TW201907022A - Substantially pb-free aluminum alloy composition - Google Patents

Abstract

A substantially Pb-free aluminum alloy consisting essentially of (in weight percent) Si < 0.40; Fe < 0.70; Cu 5.0 - 6.0; Zn < 0.30; Bi 0.20 - 0.80; Sn 0.10 - 0.50 with the remainder being aluminum and incidental impurities. In one embodiment for applications that are sensitive to cracking from stresses generated during machining, the Bi/Sn ratio (in terms of weight percent) is less than 1.32/1 and producing in a T8 temper. On another embodiment for applications that are not sensitive to cracking from stresses during machining but would benefit from smaller machine chip size and more aggressive material removal rates, the aluminum alloy is produced using a T6 temper. The substantially Pb-free aluminum alloy has mechanical properties that include Ultimate Tensile Strength ≥ 45.0 KSI / 311 MPa, Yield Strength ≥ 38.0 KSI / 262 Mpa, and % Elongation ≥ 10%.

Description

Basically lead-free aluminum alloy composition

FIELD OF THE INVENTION The present invention relates to substantially lead-free aluminum alloy compositions, and methods of making the alloy compositions, while at the same time achieving the machinability of their lead-containing counterparts.

BACKGROUND OF THE INVENTION Historically, lead-containing aluminum alloys such as 2011 and 6262 (registered with the Aluminum Association in 1954 and 1960, respectively) have been used in demanding machining applications. These applications require alloys that can be processed at high material removal rates while maintaining a good machined surface finish and that are small and easy to remove from the work area to prevent machine debris from jamming the machine. Lead-containing aluminum alloys meet this need by providing intermetallic phases in the material as chipbreakers, resulting in faster material removal rates, small machine debris, and a well machined surface. Although lead does provide an effective solution, it is a heavy metal that is considered a hazardous substance.

In order to reduce the adverse health effects and environmental risks that these alloys may have, alternative lead-free aluminum alloys with similar machinability are needed. Over the years, attempts have been made to develop process-free/lead-free alloys, including alloys 2012, 2111, 6020, and 6040. These alloys use niobium and/or tin as a substitute for lead. While many of these alloys have been successful in terms of process chip size and machined surface finish, many manufacturers of thin-walled, complex parts have found that they are unable to achieve material removal rates for lead-bearing alloy materials because of these components. Has a tendency to crack. Many of these alloys are therefore withdrawn from the market or warned customers to limit the material removal rate for certain applications. Considering that many lead bearing aluminum alloy applications are sold through distribution pipelines, material manufacturers are unaware of end processing applications, so this is problematic.

In order to avoid potential failures due to such cracking tendencies, the availability of lead-free alternative alloys that are still available is often limited and often limits processing parameters that do not achieve the same level of performance as lead-containing alternatives. Therefore, the market still needs a product that meets the machining characteristics of lead-containing alloys, and also meets the strength requirements. For example, typically, the minimum yield strength of lead-containing alloy 2011-T3 is 38 KSI/262 MPa.

SUMMARY OF THE INVENTION The substantially lead-free aluminum alloy composition of the present invention provides a process-free product that achieves the same in terms of high material removal rates, process debris sizes, and machined surface finishes as compared to existing lead-containing precursors. Superior processing performance.

The substantially lead-free aluminum alloy composition of the present invention is not susceptible to cracking in thin-walled, complex processing under severe material removal conditions. This is a key difference that has not been realized in other inventions that attempt to solve the above technical problems. Materials that are sensitive to such cracking conditions ensure the integrity of the final part by requiring substantially lower material removal rates or completely non-conforming materials to make processing performance insignificant.

The substantially lead-free aluminum alloy compositions of the present invention substantially meet or exceed the material performance requirements of existing process-free materials. In particular, in a preferred embodiment, the substantially lead-free aluminum alloy composition meets the minimum material properties of AA2011-T3, including ultimate tensile strength ≥ 45.0 KSI / 311 MPa, yield strength ≥ 38.0 KSI / 262 MPa, elongation The minimum rate is ≥10%.

