Josh Krohn, Engineering Services Manager, Triangle Fastener Corp.
Since a completely corrosion free fastener does not exist, select a fastener that is as durable as the members it is fastening.
Corrosion can be placed into two categories, general corrosion and galvanic corrosion. General corrosion is caused by air and moisture. We know that it is accelerated by salt and harsh chemicals. The second category is galvanic corrosion. There is a little more chemistry involved with galvanic corrosion and it can be a little confusing. Putting two incompatible metals together, even if they are both corrosion resistant on their own, can lead to galvanic corrosion.
First, work on mitigating general corrosion. Think about where the fastener will live. The environment in which a fastener is exposed affects the rate of corrosion immensely. Corrosion is accelerated in coastal regions or highly industrial areas. The vast majority of fasteners are steel and have a protective finish applied. Different finishes have different levels of corrosion protection and we cannot accurately predict when corrosion will develop. What we can do is compare different finishes and materials using the common ASTM B117 salt spray test. Test pieces are placed in a salt spray chamber and observed to see when the first sign of red rust or corrosion is visible. Read more.