TWI776910B - 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

Substantially lead-free aluminum alloy composition

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

BACKGROUND OF THE INVENTION Lead-containing aluminum alloys such as 2011 and 6262 (registered with the Aluminum Institute in 1954 and 1960, respectively) have historically been used in demanding machining applications. These applications require alloys that can be machined at high material removal rates, while maintaining a good machined surface finish, and producing small machine debris that can be easily removed from the work area to prevent jamming the machine tool. 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 good machined surfaces. While lead does provide an effective solution, it is a heavy metal and considered a hazardous substance.

In order to reduce the adverse health effects and environmental risks that these alloys may pose, there is a need for alternative lead-free aluminum alloys with similar machinability. Over the years, attempts have been made to develop machining-free/lead-free alloys, including alloys 2012, 2111, 6020 and 6040. These alloys use bismuth and/or tin as lead substitutes. While many of these alloys are successful in terms of machined chip size and machined surface finish, many producers of thin-walled, complex parts find they cannot achieve the material removal rates of lead bearing alloy materials because these parts Has a tendency to crack. As a result many of these alloys were withdrawn from the market, or customers were warned to limit material removal rates for certain applications. This is problematic given that many applications for lead bearing aluminum alloys are sold through distribution channels, so material producers are unaware of end-finishing applications.

To avoid potential failures due to this tendency to crack, the availability of lead-free alternative alloys that are still available is often limited and often has limitations on 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 machinability characteristics of lead-containing alloys, while also meeting the strength requirements. For example, leaded alloy 2011-T3 typically has a minimum yield strength of 38 KSI/262 MPa.

SUMMARY OF THE INVENTION The substantially lead-free aluminum alloy compositions of the present invention provide a machine-free product that achieves the same or higher levels of material removal, machined chip size, and machined surface finish compared to its existing lead-containing precursors. Superior processing performance.

The substantially lead-free aluminum alloy compositions of the present invention are not susceptible to cracking in thin-walled, complex machining under severe material removal conditions. This is a key difference that has not been achieved in other inventions that attempt to solve the above-mentioned 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 rejecting material making processability irrelevant.

The substantially lead-free aluminum alloy compositions of the present invention substantially meet or exceed the material property requirements of existing machining-free materials. Specifically, in preferred embodiments, 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 the following components (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 rest are aluminum and incidental impurities. In preferred embodiments, the substantially lead-free aluminum alloy composition maintains a Bi/Sn ratio of less than 1.32/1 (on a weight percent basis; 1.32/1 is the Bi-Sn eutectic ratio). In addition to this, producing materials in the T8 temper offers specific advantages for machining crack-sensitive machining applications due to their high material removal rates and thin-wall geometries. Conversely, specific machining applications that benefit from higher material removal rates can be produced in the T6 temper because the part geometry is more robust and insensitive to machining cracks.

DETAILED DESCRIPTION A substantially lead-free aluminum alloy composition includes or consists essentially of the following components (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 rest are aluminum and incidental impurities. In preferred embodiments, Si, Fe, Cu, Zn, Bi and Sn are the only components that are intentionally added to the alloy composition such that any other materials are present only as incidental impurities. The incidental impurities are present in a total amount of less than 1 wt%, or less than 0.5 wt%, or less than 0.1 wt%, or less than 0.05 wt%. In one embodiment, the substantially lead-free aluminum alloy composition maintains a Bi/Sn ratio of less than 1.32/1 (on a weight percent basis; 1.32/1 is the Bi-Sn eutectic ratio).

Preferably, the substantially lead-free aluminum alloy compositions of the present invention substantially meet or exceed the material property requirements of existing machining-free materials. In particular, in preferred embodiments, 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 Minimum value ≥ 10%.

