Originally Posted by
ATC Watcher
Super cold metal = another challenge is to unscrew fastened bolts torqued at or near standard temp I would say.
Sorry to be pedantic, because you have a good point.
It's just that you seem to have it around the wrong way; or so I think!
The difference in the coefficient of linear expansion for steel fasteners versus aluminium / magnesium alloy components probably means that removing bolts could actually be a little easier than at "normal" temperatures. Though there may be some "clamping" effect of aluminium alloy onto threaded fasteners.
However the inverse applies for tightening. And, at such low temperatures, you will also be entering the realm of ductile-brittle transition for some steel alloys. It is probably not so much of a problem for aluminium alloy under compression but fasteners under tension may well be affected, depending on the steel alloy used. Probably not a problem at all for any titanium alloys used.
Correct tightening values for fasteners at such low temperatures would (or should) certainly have been a consideration for this exercise.
I'm guessing that a re-torque later with everything at more normal temperatures would be on the cards.