CN107109605A - The heat treatable aluminium alloy of multipurpose and related process and purposes - Google Patents

Abstract

A kind of aluminium alloy of disclosure, the technique for preparing the aluminium alloy, the technique for manufacturing the metal parts such as car panel for including the aluminium alloy, and the auto parts manufactured from the aluminium alloy.

Description

Multipurpose heat treatable aluminum alloys and related processes and uses

Cross References to Related Applications

This application claims the benefit of US Provisional Patent Application No. 62/078,027, filed November 11, 2014, which is hereby incorporated by reference in its entirety.

technical field

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

Background technique

Aluminum alloys used in various applications must achieve certain properties. For example, aluminum alloys are used in the manufacture of interior and exterior panels of transport machinery. Aluminum alloys are useful for this application due to their combination of light weight, strength, and other properties that lead to increased fuel efficiency. In addition, aluminum alloys used in the manufacture of interior and exterior panels of transportation machinery should possess good formability, paint or other finish quality, dent resistance, and immunity to natural aging. It is also desirable that the alloys used in the manufacture of transportation machinery be recyclable. New and improved metal alloys with desirable properties suitable for transportation machinery panel fabrication could expand the range of alloys available for these applications, reduce material costs, increase aluminum recycling rates, reduce capacity constraints on the production of such alloys, and Reduce the environmental impact of aluminum production and use.

Contents of the invention

As used herein, the terms "invention," "this invention," "this invention," and "current invention" are intended to refer broadly to all of the subject matter of this patent application and the appended claims. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the appended patent claims. Included embodiments of the invention are defined by the claims, not this Summary. This Summary is a high-level overview of various aspects of the invention and introduces some concepts that are further described in the Detailed Description section below. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings and each claim.

The present invention provides improved heat treatable aluminum alloys containing higher amounts of Mg than alloys conventionally considered suitable for heat treatment and which exhibit age hardening upon solutionization in a continuous solution heat treatment line. The improved aluminum alloys provided herein can be produced as sheet alloys and can be more suitable for recycling processes than conventional alloys. Some embodiments of the present invention are improved aluminum alloys suitable for making panels for automobiles and other transportation machinery. Some other embodiments of the invention are innovative new uses and applications of aluminum alloys, improved and innovative processes for making, fabricating or manufacturing aluminum alloys, for manufacturing aluminum alloy forms, objects and parts (such as stamped sheet Formed parts, panels for transport machinery). Also provided in embodiments of the present invention are aluminum alloy objects, parts and forms manufactured from improved aluminum alloys and/or according to the innovative processes provided herein.

One embodiment of the invention provided herein is an aluminum alloy comprising > 1.5% by weight Mg produced by a process including heat treatment. The heat treatment process may include a T4 tempering state. The aluminum alloy may further include 0.2 to 0.4% by weight of Si. The aluminum alloy is age hardenable. The aluminum alloy may be a sheet aluminum alloy. Another embodiment of the invention provided herein is a stamped sheet form made from the sheet aluminum alloy described above. The stamped sheet form may be an automotive panel. One embodiment of the invention provided herein is a process for making a sheet aluminum alloy comprising ≥ 1.5% Mg and 0.2 to 0.4% Si by weight, the process including heat treatment . The process may include a T4 temper. The resulting sheet aluminum alloy may exhibit age hardening. A further embodiment of the invention described herein is a process for manufacturing a stamped sheet form comprising stamping the sheet aluminum alloy described above. The stamped sheet form may be an automotive panel.

Description of drawings

FIG. 1 is a schematic diagram illustrating process steps for producing a sheet aluminum alloy.

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 alloys in the O temper and baked paint.

Figure 4 is a bar graph showing the tensile properties of the alloy at T4, 2% stretch, and 2% stretch followed by 20 minutes at 185°C.

Figure 5 is a bar graph showing the tensile properties of the alloy in the T4 temper and after bake-on simulation (60 minutes at 180°C).

FIG. 6 is a graph illustrating age hardening of the AA5251-T4 alloy.

detailed description

In this description, reference is made to alloys identified by AA numbers and other relevant designations such as "series". To understand the numerical designation system most commonly used when naming and identifying aluminum and its alloys, see International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys published by the Aluminum Association. and Wrought Aluminum Alloys). 6xxx series aluminum alloys such as AA6111, AA6016 and AA6022 are commonly used in the production of automotive skin panels.

