUM> feet) per minute are shown in <FIG>, respectively. <FIG> show products of the present invention have a globular grain structure and are substantially free of micro-segregation. Moreover, as illustrated in <FIG>, the products of the present invention may be substantially free of dendrites and consist primarily of globular non-dendritic grains - i.e., a globular grain structure. Also, as shown by the absence of shading within the grains of <FIG> when the samples are observed in polarized light, the products are substantially free of micro-segregation effects.

Claim 1:
A cast product comprising:
an aluminum alloy strip;
wherein the aluminum alloy strip comprises:
<NUM> wt. % to <NUM> wt. % zinc;
optionally at least one of <NUM> wt. % to <NUM> wt. % Cu and <NUM> wt. % to <NUM> wt. % Mg;
optionally <NUM> wt. % to <NUM> wt. % Mn;
optionally <NUM> wt. % to <NUM> wt. % Cr;
optionally <NUM> wt. % to <NUM> wt. % Zr;
the balance being aluminum and impurities,
wherein the aluminum alloy strip has a thickness (T),
wherein the aluminum alloy realizes a zinc variation of not greater than <NUM>% as measured between a surface (S) of the aluminum alloy strip and a center (T/<NUM>) of the aluminum alloy strip,
wherein the zinc variation is calculated as {(the maximum weight percent of zinc from the surface (S) to the thickness center (T/<NUM>) minus (-) the minimum weight percent of zinc from the surface (S) to the thickness center (T/<NUM>)) divided by (/) (the mean weight percent of the zinc from the surface (S) to the thickness center (T/<NUM>))}*<NUM>, wherein the weight percent of zinc is measured according to the macro-segregation procedure disclosed in the description.