For you metallurgists-ti galling

[oldpotatoe]

Ok, here's the problem.

Legend Ti frame, Record RD with ti fixing bolt. Regular customer, I have taken his RD off and put back on many times...no problem.

He travels with bike, takes RD off..this time when putting it back on..LOTS of resistance(it's not cross threaded, lathered with antisieze)..and when he tried to take it back off..no-can-do.

Brings it to me and to take it off, the typical mucho noise, WACK, Wack, big noise as it comes of in spurts, complete with sparks..obviously galled in there. So I DO finally get it off, swap the ti bolt with another one..re lather with antisieze..put it back on, not a lot of resistance but some..same issue getting it off again...

What is going on? Undoubtedly it's ti to ti galling but why? And what to do?

I'm stumped, never seen this before.