JP2019167624A - Multipurpose heat treatable aluminum alloy, related method and use - Google Patents

Abstract

To provide a method for manufacturing a metal component containing aluminum alloy such as a panel of automobiles.SOLUTION: A semi-continuous casted alloy ingot is homogenized at over 500°C for 2 hr. or more, hot rolled to intermediate thickness at coiling temperature of 280 to 400°C, passed through one or a plurality of cold rolling to final thickness, applied to surface finish with rolling or optimized crepe processed finish, solved at over 480°C at a strip shape in a continuous annealing line, quickly cooled, and coiled at 50°C to 120°C. A high temperature coiling process is optionally selected, reactivity of coating galling of the alloy is improved by using the same. In a part of cases, dissolved coil may be washed before press processing, pretreated, and coated with a lubricant.SELECTED DRAWING: Figure 1

Description

  The present invention relates to the field of material science, material chemistry, metallurgy, aluminum alloy, aluminum production, and related fields.

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

  Aluminum alloys used in various applications need to achieve specific properties. For example, an aluminum alloy is used for manufacturing an inner panel and an outer panel of a transport machine. Aluminum alloys are useful for this application due to the combination of lightness, strength, and other properties that result in improved fuel efficiency. Among other things, the aluminum alloy used to make the inner and outer panels of a transport machine needs to have good formability, coating or other finish quality, dent resistance, and natural aging resistance. It is also desirable that the alloy used in making the transport machine be reusable. A new and improved metal alloy with desirable properties suitable for making panels for transport machines broadens the range of alloys available for these applications, lowers material costs, improves aluminum reuse rate, Capacity limits in the production of such alloys can be reduced and the environmental impact of aluminum production and use can be reduced.

  As used herein, the terms “invention,” “the invention,” “this invention,” and “the present invention” refer to all of the subject matter of this patent application and the following claims. It is intended to be used broadly. Descriptions including these terms should be understood as not limiting the subject matter described herein or as limiting the meaning or scope of the following claims. The embodiments of the invention encompassed are defined by the claims, rather than this summary. This summary is an overview of the various aspects of the invention, and introduces some of the concepts that are described in more detail 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 separately to determine the scope of the claimed subject matter. The subject matter should be understood by reference to the entire specification, any or all drawings, and appropriate portions of each claim.

  The present invention is an improved heat treatment that contains a greater amount of Mg than is considered suitable for conventional heat treatment and can exhibit age hardening when dissolved in a continuous solution heat treatment line. Provide possible aluminum alloy. The improved aluminum alloy provided herein can be fabricated as an alloy plate and can be more suitable for reuse processes than conventional alloys. Some embodiments of the present invention are improved aluminum alloys suitable for making panels for automobiles and other transport machines. Some other embodiments of the present invention include novel novel uses and applications of aluminum alloys, improved novel methods of making, making or manufacturing aluminum alloys, and pressed plate shapes And methods of making forms, aluminum alloy forms such as panels for transporting machines, objects, and parts. Also provided within embodiments of the present invention are aluminum alloy objects, parts, and features made from modified aluminum alloys and / or made according to the novel methods provided herein.

  One embodiment of the invention provided herein is an aluminum alloy containing 1.5 wt% or more of Mg made by a method including heat treatment. The heat treatment method may include T4 tempering. The aluminum alloy may further include 0.2 to 0.4 wt% Si. Aluminum alloys can undergo age hardening. The aluminum alloy can be an aluminum alloy plate. Another embodiment of the present invention provided herein is a pressed plate-like form made from the aluminum alloy plate described above. The pressed plate-shaped object can be an automobile panel. One embodiment of the present invention provided herein is a method of making an aluminum alloy plate that includes 1.5 wt% or more Mg and 0.2 to 0.4 wt% Si, including heat treatment. Is the method. This method can include T4 tempering. The resulting aluminum alloy plate can exhibit age hardening. Another embodiment of the invention described herein is a method for making a pressed plate-like feature comprising pressing the aluminum alloy plate described above. The pressed plate-shaped object can be an automobile panel.

