Aluminum alloy 7075 question

Hello all,
I have a piece of 7/8" round 7075 alloy. I've been searching the web
for information. It does appear to machine better than the 6061 I
usually use. And the web resources all say it's very strong. What
is/are the downside(s) of 7075, besides the higher cost?
I am thinking of using 7075 tubing as part of a pressure vessel, hence
the question.
Thanks -- Terry
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They don't weld the same.
Reply to
John R. Carroll
It is hard to get a good weld on 7075 but it machines beautifully. I think of it as the leadloy of aluminum.
Ed Huesers
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Ed Huesers
Corrosion resistance? Not recommended for a marine atmosphere without additional surface treatment.
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Take a look at "FORTAL" on Ebay this guy sells 7075 and has info about it on each auction.
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It has been a long, long time since I knew all the specifications, but it is the alloy that Hamilton-Standard used for the propeller blades on the C-130 and P-3. There was a time when I could have told you all the reasoning behind that decision. It is definitely from a strength and fatigue life viewpoint the good stuff. The materials guys would never let it near salt water without being anodized--we went many rounds on that on the prototype air cushion landing craft before the British won the production contract out from under us.
Reply to
J. Clarke
I sent this earlier, but as EA says, we're having some problems with our server. So I apologize if it winds up being posted twice:
Bad juju for pressure vessels. The T6 temper is strong in tension, but weak in the transverse direction when put under sustained stress. They make a special temper for that use, called T73. It's not easy to find.
Like 2024, ASM says "welding not recommended." I don't know about 7075, but 2024 is prone to cracking when it's welded. 7075 contains about half as much copper as 2024 (which is the killer for welding) but it's still 'way above the levels of the easily weldable alloys.
7075 is an aircraft alloy, primarily, for high-strength, corrosion-resistant applications. Like other high-strength aluminums, there are some fabrication problems. But it machines nicely, better than 6061. 'More like 2024 in that regard.
Reply to
Ed Huntress

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