KR20170082604A - Multipurpose heat treatable aluminum alloys and related processes and uses - Google Patents

Abstract

The present application discloses processes for manufacturing aluminum alloys, aluminum alloys, metal parts such as automotive panels comprising aluminum alloys, and processes for making automotive parts made of aluminum alloys.

Description

[0001] MULTIPURPOSE HEAT TREATABLE ALUMINUM ALLOYS AND RELATED PROCESSES AND USES [0002]

Cross-reference to related application

This application is a continuation-in-part of U. S. Patent Application No. < RTI ID = 0.0 > Patent application number. 62 / 078,027, which is hereby incorporated by reference in its entirety.

Technical field

The present invention relates to materials science, material chemistry, metallurgy, aluminum alloys, fields of aluminum making and related fields.

Aluminum alloys used for various applications must achieve certain properties. For example, aluminum alloys are used for the manufacture of interior and exterior panels of transportation machinery. Aluminum alloys are useful for this application because of their light weight combination, which leads to increased fuel efficiency, strength, and other properties. Above all, aluminum alloys used for the manufacture of interior and exterior panels of transporting machinery should have good formability, paint or other finish quality, dent resistance and tolerance to natural aging. It is also preferred that the alloys used in the manufacture of transportation machinery are renewable. New and improved metal alloys with desirable properties suitable for the manufacture of transportation machinery panels have been found to extend the range of alloys available for these applications, lower material costs, increase aluminum reuse rates, capacity limits, and reduce the environmental impact of aluminum production and use.

The terms " invention, " " the invention, " " the invention ", and the " invention " are intended to broadly refer to all of the contents of this patent application and the claims below. The description including these terms should not be construed as limiting the content described in the present application or limiting the scope or meaning of the following patent claims. The disclosed embodiments of the present invention are defined by the claims rather than by this task solution. This task solution is a high level overview of various aspects of the present invention and introduces some of the concepts further described in the Detailed Description section below. This task solution is not intended to identify key or essential features of the claimed subject matter and is not intended to be used in isolation to determine the scope of the claimed subject matter. The contents should be understood by reference to the full specification, any or all of the figures, and the appropriate portions of the respective claims.

The present invention relates to an improved heat treatment which can exhibit age hardening when treated with a continuous solution treatment line containing a greater amount of Mg than is normally considered appropriate for heat treatment Lt; RTI ID = 0.0 > aluminum alloys. The improved aluminum alloys provided in this application may be produced as sheet alloys and may be more suitable for regeneration processes than conventional alloys. Some embodiments of the present invention are suitable aluminum alloys suitable for manufacturing automotive and other transportation machinery panels. Some other embodiments of the present invention include innovative new uses and applications of aluminum alloys, improved innovative processes for making, making or manufacturing aluminum alloys, aluminum alloy shapes, objects and components such as stamped Sheet forms, and processes for making panels for transportation machinery. Aluminum alloy objects, parts and shapes made from the improved aluminum alloys and / or according to the innovative processes provided in the present application are also provided among the embodiments of the present invention.

One embodiment of the present invention provided in this application is an aluminum alloy containing > 1.5% Mg by weight produced by a process comprising heat treatment. The heat treatment process may include a T4 temper. The aluminum alloy may further include 0.2 to 0.4% Si by weight. The aluminum alloy may undergo age hardening. The aluminum alloy may be a sheet aluminum alloy. Another embodiment of the present invention provided in this application is a stamped sheet foam made from the above sheet aluminum alloy. The stamped sheet form may be an automotive panel. One embodiment of the present invention provided in the present application is a process for producing a sheet aluminum alloy comprising > 1.5% Mg and 0.2 to 0.4% Si by weight, including heat treatment. The process may include a T4 temper. The resulting sheet aluminum alloy may exhibit age hardening. One or more embodiments of the present invention described in this application is a process for manufacturing stamped sheet foams comprising stamping of sheet aluminum alloys. The stamped sheet foam may be an automotive panel.