It is a schematic diagram which shows the process of the method used for manufacture of an aluminum alloy plate. It is a schematic diagram of the various press work board used in manufacture of a motor vehicle. It is a bar graph which shows the DIN tensile characteristic of the alloy according to O quality, and the alloy of paint baking. 3 is a bar graph showing tensile properties of T4 graded alloys, alloys stretched 2%, and alloys treated at 185 ° C. for 20 minutes after 2% stretch. It is a bar graph which shows the tensile characteristic of the alloy after an alloy according to T4 quality, and a painting baking simulation experiment (180 degreeC for 60 minutes). It is a line graph which shows age hardening of AA5251-T4 alloy.

  In this description, reference is made to the alloy identified by the AA number and other related designations such as “series”. To understand the most commonly used numbering system for naming and identifying aluminum and aluminum alloys, see “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” published by The Aluminum Association. . 6xxx series aluminum alloys such as AA6111, AA6016, and AA6022 are typically used in the manufacture of automotive outer skin panels.

In general terms, the 6xxx series alloys contain relatively high concentrations of Si and low concentrations of Mg, are heat treatable and exhibit age hardening. Age hardening gives these alloys strength parameters suitable for the production of outer panels for transporting machines such as automobiles. For example, Oxxx grade 5xxx series aluminum alloys such as AA5182-O or AA5754-O are often preferred for the production of inner panels in the automotive and related industries due to their formability characteristics. The 5xxx series aluminum alloys have little tolerance to retain Si in the solid solution. When Si is added to 5xxx series aluminum alloys, there is a tendency to form coarse Mg ₂ Si particles during casting in combination with Mg. While these particles are dissolved in a continuous annealing line and rapidly cooled, it is difficult to form a supersaturated solid solution of Mg and Si during solid solution. For this reason, 5xxx series aluminum alloys contain a relatively low concentration of Si and a relatively high concentration of Mg and are considered to be incapable of heat treatment due to the high Mg content. The presence of coarse Mg ₂ Si may be undesirable for formability.

  Currently, 6xxx and 5xxx aluminum alloys cannot be easily combined and reused for the production of automotive panels and related panels. This is because the resulting recycled aluminum alloy may contain both undesirably high concentrations of Si (compared to the 5xxx series aluminum alloys) and Mg (compared to the 6xxx series alloys), thus This is because it is not suitable for heat treatment due to the high Mg concentration and does not have the formability of the 5xxx series alloy due to the combination of a relatively high Si concentration and Mg concentration. In addition, the presence of other metals such as Cu, Mn, Fe, or Zn, or combinations thereof present in the recycled alloy from the combination of 5xxx and 6xxx alloys may cause undesirable properties of the recycled aluminum alloy. Can be done. For example, due to undesired combinations of properties, recycled aluminum alloys can be unsuitable for making either an inner panel or an outer panel for a transport machine.

  The inventor is able to heat treat an alloy containing a relatively high concentration of Mg, such as 1.5% or more of Mg, with an appropriate amount of Si and / or Cu present in the alloy. Found to show. This property makes aluminum alloys having a relatively high magnesium content unexpectedly and advantageously suitable for applications where age hardening is desirable compared to traditional 6xxx alloys. For example, compared to the 5xxx series of aluminum alloys that contain higher amounts of Mg than previously considered suitable for heat treatment, but are traditionally used to make automotive inner panels such as AA5754 or AA5182. The inventor has discovered that some aluminum alloys containing a small amount of Mg and a large amount of Si can exhibit age hardening when dissolved in a continuous solution heat treatment line.

  The inventor's findings are embodied in the improved aluminum alloy described herein. The improved aluminum alloys described herein can be fabricated as plates, in which case they are singular or plural “aluminum alloy plates”, “aluminum plates”, “alloy plates”, or other related Can be called by term. As used herein, the term “aluminum alloy” and similar terms are broader than “aluminum alloy plate” and similar terms. In other words, the aluminum alloy plate is a subset of the aluminum alloy. The aluminum alloy plate can have the same or similar composition as the same alloy that is not in plate form, but in some instances can have different properties. Some of these characteristics may be provided by the manufacturing method and manufacturing method used in the manufacture of aluminum alloy plates.

