What Is Galling?
Definition: A condition whereby excessive friction between high spots results in localized welding with subsequent splitting and a further roughening of rubbing surfaces of one or both of two mating parts.
Galling takes place with nearly all metals, but is notable when using stainless steel. The solution is very simple, and is also very inexpensive. The use of anti-seize compound or thread locker compound virtually eliminates galling.
Both are available here at StainlessBits.com or at your local hardware store. You should probably use one or the other in nearly all fastener applications, stainless or otherwise.