1 is a schematic diagram illustrating process steps used to produce sheet aluminum alloys.
Figure 2 is a schematic illustration of various sheet stampings used in automotive production.
Figure 3 is a bar graph showing the DIN tensile properties of the alloy in O temper and paint bake.
4 is a bar graph showing the tensile properties of the alloy at 185 DEG C for 20 minutes followed by T4, 2% elongation, and 2% elongation.
Figure 5 is a bar graph showing the tensile properties of the alloy at T4 temper and after paint bake simulation (60 < 0 > C for 60 min).
Figure 6 is a line plot illustrating the age hardening of the AA5251-T4 alloy.

In the present description, reference is made to AA numbers and alloys identified by other related designations, e.g., " series ". For an understanding of the numerical nomenclature system most commonly used for naming and identifying aluminum and its alloys, reference is made to "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Aluminum Alloys " published by the Aluminum Association Please refer. 6xxx series aluminum alloys such as AA6111, AA6016 and AA6022 are typically used to produce automotive exterior skin panels.

In general terms, 6xxx series alloys containing relatively high levels of Si and low levels of Mg are thermally processable and exhibit age hardening, which results in the formation of outer panels for transporting machines, such as automobiles, in these alloys And gives appropriate strength parameters. O Temperatures 5xxx series aluminum alloys, such as AA5182-O or AA5754-O, are often preferred for internal panel manufacture in automotive and related industries due to their formability properties. 5xxx series aluminum alloys have very little tolerance to retaining Si in solid solution. If Si is added to 5xxx series aluminum alloys, it tends to bond with Mg to form coarse Mg ₂ Si particles during casting. These particles are difficult to solution process to produce supersaturated solid solutions of Mg and Si during solutionizing and rapid cooling on successive annealing lines. For this reason, 5xxx series aluminum alloys contain relatively low Si levels and relatively high Mg levels, and are considered not heat treatable due to their high Mg content. The presence of coarse Mg ₂ Si is potentially harmful to moldability.

Currently, 6xxx and 5xxx aluminum alloys can not be easily combined and regenerated for the manufacture of automobiles and related panels because the resulting regenerated aluminum alloys are undesirably Si (compared to 5xxx series aluminum alloys) and Mg (6xxx Series alloys), and thus may not be suitable for heat treatment due to high Mg levels or may not have the formability of 5xxx series alloys due to the relatively high combination of Si and Mg levels . In addition, the presence of other metals, such as Cu, Mn, Fe or Zn, or combinations thereof, present in the alloys recycled from the combination of 5xxx and 6xxx alloys may lead to undesirable properties of the regenerated aluminum alloys have. For example, an undesirable combination of properties may make the recycled aluminum alloy unsuitable for the manufacture of internal or external panels for transportation machinery.

The inventors have discovered that alloys containing relatively high levels of Mg, e.g., > 1.5% Mg, exhibit heat treatability and age hardening if the appropriate amount of Si and / or Cu is present in such an alloy. This property makes aluminum alloys with a relatively high magnesium content as compared to traditional 6xxx alloys, unexpectedly and preferably suitable for applications where age hardening is desirable. For example, the inventors have found that although there is a greater amount of Mg than is commonly considered suitable for heat treatment, but compared to 5xxx series aluminum alloys traditionally used in internal automotive panel manufacturing, such as AA5754 or AA5182 alloys It has been found that some aluminum alloys containing small amounts of Mg and larger amounts of Si may exhibit age hardening if they are solution treated with successive solution heat treatment lines.

The discovery of the inventors is embodied in the improved aluminum alloys described in the present application. The improved aluminum alloys described in this application may be produced as sheets, and in some cases they may be referred to as " sheet aluminum alloy ", " aluminum sheet "Quot;, " sheet alloys ", or by other related terms. The term " aluminum alloy " and similar terms as used in this application are broader than " Sheet aluminum alloys are a subset of aluminum alloys. Sheet aluminum alloys may have the same or similar composition, but, in some cases, may possess other properties than the same alloy but not sheet foams . Some of these properties may be imparted by manufacturing or manufacturing processes used in the production of sheet aluminum alloys There.

