Material
The substance from which the screw is made.
Bi-Metal
This designation means that there are two distinct types of metal used in different parts of the fastener. Usually one type of metal is used for the head and shaft, while a harder metal is used at the point or drilling tip.
Stainless Steel
An iron based material with a minimum of 10.5% chromium. This material is known for its corrosion resistance and has varying strengths depending on the amount of chromium and nickel alloy. The chromium forms a protective layer when exposed to oxygen, keeping the steel underneath from corroding. There are over 150 grades of this material with the 304 and 316 series being the most common.
Steel
The most common material used in fasteners, this material is predominantly iron mixed with carbon. It offers the highest strength compared to other metals and elements, but is the least corrosion resistant. Also known as Carbon Steel.