Improved aluminum alloys that embody Applicant's findings exhibit age hardening similar to the 6xxx series. The improved aluminum alloy can also exhibit formability characteristics similar to those of the 5xxx series aluminum alloys. The improved aluminum alloy can be heat treated. The improved aluminum alloy can be suitable for making automotive panels and other transport machinery panels, and more broadly, suitable for applications where high Mg 5xxx series alloys are traditionally used. be able to. The increased Si and / or Cu content in improved aluminum alloys according to some embodiments of the present invention is beneficial in applications where age hardening is desired. This is because Si and / or Cu can harden the solid solution alloy due to precipitation of Mg ₂ Si particles and Al ₂ CuMg particles during natural aging or artificial aging. In addition to Si and / or Cu, several other elements are present in the improved aluminum alloys described herein in amounts greater than some 5xxx series alloys conventionally used to make automotive panels. Can exist. The presence of such elements can provide advantageous properties to the improved aluminum alloys described herein. For example, increasing the concentration of Mn may promote the formation of dispersoids, which can help disperse the slip and thus improve the moldability. The inventors have also discovered that the improved aluminum alloys described herein are better suited for reuse processes than conventional alloys. This is because the improved aluminum alloy has a relatively high amount of Si, Cu, Fe or Mn compared to the 5xxx series aluminum alloys used in the manufacture of traditional automotive panels such as AA5754 and AA5182 alloys. This is because it is acceptable. Thus, an improved reuse process embodies some of the inventors' discoveries.

  In addition to improved aluminum alloys, novel and novel uses and applications of aluminum alloys, improved and novel methods of making, making or manufacturing aluminum alloys, pressed plate-like forms, and transporting machines The inventor's findings form embodiments in methods for making aluminum alloy features, objects, and parts such as structural panels. Aluminum alloy objects, parts, and features made from modified aluminum alloys and / or made according to the novel methods described herein also embody the inventors' discoveries.

Alloys Improved aluminum alloys according to embodiments of the present invention include one or more of Si, Cu, Fe, Mn, or Zn at a higher concentration than at least a portion of the 5xxx series alloys, and a lower concentration of Mg, And / or differs from conventional alloys used in automotive applications in that it contains a higher concentration of Mg than at least some 6xxx series alloys. The composition of the improved aluminum alloy is shown in Table 1 below. The content of the enumerated elements can be within a range defined by the range lower limit and the range upper limit shown in Table 1. The lower range limit can be defined by the expression “more than or equal to” (symbol ≧), or “greater than” (symbol>), or other related symbols and expressions such as “from” or “greater than”. . The upper limit of the range can be defined by the expression “˜less than” (symbol ≦), “less than” (symbol <), or other related symbols and expressions such as “up to”, “less than”. Other types of expressions such as “between” and “of range” can also be used to define the range. If the range is defined solely by the upper range limit, in some cases the element may not be present, may not be present in detectable amounts, or is meaningful in the aluminum alloy field. It should be understood that it may be present in such a small amount that it has not been conventionally recognized. It should also be understood that several other additives and / or elements may be present in the aluminum alloys described herein and they are not necessarily listed in the following table.

Properties and Benefits The improved aluminum alloys described herein, including aluminum alloy plates, have one or more properties that allow the improved aluminum alloy to be described, for example, in the manufacture of automotive panels or more broadly. It becomes suitable for use in automotive applications, such as various types of panels for transporting machines, and more broadly, pressed plate-like forms. Some of these properties are formability, yield strength, and age hardening. The improved aluminum alloy also has advantageous reusability compatibility with 6xxx series aluminum alloys such as AA6111, AA6022, or AA6016. The expression “reusability compatibility” and related terms are used herein to refer to an improved aluminum alloy according to some embodiments of the present invention as a 6xxx series alloy (and optionally other alloys) during the metallurgical process. Or in combination with the element) to illustrate the idea that commercially and technically useful aluminum alloys can be made. This can be characterized as “reused”.

Formability and paint bake reactivity The formability characteristics of the aluminum alloys described herein can be influenced by several variables. Formability characteristics include, but are not limited to, deep drawability and stretchability. One variable that affects the formability characteristics 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. The large combined amount of Mg, Si, and / or Cu generally makes it more difficult to cast an aluminum alloy and hot roll. Accordingly, the content of one or more of these elements can be varied to achieve the desired moldability characteristics. Other variables that can affect the formability are fabrication method variations and conditions, such as aluminum plate processing steps and conditions, surface embossing method steps and conditions, and lubricant application method steps. However, it is not limited to these. One or more of the above variables can be adjusted to achieve the desired formability characteristics. Another important property that can be varied by one or more of the variables discussed above is the paint bake reactivity of the aluminum alloy, which refers to strength changes during the paint hardening process. Paint bake reactivity is typically tested in the laboratory by aging T4 graded deformable or undeformed material at elevated temperatures. The exact simulated test conditions that determine paint bake reactivity vary from car company to car company. For example, paint baking reactivity can be defined as a change in strength due to aging of an aluminum alloy at 180 ° C.

