"Rawlplug has recently developed the R-HPTII-A4 throughbolt which is specially coated to avoid galling. Below Rawlplug explains how it developed the coating and how it overcame the galling issues.
Galling, a phenomenon where mating surfaces seize together is a common problem with stainless steel heavy duty anchors. The issue, although not always apparent, is inherent in stainless steel and other corrosion resistant alloys which produce a self-healing oxide layer. The mechanism of galling is adhesion between the contact surfaces on the atomic scale ( when under high pressure ) - a process occasionally referred to as cold pressure welding."
source: Fastener + Fixing, March 2011
