# Round number for heat treatment?

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#### Dan Thomas

##### Well-Known Member
No other plans seller prescribes heat treatment, as far as I know. They all use 6061-T6 or T4 as supplied and use fluting instead of heat treating.
That's mostly because homebuilders are trying to obtain an airplane economically. (Some do it for the art of it, the joy of creating.) Everything you farm out instead of doing it yourself raises the price of the airplane, and at some point you're better off just getting a second job---or working some overtime---to pay for buying an airplane. It's a lot surer way to get flying within a few years.

Even Cessna used fluted ribs. Heat treating costs money. The only time I ran into heat-treated -O parts was on transport-category airplanes, and it wasn't cheap. The shop had an oven but nobody certified to do the work. It's not that simple, and a mistake can be lethal.

#### PMD

##### Well-Known Member
When I built airboats all of the superstructure and harvesting equipment supporting structure was in 6061. We could only practically buy it in T6 condition and at one point brittle failures during forming became a problem so I built an oven and partially annealed and quenched prior to forming. ZERO failures after that and it would age back to quite liveable hardness. However, after asking around to our supplier, we realized we started having trouble when they switched from Alcan/Alcoa to a different source, so back to Alcan and no more brittle failures.

Moral of the story is that the state of heat treatment indeed is critical and not every supplier hits the mark (would hope much less of a problem with 2024). So, it is not an impossible task to undertake at home, just be very careful to hit the numbers and do some testing to verify (hardness being the obvious and easiest).

#### BBerson

##### Light Plane Philosopher
HBA Supporter
Everything you farm out instead of doing it yourself raises the price of the airplane
Right. And if you need one more replacement part heat treated it costs about the same all over again.

#### Fiberglassworker

##### Well-Known Member
Don't forget, after you get the parts back packed in dry ice, you have about 10 minutes to get any hand straightening done once you take it out of that box. I used to be a hand straightener.

#### wktaylor

##### Well-Known Member
FYI... only...

MIL-H-6088 Heat Treatment of Aluminum Alloys

NOTES1.
A. This spec was used for decades. https://quicksearch.dla.mil/qsSearch.aspx search 'document' => mil-h-6088
B. MIL-H-6088 was S/S by SAE-AMS-H-6088 and [now] the current Al-alloy HT spec(s) are...
AMS2770 [wrought materials made into parts]
AMS2771 [castings]
AMS2772 [OEM, wrought stock, sheet/plate/extrusions/impacts/forgings, etc

NOTE2.
2024-x sheet metal comes in [2] flavors: bare and clad aluminum. Bare aluminum, can usually be re-heat treated several times. HOWEVER...
clad sheet aluminum [0.032 and thinner] should only undergo ONE [1] solution-HT, quench, forming ['W' temper], Age harden to -T42 [96-hrs. at room temp]. More than [1] solution HT [@+850F] will initiate cladding migration into the base metal and cause significant strength/toughness reductions.

Aviacs -

PMD

#### pfarber

##### Well-Known Member
Feasibility is determined from understanding the process.
See page 11 of: Light Airplane Construction for Amateur Builders, L.Pazmany.
If you cant afford it, then nothing else matters.

The original e/ab pioneers were mostly all engineers. Now a days not so much.

The best idea in the world means nothing without

#### BBerson

##### Light Plane Philosopher
HBA Supporter
If you cant afford it, then nothing else matters.
If they won't take your small job, then nothing else matters.
You can build an oven yourself. I have.

#### Angusnofangus

##### Well-Known Member
You can build an oven yourself. I have.
If you are solution heat treating 2024 you need 919F and for annealing 2024-T3 you need 775F, as per Aluminum 2024-T3. A little outside of the range of your standard oven. You would need a proper kiln, plus precise controls. And then be able to check the hardness in order to ensure that everything was up to snuff.

#### Deuelly

##### Well-Known Member
Log Member
Heat treatment of 2024-O is pretty easy if you have the right equipment. I do hundreds of aircraft parts a year and hardly ever have problems with warpage or twisting. The correct quench fluid and quench process is key.
That being said, doing it for a homebuilt is a waste of time and not cost effective. A better idea is to find a shop with a rubber press. Make all your tooling with a seven degree under cut. Then, when the parts get pressed in 2024-T the sides will come out straight. Still costly but cheaper than the heat treat process.

Brandon

#### Angusnofangus

##### Well-Known Member
Heat treatment of 2024-O is pretty easy if you have the right equipment. I do hundreds of aircraft parts a year and hardly ever have problems with warpage or twisting. The correct quench fluid and quench process is key.
That being said, doing it for a homebuilt is a waste of time and not cost effective. A better idea is to find a shop with a rubber press. Make all your tooling with a seven degree under cut. Then, when the parts get pressed in 2024-T the sides will come out straight. Still costly but cheaper than the heat treat process.