Improved aluminum alloys embodying Applicants' inventions exhibit a similar age hardening to 6xxx series alloys. They can also exhibit similar moldability characteristics to those of 5xxx series aluminum alloys. Improved aluminum alloys are heat treatable. Improved aluminum alloys produce automotive and other transportation machinery panels, and more generally, high-Mg 5xxx series alloys may be suitable for applications that are traditionally used. The increased content of the improved aluminum alloy in accordance with some embodiments of the present invention, Si and / or Cu are used beneficial to the age hardening preferred application, which is Si and / or Cu, Mg ₂ Si during the natural or artificial aging And it is possible to impart cure on the solution-treated alloys due to precipitation of Al ₂ CuMg particles. In addition to Si and / or Cu, some other elements may be present in the improved aluminum alloys described in this application in greater amounts than some 5xxx series aluminum alloys typically used in the manufacture of automotive panels. The presence of these elements can impart beneficial properties on the improved aluminum alloys described in this application. For example, increased levels of Mn can promote the formation of dispersoids that can help disperse the slip, thus improving moldability. The inventors have also found that the improved aluminum alloys described in this application are more suitable for regeneration processes than conventional alloys because improved aluminum alloys are typically used in 5xxx series aluminum alloys, Cu, Fe or Mn relative to the AA5754 and AA5182 alloys. Thus, the improved regeneration processes embody some of the inventors' findings.

In addition to the improved aluminum alloys, the inventors ' findings show that with the innovative new uses and applications of aluminum alloys, improved and innovative processes for making, manufacturing or manufacturing aluminum alloys, aluminum alloy shapes, For example, stamped sheet forms, processes for manufacturing panels for transportation machinery. Aluminum alloy objects, parts, and shapes made with the improved aluminum alloys and / or in accordance with the innovative processes described in this application also embody inventors' findings.

Alloys

Improved aluminum alloys according to embodiments of the present invention may be made of at least one of the following levels of Si, Cu, Fe, Mn, or Zn and at least a lower level of Mg and / or at least It differs from conventional alloys used in automotive applications in that it contains more levels of Mg than some 6xxx series alloys. The composition of the improved aluminum alloys is illustrated in Table 1 below. The contents of the listed elements may fall within the ranges delimited by the lower range limit and the upper range limit shown in Table 1. [ The lower range limit value may be expressed as "equal or greater" (≥ symbol) or "larger" (> symbol), or other related symbols and expressions such as "... Quot ;, &quot; more than &quot;, and the like. The upper range limit value may be described by expressions "equal or smaller" (≤ symbol), "less than" (<symbol) or other related symbols and expressions such as "up to," "less than, have. Other types of expressions may also be used to describe ranges, such as &quot; within range &quot;, &quot; &quot; and the like. When the range is described only by the upper range limits, in some examples, the element in question may not be present, may not be present in detectable quantities, or there are too small quantities so that they are typically aluminum alloy It is to be understood that they are not perceived as meaningful in the field of the present invention. It should also be understood that some of the other additives and / or elements that are not inevitably listed in the tables below may be present in the aluminum alloys described in this application.

Table 1. Composition of improved aluminum alloys (element content in wt%)

Table 2. Representative compositions of typical 5xxx series alloys used in automotive applications (elemental content expressed in wt%)

Features and Benefits

The improved aluminum alloys described in this application including sheet aluminum alloys can be used in the manufacture of automotive applications, such as automotive panels, or, more generally, panels for various types of transportation machinery, or even more generally , And one or more properties that make them suitable for use with stamped sheet foams. Some of these properties are formability, yield strength and age hardening. The improved aluminum alloys also have beneficial regeneration compatibility with 6xxx series aluminum alloys such as AA6111, AA6022 or AA6016. It will be appreciated that the expressions &quot; recycling compatibility &quot; and related terms are used to describe aluminum alloys in which improved aluminum alloys in accordance with some embodiments of the present invention during metallurgical processes to produce commercially and technically useful aluminum alloys comprise 6xxx series alloys (and, Optionally, other alloys or elements), which may be described as being &quot; recycled &quot;.