In general, the phrase "substantially lead-free" is defined as the aluminum alloy composition without intentional addition of lead. Preferably, any lead that may be included in the aluminum alloy composition is the result of contamination by impurities. In a preferred embodiment, the aluminum alloy composition of the present invention contains <0.05 wt% lead. In another embodiment, the aluminum alloy composition of the present invention contains <0.01 wt% 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 is to be understood that the ranges established above for substantially lead-free aluminum alloy compositions include upper or lower limits for the selected elements, and that each numerical range and portions provided within that range may be considered an upper or lower limit. For example, it should be understood that in the range of Si < 0.40, the upper or lower limit of Si may be selected from 0.30, 0.25, 0.20, 0.15 and 0.10 wt %. In one embodiment, the amount of Si is in the range of <0.20 wt%. In another embodiment, the amount of Si is in the range of <0.16 wt%. In another embodiment, the amount of Si is 0.10-0.16 wt%. For example, it should also be understood that in the range Fe < 0.70, the upper or lower Fe limit may be selected from 0.60, 0.50, 0.40, 0.30, 0.20, and 0.10 wt %. In one embodiment, the amount of Fe is 0.30-0.50 wt%. In another embodiment, the amount of Fe is 0.33-0.44 wt%. For example, it is also understood that within the range of Cu 5.0-6.0, the upper or lower limit of Cu may be selected from 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, and 5.9. In one embodiment, the amount of Cu is 5.1-5.8 wt%. In another embodiment, the amount of Cu is 5.13-5.63 wt%. For example, it should also be understood that in the range Zn < 0.30, the upper or lower limit of Zn may be selected from 0.20, 0.10, 0.05, 0.01 and 0.005 wt %. In one embodiment, the amount of Zn is 0.002-0.05. In another embodiment, the amount of Zn is 0.002-0.044. For example, it should also be understood that within 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 0.40-0.80. In another embodiment, the amount of Bi is 0.20-0.40. For example, it should also be understood that in the range of Sn 0.10-0.50, the upper or lower limit of Sn may be selected from 0.20, 0.30 and 0.40. In one embodiment, the amount of Sn is 0.20-0.50. In addition, for example, it should also be understood that 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 in the range where the Bi/Sn ratio is less than 1.32/1 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 should also be understood that any and all permutations of the above-identified ranges are included within the scope of the present invention. For example, a substantially lead-free aluminum alloy composition may consist essentially of the following components (by weight percent): 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 remainder being aluminum and incidental impurities, while maintaining a Bi/Sn ratio of less than 1.32/1 (by weight; 1.32/1 is the Bi-Sn eutectic ratio), or a Bi/Sn ratio of 1.32/1 to 0.80/ 1, or have a total of less than 1 wt%, or less than 0.5 wt%, or less than 0.1 wt%, or less than 0.05 wt% incidental impurities.

In addition to this, producing materials in the T8 temper offers specific advantages for machining crack-sensitive machining applications due to their high material removal rates and thin-wall geometries. In this way, a machining-free, machining-crack-insensitive aluminum alloy can be produced. 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 (weight percent) of less than 1.32/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (weight percent) of 1.32/1 to 0.8/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (weight percent) of 1.20/1 to 1/1.

Conversely, specific machining applications that benefit from higher material removal rates can be produced in the T6 temper because the part geometry is more robust and insensitive to machining cracks. In this way, excellent machining-free aluminum alloy materials can be produced for applications that do not require machining 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 (weight percent) of less than 1.32/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (weight percent) of 1.32/1 to 0.8/1. In yet another preferred embodiment, the alloy has a Bi/Sn ratio (weight percent) of 1.20/1 to 1/1.

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

Preferred methods for making the alloy compositions of the present invention are similar to those described in US Pat. No. 5,776,269 and US Pat. No. 5,916,385, the contents of which are expressly incorporated herein by reference. 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 not 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. It should be understood, however, that one of ordinary skill in the art may choose different times and temperatures and still remain within the scope of the present invention.

In one embodiment, the extruded alloy shape is then thermomechanically treated to obtain desired mechanical and physical properties. For example, to obtain mechanical and physical properties in the T8 temper, solution heat treatment is performed at a temperature of about 930° to 1030°F, preferably about 1000°F for a period of about 0.5-2 hours, water quenched to room temperature, cold worked, and artificially aged for about 2 to 12 hours at a temperature of about 250° to 400°F. It should be understood, however, that one of ordinary skill in the art may select different times, quenching conditions and temperatures and still remain within the scope of the present invention.