In general, the 6xxx series alloys contain relatively high levels of Si and low levels of Mg, are heat treatable, and exhibit age hardening, which gives these alloys strength parameters suitable for the manufacture of exterior panels for transportation machinery such as automobiles. 5xxx series aluminum alloys in the O temper such as AA5182-O or AA5754-O are often preferred for interior panel fabrication in the automotive and related industries due to their formability properties. The 5xxx series aluminum alloys hardly allow Si to remain in solid solution. If Si is added to _5xxx series aluminum alloys, Si tends to combine with Mg during casting to form coarse Mg2Si particles. During solutionization and rapid cooling on a continuous annealing line, these particles are difficult to solutionize to produce a supersaturated solid solution of Mg and Si. For this reason, the 5xxx series aluminum alloys contain relatively low Si content and relatively high Mg content and are not considered heat treatable due to their high Mg content. _The presence of coarse Mg2Si is potentially detrimental to formability.

Currently, 6xxx and 5xxx aluminum alloys cannot be easily combined and recycled for use in the manufacture of automobiles and related panels because the resulting recycled aluminum alloys may contain undesirably high levels of Si (compared to the 5xxx series aluminum alloys) and Mg (compared to 6xxx series alloys), and thus are not suitable for heat treatment due to the high Mg content, nor do they possess the formability of the 5xxx series alloys due to the combination of relatively high Si and Mg content. Additionally, the presence of other metals such as Cu, Mn, Fe or Zn or combinations thereof in alloys recycled from combinations of 5xxx and 6xxx alloys can lead to undesirable properties of the recycled aluminum alloys. For example, an undesirable combination of properties can render recycled aluminum alloys unsuitable for the manufacture of interior or exterior panels for transportation machinery.

The inventors have found that alloys containing relatively high levels of Mg (eg > 1.5% Mg) are heat treatable and exhibit age hardening provided that appropriate amounts of Si and/or Cu are present in the alloy. This property makes aluminum alloys with relatively high magnesium content compared to traditional 6xxx alloys unexpectedly and advantageously suitable for applications requiring age hardening. For example, the inventors have discovered that aluminum alloys containing higher amounts of Mg than conventionally considered suitable for heat treatment but lower than 5xxx series aluminum alloys traditionally used in interior automotive panel fabrication (such as AA5754 or AA5182 alloys) Some aluminum alloys with high amounts of Mg and higher amounts of Si exhibit age hardening when solutionized in a continuous solution heat treatment line.

The inventors' findings are embodied in the improved aluminum alloys described herein. The improved aluminum alloys described herein may be produced as sheets, in which case they may be referred to in the singular or in the plural as "sheet aluminum alloys," "aluminum sheets," "sheet alloys," or other related terms. The term "aluminum alloy" and similar terms used herein are broader in scope than "sheet aluminum alloy" and similar terms. In other words, sheet aluminum alloys are a subset of aluminum alloys. Sheet aluminum alloys may possess the same or similar composition, but in some instances, possess different properties than the same alloy not in sheet form. The manufacturing or fabrication processes used in the production of sheet aluminum alloys may impart some of these properties.

Improved aluminum alloys embodying applicant's discovery exhibit age hardening similar to the 6xxx series alloys. They may also exhibit formability properties similar to those of the 5xxx series aluminum alloys. The modified aluminum alloys are heat treatable. The improved aluminum alloys may be suitable for making automotive and other transportation machinery panels, and more generally in applications where high Mg 5xxx series alloys have traditionally been used. _The increased content of Si and/or Cu in the improved aluminum alloys according to some embodiments of the present invention is beneficial in applications requiring age hardening because due to the precipitation of Mg2Si and _Al2CuMg particles during natural or artificial aging, Si And/or Cu can impart hardening to the solid solution alloy. In addition to Si and/or Cu, some other elements may also be present in the improved aluminum alloys described herein in amounts higher than in some 5xxx series aluminum alloys conventionally used in automotive panel fabrication. The presence of these elements can impart beneficial properties to the improved aluminum alloys described herein. For example, increased levels of Mn can promote dispersion formation, which can help disperse slip and thus improve formability. The inventors have also found that the improved aluminum alloys described herein are more suitable for recycling processes than conventional alloys because the improved aluminum alloys allow relative Higher amounts of Si, Cu, Fe or Mn. Thus, an improved recycling process embodies some of the inventors' discoveries.