Formability and paint bake response

The moldability characteristics of the aluminum alloys described in this application can be influenced by many variables. Moldability properties include, but are not limited to, deep drawability and stretchability. One parameter that affects the moldability properties is the composition of the aluminum alloy. For example, the formability, including castability, is affected by the amount of Mg, Cu and Si in the aluminum alloy. Highly bonded amounts of Mg, Si and / or Cu generally make it more difficult to cast and hot roll the aluminum alloy. Accordingly, the content of one or more of these elements may be varied to reach the desired moldability characteristics. Other variables that may affect formability include manufacturing process variations and conditions such as, but not limited to, aluminum sheet processing steps and conditions, surface texturing process steps and conditions, and lubrication process steps And states. One or more of the above variables may be adjusted to achieve the desired moldability characteristics. Another important property that can be changed by one or more of the variables discussed above is the paint bake response of the aluminum alloy, which represents a change in strength during the paint curing process. The paint bake response is typically tested in the laboratory by aging the deformed or unmodified material in the T4 temper at elevated temperatures. The exact simulation conditions that determine the paint bake response vary from vehicle to vehicle. For example, the paint bake response can be defined as a change in strength by aging the aluminum alloy at 180 &lt; 0 &gt; C.

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The improved aluminum alloys according to embodiments of the present invention may exhibit yield strengths of 80 to 160 MPa (YS), which is typical of the finishes and painted parts required for automotive applications, and the yield strength of AA5754 or AA5182 &Lt; / RTI &gt; In some embodiments, the strength of the improved aluminum alloy is typically influenced by increasing the amount of Cu in the aluminum alloy relative to the Cu content of alloys used in the manufacture of panels for automobiles and other transportation machinery.

Hardness

Certain embodiments of the improved aluminum alloys described in this application exhibit heat treatability and aging-related hardening, while exhibiting moldability comparable to typical 5xxx aluminum alloys typically used in automotive applications. 5xxx aluminum alloys are not previously known to be heat treatable or to exhibit aging-related cures upon heat treatment. Improved aluminum alloys according to some embodiments of the present invention typically contain a greater level of Mg than aluminum alloys that are perceived to be heat treatable. Some examples of the improved aluminum alloys of the present invention contain &gt; 1.5% Mg and are heat treatable. The presence of a suitable amount of Si and / or Cu imparts heat treatability and age hardening properties to an improved aluminum alloy containing &gt; 1.5% Mg. This is because some advanced aluminum alloys according to embodiments of the present invention exhibit moldability (typically imparted by more Mg levels than are present in thermally-processable alloys) and age hardening such as T4 tempering (Imparted by more Si levels than are typically present in 5xxx series alloys).

In some embodiments, the improved aluminum alloys of the present invention contain a reduced amount of Mg, as compared to some of the 5xxx aluminum alloys and, for example, those typically employed in the manufacture of internal automotive panels. The reduced levels of Mg can result in lower costs of shapes objects made with these alloys as less Mg is required for production, as well as lower costs of the improved aluminum alloys described in this application. The reduced levels of Mg in the improved aluminum alloys described in this application can also result in improved solubility of Si in aluminum during solutionizing, which has a favorable effect on the properties of the alloys. Both Si and Cu are capable of improving the curing of the solution-treated advanced aluminum alloys described in this application because of the precipitation of Mg ₂ Si and Al ₂ CuMg or Q (AlMgSiCu) containing particles during aging.