The substantially lead-free aluminum alloy composition comprises or consists essentially of (by weight percent): Si < 0.40; Fe < 0.70; Cu 5.0 - 6.0; Zn < 0.30; Bi 0.20 - 0.80; Sn 0.10-0.50, the balance is aluminum and incidental impurities. In a preferred embodiment, the substantially lead-free aluminum alloy composition maintains a Bi/Sn ratio of less than 1.32/1 (in weight percent; 1.32/1 is a co-crystal ratio of Bi-Sn). In addition, the production of materials in the T8 state offers specific advantages for processing crack-sensitive processing applications because of their high material removal rates and thin-walled geometries. Conversely, because the part geometry is more robust and insensitive to process cracking, specific processing applications that can benefit from higher material removal rates can be produced in the T6 state.

DETAILED DESCRIPTION OF THE INVENTION A substantially lead-free aluminum alloy composition comprises or consists essentially of (by weight percent): Si < 0.40; Fe < 0.70; Cu 5.0 - 6.0; Zn < 0.30; Bi 0.20 - 0.80; Sn 0.10-0.50, the balance being aluminum and incidental impurities. In a preferred embodiment, Si, Fe, Cu, Zn, Bi, and Sn are the only components deliberately added to the alloy composition such that any other material is only present as an incidental impurity. The incidental impurities are present in a total amount of less than 1% by weight, or less than 0.5% by weight, or less than 0.1% by weight, or less than 0.05% by weight. In one embodiment, the substantially lead-free aluminum alloy composition maintains a Bi/Sn ratio of less than 1.32/1 (in percent by weight; 1.32/1 is a co-crystal ratio of Bi-Sn).

Preferably, the substantially lead-free aluminum alloy compositions of the present invention substantially meet or exceed the material performance requirements of existing process-free materials. In particular, in a preferred embodiment, the substantially lead-free aluminum alloy composition meets the minimum material properties of AA2011-T3, including ultimate tensile strength ≥ 45.0 KSI / 311 MPa, yield strength ≥ 38.0 KSI / 262 MPa, elongation The minimum value is ≥10%.

Generally, the phrase "substantially lead-free" is defined as the inadvertent addition of lead when making an aluminum alloy composition. Preferably, any lead that may be included in the aluminum alloy composition is the result of impurity contamination. In a preferred embodiment, the aluminum alloy composition of the present invention contains <0.05% by weight lead. In another embodiment, the aluminum alloy composition of the present invention contains <0.01% by weight lead. In another preferred embodiment, the aluminum alloy composition of the present invention contains <0.005 wt% lead. In another preferred embodiment, the aluminum alloy composition of the present invention contains < 0.003 wt% lead.

It should be understood that the above ranges for the substantially lead-free aluminum alloy composition include the upper or lower limit of the selected element, and each numerical range and the portion provided within the range can be considered as the upper or lower limit. For example, it should be understood that the upper or lower limit of Si may be selected from the group consisting of 0.30, 0.25, 0.20, 0.15, and 0.10% by weight in the range of Si < 0.40. In one embodiment, the amount of Si is in the range of <0.20% by weight. In another embodiment, the amount of Si is in the range of <0.16 wt%. In another embodiment, the amount of Si is from 0.10 to 0.16% by weight. For example, it should also be understood that in the range of Fe < 0.70, the upper or lower limit of Fe may be selected from 0.60, 0.50, 0.40, 0.30, 0.20, and 0.10% by weight. In one embodiment, the amount of Fe is from 0.30 to 0.50% by weight. In another embodiment, the amount of Fe is from 0.33 to 0.44% by weight. For example, it should also be understood that the upper or lower limit of Cu may be selected from the group consisting of 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, and 5.9 in the range of Cu 5.0-6.0. In one embodiment, the amount of Cu is from 5.1 to 5.8% by weight. In another embodiment, the amount of Cu is from 5.1 to 3.63 wt%. For example, it should also be understood that the upper or lower limit of Zn may be selected from the group consisting of 0.20, 0.10, 0.05, 0.01, and 0.005 wt% in the range of Zn < 0.30. In one embodiment, the amount of Zn is from 0.002 to 0.05. In another embodiment, the amount of Zn is from 0.002 to 0.044. For example, it should also be understood that in the range of Bi 0.20-0.80, the upper or lower limit of Bi may be selected from 0.30, 0.40, 0.50, 0.60, and 0.70. In one embodiment, the amount of Bi is from 0.40 to 0.80. In another embodiment, the amount of Bi is from 0.20 to 0.40. For example, it should also be understood that the upper or lower limit of Sn may be selected from 0.20, 0.30, and 0.40 in the range of Sn 0.10-0.50. In one embodiment, the amount of Sn is from 0.20 to 0.50. Further, for example, it should also be understood that, in the range where the Bi/Sn ratio is less than 1.32/1, the upper or lower limit of the Bi/Sn ratio may be selected from the group consisting of 1.30/1, 1.25/1, 1.20/1, 1.15/1, 1.10/ 1, 1.05/1, 1.00/1, and 0.80/1. In one embodiment, the Bi/Sn ratio may be between 1.32/1 and 0.80/1. It is also to be understood that any and all substitutions of the above identified ranges are included within the scope of the invention. For example, a substantially lead-free aluminum alloy composition can consist essentially of the following components (in percent by weight): Si < 0.15; Fe < 0.50; Cu 5.1 - 5.7; Zn < 0.05; Bi 0.40 - 0.80; Sn 0.20 - 0.50, the balance being aluminum and incidental impurities while maintaining a Bi/Sn ratio of less than 1.32/1 (in weight percent; 1.32/1 is the eutectic ratio of Bi-Sn), or a Bi/Sn ratio of 1.32/1 to 0.80/ 1, or have a total amount of less than 1% by weight, or less than 0.5% by weight, or less than 0.1% by weight, or less than 0.05% by weight of incidental impurities.