In addition to improved aluminum alloys, the inventors' discoveries are embodied in innovative new uses and applications of aluminum alloys, in improved and innovative processes for making, fabricating or manufacturing aluminum alloys, in the manufacture of aluminum alloys forming In the process of parts, objects and parts (such as stamping sheet forms, panels for transport machinery). The inventors' discoveries are also embodied in aluminum alloy objects, parts and forms made from improved aluminum alloys and/or according to the innovative processes described herein.

alloy

Improved aluminum alloys according to embodiments of the present invention differ from conventional alloys used in automotive applications in that they contain higher levels of one of Si, Cu, Fe, Mn, or Zn than at least some of the 5xxx series alloys One or more and lower levels of Mg and/or higher levels of Mg than at least some 6xxx series alloys. The composition of the modified aluminum alloy is illustrated in Table 1 below. The contents of the listed elements may fall within the ranges bounded by the lower and upper range limits shown in Table 1. Lower range limits may be described by the expression "equal to or more than" (≧ sign) or "more than" (> sign) or other related symbols and expressions, such as "from", "above" and the like. Upper range limits may be described by the expression "equal to or less than" (≤ sign), "less than" (< sign), or other related symbols and expressions, such as "to", "less than", and the like. Other types of expressions may also be used to describe ranges, such as "between," "in the range of," etc. When a range is described by means of only the upper limit of the range, it is understood that in some instances, the elements in question may not be present, may not be present in detectable amounts, or may be present in such low amounts that they are routinely used in the aluminum alloy art. is not considered meaningful. It should also be understood that some other additives and/or elements may be present in the aluminum alloys described herein, not necessarily listed in the table below.

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

Table 2. Exemplary compositions of conventional 5xxx series alloys used in automotive applications (element contents expressed in weight %)

element AA5182 AA5754 Mg 4 to 5 2.6 to 3.6 Cu ≤0.15 ≤0.10 Fe ≤0.35 ≤0.40 mn 0.2 to 0.5 ≤0.50 Cr ≤0.10 ≤0.30 Si ≤0.20 ≤0.40 Zn ≤0.20 ≤0.20

properties and advantages

The improved aluminum alloys described herein, including sheet aluminum alloys, possess one or more properties that make them suitable for use in automotive applications, such as the manufacture of automotive panels, or more generally, for various types of Panels for transportation machinery, or even more generally, stamped sheet forms. Some of these properties are formability, yield strength and age hardening. The improved aluminum alloy also possesses favorable recycling compatibility with 6xxx series aluminum alloys such as AA6111, AA6022 or AA6016. The expression "recycling compatibility" and related terms are used herein to describe the concept that improved aluminum alloys according to some embodiments of the present invention may be combined with 6xxx series alloys (and optionally other alloys or elements) during metallurgical processes This can be characterized as "recycling" to produce commercially and technically useful aluminum alloys.

Formability and paint responsiveness

The formability properties of the aluminum alloys described herein can be affected by several variables. Formability properties include, but are not limited to, deep drawability and stretchability. One variable that affects formability properties is the composition of the aluminum alloy. For example, formability, including castability, is affected by the amount of Mg, Cu and Si in the aluminum alloy. High combined amounts of Mg, Si and/or Cu generally make casting and hot rolling aluminum alloys more difficult. Accordingly, the content of one or more of these elements can be varied to achieve the desired formability properties. Other variables that can affect formability are 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 conditions. One or more of the above variables can be adjusted to achieve the desired formability properties. Another important property that can be changed by one or more of the variables discussed above is the paint bake responsiveness of aluminum alloys, which refers to the change in strength during the paint curing process. Baking paint responsiveness is typically tested in the laboratory by aging deformed or undeformed material in the T4 temper at elevated temperatures. The exact simulation conditions that dictate paintbake responsiveness vary between automotive companies. For example, bake responsiveness can be defined as the change in strength by aging an aluminum alloy at 180°C.