Strength An improved aluminum alloy according to embodiments of the present invention can exhibit a yield strength (YS) of 80-160 MPa, which is similar to that of AA5754 or AA5182 in typical finishes and painted parts required in automotive applications. It can be similar or equivalent to the yield strength. In some embodiments, the strength of the improved aluminum alloy is such that the amount of Cu in the aluminum alloy is compared to the Cu content of alloys conventionally used in making panels for automobiles and other transport machines. Affected by increasing.

Hardness Certain embodiments of the improved aluminum alloys described herein are heat treatable and exhibit aging related hardening, but formability comparable to typical 5xxx aluminum alloys conventionally used in automotive applications Indicates. It has not previously been known that 5xxx aluminum alloys are heat treatable or exhibit aging related hardening upon heat treatment. Improved aluminum alloys according to some embodiments of the present invention contain a higher concentration of Mg than aluminum alloys that are conventionally recognized as heat treatable. Some examples of the improved aluminum alloy of the present invention contain 1.5% or more Mg and can be heat treated. The presence of a suitable amount of Si and / or Cu provides heat treatability and age hardening properties to an improved aluminum alloy containing 1.5% or more Mg. This allows some improved aluminum alloys according to embodiments of the present invention to have formability (given by a higher Mg concentration than is conventionally present in heat treatable alloys) and heat treatments such as T4 tempering. It is possible to obtain a surprising and advantageous combination with age hardening (given by a higher Si concentration than is conventionally present in 5xxx series alloys).

Compared to some 5xxx aluminum alloys such as those conventionally used in the manufacture of automotive inner panels, in some embodiments, the improved aluminum alloys of the present invention contain a lower amount of Mg. The low Mg concentration reduces the amount of Mg required for fabrication, thus reducing the cost of the improved aluminum alloy described herein and the cost of features and objects made from such an alloy. Can be done. Also, the low concentration of Mg in the improved aluminum alloys described herein can result in improved solubility of Si in aluminum during solid solution. This has an advantageous effect on the properties of the alloy. Both Si and Cu improve the hardening of the improved aluminum alloy described herein as a solid solution due to precipitation of Mg ₂ Si and Al ₂ CuMg or Q (AlMgSiCu) containing particles during aging. Can do.

Reusability The improved aluminum alloy of the present invention is tolerant to higher amounts of Si than the conventional 5xxx series alloys used in the manufacture of automotive panels. This improved aluminum alloy's ability to exhibit high tolerance to Si and / or paint baking reactivity makes this improved aluminum alloy suitable for reuse and compatible with 6xxx alloys for reuse. It becomes sex.

  In short, the improved aluminum alloys of the present invention have an advantageous combination of properties that allow these improved alloys to be used in place of conventional high Mg aluminum alloys in a variety of applications. The improved aluminum alloys described herein can expand the range of alloys that can be used in a variety of applications. One of its uses is the production of pressed plate-like forms such as automobile and other transport machine panels. The improved aluminum alloy described herein can also increase the aluminum reuse rate, reduce the cost of aluminum alloy production, and reduce the environmental impact of aluminum alloy production.

Method of making A method of making an improved aluminum alloy or a method of making it is also within the scope of the present invention. The improved aluminum described herein can be made by a method that includes at least some of the technical steps described below. At least some of these technical steps can impart advantageous properties to the improved aluminum alloy. Thus, in some cases, it is important to include method steps in describing the improved aluminum alloy. For example, one exemplary embodiment of the improved aluminum alloy described herein is AA5251 alloy. Prior to discovery by the inventor, it was not known that AA5251 alloy containing more than 1.5% Mg is suitable for heat treatment and shows age hardening when T4 is graded. Thus, an exemplary embodiment of the improved aluminum alloy described herein is a T4 graded AA5251 alloy, which can be referred to as AA5251-T4.

  The method of making or making the improved aluminum alloy can include heat treating to change the physical and / or chemical properties of the improved aluminum alloy. The heat treatment includes obtaining desired results, such as hardening, using heating and / or cooling of the aluminum alloy. Embodiments of the methods described herein use T4 or T4P tempering, which includes solution heat treatment of aluminum alloys and natural aging to a substantially stable state. including. T4P tempering refers to a special thermal treatment included after solid solution. This treatment can be performed by controlled cooling from the solid solution temperature, or by reheating to a temperature in the range of 50 to 110 ° C. within 1 hour after dissolution. In some other embodiments, T6 and T8 tempering can also be used.