Brandon
I agree with what you have said here, but here is the rub; making parts out of 2024-T3 requires a larger bend radius than parts made from O, depending on the material thickness, which may or may not be a deal breaker depending on where the piece fits into the puzzle.

#### BBerson

##### Light Plane Philosopher
HBA Supporter
If you are solution heat treating 2024 you need 919F and for annealing 2024-T3 you need 775F, as per Aluminum 2024-T3. A little outside of the range of your standard oven. You would need a proper kiln, plus precise controls. And then be able to check the hardness in order to ensure that everything was up to snuff.
A standard oven can be insulated with high temp insulation and exceed 1000F °.
This controller is around plus or minus 1 percent, I think. I bought one, seemed good.

#### Deuelly

##### Well-Known Member
Log Member
I agree with what you have said here, but here is the rub; making parts out of 2024-T3 requires a larger bend radius than parts made from O, depending on the material thickness, which may or may not be a deal breaker depending on where the piece fits into the puzzle.
I understand what you're saying but most plans built planes are designed around a "T" condition bend radius. And with the typical aluminum thicknesses used in homebuilt, the minimum bend radius is pretty small. A 5/8" flange is all you would need in most cases.

Brandon

#### 12notes

##### Well-Known Member
Log Member
Before I call up the company's I have found I wanted to get a general idea of what the cost of heat treating a -O aluminum alloy to the -T3 state.

Anyone have any small projects done (ie wing ribs)? I know I can form the 2024-T3 around a form, but I think It will be much easier if I did all the forming to -O 2024 the get the lot heat treated... unless the cost is just unrealistic.

Anyone do it and have a recent price/quote?
As someone who wasted a lot of time building a rubber press to only be disappointed with the results, then finding out I could bend nearly all the 2024-T3 ribs for my build by hand in less than 2 hours, I think you may be overestimating the difficulty of bending and the importance of the smaller radius bends on the flanges. I used a 1/4" roundover bit on my forms, which would be an acceptable radius for up to .063" 2024-T3, even though my ribs were mostly .020" thick.

I would recommend trying bending one with a hammer over a form first, and seeing how it stacks up in regard to time and results before going down the longer path.

Last edited:

#### karmarepair

##### Well-Known Member
HBA Supporter
I just sent a query to a local heat treater asking about costs, in an attempt to answer the OP's actual question.

#### BJC

##### Well-Known Member
HBA Supporter
Before I call up the company's I have found ...
I just sent a query to a local heat treater asking about costs, in an attempt to answer the OP's actual question.
I’m sure that he appreciates your making the contact.

BJC

#### Dan Thomas

##### Well-Known Member
As someone who wasted a lot of time building a rubber press to only be disappointed with the results, then finding out I could bend nearly all the 2024-T3 ribs for my build by hand in less than 2 hours, I think you may be overestimating the difficulty of bending and the importance of the smaller radius bends on the flanges. I used a 1/4" roundover bit on my forms, which would be an acceptable radius for up to .063" 2024-T3, even though my ribs were mostly .020" thick.

I would recommend trying bending one with a hammer over a form first, and seeing how it stacks up in regard to time and results before going down the longer path.
Yup. Sometimes overthinking something ends up in a lot of additional time and cost for no good reason. And it's easy to overthink a process you've never tried before.

HBA Supporter

#### Deuelly

##### Well-Known Member
Log Member
I just sent a query to a local heat treater asking about costs, in an attempt to answer the OP's actual question.
The OP already said in the first post he had some places to get quotes from. Why he just didn't do that instead of asking a forum is beyond me. What he did get and maybe should have asked in the first place are some of the gotchas you need to look for when getting stuff heat treated.
I'm sure he'll appreciate your quote, which he stated he can already get. I think he'll appreciate more the other information he received that cover the hidden costs and work.

Brandon

#### karmarepair

##### Well-Known Member
HBA Supporter
As Deully pointed out, perhaps the OP could have gotten this himself, but here's a dialogue I had with a local heat treating house, because I was interested in the answer:
 Are there any "rules of thumb" for the cost of solution treating formed .032" thick parts from 2024-0 to 2024-T3? For the purposes of this exercise, assume parts are roughly 12 inches by 40 inches, and there are at least 30 of them in a batch. Is there a set up charge, a minimum job charge, etc? I'm trying to evaluate using this material vice cold forming 6061-T6 to the same net shape, without having you chew up your overhead giving me a quote for a speculative exercise.
I”m not sure how we can go from 2024 T-O to 2024 T-3. AMS 2770 only references going from T-O to “as quenched” and then to T-4 or T-42.