strength

Improved aluminum alloys according to embodiments of the present invention may exhibit yield strengths (YS) of 80 to 160 MPa, which may be similar or equivalent to those of AA5754 or AA5182 in typical finished and painted parts required for automotive applications. In some embodiments, improving the strength of aluminum alloys is effected by increasing the amount of Cu in the aluminum alloys compared to the Cu content of alloys conventionally used in the manufacture of panels for automobiles and other transportation machinery.

hardness

Certain embodiments of the improved aluminum alloys described herein are heat treatable and exhibit age-related hardening while exhibiting formability comparable to typical 5xxx aluminum alloys conventionally used in automotive applications. 5xxx aluminum alloys were not previously known to be heat treatable or to exhibit age-related hardening upon heat treatment. Improved aluminum alloys according to some embodiments of the present invention contain higher levels of Mg than aluminum alloys conventionally considered heat treatable. Some examples of the improved aluminum alloys of the present invention contain > 1.5% Mg and are heat treatable. The presence of appropriate amounts of Si and/or Cu imparts heat treatability and age hardenability to the modified aluminum alloys containing > 1.5% Mg. This allows some improved aluminum alloys according to embodiments of the present invention to achieve formability (imparted by a higher Mg content than conventionally present in heat treatable alloys) and age hardening upon heat treatment such as the T4 temper (imparted by a higher Si content than conventionally present in 5xxx series alloys) a surprisingly advantageous combination.

In some embodiments, the improved aluminum alloys of the present invention contain reduced amounts of Mg compared to, for example, some 5xxx aluminum alloys conventionally used to make interior automotive panels. Reduced levels of Mg can lead to lower costs of the improved aluminum alloys described herein, as well as lower costs of formed objects made from these alloys, since less Mg is required for production. The reduced content of Mg in the improved aluminum alloys described herein can also lead to improved solubility of Si in the aluminum during solutionization, which favorably affects the properties of the alloy. _Both Si and Cu are capable of improving the hardening of the solution-modified aluminum alloys described herein due to the precipitation of particles containing Mg2Si and Al2CuMg or Q( _AlMgSiCu ) during aging.

Recyclability

The improved aluminum alloys of the present invention possess tolerance for higher amounts of Si than conventional 5xxx series alloys used in automotive panel manufacturing. This higher tolerance for Si and/or the ability of the improved aluminum alloys described herein to exhibit paint bake responsiveness make them suitable and compatible with 6xxx alloys for recycling.

In summary, the improved aluminum alloys of the present invention possess an advantageous combination of properties that allow these improved alloys to be used in place of conventional high Mg aluminum alloys for a variety of applications. The improved aluminum alloys described herein expand the range of alloys that can be used in a variety of applications, one of which is the manufacture of stamped sheet forms such as panels for automobiles and other transportation machinery, increasing aluminum recycling rates, reducing The cost of aluminum alloy manufacturing, and reduce the environmental impact of aluminum production.

manufacturing process

Processes for forming or manufacturing modified aluminum alloys are also within the scope of this invention. The improved aluminum described herein can be manufactured by a process comprising at least some of the technical steps described below. At least some of these technical steps may impart beneficial properties to the improved aluminum alloy. It is therefore important in some cases to include process steps when describing improved aluminum alloys. For example, one exemplary embodiment of the improved aluminum alloy described herein is the AA5251 alloy. Prior to the inventors' discovery, AA5251 alloys containing >1.5% Mg were not known to be suitable for heat treatment and exhibit age hardening when in the T4 temper. Accordingly, an exemplary embodiment of an improved aluminum alloy described herein is an AA5251 alloy in the T4 temper, which may be referred to as AA5251-T4.

The process of forming or manufacturing the modified aluminum alloy may involve heat treatment in order to alter the physical and/or chemical properties of the modified aluminum alloy. Heat treatment involves the use of heating and/or cooling of aluminum alloys to achieve a desired result, such as hardening. Embodiments of the processes described herein employ the T4 or T4P temper, which involves solution heat treatment and natural aging of the aluminum alloy to substantially stable conditions. The T4P temper designates a special heat treatment involving subsequent solutionization. This treatment can be carried out by controlled cooling from the solutionization temperature or reheating to a temperature ranging from 50 to 110° C. within one hour of solutionization. In some other embodiments, T6 and T8 tempers may also be used.