In one embodiment, to achieve the properties of T6 in the T6511 temper, the billet is homogenized at a temperature of about 950° to 1050°F prior to extrusion, and then extruded to near desired dimensions. The rod or bar is then straightened using any known straightening operation (eg, about 1 to 3% stress relief stretch). 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 about 250° to 400°F for a period of about 2 to 12 hours. It should be understood, however, that one of ordinary skill in the art may select different times, quenching conditions and temperatures and still remain 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

表2：示例1中評估的材料的機械性能

The billets produced were 10 inches (254 mm) in diameter and the target compositions are shown in Table 1. These billets were extruded and machined to T3, T4, T6 and T8 tempers to produce 1.000 inch (25.4 mm) diameter rods using the process parameters shown in Figure 1 . Casting of the billets is done using conventional direct chill casting techniques. The 6040 alloy variant is produced in both pressure quench (T6511 temper) and separate solution heat treatment (T651 temper) processes. Homogenization, extrusion, solution heat treatment, quenching, drawing and artificial aging operations are all done using typical industrial practices. Samples from this material were evaluated for tensile and machinability properties. Tensile property results are shown in Table 2. Use the mechanical property limits of 2011-T3 as the minimum acceptable standard. These results show that all materials except BISN-31-T451 pass the aluminum alloy minimum properties of 2011-T3 (yield strength 38.0 KSI/262 MPa; ultimate strength 45.0 KSI/311 MPa; elongation 10%). Table 1: Composition of Example 1 (weight percent)

Table 2: Mechanical properties of the materials evaluated in Example 1

Machinability testing is performed by producing representative parts using multiple machining operations. This part is conceptually depicted in Figure 2. By keeping the cutting speed and feed rate constant for all machining operations, the material removal rate remains constant from material to material. Chip size is assessed by determining the number of clean, dry chips per gram. The results of this evaluation are shown in Figure 3 and compared to the current lead-containing process-free material 2011-T3 as a benchmark comparison. This indicates that the tested alloy/state combination is better or comparable to existing materials. The currently available lead-free 6040 composition was also tested in this matrix. These tests have historically underperformed 2011-T3, and this test validates their poor performance.

Rigorous machining tests were developed to test the material's resistance to cracking in thin-walled, rigorous machining applications. This involved drilling the center of a 1.000'' (25.4mm) rod with a 0.969'' (24.6mm) diameter twist drill, resulting in a 0.015'' (0.38mm) wall thickness, as shown in Figure 4. RPM and feed rate were kept constant at 1500 RPM and 0.035'' (1.27mm)/revolution feed rate. Once the test is complete, the condition of the sample is checked as depicted in FIG. 5 . This test was developed to test the susceptibility of materials to cracks under extreme processing conditions with thin walls, high material removal rates and high torque applications. The test was repeated at least 12 times for each tested material to have acceptable performance from a chip size and material performance standpoint. The percentage of parts with tears (or cracks) and bursts is recorded in Figure 6 and the results are shown. For simplicity, BISN-31 is designated with different states (T3, T4, and T8) in this figure. This shows that 2011 (the existing leaded alloy), as well as the lead-free 6040 alloy variant (but note that these alloy variants perform poorly from a chip size perspective) passed smoothly as expected. The only experimental alloy that passed was BISN-31-T4, but unfortunately this did not meet the tensile properties requirements.

示例2Analysis of these results shows that alloy/condition combinations with lower yield to ultimate strength ratios perform better from a work crack susceptibility standpoint. 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 susceptibility perspective considering the severity of failure. The Bi/Sn ratio appears to have a stronger effect relative to the composition-related performance input variables. This is shown in Table 3. Note that the Bi/Sn ratio of the Bi-Sn eutectic composition based on weight percent is 1.32 (as shown in Figure 11). Table 3: Severity of machining crack susceptibility results for alloys BISN-01 to BISN-04

Example 2

10" (254 mm) diameter billets were cast and machined into 1" (25.4 mm) rods using the method shown in Figure 1 and the compositions listed in Table 4. This study evaluated the percentage ROA (reduction in area) during the drawing operation, especially in the T3 temper. The effect of homogenization was also evaluated with casting 1110 homogenizing and comparing with non-homogenizing casting 1108. The 1" (25.4 mm) rods were evaluated for mechanical properties, machinability and machining crack susceptibility using the same techniques as described in Example 1. Table 4: Composition and state (weight percent) of Example 2

Mechanical properties are shown in Table 5. This indicates that all compositions and state combinations are able to achieve the lowest 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 achieves these properties in the T4 state. Table 5: Mechanical properties of the materials evaluated in Example 2