Recyclability

The improved aluminum alloys of the present invention have a greater resistance to Si than 5xxx series alloys typically used in the manufacture of automotive panels. The ability of the improved aluminum alloys described in this application to indicate paint bake response and / or the higher resistance of Si make aluminum alloys compatible and suitable for 6xxx alloys for regeneration.

In summary, the improved aluminum alloys of the present invention have a beneficial combination of properties, allowing these advanced alloys to be used in place of conventional high-Mg aluminum alloys for a variety of applications. The improved aluminum alloys described in this application can extend the range of alloys available for various applications, one of which is the manufacture of stamped sheet forms, such as panels for automobiles and other transportation machinery, Increase recycling ratios, lower the cost of manufacturing aluminum alloys, and reduce the environmental impact of aluminum production.

Manufacturing Processes

Processes for making or manufacturing improved aluminum alloys are also within the scope of the present invention. The improved aluminum described in this application can be made by processes that include at least a portion of the technology steps described below. At least some of these technological steps may impart beneficial properties to the improved aluminum alloys. Thus, in some cases, it is important to include process steps when describing improved aluminum alloys. For example, one exemplary embodiment of the improved aluminum alloy described in this application is the AA5251 alloy. Prior to the discovery of the inventors, the AA5251 alloy containing > 1.5% Mg was suitable for heat treatment and was not known to exhibit age hardening when in T4 tempering. Thus, one exemplary embodiment of the improved aluminum alloys described in this application is the AA5251 alloy in the T4 temper, which may be referred to as AA5251-T4.

The processes of making or manufacturing improved aluminum alloys may include heat treating to alter the physical and / or chemical properties of the improved aluminum alloys. Thermal treatments include the use of heating and / or chilling of aluminum alloys to achieve desired results such as hardening. Embodiments of the processes described in this application employ T4 or T4P tempering, which involves the natural aging and solution treatment of aluminum alloys in a substantially stable state. T4P tempering refers to the special thermal heat treatment involved in the following solutionizing. This treatment may be reheated to a temperature ranging from 50 to 110 캜 within the time of the solution treatment or by cooling controlled from the solution treatment temperature. In some other embodiments, T6 and T8 tempers may also be used.

The descriptions and illustrations of the processes described in this application should be understood as non-limiting. The process steps described in this application may be combined and modified in a variety of ways and may be suitably employed to produce improved aluminum alloys or shapes and objects with these alloys. Although not explicitly described in the present application, the process steps and states employed in the fields of metallurgy and aluminum processing and fabrication in general can also be incorporated into the processes described in this application.

A representative process is schematically illustrated in FIG. It should be understood that one or more of the process steps illustrated in Figure 1 may be incorporated into the processes for making the improved aluminum alloys.

Another example of a process incorporating one or more steps that may be suitably employed and combined in various ways to produce improved aluminum alloys is described in this paragraph. Improved sheet aluminum alloys are produced from direct chilled (DC) ingots. However, hot rolled stock can also be produced from continuous cast slabs. The DC cast ingots are grown on both sides of the ingot at a temperature of 500 &lt; RTI ID = 0.0 &gt; and / or &lt; / RTI &gt; during time periods between 1 and 48 hours before the surface is scaled and subjected to hot and cold rolling with a final gauge to remove near the surface separation layer. 0.0 &gt; 575 C. &lt; / RTI &gt; The improved sheet aluminum alloy may also undergo special surface texturing to improve the moldability of the final sheet, such as, but not limited to, electron discharge texturing. Cold rolled strips are solution treated by heating at> 3 ° C / s with continuous annealing lines at temperatures between 500 and 575 ° C, followed by rapid cooling and natural aging to produce sheets on a T4 temper. The solution treatment process may re-dissolve soluble particles, such as Mg ₂ Si or other particles, back to the matrix depending on the alloy composition. Fast quenching is used to produce solids and supersaturated solids in the face to excess vacancies. Rapid cooling from the solution treatment temperature can be performed with forced air, water mist, or a combination of water spray and forced convection. Coiling is performed at a temperature of 50-110 占 폚 followed by coil cooling at a rate of? 10 占 폚 / hour. The coils may be reheated in strip form to ensure a coiling temperature between 50 and 110 &lt; 0 &gt; C. It is possible to subject the solution treated sheet alloy to acid or alkaline scrubbing followed by pretreatment with special chemical materials and lubricants, oils or waxes before coiling at a temperature between 50 and 110 &lt; 0 &gt; C . The coils may be blanked and used to stamp internal panels such as those illustrated in FIG.