It should be understood that the description and illustration of the processes described herein are non-limiting. The process steps described herein can be combined and modified in various ways and are suitable for use in the manufacture of modified aluminum alloys or in the manufacture of shaped parts and objects from these alloys. Process steps and conditions not explicitly described herein but commonly used in the fields of metallurgy and aluminum processing and fabrication may also be incorporated into the processes described herein.

One exemplary process is schematically illustrated in FIG. 1 . It should be understood that one or more of the process steps illustrated in FIG. 1 may be incorporated into a process for making the improved aluminum alloy.

Another example of a process that incorporates one or more steps that can be combined in various ways and that are suitable for making an improved aluminum alloy is described in this paragraph. Production of improved sheet aluminum alloys from direct cooled (DC) ingots. However, it is also possible to produce hot-rolled billets from continuously cast billets. The DC ingots were scraped to remove the near-surface barrier layer on both sides of the ingot and homogenized at a temperature between 500 and 575°C for a time period between 1 and 48 hours, then subjected to heat and cold Rolled to final specification. The improved sheet aluminum alloys may also be subjected to special surface texturing, such as but not limited to electrical discharge texturing, in order to improve the formability of the final sheet. The cold rolled strip was solutionized by heating at >3°C/s to temperatures between 500 and 575°C in a continuous annealing line followed by rapid cooling and natural aging to produce sheets in the T4 temper. Depending _on the alloy composition, solution heat treatment can redissolve soluble particles such as Mg2Si or other particles back into the matrix. Rapid quenching is used to produce supersaturated solid solutions in terms of solute and excess vacancies. Rapid cooling from the solution temperature can be effected with forced air, water mist, or a combination of water mist and forced air. Winding is performed at a temperature between 50 and 110°C, followed by coil cooling at a rate of ≤10°C/hour. The coils can be reheated in strip form to ensure a winding temperature between 50 and 110°C. It is possible to subject solutionized sheet alloys to acidic or alkaline cleaning, followed by pretreatment with special chemicals and lubricants, oils or waxes, before coiling at temperatures between 50 and 110°C. The coils may be blanked and used to stamp interior panels, such as those illustrated in FIG. 2 .

Yet another example of a process that incorporates one or more steps that can be combined in various ways and that are suitable for making an improved aluminum alloy is described in this paragraph. Directly cooled alloy ingots homogenized above 500°C for ≥ 2 hours, hot rolled to intermediate gauge at coiling temperatures between 280 and 400°C, cold rolled in one or more passes with milling or The final specification of the finished texture is optimized and solutionized in strip form at temperatures above 480°C in a continuous annealing line, rapidly cooled and coiled between 50°C and 120°C. The hot coiling step is optional and serves to improve the paint bake responsiveness of the alloy. In some cases, it is also possible to clean, pre-treat and lubricate the solution coils prior to stamping.

The following discussion is included to illustrate the advantageous properties that manufacturing process steps can impart to the improved aluminum alloys described herein. Traditionally, AA5754 or AA5182 alloys have been supplied in the soft O temper for the manufacture of automotive panels so that parts can be formed from these alloys and then subjected to paint curing operations. AA5754 or AA5182 in the O temper exhibits softening due to recovery during paint baking. Improved aluminum alloys according to some embodiments of the present invention do not undergo this softening, or do not undergo softening to the same extent as AA5754 or AA5182 in the O temper. The improved aluminum alloys described herein can maintain a strength closer to that of AA5754 and AA5182 after forming and paint curing. For example, the strength properties of final parts fabricated from the improved aluminum alloys of the present invention may be similar or equivalent to AA5754 alloys.

Uses and Applications

Uses and applications of the improved aluminum alloys described herein are included within the scope of the present invention as objects, forms, apparatus and the like manufactured from or comprising the improved alloys described herein. Processes for making, producing or manufacturing these 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 herein are suitable for the manufacture of automotive panels. Various automotive panels, including interior and exterior automotive panels, are thus included within the scope of the present invention. They are described, for example, in US Patent Publication No. 2010/0279143 and are also illustrated in FIG. 2 .