In addition, the production of materials in the T8 state offers specific advantages for processing crack-sensitive processing applications because of their high material removal rates and thin-walled geometries. In this way, it is possible to produce an aluminum alloy which is free from processing and is insensitive to cracking. Aluminum alloy products have been homogenized to improve recrystallization to improve grain size control. In a preferred embodiment, the alloy has a Bi/Sn ratio (% by weight) of less than 1.32/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (% by weight) of from 1.32/1 to 0.8/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (% by weight) of 1.20/1 to 1/1.

Conversely, because the part geometry is more robust and insensitive to process cracking, specific processing applications that can benefit from higher material removal rates can be produced in the T6 state. In this way, an excellent process-free aluminum alloy material can be produced for applications that do not require crack insensitive properties. Aluminum alloy products have been homogenized to improve recrystallization to improve grain size control. In a preferred embodiment, the alloy has a Bi/Sn ratio (% by weight) of less than 1.32/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (% by weight) of from 1.32/1 to 0.8/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (% by weight) of 1.20/1 to 1/1.

It is important to note that the preferred method according to the present application does not include any natural aging that is beyond the natural aging inherent in the methods described herein. In particular, the present invention does not include any T3 or T4 natural aging of the alloy composition.

The preferred method for making the alloy composition of the present invention is similar to that described in U.S. Patent No. 5,776,269 and U.S. Patent No. 5,916,385, the disclosure of each of In one embodiment, the alloy is first cast into an ingot and the ingot is homogenized at a temperature of about 900 to 1170 °F for at least 1 hour but typically no more than 24 hours, optionally followed by fan cooling or air cooling. In one embodiment, the ingot is soaked at about 1020 °F for about 4 hours and then cooled to room temperature. Next, in one embodiment, the ingot is cut into shorter billets, heated to a temperature of about 500 to 720 °F, and then extruded into the desired shape. However, it should be understood that one of ordinary skill in the art can select different times and temperatures and still be within the scope of the present invention.

In one embodiment, the extruded alloy shape is then thermomechanically processed to achieve the desired mechanical and physical properties. For example, in order to obtain the mechanical and physical properties of the T8 state, the solution heat treatment is carried out at a temperature of about 930 ° to 1030 ° F, preferably about 1000 ° F for about 0.5-2 hours, the water is quenched to room temperature, and cold worked, And artificially aged at a temperature of about 250 to 400 °F for about 2 to 12 hours. However, it should be understood that one of ordinary skill in the art can select different times, quenching conditions, and temperatures, and still be within the scope of the present invention.

In one embodiment, to achieve the performance of T6 in the T6511 state, the billet is homogenized at a temperature of about 950 to 1050 °F prior to extrusion and then extruded to near the desired size. The rod or strip is then straightened using any known straightening operation (e.g., about 1 to 3% strain relief stretching). In order to further improve its physical and mechanical properties, the alloy is heat treated by precipitation artificial age hardening. Typically, this can be done at a temperature of from about 250 to 400 °F for a period of from about 2 to 12 hours. However, it should be understood that one of ordinary skill in the art can select different times, quenching conditions, and temperatures, and still be within the scope of the present invention.

