About Aluminum 6061-T6

[rbattelle]

I constantly hear people and companies spout off about using "6061-T6" aluminum parts, as though that particular alloy is some special grade.



So I thought I would post some information about Al-6061-T6.



According to Machinery's Handbook (26th ed. , page 549):

6000 Series: Alloys in this group contain silicon and magnesium in approximate proportions to form magnesium silicide, thus making them capable of being heat treated. The major alloys in this series are 6061, one of the most versatile of the heat-treatable alloys. Though less strong than most of the 2000 or 7000 alloys, the magnesium-silicon (or magnesium-silicide) alloys possess good formability and corrosion resistance, with medium strength. Alloys in this heat-treatable group may be formed in the -T4 temper (solution heat treated by not artificially aged) and then reach full -T6 properties by artificial aging.

The 4-digit designation system for aluminum alloys is decoded as follows:



The first digit indicates the alloy type:

1 - 99% or greater pure aluminum

2 - copper

3 - manganese

4 - silicon

5 - magnesium

6 - magnesium and silicon

7 - zinc

8 - some other element



If the second digit is 0 (as in 6061), it indicates there's no control on individual impurities. The last 2 digits have no significance other than identification.



Something like 6066-T6 is about 27% stronger in tensile stress and 13% better shear stress. 7049-T73 is 67% higher tensile stress and 30% better shear stress. Meanwhile 7178-T6 gives you 96% better tensile stress than 6061-T6 (and you get impurities control too!).



Now, to you manufacturers out there. If you really want to impress me with an aluminum alloy, how about using 7075-T6? 84% better tensilte stress and 60% better shear stress than 6061-T6.



General purpose 6061-T6 is a great alloy... but not that great.



-Ryan

 

[SGibson]

I agree, I always read about "cast from aerospace quality 356 alloy", 25+ yrs. in aerospace and I still haven't seen much in the way of castings. 7075t-6 is tough stuff, I'd like to see some parts made from 6AL-4V as long as I don't have to machine much on 'em.

 

[Hohn]

I think Lentz makes titanium connecting rods from 6al-4v

 

[lil red cummins]

excellent subject ryan.



6061 in T6, T651 or T6511 tempers is about 90% of what i/we machine at our company. the MAIN reason we use 6061 is for its excellent anodizing characteristics. we get just the color and satin finish we need with 6061. other grades such as 2024 and 7075 have an unacceptable finish for us.



and honestly 6061 is not the easiest to machine. it tends to be gummy and will clog cutters and taps with relative ease if the coolant is not right. it does lend itself to excellent "form" tapping rather than standard cut tapping method. this is a good thing in bottom tapped holes (which we do a lot of). no chips means full depth tapping in a single pass.



FYI



if you would like to see what keeps me busy check here



and this is where i work. the 2 sites are linked together since both companies have common ownership.



jim

 

[evldsl]

Check out what boeing builds their planes out of.

 

[Boomer II]

Alloy doesn't matter, you just have to call it "Billet"!!!!

 

[rbattelle]

Alloy doesn't matter, you just have to call it "Billet"!!!!

Funny you should mention billet. Check out this discussion over at Home Machinist.

[I complain about the 6061 part on page 2... my username there is "Grey Rider"]

Ryan

 

[Boomer II]

I'm glad to see I'm not the only one that "billet" drives crazy. We won't even get in to "tactical". I figger "Tactical billet" has to be the best stuff there is.

 

[rbattelle]

We won't even get in to "tactical".

Never heard anyone use that term other than references to military maneuvers. What's the use that drives you crazy?



Ryan

 

[Boomer II]

Never heard anyone use that term other than references to military maneuvers. What's the use that drives you crazy?



Ryan

Knives, guns, vests, flashlights, everything is "tactical", just like anything aluminum is "billet". I first noticed it with Harley stuff, then Jeep stuff and now all stuff is "billet".

 

[rbattelle]

Knives, guns, vests, flashlights, everything is "tactical", just like anything aluminum is "billet". I first noticed it with Harley stuff, then Jeep stuff and now all stuff is "billet".

Oh yeah, I have heard that. I thought you meant there was some use for the word "tactical" as regards metalworking.



It is pretty silly to market things as "tactical knife" or "tactical flashlight".



Are there "strategic knives" and flashlights?



Ryan

 

[CWebster]

Can't bend 6061 (significant bend) without heating either. I get a lot of customers that buy 6061 and bring it in to get formed only to balk at the difference in price (cause of the time to heat it up)..... cracks in the bend almost every time. 3003 is then what we go to... .

 

[sdstriper]

I used to work at an Alumax extrusion plant. IIRC they cast and extruded mostly 6061, 6062 and occasionally 6351. The 6351 was hard on everything, dies especially. Slow pushing on that alloy...