It should be understood, however, that the uses and applications of the improved aluminum alloys and objects fabricated from these alloys are not limited to automotive panels. Other objects may be suitably fabricated from the modified aluminum alloys described herein. One example is the panels generally incorporated into various transportation vehicles and other mobile machinery, which may be referred to as "transport panels" or "machine panels." For example, panels for delivery trucks can be advantageously fabricated from the improved aluminum alloys described herein. Haul trucks with aluminum cabs are traditionally produced from the AA5052 alloy. This alloy has a tendency to exhibit tensile bands or elongation of the yield point during forming, resulting in an objectionable surface appearance. Improved aluminum alloys according to some embodiments of the present invention do not exhibit yield point elongation and can be used to advantageously replace AA5052 alloys for the manufacture of panels used in delivery trucks.

More generally, some examples of the improved aluminum alloys described herein exhibit less tendency to exhibit Lüders bands, also known as "slip bands," than conventional 5xxx alloys Or "tensile-strain markers", which are localized bands of plastic deformation in metals undergoing tensile stress. Accordingly, the improved aluminum alloys described herein may be advantageously used in the manufacture of parts or objects in which Luders strips are objectionable, such as exterior panels for automobiles and other transportation vehicles and mobile machinery.

Some embodiments of the alloys described herein are suitable for complex electronic applications. An example of this application is aluminum TV frames. More generally, various sheet stampings, stamped sheet forms, stamped panels, or related objects fabricated from the modified aluminum alloys described herein are within the scope of embodiments of the present invention.

The following examples will be used to further illustrate the present invention, but simultaneously do not constitute any limitation to the present invention. On the contrary, it is clearly understood that various embodiments, modifications and their equivalents may be made apparent to those skilled in the art after reading the description herein without departing from the spirit of the invention. During the studies described in the following examples, routine procedures were followed unless otherwise stated. Some procedures are described below for illustrative purposes.

Example 1

Test of Tensile Properties of AA5251 Alloy in O Temper

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 3.2mm gauge, cold rolled to final 1.3mm gauge, and rolled at 340 Batch annealing at °C for up to 1 h to obtain an O temper. The transverse tensile properties of the annealed sheets were determined using DIN test pieces. Figure 3 shows the DIN tensile properties of the alloys in the O and baked tempers (5% stretch plus 20 minutes at 185°C). The alloy exhibits a yield strength (YS) of 70 MPa, an ultimate tensile strength (UTS) of 164 MPa, and an overall elongation of 23% in the O temper, and exhibits no hardening after aging at 185°C for 20 minutes. The higher YS in the baked temper state (5% stretch plus 20 minutes at 185°C) is the net result of work hardening due to stretching and recovery due to aging.

Example 2

Effect of Solution Solution on Tensile Properties of AA5251 Aluminum Alloy

This example shows the effect of solutionization 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 3.2mm gauge and cold rolled to final 1.3mm gauge. Cold rolled 1.3mm gauge sheets were solutionized at 560°C for 2 minutes, cooled and immediately pre-aged at 85°C for 8 hours. The transverse ASTM properties of the solutionized alloys were determined after 24 hours of natural aging. Figure 4 shows the comparative tensile properties of alloys in the T4 temper, 2% elongation, and 2% elongation plus 20 minutes in the 185°C temper. Aluminum alloys in the T4 temper are stronger than their O temper counterparts, as illustrated by the comparison of FIGS. 3 and 4 . Aluminum alloys in the T4 temper exhibit a significant increase in YS due to 2% stretch and after subjecting the tensile specimens to aging at 185°C for 20 minutes. The tensile properties of the aluminum alloy in the T4 temper are close to those of the conventional AA5754 alloy. After subjecting the aluminum alloys to a similar paint bake treatment, the yield strength of the aluminum alloys is close to that expected for the AA5182 or AA5754 alloys.

Example 3

Effect of Cu Addition on Alloy

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, followed by hot and cold rolling to final 1.6mm gauge, and at Solid solution at 540°C in a continuous annealing line, cooled and pre-aged. The transverse direction tensile properties of the 1.6 mm gauge sheet were determined using ASTM test specimens.

Figure 5 shows the tensile properties of the alloys in T4 and baked condition (60 minutes at 180°C). This alloy, which contains a higher amount of copper than the AA5251 alloy discussed in Examples 1 and 2, is significantly stronger than the AA5251 alloy. The alloy tested in this example exhibited 143 MPa YS, 284 MPa UTS, and 28% total elongation in the T4 temper and after aging at 180°C for 60 minutes due to precipitation of _CuMgAl2 and _Mg2Si particles significantly hardened.