The results shown in Figure 7 were used to evaluate the machinability test with respect to chip size. These results show that the higher Bi + Sn composition (BI39) performs better from a machinability perspective, measured in chips/gram, and performs on par or better than the existing 2011-T3. The lower Bi + Sn composition (BI26) generally underperformed the existing 2011-T3, but was comparable. It also shows that there is little difference in the machinability related to the percent reduced area of the T3 state regardless of the Bi+Sn level. The addition of homogenization did not improve machinability, but a study of the grain structure showed a significant improvement relative to the peripheral coarse grains (recrystallized grain size on the outer periphery of the rod). Therefore, for some applications requiring improved surface appearance (eg parts requiring anodization), the use of homogenization, although not necessary for machinability, may be beneficial. Regardless of alloy composition, the T651 temper material performed well with a small chip size. For a given alloy, especially the BI26 composition, the T8 temper generally performs better than the T3 counterpart.

These results are shown in Figure 8 in terms of process crack susceptibility testing, in which case wrinkling on the surface (according to Figure 5) was also considered unacceptable. These results show that while composition BI26 performs significantly better than BI39 (confirming that higher Bi+Sn makes the material more susceptible to processing cracks), this state has a stronger effect. Note that all compositions in this example have Bi/Sn ratios of less than 1.32. The T8 temper did not crack in this test, regardless of the composition, while the T6 sample performed very poorly. All T3 states have some failures, with higher Bi+Sn-containing materials having significantly higher failure rates. According to Figure 5, the BI26-T3 composition did not fail in tearing or bursting, so Bi+Sn has a significant effect on performance.

Therefore, these results show that by producing the material in the T8 temper, higher levels of Bi+Sn can be used, also achieving excellent machinability from a chip size perspective. Example 3

10'' (254mm) diameter billets were cast and machined into 1'' (25.4mm) and 2'' (50.8mm) T3 and T8 bars using the method shown in Figure 1 and the compositions listed in Table 6 . The rods were evaluated for mechanical properties, machinability and work crack susceptibility using the same techniques described in Example 1. Table 6: Composition and state (weight percent) of Example 3

Mechanical properties are shown in Table 7. This indicates that all compositions and state combinations are able to achieve the lowest 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 chip size was evaluated using the results depicted in Figure 9 for 1.000'' (25.4 mm) diameter material. The results show that T8 outperforms the leaded 2011 material, while the T3 material still performs acceptable, but not as good as the leaded 2011 material. The test was repeated for a diameter of 2.000'' (50.8mm) to ensure the material worked well over a wider range of diameters. Although the 2.000" (50.8mm) diameter results in this test are slightly worse than the leaded 2011 existing material, it must be noted that it is slightly worse than any 1.00" (25.4mm) in terms of chips per gram of foundation ) diameter test results are good. It can therefore be concluded that the material performs well in these diameter ranges.

Process crack susceptibility testing was also performed on the 1.000" (25.4 mm) diameter material, considering wrinkling, tearing and popping (as per Figure 5) as failures. The results of this test are shown in Table 8. Table 8: Summary of results of 1.000" (25.4 mm) diameter machining crack susceptibility testing in Example 3

These results confirm that for applications with demanding material removal rates and thin-walled part geometries prone to tearing, processing the material in the T8 temper and keeping the Bi/Sn ratio less than 1.32 virtually eliminates this failure mechanism.

Although the present invention has been disclosed in terms of preferred embodiments, it should be understood that many additional modifications and changes can 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 the following detailed description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings, wherein:

1 is a schematic diagram illustrating the sequence of operations for producing a substantially lead-free aluminum alloy composition in accordance with various examples of the present invention;

2 is a conceptual diagram of a representative component for evaluating machinability in terms of 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 combinations evaluated in Example 1, measured in chips/gram;

FIG. 4 is a conceptual diagram of a machined crack susceptibility test component;

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

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

Figure 7 is a graph showing the machinability results of Example 2 measured in chips/gram;

Figure 8 is a graph showing the results of the machining crack susceptibility test of Example 2, expressed in %, without wrinkling, tearing or popping;

Figure 9 is a graph showing the machinability results of Example 3 measured in chips/gram;

Figure 10 is a graph showing the machinability results of Example 3, measured in chips/gram for a 2.000" diameter rod; and

Figure 11 is a Bi-Sn phase diagram.

