Regarding the requirement of the strength and circumstance,there are several types of material can be used for the Fastener MaterialSelection.

Steel Fasteners (Grade 2,5,8) - the level of strength

Stainless Steel Fasteners (Martensitic Stainless Steel,Austenitic Stainless Steel)

Bronze and Brass Fasteners - Water proof usage

Nylon Fasteners - it is used for the light material and waterproof usage.

In general, Steel is the most commonly used material of allfasteners (90%) or more.