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
Thanks -- Terry
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.
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