Claims (20)

A substantially lead-free aluminum alloy product comprising an aluminum alloy composition comprising the following components (in 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 The substantially lead-free aluminum alloy product is provided in the T8 temper and the substantially lead-free aluminum alloy product has ultimate tensile strength

45.0KSI/311MPa, yield strength

38.0KSI/262MPa and minimum elongation

10%, and the substantially lead-free aluminum alloy product can withstand 0.015" (0.38mm) thick machined walls using a 0.969" (24.6mm) diameter twist drill at 1500RPM and 0.035" (1.27mm)/rotary feed <10% wall tear or crack failure at rate. The product of claim 1, wherein the aluminum alloy composition has <0.05 wt% Pb. The product of claim 1, wherein the aluminum alloy composition comprises 0.10-0.16 wt% Si. The product of claim 1, wherein the aluminum alloy composition comprises 0.30-0.50 wt% Fe. The product of claim 1, wherein the aluminum alloy composition comprises 5.1-5.8 wt % Cu. The product of claim 1, wherein the aluminum alloy composition comprises 0.002-0.05 wt% Zn. The product of claim 1, wherein the aluminum alloy composition comprises 0.20-0.40 wt % Bi. The product of claim 1, wherein the aluminum alloy composition comprises 0.20-0.40 wt% Sn. The product of claim 1, wherein the aluminum alloy composition comprises the following components (in 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 product of claim 1, wherein the aluminum alloy composition has a Bi/Sn weight ratio in the range of 1.32/1 to 0.8/1. The product of claim 1, wherein the incidental impurities are present in a total amount of less than 0.5% by weight. A substantially lead-free aluminum alloy product comprising an aluminum alloy composition comprising the following components (in 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 aluminum alloy composition has a Bi/Sn weight ratio of less than 1.32/1; The substantially lead-free aluminum alloy product is provided in the T6 temper; the substantially lead-free aluminum alloy product has ultimate tensile strength

45.0KSI/311MPa, yield strength

38.0KSI/262MPa and elongation

10%, and the substantially lead-free aluminum alloy product has superior machinability as measured by chip size (crumb size) when compared to a product with the same aluminum alloy composition in the T8 temper. Chips/gram), where a larger amount of chips/gram is considered an excellent measure of machinability. The product of claim 12, wherein the machinability is excellent when compared to a product having the same aluminum alloy composition in the T3 temper. The product of claim 12, wherein the product when provided as a 1.000" diameter rod can withstand a 0.015" (0.38mm) thick machined wall using a 0.969" (24.6mm) diameter twist drill at 1500RPM and Failure with <10% wall tear or crack at 0.035" (1.27mm)/rotary feed rate. A substantially lead-free aluminum alloy composition, the aluminum alloy composition is composed of the following components (in weight percent of the aluminum alloy composition): 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; wherein Si, Fe, Cu, Zn, Bi and Sn are the only components intended to be added to the alloy composition, so any other materials are only present as incidental impurities, And except for incidental impurities, the remainder is aluminum; the aluminum alloy composition has a Bi/Sn weight ratio of less than 1.32/1; the aluminum alloy composition is only manufactured in the T8 or T6 temper to provide the alloy composition, so The alloy composition has ultimate tensile strength

45.0KSI/311MPa, yield strength

38.0KSI/262MPa and elongation

10%. The composition of claim 15, wherein the incidental impurities are present in a total amount of less than 0.5% by weight. The composition of claim 15, wherein the incidental impurities are present in a total amount of less than 0.1% by weight. The product of claim 1, wherein the incidental impurities are present in a total amount of less than 0.1% by weight. The product of claim 1, wherein the aluminum alloy composition comprises the following components (in percent (weight/weight) of the aluminum alloy composition): Si 0.1-0.16; Fe 0-0.50; Cu 5.1-5.8 ; Zn 0-0.05; Bi 0.20-0.40; Sn 0.20-0.50. The product of claim 1 wherein the product when provided as a 1.000" diameter rod can withstand a 0.015" (0.38mm) thick machined wall using a 0.969" (24.6mm) diameter twist drill at 1500RPM and Failure with <10% wall tear or crack at 0.035" (1.27mm)/rotary feed rate.

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