The following examples illustrate various aspects of the invention and are not intended to limit the scope of the invention. Example 1

The billet produced was 10 inches (254 mm) in diameter and the target composition is shown in Table 1. These blanks were extruded and processed into T3, T4, T6 and T8 states using the process parameters shown in Figure 1 to produce rods having a diameter of 1.000 inches (25.4 mm). The casting of the blanks is done using conventional direct chill casting techniques. The 6040 alloy variant is produced in both pressure quenching (T6511 state) and separate solution heat treatment (T651 state) processes. Homogenization, extrusion, solution heat treatment, quenching, drawing, and artificial aging operations are all performed using typical industrial practices. The tensile properties and machinability of the samples from this material were evaluated. The tensile properties are shown in Table 2. The 2011-T3 mechanical performance limit was used as an acceptable minimum standard. These results indicate that all materials except BISN-31-T451 passed the lowest performance of the 2011-T3 aluminum alloy (yield strength 38.0 KSI/262 MPa; ultimate strength 45.0 KSI/311 MPa; elongation 10%). Table 1: Composition of Example 1 (% by weight) Table 2: Mechanical properties of the materials evaluated in Example 1

Machinability testing is performed by producing representative components that use multiple machining operations. This part is conceptually depicted in Figure 2. By maintaining a constant cutting speed and feed rate for all processing operations, the material removal rate between materials remains the same. The size of the crumb is evaluated by determining the amount of clean dry debris per gram. The results of this evaluation are shown in Figure 3 and compared to the current lead-free work-free material 2011-T3 as a baseline comparison. This indicates that the alloy/state combination tested is better or comparable to existing materials. Lead-free 6040 compositions currently available on the market were also tested in the matrix. These tests have not performed as well as 2011-T3 in history, and this test verifies their poor performance.

In order to test materials that are not susceptible to cracking in thin-walled, rigorous processing applications, rigorous processing tests have been developed. This involves drilling a center of a 1.000'' (25.4 mm) rod with a 0.969'' (24.6 mm) diameter twist drill to produce a wall thickness of 0.015'' (0.38 mm), as shown in FIG. The RPM and feed rate were kept constant at 1500 RPM and 0.035'' (1.27 mm) / rotational feed rate. Once the test is complete, the conditions of the sample are examined as depicted in FIG. This test was developed to test the sensitivity of materials to cracks under extreme processing conditions with thin wall, high material removal rates and high torque applications. From the standpoint of chip size and material properties, the test is repeated at least 12 times for acceptable performance for each test material. The percentage of parts with tears (or cracks) and bursts is recorded in Figure 6 and the results are shown. For simplicity, the BISN-31 is specified in this figure in different states (T3, T4 and T8). This indicates that 2011 (existing lead-containing alloys) and lead-free 6040 alloy variants (but note that the performance of these alloy variants is not good from the perspective of chip size) passed as expected. The only experimental alloy that passed was BISN-31-T4, but unfortunately this did not meet tensile performance requirements.

Analysis of these results shows that the alloy/state combination performance with lower yield to ultimate strength ratio is better from the point of view of processing crack sensitivity. A closer analysis of the BISN-01 to BISN-04 compositions shows that lower Bi + Sn content and lower Bi/Sn ratio are beneficial from a processing crack sensitivity perspective, considering the severity of the failure. The Bi/Sn ratio appears to have a stronger effect relative to the performance input variables associated with the composition. This is shown in Table 3. Note that the Bi/Sn ratio of the Bi-Sn eutectic composition based on the weight percentage was 1.32 (as shown in FIG. 11). Table 3: Severity of processing crack sensitivity results for alloys BISN-01 to BISN-04 Example 2

A billet having a diameter of 10" (254 mm) was cast and processed into a 1" (25.4 mm) rod using the method shown in Figure 1 and the composition listed in Table 4. This study evaluated the percentage of ROA (area reduction) during the drawing operation, especially in the T3 state. The homogenization effect was also evaluated by homogenization of casting 1110 and comparison with heterogeneous casting 1108. The mechanical properties, machinability and processing crack sensitivity of the 1'' (25.4 mm) rod were evaluated using the same technique as described in Example 1. Table 4: Composition and state of Example 2 (% by weight)

