A Lock washer exerts a spring force between the fastener's head and the substrate, which maintains the washer hard against the substrate and the bolt thread hard against the nut or substrate thread, creating more friction and resistance to rotation.
Stainless Steel - With the addition of 12% chromium to iron, stainless steel is formed. The chromium protects the iron against most corrosion or red-colored rust; thus the term "stainless" steel. The ability of stainless to form a thin layer of protection on its outside surface, called a "passive film" is its most important characteristic in preventing corrosion.
"18-8" - 300 series stainless steel having approximately 18% chromium and 8% nickel. The term "18-8" is used interchangeably to characterize fasteners made of 302,303,304,305 and other variables of these grades with close chemical compositions. There is little overall difference in corrosion resistance between the 18-8 types. 18-8 has superior corrosion resistance in comparison to 400 series stainless, and is generally non-magnetic
