Ductility of T-6 Aluminum

Yes, there's a lot of different alloys that can be tempered to T6 -- so
feel free to educate me.
Is it at all a sensible thing to think that I could get some 40 - 60 mil
aluminum sheet that's already tempered to somewhere between T3 and T6
(harder is better), and be able to put 45 degree bends in it? 60
degree? 90? Bend radius? Is this something that could be done on a
normal brake? Clearly springback would be an issue, but is it just a
pain, or a real @#$% pain?
Or did I accidentally smoke something this morning, and do I just have
to get some decent alloy in an annealed condition, bend it up, and
figure out how to bake it?
Reply to
Tim Wescott
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Can't help you with I.D.s but "the Kid" raced super modified for a couple years. The skin he used was AL, easy enough to bend on our hand brake, cut on our foot stomp shear and it had to be hardened. I could ask him the grade if this is what you're after.
Karl
Reply to
Karl Townsend
Where I'm coming from is more this:
I've brushed up against the need -- mine, or acquaintances -- to bend up aluminum landing gear for model airplanes. If you use the usual 3003 "nice and soft" aluminum for this it bends each and every time you land, if it doesn't do so the first time you set the plane on it.
But you can buy nice aluminum landing gear, some of which is advertised as being heat treated to T6 condition. It's nice stuff -- you really have to thump it to make it bend, and it's at least ductile enough that you can generally bend it back and go flying again after a hard landing.
So I'm wondering -- before I go pay money for something wrong -- if this is something that I can just get and use, or if I'd have to mess around with hardening.
To date I've always been able to make up my LG from wire -- but there are times when a nice sheet aluminum gear would work out better.
Reply to
Tim Wescott
Get 6061t6 or 6061t650 and cold bend it - minimum bending radius is 3X the thickness? Something like that. Actually I looked it up - 2X thickness is minimum radius 3x preferred. Or you can anneal it, bend it, and let it sit for about 6 months and it will be age-hardened back to something like a T3.
Reply to
clare
I don't know what the minimum recommended bend radius is with that material so would go with what Clare has mentioned in another post. My experience is with 2" wide by 3/8" thick 6082 (IIRC) T6 and I was bending it 90 degrees at about a 5" radius former to end up with a 6" radius. I had to bend it to about 120 - 130 degrees to end up with a 90 degree bend due to the spring back. I had a section of 2" x 2" x 16swg steel box section about 5' long clamped to it for mechanical advantage. I would say your landing gear shouldn't be a problem to bend in T6 providing you use a sensible radius for the bends.
Reply to
David Billington
Usually 1/16"6061-T6 was the only material available when I fabricated electronics enclosures. It cracks somewhat if bent sharp so I padded the brake with another prebent strip.
0.050" material is considerably easier to work on a 3-in-1 combo machine.
The fuselage of a B-17 was made from 0.040" - 0.063" sheet. It should be good enough for a model.
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stringers are bulb angle instead of hat sections . I measured only worn exposed edges so not to scratch the paint.
jsw
Reply to
Jim Wilkins
T-6 is an aluminum designation for heat treated and age hardened. I may be mistaken but it may be possible to heat treat the part, bend it fairly quickly and then let it age harden. Certainly there were "ice box" rivets used on aircraft that were heat treated, kept on dry ice, until driven and which were T-6 after being the driving and age hardening process.
Cheers,
John D. Slocomb (jdslocombatgmail)
Reply to
J. D. Slocomb
Read up on the details of heat treating 6061 aluminum. If I remember correctly it is doable in the kitchen oven.
Cheers,
John D. Slocomb (jdslocombatgmail)
Reply to
J. D. Slocomb
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Bend it with the "grain" of the aluminum (from rolling, I think) parallel to the bend seam and it *will* crack unless you go to a rather large bend radius.
Bend it with the grain at 90 degrees to the bend seam and you can get away with less cracking for the same bend radius.
It seems to open up along the grain lines when it is being bent -- on the outside of the bend where the metal is being stretched.
Enjoy, DoN.
Reply to
DoN. Nichols
You can probably get by with 6061-T6, especially if you don't set the brake for a sharp bend. No way on earth with 2024, it will snap almost like glass. With the 6061, you can heat it along the bend line with a torch until a soap streak turns brown, then immediately hold under running water. This will anneal it so it can be easily bent, even 1/8" thickness. It will re-harden over time. (Heat treat can be hurried with an oven, of course.)
Jon
Reply to
Jon Elson
I've never heard of the running water part before.
What I did was mark the bend area with a marks-a-lot and burn it off with a PROPANE torch. OA will burn it off - along with the metal - if you are not really really careful.
Reply to
CaveLamb
I don't know very much about metal - are you talking about the wheel struts themselves made out of sheet, and not just "pants" with piano wire struts/axles?
When I envision something like this, something in my mind screams "spring steel!" but that's just something that popped up, and I don't really know the configuration of your LG, so what do I know?
Thanks, Rich
Reply to
Rich Grise
I've also had real issues with spring-back on 6061-T6, or why I stopped using it
Reply to
Ralph E Lindberg
Yes. It's done all the time.
With enough width, you can think "spring aluminum!"
Reply to
Tim Wescott
A friend has made quite a few lanring gears for Zenith 701 aircraft - cold-bending 6061T6 in a 40 ton hydraulic press. 3/4 inch iirc.
Reply to
clare
A propane torch is hot enough for most applications. The cold water does a better quench to soften the aluminum. You can bend 2024 is your are careful and don't try for a square corner. two backup strips of the same gauge will usually keep it from cracking especially if you anneal it. When I was doing STC's for autopilot servo installations I would order the metal in the annealed condition T0 and then after it was bent it would be sent to an approved heat treat company but that would probably be too expensive for your application.
John
Reply to
John
You may be right about the propane - if the part is more than .125 thick or too large to pick up...
My experience was hammer forming fairing strips around windshields and tail feathers.
Propane is plenty hot enough for small parts.
Reply to
CaveLamb

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