"Keith Willshaw" wrote in message
...

"The Enlightenment" wrote in message
om...


All hypersonic aircraft, like the SR71 irrespective of material
don't
have fatique problems becuase the heat effectively heat treates
(aneals) any work hardening metal. Titanium, inconel, austenitic
steels all are the same.



Complete and utter cobblers

A statement that is complete hyperbole.



The normal stress relief temperature for titanium is around 1000 F
and the annealing temperature is closer to 1300 F

source:
Titanium Metals Corporation
Titanium Design and Fabrication Handbook for Industrial Applications

Keith



This web site recommends a 2 hour holding temperature as low as 500C
for stress relief heat treatment.
http://www.deutschetitan.de/eng/profi/kb6.html

The SR71 achieves a temperature of between 300C and 450C in localised
areas that Janes listed in 1974 while many web sites speak of 1100F as
the Blackbirds skin temperature. This is well withing the heat
treatment range though short of the full annealing I claimed.

The article I read regarding this effect seemed quite plausible and of
positive benefit.