Another example of a process incorporating one or more steps that may be suitably employed and combined in various ways to produce improved aluminum alloys is described in this paragraph. Directly cold-rolled cast alloy ingots are homogenized above 500 ° C for ≥2 hours, hot rolled to an intermediate gage at a coiling temperature between 280 and 400 ° C, and one or more passes having a mill or optimized finish texture Rolled to final gauge and solution treated to form strips at a temperature above 480 DEG C in a continuous annealing line and rapidly cooled and coiled between 50 DEG C and 120 DEG C. The heat coiling step is optional and is used to improve the paint bake response of the alloy. In some situations, the solution treated coils may also be cleaned, pretreated and lubricated prior to stamping.

The following discussion is included to illustrate the beneficial properties that fabrication process steps may impart on the improved aluminum alloys described in the present application. Traditionally, AA5754 or AA5182 alloys have been supplied for the manufacture of automotive panels in soft O temperers so that the parts can be formed of these alloys and undergo paint curing operations. O Temperer AA5754 or AA5182 shows softening due to restoration during paint bake. The improved aluminum alloys according to some embodiments of the present invention do not undergo such softening in the O temper or have undergone softening to the same size as AA5754 or AA5182. The improved aluminum alloys described in this application can maintain strength closer to AA5754 and AA5182 after formation and paint curing. For example, the strength properties on the final part made from the improved aluminum alloys of the present invention may be similar or equivalent to AA5754 alloy.

Uses and Applications

The uses and applications of the improved aluminum alloys described in this application as objects, shapes, devices, and the like, including the improved alloys described herein or made from the improved alloys, . Processes for making, producing, or manufacturing such objects, forms, devices, and the like are also within the scope of the present invention. For example, some embodiments of the improved aluminum alloys described in this application are suitable for the manufacture of automotive panels. Various automotive panels, including internal and external automotive panels, are thus within the scope of the present invention. They are described, for example, in U.S. Pat. Patent publication number. 2010/0279143, and is also illustrated in Fig.

However, it should be understood that the uses and applications of the improved aluminum alloys and objects made from these alloys are not limited to automotive panels. Other objects may be suitably made of the improved aluminum alloys described in the present application. One example is panels that are incorporated in various transport vehicles and other moving machinery, which may be generally referred to as &quot; transportation panels &quot; or &quot; machinery panels. &Quot; For example, the panels used for transportation trucks may preferably be made of the improved aluminum alloys described in this application. Transport trucks with aluminum cabs are traditionally made of AA5052 alloy. This alloy tends to show yield point elongation or stretch bands during formation, resulting in objectionable surface appearance. Improved aluminum alloys according to some embodiments of the present invention may be used to replace the AA5052 alloy for the manufacture of panels that do not exhibit a yield point elongation and are preferably used in transportation trucks.

More generally, some embodiments of the improved aluminum alloys described in this application, as compared to conventional 5xxx alloys, are also referred to as "slip bands ", which are local bands of plastic deformation to metals experiencing tensile stresses quot; bands "or" stretcher-strain marks &quot;. Thus, the improved aluminum alloys described in this application can be employed in the manufacture of parts or objects, where ruddle bands are preferably bad, such as automobiles and other transport vehicles and outer panels for moving machinery.

