6061-T8 temper

[vibman]

Would anyone know the mechanical (tensile yield) and electrical property (electrical resistance) differences between the following aluminum alloys:
6061-T8
6061-T851

I believe the last two numbers (51) designates the type of stress-relieving, but would that affect the properties as compared to a T8 temper. Can a plain T8 temper be obtained? I've been discussing with a vendor that forges aluminum rings, but he didn't have much information about it.

We've been using T6 temper, but the electrical resistance was too high, and from what I've found online, the T8 has lower resistivity with similar mechanical properties.

Thanks.

 

[3DDave]

matweb shows little difference in conductivity. If you need around a 10% improvement then good.

 

[vibman]

Yes, 10% is a big difference for us.
So are there any property differences between T8 and T851?

 

[3DDave]

You can use matweb as well as I can.

 

[vibman]

T851 isn't listed on MatWeb. This is why I'm inquiring on this forum.
If anyone has any reference books with properties of 6061-T851, that would be appreciated.

 

[MagBen]

T851 really is not a practice change per say, T-851 is a sub-set of the T8 Temper. In a strict sense the T851 temper is simply an extension of T8 where a stress relief operation is included to stabilize the material for ease of machining. Generally, that stress relief operation is a stretch that is 1-3 % beyond the yield point. This is a very subtle operation the effects are not easily observable other than ease of machining. Chemistry, grain structure, and mechanical strength are not altered. Thermal stress relief could decrease electrical resistance a bit, but i donot expect a stretch stress relief will make a noticeable chnage on resistance.

 

[vibman]

Thanks MagBen for clarifying! Not too much info out there about this temper for 6061.

 

[WKTaylor]

Whoa Tigers...

Alloy/temper '6061-T851' is nonsensical: the Temper '-T851' does-not/never-has, existed ... for alloy 6061... per the Aluminum Association, MMPDS or ASMH-3206.

Per MMPDS-17
The temper index for 6061 is as follows:
Section Temper
3.6.2.1 T4, T42, T451, T4510, and T4511
3.6.2.2 T6, T62, T651, T652, T6510, and T6511

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[vibman]

Probably why I couldn't find a lot of info! It's strange that MatWeb came up with the T8 alloy when I entered the specific properties in their search. Is this just an alloy that some vendor decided to propose but never produced? I guess I'll have to stick with T6 for now...

 

[3DDave]

They made a -T8 sample, tested it, submitted it to matweb. Maybe no one wanted it. Plenty of alloys like that. -T8 indicates cold-worked, but 6061 is an age hardening material, so why beat the snark out of it?

"Some data provided by Alcoa."

May have to contact the metallurgists at Alcoa to see if they have much to say. Usually engineers in these companies are pining for outside contact about their work.

 

[vibman]

Thank you for the suggestion. I've contacted a forging company that will look into it, but I'm not expecting too much at this point.

 

[3DDave]

Unless it is cold forging it's not applicable. The forging company wasn't the source of the information.

 

[WKTaylor]

Vibmman... Alloy, Temper, Form are critical baseline definitions of any metallic material.

6061 [example] is the aluminum Alloy... the temper of the alloy is designated by the -# following the alloy designation

The 'form' of the material is the wrought end product definition, IE: sheet, plate, extruded bar/rod/shape, rolled bar/rod/shape, die forging, forged block, etc.

I listed all applicable -# tempers... but be aware... not all tempers are applicable to all of the 'forms'.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[vibman]

Got it. Thanks for the explanation. It doesn't seem like this alloy of interest is not common. I've contacted Alcoa to see if they can guide me, but I don't think this is going to happen.

 

[Stick.]

Alcoa spun off what I think might be the relevant division a while back. So if Alcoa doesn't get you the info you need, you might try to contact either Howmet Aerospace or Arconic (I don't know which one is the correct one these days).

 

[vibman]

Thanks. I'll look into those two companies.

 

[WKTaylor]

DANG I stand corrected... obscure tempers for 6061 do exist... see bottom of this chart extracted from Aluminum Association YL-1-2018...

CURRENT ACTIVE TEMPERS...

INACTIVE TEMPERS...

DuhOooo, Now I feel really dumb... my head hurtz.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[vibman]

Hmm...Why is 6061-T8 listed under both active and inactive tempers? Was it deactivated in 1989 and then re-activated in 2017? I wonder if they make 1.9" thick wall tubing...

 

[vibman]

From Alfiniti's website: