Gunsmithing  Question about 6061 aluminum

gunnergirl81

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What is the difference between T6 and T651? Which would provide greater strength when used as a barrel tensioning sleeve on a rimfire?
 

turbo54

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Re: Question about 6061 aluminum

They are both a T6-spec temper, while T651 refers to a method to achieve the condition.

It will make no difference whatsoever for you. If you wanted a stronger alloy, look at 7075 T6.

Oh, and check out Matweb.com for all your material property questions!
 

JJones75

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Re: Question about 6061 aluminum

T651 is said to have less residual stress from the tempering process , it's prestressed during tempering and is supposedly less stressed and moves less when machining .

I've never seen a difference

Personally I would not use 6061 for a tensioning sleeve as it's very soft and pretty week and will compress over time 7075 T6 (or T651) is a much better choice. And if it's for your personal weapon pay extra and get 7068 , it's WAY harder and stronger than 6061 probably 4-5 times
 

JJones75

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Re: Question about 6061 aluminum

Turbo54 beat me to it
Here is an idea

6061 T6 , yield=35,000psi , Hardness=95 Brinell
7075 T6 , yield=68,000psi , Hardness=150 Brinell
7068 T6 , Yield=97,000psi , Hardness=190 Brinell
 

turbo54

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Re: Question about 6061 aluminum

7075 is some tough stuff. Machines noticeably different than 6061. 7068 is a new one on me and I'm a metal/materials junkie. I'll have to look into it.

Learn something every day!
 

JJones75

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Re: Question about 6061 aluminum

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">7075 is some tough stuff. Machines noticeably different than 6061. 7068 is a new one on me and I'm a metal/materials junkie. I'll have to look into it.

Learn something every day! </div></div>

I work for a NASA contractor as a machinist and get to play with some pretty cool stuff like the 2024 lithium/aluminum alloy they made the fuel tanks for the shuttle with , we used some 7068 and alot of 7075 thats where I was introduced to 7068. So I started shopping around and found that McMaster Carr has is , but if you shop around you can find it cheaper.
They never used and round stock at work so I couldent scavange their scraps :-( but it's great stuff , I recently made a form-1 suppressor for my 22 out if it
 

gunnergirl81

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Re: Question about 6061 aluminum

Pricey stuff.

Any other metals that would be suitable? Stainless steel? I'd like to not get more into the sleeve that the rest of the rifle.
 

JJones75

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Re: Question about 6061 aluminum

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kenda</div><div class="ubbcode-body">Pricey stuff.
Any other metals that would be suitable? Stainless steel? I'd like to not get more into the sleeve that the rest of the rifle. </div></div>

I think stainless with .050-.075" wall would be good not real heavy.

When I get home this weekend let me look , I may have some 1" OD .065" wall 321 Stainless steel in the shed. What size were you looking to use ?

I was going to do an intrigule suppressor with it (and i had had got a bunch extra to play with making hydrogen generator for my truck)
 

gunnergirl81

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Re: Question about 6061 aluminum

Looking for 1" O.D., 0.125" wall, 20-26" length. Not concerned about weight at all.

What about 304 SS?

Either way we're looking at a 2 hole end cap (like a can) that we can torque to whatever spec, so we can check to see if its losing tension.

I'd even be open to regular steel.
 

gunnergirl81

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Re: Question about 6061 aluminum

Hey, I didn't think about that. Would it make a difference on using the heavy wall thickness? Since I'm looking at using the 1/8" wall will that put 6061 T6 back in the running?
 

JJones75

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Re: Question about 6061 aluminum

.125" wall 6061 will have more tension loss to compression overtime and heating and cooling than pretty much ANY steel with .062" wall .

If weight is no concern I'd just use whatever you can find.

You could use .125" wall steel tube that would give you an ID of .750" turn the barrel down to say .725" to allow for a little air circulation.
 

JJones75

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Re: Question about 6061 aluminum

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kenda</div><div class="ubbcode-body">So 304 stainless in the dimensions quoted would suffice? </div></div>

Absolutely , any steel with 1/8 wall wil be very very stiff