Some embodiments of the alloys described in this application are suitable for complex electronic applications. One example of such an application is aluminum TV frames. More generally, various sheet stampings, stamped sheet forms, stamped panels, or related objects made from the improved aluminum alloys described in this application are included within the scope of embodiments of the present invention.

The following examples will serve to further illustrate the present invention at the same time, but without constituting any limitation of the present invention. On the contrary, it is evident that the means may have various embodiments, modifications and equivalents thereof, which can be suggested by those skilled in the art without departing from the scope of the invention, after reading the description in this application It will be understood. During the studies described in the following examples, ordinary procedures are followed unless otherwise stated. Some procedures are described below for illustrative purposes.

Example 1

Testing of Tensile Properties of AA5251 Alloy in O Temperer

Aluminum ingots containing 1.85% Mg, 0.3% Fe, 0.28% Mn and 0.29% Si were homogenized at 540 ° C for> 5 hours to obtain an O temper, hot-rolled to 3.2 mm gauge, Cold rolled and annealed at 340 [deg.] C for 1 hour. The lateral tensile properties of the annealed sheets were determined using DIN specimens. Figure 3 shows the DIN tensile properties of the alloy in both O and paint bake (5% elongation plus 20 minutes at 185 [deg.] C). The alloys exhibited a yield strength (YS) of 70 MPa, an ultimate tensile strength of 164 MPa, and a total elongation of 23% at O temperer and no cure after aging at 185 ° C for 20 minutes . In paint bake tempering (5% elongation plus 20 minutes at 185 ° C), the larger YS is the net result of work-hardening due to elongation and restoration due to aging.

Example 2

Effect of Solution Treatment on Tensile Properties of AA5251 Aluminum Alloy

This example shows the effects of solution treatment on the tensile properties of aluminum alloys. Aluminum ingots containing 1.85% Mg, 0.3% Fe, 0.28% Mn and 0.29% Si were homogenized at 540 ° C for> 5 hours, hot rolled to 3.2 mm gauge and cold rolled to a final 1.3 mm gauge. Cold rolled 1.3 mm gauge sheets were solution treated at 560 캜 for 2 minutes, cooled and immediately pre-aged at 85 캜 for 8 h. The solubilized alloy lateral ASTM properties were determined after 24 hours of natural aging. Figure 4 shows comparative tensile properties of alloys at T4 temper, 2% elongation, and 2% elongation plus 20 minutes temperatures at 185 [deg.] C. The aluminum alloy on the T4 tempering was stronger as compared to its O-tempered counterpart, as illustrated by comparison of Figures 3 and 4. The aluminum alloy on the T4 tempering showed a significant increase in YS due to 2% elongation and after undergoing aging at 185 [deg.] C for 20 minutes in the elongated sample. The tensile properties of the aluminum alloy on the T4 tempering were close to the conventional AA5754 alloy. The yield strength of aluminum alloys was close to the expected strength of AA5182 or AA5754 alloys after undergoing similar paint bake treatment of AA5182 or AA5754 alloys.

Example 3

Role of adding Cu to alloys

Aluminum ingots containing 1.75% Mg, 0.78% Cu, 0.23% Fe, 0.11% Mn and 0.38% Si were homogenized at 560 ° C for> 18 hours and then hot rolled and cold rolled Lt; RTI ID = 0.0 &gt; 540 C &lt; / RTI &gt; as a continuous annealing line, cooled and pre-aged. The lateral tensile properties of 1.6 mm gauge sheets were determined using ASTM specimens.

Figure 5 shows the tensile properties of the alloy at T4 temper and paint bake (180 &lt; 0 &gt; C for 60 min). This alloy containing more levels of copper than the AA5251 alloy discussed in Examples 1 and 2 was significantly stronger than the AA5251 alloy. The alloys tested in this example showed 143 MPa YS, 284 MPa UTS and 28% total elongation at T4 tempering and significant curing after aging at 180 ° C for 60 minutes due to precipitation of CuMgAl ₂ and Mg ₂ Si particles.