  It should be understood that the method descriptions and illustrations described herein are non-limiting. The method steps described herein can be combined and modified in various ways and can be suitably used to make modified aluminum alloys or forms and objects from such alloys. Although not explicitly described herein, process steps and conditions commonly used in the metallurgical field and in the field of aluminum processing and fabrication can also be incorporated into the methods described herein.

  One exemplary method is schematically illustrated in FIG. It should be understood that one or more of the method steps shown in FIG. 1 can be incorporated into a method of making an improved aluminum alloy.

This paragraph describes another example of a method that incorporates one or more steps that can be combined in various ways and that can be suitably used in the production of improved aluminum alloys. The improved aluminum alloy plate is made from a semi-continuous cast (DC) ingot. However, the hot rolled material may be made from a continuously cast slab. The surface of the DC ingot is scraped to remove the segregation layer near the surfaces on both sides of the ingot, homogenized at a temperature of 500 to 575 ° C. for 1 to 48 hours, and then subjected to hot rolling and cold rolling. To the final thickness. The improved aluminum alloy plate can also be subjected to special surface embossing to improve the formability of the final plate. The embossing is electric discharge dull machining, but is not limited to this. In a continuous annealing line, the cold-rolled strip is dissolved by heating to a temperature of 500-575 ° C. at a temperature exceeding 3 ° C./s, and then rapidly cooled and naturally aged to produce a T4 graded plate. To do. In the solution heat treatment, depending on the composition of the alloy, soluble particles such as Mg ₂ Si or other particles can be dissolved again and returned to the matrix. Rapid quenching is performed to produce a supersaturated solid solution with respect to both solute and excess vacancies. The rapid cooling from the solution temperature can be performed by forced air cooling, water mist, or a combination of both water mist and forced air cooling. Coiling is performed at a temperature of 50 to 110 ° C., and then the coil is cooled at a rate of 10 ° C./hour or less. The coil can be reheated in the form of a strip to ensure a coiling temperature of 50-110 ° C. Solid solution alloy plates can be either acid cleaned or alkali cleaned, then pretreated with special chemicals and lubricants, oils, or waxes, and then coiled at a temperature of 50-110 ° C. Is possible. The coil can be stamped and used to press an inner panel such as that shown in FIG.

  This paragraph describes yet another example of a method that incorporates one or more steps that can be combined in various manners and that can be suitably used in making improved aluminum alloys. Semi-continuously cast alloy ingot is homogenized at over 500 ° C for 2 hours or more, hot rolled to an intermediate thickness at a coiling temperature of 280 to 400 ° C, and finally passed through one or more cold rollings To a thick thickness, with a surface finish as rolled, or with an optimized textured finish, solid solution in strip form at a temperature above 480 ° C in a continuous annealing line, rapidly cooled, 50 ° C Coiling at ~ 120 ° C. The high temperature coiling process is optional and is used to improve the paint bake reactivity of the alloy. In some cases, the solid-solubilized coil may be washed before pressing and pre-treated to apply a lubricant.

  The following considerations are included to illustrate the advantageous properties that the fabrication process steps can provide for the improved aluminum alloy described herein. Conventionally, AA5754 or AA5182 alloys are supplied for the manufacture of automotive panels with flexible O qualities, so that parts can be formed from these alloys and then subjected to a paint hardening operation. O-type AA5754 or AA5182 shows softening due to recovery during paint baking. Improved aluminum alloys according to some embodiments of the present invention do not undergo such softening or to the same extent as O graded AA5754 or AA5182. The improved aluminum alloys described herein can maintain similar strength to AA5754 or AA5182 after molding and paint hardening. For example, the strength properties of the final part made from the improved aluminum alloy of the present invention can be similar or equivalent to the AA5754 alloy.

Uses and Applications Uses and applications of the improved aluminum alloys described herein are within the scope of the present invention, and objects, forms, devices and devices made from or including the improved alloys described herein. Similar items are also included. Also within the scope of the invention are methods of making, making or manufacturing such objects, features, devices and the like. For example, some embodiments of the improved aluminum alloy described herein are suitable for the manufacture of automotive panels. Accordingly, various automobile panels including an automobile inner panel and an outer panel are included in the scope of the present invention. They are described, for example, in US 2010/0279143 and are also shown in FIG.

