Heat treatment of aluminium (T4, T5, T6, .... total confusion)


Anybody here who has some knowledge about heat treatment of aluminium, specifically AL6061? I would like to take advantage of an online service to machine a few parts out of Al6061. Unfortunately, the specification on the source material is quite sparse, and hence I would like to know what the common process is to achieve the T6 temper? So, do I have to heat treat the material afterwards or how does it usually work?


“This involves two steps—solution heat treating and aging. Solution heat treatment is done by raising the alloy temperature to about 980 degrees F and holding it there for about an hour. … This heat treatment is called aging, which results in material with a T6 temper.“

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You want to treat the material befor manufacturing your part[s] @GrecoMan is right on the process

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So, then I assume the company who provides the service uses the heat treated material already? But what temper is it, T4 or T6? Also, …

So we have a solid solution of magnesium, silicon, and other elements in aluminum at room temperature. This is called the T4 temper. If we take this material and heat treat it at a temperature between 325 and 400 degrees F, the alloying elements begin to form ordered arrays of atoms in the aluminum matrix. These arrays are called GP zones, and they strengthen the aluminum considerably. This heat treatment is called aging, which results in material with a T6 temper.

Three commonly used time/temperature cycles are used for aging—one hour at 400 degrees F; five hours at 350 degrees F; and eight hours at 325 degrees F. All are equally effective.

The question, however, is whether you can perform this yourself. There is no doubt that the result will be 6061-T6 properties if you do it properly. The main difficulty is that the component usually distorts quite a bit during quenching and requires significant mechanical straightening before aging.

(Source: https://www.thefabricator.com/article/aluminumwelding/achieving-t6-designation-for-6061)

Bit worried about the “usually distorts quite a bit” bit …

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You should buy a block of material that is already heat treaded and then machine your parts out of it. Or else you will get part distortion due to the high temps of the treatment process.

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For milling use T6. For example if you want to make a bike frame than you use T4 for bending and welding because it’s softer. Welding will bend the material so you’ll have to make mechanical correction to have all correct measurements. After that you put those into big owen and do heat treatment and maybe after that you will require slight correction again but much less than before. Same is with extruded profiles. They are all T4 after pressing them and goes for the treatment. Never heard about need of correcting them after that (not sure if it’s possible even). There’s also T66 which is better than T6 :slight_smile: What do you want to do and what process you want to use?

The thing is, I just can’t buy the material and then send it to 3D hubs to machine my parts.

Milling parts out of Al6061 through 3Dhubs:

because i’m a nosy fucker, what you makin?

Maybe my truck hangers. How do you do it?

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Just use T6 as stock material. I would suggest to use 6082 alloy which is not much more expensive but stronger than 6061. For hanger I would go with 7075 :wink:

Ok, I found this:

just something to keep in mind - the actual 3dhubs final prices are higher than the initial quote they give you

Hmm, they differ actually widely from quote to quote. Some day my quote is $200 cheaper for the exact same part compared to a few days earlier (might be a bug in the system). In general, my quotes are appox. $30-50 more expensive as I have some tolerances in the 2d drawing. Also, when I submit the actual *.ipt file rather than a STEP file, the online calculator gives me a more accurate offer.

My local anodizer doesn’t like 7075 since:

Got a reply from 3Dhubs, just in case somebody wants to know:

I assume 8082 = 6082 :slight_smile:

Yes probally 6082 :wink: So you have all you need. I just hope that price won’t kill you :wink:

If my customers demand it I order my stock materials with material certificate showing all needed info about the stock. I tested it once but never used the certificate… I would assume that this is possible everywhere. I’m just starting out in the cnc business and this far my customers have been satisfied with me signing off that I use (as an example) 6061. I guess bigger more important ones demand a certificate :slight_smile:

It will be expensive but I got only one board, so why not putting all the $$$$ into one :grinning:

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you should send me 1 to compare to my hangers :wink:

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