HARDENABLE Al-Mg-Si-BASED ALUMINUM ALLOY

Abstract

A hardenable AlMgSi-based aluminum alloy is shown. In order to provide a recycling-friendly, storage-stable and particularly thermosetting aluminum alloy, it is proposed that this aluminum alloy should contain from 0.6 to 1% by weight of magnesium (Mg), from 0.2 to 0.7% by weight of silicon (Si), from 0.16 to 0.7% by weight of iron (Fe), from 0.05 to 0.4% by weight of copper (Cu), a maximum of 0.15% by weight of manganese (Mn), a maximum of 0.35% by weight of chromium (Cr), a maximum of 0.2% by weight of zirconium (Zr), a maximum of 0.25% by weight of zinc (Zn), a maximum of 0.15% by weight of titanium (Ti), 0.005 to 0.075% by weight of tin (Sn) and/or indium (In), and the remainder aluminum and production-related unavoidable impurities, wherein the ratio of the weight percentages of Si/Fe is less than 2.5 and the content of Si is determined according to the equation wt. % Si=A+[0.3*(wt. % Fe)], with the parameter A being in the range of 0.17 to 0.4% by weight.

Claims

1. A hardenable AlMgSi-based aluminum alloy, comprising: from 0.6 to 1% by weight of magnesium (Mg), from 0.2 to 0.7% by weight of silicon (Si), from 0.16 to 0.7% by weight of iron (Fe), from 0.05 to 0.4% by weight of copper (Cu), a maximum of 0.15% by weight of manganese (Mn), a maximum of 0.35% by weight of chromium (Cr), a maximum of 0.2% by weight of zirconium (Zr), a maximum of 0.25% by weight of zinc (Zn), a maximum of 0.15% by weight of titanium (Ti), 0.005 to 0.075% by weight of tin (Sn) and/or indium (In), and aluminum as a remainder as well as production-related unavoidable impurities, wherein a ratio of the weight percentages of Si/Fe is less than 2.5, and the content of Si is determined according to the equation
wt. % Si=A+[0.3*(wt. % Fe)], with the parameter A being in a range of 0.17 to 0.4% by weight.

2. Aluminum alloy according to claim 1, wherein the parameter A is in the range of 0.26 to 0.34% by weight.

3. Aluminum alloy according to claim 1, wherein the parameter A is 0.3% by weight.

4. Aluminum alloy according to claim 1, wherein the content of Si is determined according to the equation
wt. % Si=A+[0.3*(wt. % Fe)]?wt % Ti.

5. Aluminum alloy according to claim 1, wherein the ratio of the weight percentages of Si/Fe is less than 2.

6. Aluminum alloy according to claim 1, wherein the ratio of the weight percentages of Si/Mg is in the range of 0.3 to 0.9.

7. Aluminum alloy according to claim 1, wherein the aluminum alloy has at least 0.25% by weight of copper (Cu).

8. Aluminum alloy according to claim 1, wherein the aluminum alloy comprises tin (Sn) in a range of 0.005 to 0.05% by weight in solid solution in an aluminum mixed crystal.

9. Aluminum alloy according to claim 1, wherein the aluminum alloy belongs to the 6xxx series.

10. Aluminum alloy according to claim 1, wherein the aluminum alloy has a maximum of 0.05% by weight of chromium (Cr) and more than 0.05% by weight of zirconium (Zr).

11. Aluminum alloy according to claim 1, wherein the aluminum alloy has at least 0.02% by weight of chromium (Cr).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a graphical depiction of the Si and Fe content of alloys 1 and 2 listed in Table 1, in comparison to the Si/Fe content tuned according to the invention.

[0026] FIG. 2 is a graphical comparison of the storage stability of alloys 1 and 2 listed in Table 1.

[0027] FIG. 3 is a graphical comparison of the temperature-dependent age-hardening of alloys 1 and 2 listed in Table 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] To demonstrate the effects achieved, thin sheets of various AlMgSi-based aluminum alloys (6xxx series) were produced. The compositions of the alloys investigated are listed in Table 1.

TABLE-US-00001 TABLE 1 Overview of the investigated alloys in weight percent Alloys Sn Mg Si Cu Fe Mn Cr Zn Ti 1 0.04 0.8 0.64 0.22 0.47 0.11 0.16 0.05 0.05 2 0.04 0.78 0.43 0.36 0.46 0.11 0.14 0.05 0.06

[0029] The aluminum alloy 1 of Table 1 essentially corresponds to a standard alloy AA6061 after addition of the trace element Sn, wherein it is conceivable to use indium or a combination of Sn and In instead of tin. Alloy 2 represents the composition according to the invention of the 6xxx series and is comparatively recycling-friendly due to the comparatively high Fe content.

[0030] The aluminum alloy 1 is well outside the Si/Fe content tuned according to the invention, which is shown by way of example in FIG. 1. The aluminum alloy 2 is placed substantially centrally in this tuned Si/Fe content.

[0031] Both aluminum alloys 1 and 2 were solution-annealed in solid solution, quenched, and cold-hardened by aging at room temperature, and then hot-hardened. Solution annealing was carried out at a temperature greater than 530 degrees Celsiusquenching at a quench rate greater than 20 degrees Celsius/second. Both alloys 1 and 2 were subjected to a storage time or cold age-hardening of 180 days [d] and 30-minute hot age-hardening at different temperatures. Brinell hardness [HBW] was determined during cold aging and after hot aging.

[0032] With regard to the storage stability, it can be seen from FIG. 2 that the alloy 1 undergoes a comparatively rapidly increasing cold hardening during storage at room temperature after only 14 dayswhich leads disadvantageously to a comparatively high and increasing Brinell hardness over a longer storage time and has a disadvantageous effect on forming before hot age-hardening.

[0033] In contrast, alloy 2 shows an onset of cold age-hardening only after approx. 180 days, whereby the alloy 2 according to the invention is considered to be particularly resistant to storage. Such a surprisingly high storage stability has not yet been observed with any 6xxx alloy. This leads to an unexpected, enormous gain in the manipulation time of the alloy after quenching in a soft state.

[0034] In the subsequent hot age-hardening, it can be seen in the comparison of the two alloys according to FIG. 3 that the alloy 2 initially lags behind the alloy 1 at lower aging temperatures in the Brinell hardness. At higher aging temperatures, the Brinell hardness of the alloy 1 can be significantly exceeded.