Mechanical properties are shown in Table 5. This indicates that all compositions and combinations of states are capable of achieving a minimum 2011-T3 target mechanical properties (yield strength 38 KSI/262 MPa; ultimate strength 45.0 KSI/311 MPa; elongation 10%). The addition of Mg also successfully achieved these properties in the T4 state. Table 5: Mechanical properties of the materials evaluated in Example 2

The machinability test relative to the size of the chips was evaluated using the results shown in FIG. These results indicate that the higher Bi + Sn composition (BI39) performs better in terms of machinability, measured in chips/gram, and the performance is comparable to or better than the existing 2011-T3. Lower Bi + Sn compositions (BI26) generally do not perform as well as existing 2011-T3, but are comparable. It also shows that there is almost no difference in machinability associated with the percentage reduction area of the T3 state, regardless of the Bi + Sn level. The addition of homogenization did not improve the machinability, but studies on the grain structure showed a significant improvement with respect to the surrounding coarse crystals (recrystal grain size on the outer circumference of the rod). Thus, for some applications where it is desirable to improve the appearance of the surface, such as parts that require anodization, the use of homogenization, while not necessary for machinability, may be beneficial. Regardless of the alloy composition, the T651 state material performs well with a small chip size. For a given alloy, particularly a BI26 composition, the T8 state is generally better than the T3 counterpart.

For the processing crack sensitivity test, these results are shown in Figure 8, in which case the wrinkles on the surface (according to Figure 5) are also considered unacceptable. These results show that this state has a stronger effect, although the composition BI26 performs significantly better than BI39 (proving that the higher Bi + Sn makes the material easier to process cracks). It is to be noted that all of the compositions in this example have a Bi/Sn ratio of less than 1.32. The T8 state did not crack in this test, regardless of the composition, and the T6 sample performed very poorly. The T3 state has some failures, and the higher Bi + Sn containing material has a significantly higher failure rate. According to Figure 5, the BI26-T3 composition did not fail in tearing or bursting, so Bi + Sn had a significant effect on performance.

Therefore, these results show that by producing materials in the T8 state, higher Bi + Sn levels can be used, and excellent machinability is also achieved from the viewpoint of chip size. Example 3

Billets with a diameter of 10'' (254 mm) were cast and processed into 1'' (25.4 mm) and 2'' (50.8 mm) T3 and T8 rods using the method shown in Figure 1 and the compositions listed in Table 6. . The mechanical properties, machinability and processing crack sensitivity of the rods were evaluated using the same technique as described in Example 1. Table 6: Composition and state of Example 3 (% by weight)

Mechanical properties are shown in Table 7. This indicates that all compositions and combinations of states are capable of achieving a minimum 2011-T3 target mechanical properties (yield strength 38 KSI/262 MPa; ultimate strength 45.0 KSI/311 MPa; elongation 10%). Table 7: Mechanical properties of the materials evaluated in Example 3

The machinability test relative to the size of the crumb was evaluated using the results depicted in Figure 9 for a 1.000'' (25.4 mm) diameter material. The results show that the performance of T8 is better than that of lead-containing 2011 materials, while the performance of T3 materials is still acceptable, but not as good as lead-containing 2011 materials. The test repeated a diameter of 2.000'' (50.8 mm) to ensure that the material worked well over a wider range of diameters. Although in this test, the 2.000'' (50.8mm) diameter result is slightly worse than the leaded 2011 existing material, it must be noted that from the gram of base gram per gram, it is 1.00'' (25.4mm) The test results for the diameter are good. It can therefore be concluded that the material performs well over these diameter ranges.

A processing crack sensitivity test was also performed on a 1.000'' (25.4 mm) diameter material in consideration of wrinkling, tearing, and bursting (according to Figure 5) as a failure. The results of this test are shown in Table 8. Table 8: Summary of the results of the machining crack sensitivity test for the diameter of 1.000'' (25.4 mm) in Example 3.

These results demonstrate that for applications with harsh material removal rates and thin-walled component geometries that are prone to tearing, treating the material in the T8 state and maintaining a Bi/Sn ratio of less than 1.32 virtually eliminates this failure mechanism.

While the invention has been described in terms of the preferred embodiments thereof, it is understood that many modifications and changes may be made thereto without departing from the scope of the invention as defined by the appended claims.