Example 4

Comparison testing of AA5754 in O Temperatures and AA5251 in O and T Temperers

Aluminum ingots of AA5754 and AA5251 alloys having the compositions shown in Table 3 were homogenized at 540 DEG C for> 5 hours, hot rolled and individually cold rolled to final 1 and 1.3 mm gauges in separate tests. The coils of AA5754 and AA5251 were individually solution treated at 500 and 560 ° C on a continuous annealing line.

The tensile tests resulting from the test coils are shown in Table 4. It can be seen that the yield strength and the ultimate tensile strength of a typical AA5754 sheet at 0 °, 45 ° and 90 ° O tempera- tures in the rolling direction are individually close to the range of 100 MPa and 219 to 231 MPa. The AA5251 alloy in the O temperer shows smaller values compared to AA5754, except for the strain hardening exponent (n) value. T tempering, the AA5251 alloy shows a significant improvement in strength properties, such as yield strength and ultimate tensile strength, compared to AA5251 O temper alloy. In terms of strength, the AA5251T temper alloy is between AA5754 and AA5251-O temper. The AA5251 T temper alloy typically exhibits unprecedented paint bake response in AA5251 and AA5754-O temper alloys. Improvements detected in the AA5251 T temper alloy provide the possibility of using it as a replacement for AA5754 and possibly AA5182 alloys. The slightly poorer properties of the AA5251T temper alloy indicated by the lower elongation, UTS and n values are due to a variety of properties, including optimizing alloy and process compositions using the preferred sheet surface texture, or choice of lubricant, during formation Technologies. &Lt; / RTI &gt;

Table 3. Aluminum alloy composition

Table 4. Comparison Test Results of AA5754 at O Temperatures and AA5251 at O and T Temperers

Example 5

Aging hardening of AA5251 T4 tempering alloy at 185 ° C

Aging hardening studies of AA5251 T4 tempered alloys were carried out by placing tensile samples of alloys in a furnace set at 180 占 폚. Samples were taken from the furnace after different aging times. 6 shows the aging hardening behavior of the alloy at 180 &lt; 0 &gt; C. The alloys showed about 70% and 20% increase in YS and UTS individually after about 8 h of aging. The results illustrated in FIG. 6 support the conclusion that the alloy underwent aging hardening.

All patents, publications and abstracts cited above are incorporated herein by reference in their entirety. Different arrangements and combinations of the elements and features described in this application are possible. Similarly, some features and subcombinations are available and may be employed without reference to other features and subcombinations. Various embodiments of the invention have been described with the realization of the various objects of the invention. It should be appreciated that these embodiments are merely illustrative of the principles of the present invention. Many modifications and adaptations thereof will become readily apparent to those skilled in the art without departing from the scope and spirit of the invention.

Claims (12)

An aluminum alloy, containing &gt; 1.5% Mg by weight, produced by a process comprising heat treatment. The aluminum alloy of claim 1, wherein the process comprises a T4 temper. The aluminum alloy according to claim 1 or 2, wherein the aluminum alloy further comprises 0.2 to 0.4% Si by weight. The aluminum alloy according to any one of claims 1 to 3, wherein the aluminum alloy exhibits age hardening. The aluminum alloy according to any one of claims 1 to 4, wherein the aluminum alloy is a sheet aluminum alloy. A stamped sheet foam made from the sheet aluminum alloy of claim 5. 7. The stamped sheet foam of claim 6, wherein the stamped sheet form is an automotive panel. A process for producing a sheet aluminum alloy comprising &gt; = 1.5% Mg and 0.2% to 0.4% Si by weight, comprising heat treatment. 9. The process according to claim 8, wherein the process comprises a T4 temper. The process according to claim 8 or 9, wherein the sheet aluminum alloy exhibits age hardening. A process for making a stamped sheet foam comprising stamping the sheet aluminum alloy of claim 5. 12. The process of claim 11, wherein the stamped sheet foam is an automotive panel.

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