  However, it should be understood that the use and application of improved aluminum alloys and objects made from such alloys are not limited to automotive panels. Other objects can be suitably manufactured from the improved aluminum alloy described herein. One example is panels that are generally incorporated into various transport vehicles and other mobile machines, which can be referred to as “transport panels” or “mechanical panels”. For example, panels used in transport trucks can be advantageously manufactured from the improved aluminum alloys described herein. Transportation trucks with aluminum cabs are traditionally made from AA5052 alloy. This alloy tends to exhibit stretch bands or yield point elongation during forming, resulting in an undesirable surface appearance. Improved aluminum alloys according to some embodiments of the present invention do not exhibit yield point elongation and can be advantageously used to make panels used in transport trucks, advantageously replacing AA5052 alloy.

  More broadly, some embodiments of the improved aluminum alloys described herein are compared to conventional 5xxx alloys, with Luders bands (also known as “slip lines” or “tensile wrinkle marks”). There is little tendency to show. The Luders band is a local band of plastic deformation in a metal subjected to tensile stress. Thus, the improved aluminum alloys described herein can be advantageously used in the manufacture of parts or objects where the Luders band is not preferred, such as outer panels for automobiles and other transport vehicles, and mobile machines.

  Some embodiments of the alloys described herein are suitable for composite electronic applications. An example of such an application is an aluminum TV frame. More broadly, various pressed plates, pressed plate features, pressed panels, or related objects made from the improved aluminum alloys described herein are within the scope of embodiments of the present invention. included.

  The following examples will serve to further illustrate the present invention. On the other hand, however, no limitation of the present invention is set. On the contrary, it should be clearly understood that various embodiments, modifications, and equivalents may be employed without departing from the spirit of the present invention. Those embodiments, modifications, and equivalents may occur to those skilled in the art after reading the description herein. During the work described in the examples below, conventional procedures were followed unless otherwise specified. A portion of the procedure is described below for illustrative purposes.

Example 1
Tensile property test of AA5251 alloy according to O quality Aluminum ingot containing 1.85% Mg, 0.3% Fe, 0.28% Mn and 0.29% Si is homogenized at 540 ° C for more than 5 hours, The steel was hot-rolled to 3.2 mm, cold-rolled to a final thickness of 1.3 mm, and batch-annealed at 340 ° C. for 1 hour to obtain O qualities. The transverse tensile properties of the annealed plates were measured using DIN samples. FIG. 3 shows the DIN tensile properties of both O grade and paint bake (5% elongation and 20 minutes at 185 ° C.) alloys. The alloys showed yield strength (YS) of 70 MPa, maximum tensile strength (UTS) of 164 MPa, and total elongation of 23% by O type, and showed no hardening after aging at 185 ° C. for 20 minutes. The higher YS by paint bake quality (5% elongation and 20 minutes at 185 ° C.) is the final result of work hardening by stretching and recovery by aging.

Example 2
Effect of solid solution on tensile properties of AA5251 aluminum alloy In this example, the effect of solid solutions on the tensile properties of aluminum alloy is shown. An aluminum ingot containing Mg 1.85%, Fe 0.3%, Mn 0.28%, and Si 0.29% was homogenized at 540 ° C. for more than 5 hours and hot-rolled to a thickness of 3.2 mm. Cold rolled to a final thickness of 1.3 mm. A cold-rolled 1.3 mm thick plate was dissolved at 560 ° C. for 2 minutes, cooled, and immediately preliminarily aged at 85 ° C. for 8 hours. The transverse ASTM properties of the solid solution were measured after 24 hours of natural aging. FIG. 4 shows the comparative tensile properties of T4 graded, 2% stretch, and 2% stretch and alloys treated at 185 ° C. for 20 minutes. As shown in the comparison between FIG. 3 and FIG. 4, the T4 graded aluminum alloy was stronger than the O graded equivalent. The T4 graded aluminum alloy showed a significant increase in YS due to 2% elongation and after aging the stretched sample at 185 ° C. for 20 minutes. The tensile properties of the T4 graded aluminum alloy were similar to the conventional AA5754 alloy. The yield strength of the aluminum alloy was similar to the expected strength of the AA5182 or AA5754 alloy after being subjected to the same paint baking process.