The features and advantages of the present invention will become apparent from

1 is a schematic diagram showing an operational sequence of a substantially lead-free aluminum alloy composition produced in accordance with various examples of the present invention;

2 is a conceptual diagram of representative components for evaluating machinability from the perspective of a chip size of a substantially lead-free aluminum alloy composition in accordance with the present invention;

Figure 3 is a graph showing the machinability of the alloy/state combination evaluated in Example 1 measured in chips/gram;

Figure 4 is a conceptual diagram of a process crack sensitivity test component;

Figure 5 shows a picture of the observations made according to the processing crack sensitivity test, showing the four classifications used;

Figure 6 is a graph showing the results of the test crack sensitivity test of Example 1, expressed in %, without tearing or bursting;

Figure 7 is a graph showing the results of the machinability of the display example 2 measured by the crumb/g;

Figure 8 is a graph showing the results of the test crack sensitivity test of Example 2, expressed in %, without wrinkles, tears or bursts;

Figure 9 is a graph showing the results of the machinability of the display example 3 measured by the crumb/g;

Figure 10 is a graph showing the results of the machinability of Example 3, measured as chips/gram for a rod having a diameter of 2.000'';

Figure 11 is a Bi-Sn phase diagram.

Claims (15)

A substantially lead-free aluminum alloy composition comprising the following components (by weight percent of the aluminum alloy composition): Pb 0-0.10; Si 0 -0.40; Fe 0-0.70; Cu 5.0-6.0; Zn 0- 0.30; Bi 0.20-0.80; Sn 0.10-0.50; except for incidental impurities, the remainder is aluminum; the alloy composition has a Bi/Sn weight ratio of less than 1.32/1; the alloy composition uses only the T8 or T6 state Manufactured to provide an alloy composition having an ultimate tensile strength ≥ 45.0 KSI / 311 MPa, a yield strength ≥ 38.0 KSI / 262 MPa, and a minimum elongation ≥ 10%. The composition of claim 1 wherein the aluminum alloy composition has <0.05% by weight of Pb. The composition of claim 1, wherein the aluminum alloy composition comprises 0.10 to 0.16% by weight of Si. The composition of claim 1 wherein the aluminum alloy composition comprises from 0.30 to 0.50% by weight of Fe. The composition of claim 1, wherein the aluminum alloy composition comprises 5.1 to 5.8% by weight of Cu. The composition of claim 1 wherein the aluminum alloy composition comprises 0.002 to 0.05% by weight of Zn. The composition of claim 1, wherein the aluminum alloy composition comprises 0.20-0.40% by weight of Bi. The composition of claim 1 wherein the aluminum alloy composition comprises from 0.20 to 0.50% by weight of Sn. The composition of claim 1, wherein the aluminum alloy composition comprises, optionally consisting of (in terms of percentage (weight/weight) of the aluminum alloy composition): Si 0-0.16; Fe 0- 0.50; Cu 5.1-5.8; Zn 0-0.05; Bi 0.20-0.40 and Sn 0.20-0.50. The composition of claim 1, wherein the aluminum alloy composition has a Bi/Sn weight ratio ranging from 1.32/1 to 0.8/1. The composition of claim 1 wherein the incidental impurities are present in a total amount of less than 0.5% by weight. The composition of claim 1 wherein the manufacturing comprises only the T8 state. The composition of claim 1 wherein the aluminum alloy composition is not subjected to a T3 or T4 state. A method of forming an aluminum alloy comprising the steps of: a. casting an alloy blank of the aluminum alloy composition of claim 1; b. optionally homogenizing the strand; c. extruding the strand to form a contour a shaped extrusion; d. solution heat treatment of the extrusion by heating to a hot refining temperature between 900-1060 ° F (482-571 ^° C) and quenching from the hot refining temperature to room temperature; e. After step d), the extrusion is cold worked to a minimum of 5% cross-sectional area by drawing, drawing or rolling; and f. The extrusion of step e) is artificially aged to a peak in the T8 or T6 state. Hardness to produce the aluminum alloy having an ultimate tensile strength ≥ 45.0 KSI / 311 MPa, a yield strength ≥ 38.0 KSI / 262 MPa and a minimum elongation ≥ 10%. The method of claim 14, wherein the step of homogenizing the slab is performed in a temperature range of 900-1050 °F for a period of not less than 1 hour; and by heating to 900-1060 °F (482) The step of solution heat treatment of the extrusion is carried out for 0.5 to 2 hours at a temperature between -571 ^° C).