316 Stainless Steel:
(16%-18% Chrome, 10%-14% Nickel, .08% Maximum Carbon, 2.00% Maximum Molybdenum) - This grade of steel is used and recommended for applications in severe, harsh or marine environments. Its corrosion resistance is greater than 18-8 stainless, which is why we recommend using 316 stainless steel fasteners for salt-water application. It is important to remember that even the salt in the air near a body of salt-water can do damage to dry applications, so 316 is the material of choice. Common applications of 316 stainless fasteners include use on boats, docks, piers, and pools.
Stainless steel will not rust due to scratching due to the thin layer of chromium creating an invisible protective layer. This thin layer will rebuild itself in the presence of oxygen. Note: If you are not in an oxygen rich environment the material will take longer to rebuild or not rebuild at all. This will leave it open to possible corrosion. Stainless steel can be broken down into three different types: Austenitic, Martensitic and Ferritic.