actually dave....
solution heat treating is to do just that, dissolve the second and third phase particles back into the metal.. afaik, the carbon content of the alloy is fixed at the time of ingot casting.
more second phase particles makes aluminium more brittle usually, because they themselves are very brittle, and they decrease the ductility by providing fracture paths.
aluminium will naturally age. this is because the solution heat treating is at a temp higher than service temp, and so the system is not in equilibrium, and so the system naturally wants to precipitate second phase particles..
aluminium is actually softest in the as-solution-heat-treated condition. as seen from the metal specs listed above... less than half the strength of T6.. but a heck of a lot more ductility (UTS is more than double proof stress
with aging (ie second phase particle growth) strength INCREASES, whilst ductility and fracture toughness both decrease.. ie brittleness INCREASES..you can tell this fromt he specs below.. ie the seperation between yield point (where it starts to deform, 0.2 or 0.5% proof stress) and UTS (ultimate tensile strength)..
i would have given you neg rep for misleading information.. but it's christmas
Bullit, check that the bare 6061 is actually the annealed metal.. they supply this as it is easier to machine the annealed material, and then get it heat treated after, but this can cause warping esp for thin walled stuff with complex shapes..
i think it would be wise to consult the engineer that will pass it, and the machinist who will make it.... or at least, talk to some of the race kiddies or ppl who make custom race parts and ask what they use, and if they machine un-heat-treated material first or if they just go straight for the T6...
adn remember that it can be heat-treated after, so if you can't find T6, it's not the end of the world
Cya, Stewart
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