Example 3
Role of Cu addition to the alloy Homogenizing aluminum ingot containing Mg 1.75%, Cu 0.78%, Fe 0.23%, Mn 0.11%, and Si 0.38% for more than 18 hours at 560 ° C. Next, hot rolling and cold rolling were carried out to a final thickness of 1.6 mm, and solid solution was dissolved at 540 ° C. in a continuous annealing line, followed by cooling and pre-aging. The transverse tensile properties of a 1.6 mm thick plate were measured using ASTM samples.

FIG. 5 shows the tensile properties of both T4 and paint baking (180 ° C. for 60 minutes) alloys. This alloy containing a higher concentration 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 show 143 MPa YS, 284 MPa UTS, and 28% total elongation by T4 grade, and after aging at 180 ° C. for 60 minutes, CuMgAl ₂ and Mg ₂ Si particles precipitate. Due to this, it showed significant curing.

Example 4
Comparison test between A graded AA5754 and O graded and AA5251 graded in O and T In a separate experiment, AA5754 and AA5251 alloy ingots having the compositions shown in Table 3 were homogenized at 540 ° C for more than 5 hours, Cold rolling and cold rolling were performed to final thicknesses of 1 mm and 1.3 mm, respectively. The coils of AA5754 and AA5251 were dissolved in a continuous annealing line at 500 and 560 ° C., respectively.

  Table 4 shows the tensile test results of the experimental coil. The yield strength and the maximum tensile strength at 0 °, 45 °, and 90 ° of the conventional AA5754 plate classified by O type are within the range of 219 to 231 MPa and values close to 100 MPa, respectively. I understand. The O-type AA5251 alloy shows a lower value than AA5754 except for the strain hardening index (n) value. T grade AA5251 alloy shows significant improvements in strength properties such as yield strength and maximum tensile strength compared to O grade AA5251 alloy. In terms of strength, T grade AA5251 alloy is between AA5754 and AA5251-O grades. T-type AA5251 alloys exhibit paint bake reactivity that is typically not observed with AA5251 and AA5754-O graded alloys. The improvements seen in T-sorted AA5251 alloy offer the possibility of being used as a substitute for AA5754 and possibly as a substitute for AA5182 alloy. Slightly inferior forming properties of T graded AA5251 alloy, indicated by low elongation, UTS, and n value, optimize alloy and process composition, use preferred sheet surface texture, or It can be supplemented by a variety of techniques including selecting a lubricant during molding.

Example 5
Age hardening of T4 graded AA5251 alloy at 185 ° C. The age hardening study of T4 graded AA5251 alloy was performed by placing a tensile sample of the alloy in a furnace set at 180 ° C. Samples were removed from the furnace after different aging times. FIG. 6 shows the age hardening behavior of the alloy at 180 ° C. The alloy showed a 70% and 20% increase in YS and UTS, respectively, after aging for about 8 hours. The results shown in FIG. 6 support the conclusion that the alloy has undergone age hardening.

  All patents, publications and abstracts cited above are hereby incorporated by reference in their entirety. Different arrangements and combinations of the components and features described herein are possible. Similarly, some features and subcombinations are useful and may be used without reference to other features and subcombinations. Various embodiments of the invention have been described in the practice of the various objects of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Many modifications and adaptations will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention.

Claims (12)

  An aluminum alloy containing 1.5% by weight or more of Mg manufactured by a method including heat treatment.   The aluminum alloy of claim 1, wherein the method comprises a T4 tempering.   The aluminum alloy according to claim 1 or 2, wherein the aluminum alloy further contains 0.2 to 0.4 wt% of Si.   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 an aluminum alloy plate.   A pressed plate-like product made from the aluminum alloy plate according to claim 5.   The pressed plate-shaped object according to claim 6, wherein the pressed plate-shaped object is an automobile panel.   A method for producing an aluminum alloy sheet containing 1.5% by weight or more of Mg and 0.2 to 0.4% by weight of Si, comprising heat treatment.   The method of claim 8, wherein the method comprises T4 tempering.   The method according to claim 8 or 9, wherein the aluminum alloy sheet exhibits age hardening.   A method for producing a pressed plate-like form, comprising pressing the aluminum alloy plate according to claim 5.   The method of claim 11, wherein the pressed plate-like feature is an automotive panel.

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