Hardening aluminum

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We were talking about welding up a structural frame out of aluminum today and my boss is worried about the anealing process and doesn't think we can get it hardened back up. I have seen a lot of talk about age hardening but we would need to use it in a couple days. Would it be possible to get a reasonable temper back into the aluminum in that time and how would we do it? We have an oven that would fit the frame that goes up to I think at least 450f if that helps.
Reply:What type of aluminum
Reply:I believe 6061Possibly 6063 but I don't think so.
Reply:450F?Nope.For 6061, try more like soaking at around 1000F, and then a water quench.  Then an artificial aging to T6 temper by heating and soaking at around 400F.And that is not so much "hardening" as heat-treating for strengthening, as in raising the yield strength of the aluminum alloy.  I personally don't consider 65 (T4) - 95 (T6) Brinell hardness all that hard.  Yes the heat treatment -does- harden the aluminum somewhat, but it is still just aluminum.  The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by MoonRise450F?Nope.For 6061, try more like soaking at around 1000F, and then a water quench.  Then an artificial aging to T6 temper by heating and soaking at around 400F.And that is not so much "hardening" as heat-treating for strengthening, as in raising the yield strength of the aluminum alloy.  I personally don't consider 65 (T4) - 95 (T6) Brinell hardness all that hard.  Yes the heat treatment -does- harden the aluminum somewhat, but it is still just aluminum.
Reply:From a Lincoln Electric info page on aluminum:There is one final alternative to discuss. If after welding, the structure is given a complete heat treatment (i.e., solution treat at 1000°F [540°C], quench, age at 400°F [205°C]), all of the material properties (even in the weld) will be recovered and T6 properties will be obtained. This practice is frequently followed on small structures such as bicycle frames, but it is impractical for larger structures. Furthermore, the quenching usually causes enough distortion of the structure that a straightening operation is necessary before aging. http://www.lincolnelectric.com/knowl...comistakes.aspRosebud?  Nope.  The solidus temp for 6061 is 1080F and the liquidus temp is 1206F (per Alcoa).  Do you think you can get a 2' part evenly to 1000F and hold it ALL there for the required time by waving a rosebud over it?  If you can, then  cause you're better than most people.Also note that since the aluminum starts to 'melt' at 1080F and the desired temperature for the oven (and the part) is 1000F, then there is not much difference between too cold and just right and too hot (and melted).Torch?  Nope.  A well controlled heat-treating oven is pretty much needed.  The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by MoonRiseFrom a Lincoln Electric info page on aluminum:There is one final alternative to discuss. If after welding, the structure is given a complete heat treatment (i.e., solution treat at 1000°F [540°C], quench, age at 400°F [205°C]), all of the material properties (even in the weld) will be recovered and T6 properties will be obtained. This practice is frequently followed on small structures such as bicycle frames, but it is impractical for larger structures. Furthermore, the quenching usually causes enough distortion of the structure that a straightening operation is necessary before aging. http://www.lincolnelectric.com/knowl...comistakes.aspRosebud?  Nope.  The solidus temp for 6061 is 1080F and the liquidus temp is 1206F (per Alcoa).  Do you think you can get a 2' part evenly to 1000F and hold it ALL there for the required time by waving a rosebud over it?  If you can, then  cause you're better than most people.Also note that since the aluminum starts to 'melt' at 1080F and the desired temperature for the oven (and the part) is 1000F, then there is not much difference between too cold and just right and too hot (and melted).Torch?  Nope.  A well controlled heat-treating oven is pretty much needed.