aluminium grade question

[bullitt]

Gday..

Can someone teach me what are different between 6061 and 6061-T6 aluminium?
I need info,cause i want to make my custom rotor hat and engine pulley..Thanks.

Happy holiday and Merry Xmas.

-megat-
















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[gemtoy]

T6 has to do with the strength grades. I copied this off the net. Hope this helps.


The 6061 series of aluminum is alloyed with magnesium & silicon. However, these are only the majority of alloying elements as other elements are included such as copper, zinc, maganese and titanium. A total of 4% of alloying elements comprise the 6061 specification. The 6061 series is divided into grades or designations that refer to the post temper process. The most common grades are T0, T4, and T6. The grades, processes and strengths are depicted below:

Temper Process Tensile(PSI) Yield(PSI)
T0 fully annealed aluminum 18,000 8,000
T4 Solution heat treated and naturally aged 35,000 21,000
T6 Solution heat treated and artificially aged 45,000 40,000

[Dangerous Dave]

Just in case you don't know.
Solution heat treated does harden the aluminium, but it also causes more carbon content to be present in the aluminium. More carbon content means the aluminium becomes very brittle. This is why the aluminium is aged. Aging decreases the brittlement of the aluminium while the strength from the solution heat treatment is kept.
Hope that helps a bit

[bullitt]

I can't find 6061-T6 aluminium grade in my place...
It is posible to make rotor hat or pulley from 6061 aluminium without temper process T0,T4 or T6. Thanks..

[oldcorollas]

Just in case you don't know.
Solution heat treated does harden the aluminium, but it also causes more carbon content to be present in the aluminium. More carbon content means the aluminium becomes very brittle. This is why the aluminium is aged. Aging decreases the brittlement of the aluminium while the strength from the solution heat treatment is kept.
Hope that helps a bit

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

[takai]

Go for the T6 to start with, last year we had an SR20 in with a warped crank pulley because the owner had a mate make it out of non treated alloy. It was good that he noticed it soon after it warped because i daresay that if it had sheared (which the cracks indicated it might) then a chunk of alloy spitting around your engine bay at 8000rpm isnt very pretty.

[ed]

id even go 7075 T6 for the pulley if you can get it

[RobertoX]

Hi Guys,

We have had structural members machined straight out of 6061 T6, I believe that as long as you have the correct toolpiece (as your machine shop always should) then it's machinability is quite good.

Have a look:
http://www.tekcities.com/robert_ae86/rearend_lores.JPG


Does anybody know if there are any companies in Aus that spin (or forge) 6061 T6 rims?
Shipping from the US is a 'bee hutch'

[Dangerous Dave]

Stewart,
I just checked my phase diagrams, and you are correct. I got confused

[bullitt]

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

Great explanation Stewart..Are you a doctor??.....

[takai]

Yes he is, but not that kind of doctor

[oldcorollas]

Great explanation Stewart..Are you a doctor??.....

i have a PhD in Metallurgy

[gold28]

We use this alloy a bit in aircraft, although the 2000 and 7000 grades are much more common for us. This alloy is mainly used when welding is needed as most other alloys don´t weld too well.

6061 or 6061-T0 condition has no heat treating and is quite soft. This is great for machining and is welded easily but the strength is a lot lower.

The -T6, -T4, -T651 etc designates the heat treating process and each will give different strength and fatigue properties.

I would look at the T6 temper as it is stronger. Talk to your machinist and see if he is happy to machine the T6 or wether he would prefer to machine the anealed alloy then treat it.

Oh and personally I would avoid 7075-T6. It has a very high strength but suffers from corrosion and fatigue issues.

2024-T3 may also be a good option for you. Not as easily machined but a very good general purpose alloy.