Example 4

Comparative testing of AA5754 in O temper and AA5251 in O and T tempers

Aluminum ingots of AA5754 and AA5251 alloys with the compositions shown in Table 3 were homogenized at 540°C for >5 hours, hot rolled and cold rolled to final 1 and 1.3mm gauge respectively in separate trials. Coils of AA5754 and AA5251 were solutionized on a continuous annealing line at 500 and 560°C, respectively.

The tensile test results from the test coils are shown in Table 4. It can be seen that the yield and ultimate tensile strengths of conventional AA5754 sheets in the O temper at 0°, 45° and 90° relative to the rolling direction are close to 100 MPa and in the range of 219 to 231 MPa, respectively. The AA5251 alloy in the O temper exhibits lower values compared to AA5754, except for the strain hardening exponent (n) value. The AA5251 alloy in the T temper exhibits significant improvements in strength properties, such as yield strength and ultimate tensile strength, compared to the AA5251 O temper alloy. In terms of strength, the AA5251 T temper alloy falls between the AA5754 and AA5251-O tempers. The AA5251 T temper alloy exhibits a paint bake responsiveness not normally observed in the AA5251 and AA5754-O temper alloys. The improvement detected in the AA5251 T temper alloy offers the possibility of using it as a replacement for the AA5754 and possibly AA5182 alloys. The somewhat poor formability of the AA5251 T temper alloy, indicated by lower elongation, UTS, and n-values, can be compensated by a variety of techniques, including optimization of the alloy and process composition, use of preferred sheet surface texture, or in the Selection of lubricant during forming.

Table 3. Aluminum Alloy Composition

Table 4. Comparative test results for AA5754 in O temper and AA5251 in O and T tempers

Example 5

Age Hardening of AA5251 T4 Tempered Alloy at 185℃

Age hardening studies of the AA5251 T4 tempered alloy were performed by placing tensile samples of the alloy in a furnace setup at 180°C. Samples were removed from the furnace after various aging times. Figure 6 shows the age hardening behavior of the alloy at 180 °C. The alloy exhibited about 70% and 20% increases in YS and UTS, respectively, after about 8 hours of aging. The results illustrated in Figure 6 support the conclusion that the alloy undergoes age hardening.

All patents, publications, and abstracts cited above are hereby incorporated by reference in their entirety. Different arrangements and combinations of the elements and features described herein are possible. Similarly, some features and subcombinations are useful and can be used without reference to other features and subcombinations. Various embodiments of the invention have been described in terms of the achievement of the various objects of the invention. It should be realized that these Examples merely illustrate the principles of the invention. Numerous modifications and adaptations of this invention will be readily apparent to those skilled in the art without departing from the spirit and scope of this invention.

Claims (12)

1. a kind of aluminium alloy by being produced including process of thermal treatment, it includes Mg by weight >=1.5%.

2. aluminium alloy according to claim 1, wherein the technique includes T4 Annealed Strips.

3. aluminium alloy according to claim 1 or 2, wherein the aluminium alloy further comprises by weight 0.2 to 0.4% Si.

4. the aluminium alloy according to any claim in Claim 1-3, wherein the aluminium alloy shows age-hardening.

5. the aluminium alloy according to any claim in claim 1 to 4, wherein the aluminium alloy is sheet material aluminium alloy.

6. a kind of punching press sheet material drip molding manufactured from sheet material aluminium alloy according to claim 5.

7. punching press sheet material drip molding according to claim 6, wherein the stamping material drip molding is car panel.

8. a kind of technique for being used to manufacture sheet material aluminium alloy, the sheet material aluminium alloy includes Mg and 0.2 by weight >=1.5% To 0.4% Si, the technique includes heat treatment.

9. technique according to claim 8, wherein the technique includes T4 Annealed Strips.

10. technique according to claim 8 or claim 9, wherein the sheet material aluminium alloy shows age-hardening.

11. a kind of technique for being used to manufacture punching press sheet material drip molding, it includes punching press sheet material aluminium according to claim 5 and closed Gold.

12. technique according to claim 11, wherein the stamping material drip molding is car panel.