Yep, known as Galling.max corrigan said:....
loosening or tightning a nut and bolt would for no apparent reason (that i could see) seize up solid, and would need to be cut of with and angle grinder! (no joke when you up a ladder)
Good advice Ken!Ken I said:The work hardening property is a SOB.
It's a case of he who hesitates is lost.
A moments hesitation leads to rubbing - game over.
As Entropy 45 pointed out, heavy cuts work best.
Feed aggressively (that doesn't mean go at it like a bull in a china shop) similarly terminate cuts rapidly - particularly when peck drilling deep holes - back away rapidly at the end of each "peck" resume "at feed" rate - don't "search" for the material.
Carbides are fine if you have the horsepower - and you use appropriate grades - galling buildup on the tool can be a big problem with some tips / stainless grades.
Otherwise use sharp heavilly raked HSS (hook rake) and HP lubricants (the dark smelly stuff Machine Tom suggests).
When screw cutting use the half thread angle approach so as you are only cutting on one flank - plunge cutting on stainless is just looking for trouble.