|
A Basic Guide to the Corrosion Resistance of Common Fastener Alloys*
|
Grade
|
Corrosion
Resistance
|
|
Carbon and alloy steels
|
Rust in moist air but coating or plating can be used for
protection.
|
|
Stainless steels
|
Good resistance in mild environments without coatings.
Pitting is a problem when chlorides are present.
|
|
Specialty alloys
|
Excellent resistance to specific environments.
|
Recommended Fastener Alloys for Joining Metal in Mild Environments*
|
Metals Joined
|
Recommended
Fastener Alloys
|
|
Steel to steel
|
Carbon & alloy steels
Stainless steels
A286
Alloy 718
|
|
Steel to stainless
|
Carbon & alloy steels (coated)
Stainless steels
A286
Alloy 718
|
|
Stainless to stainless
|
Stainless steels (300 series)
A286
Alloy 718
Specialty alloys
Titanium
|
|
Steel to aluminum
|
Carbon & alloy steels
Stainless steels (300 series)
A286
Alloy 718
Titanium
|
|
Aluminum to aluminum
|
Aluminum
Stainless steels (300 series)
A286
Alloy 718
Titanium
|
*Note: Corrosion is basically an electro-chemical reaction between the fastener metal and its environment.
An example of this is unprotected steel becoming rusty. The iron in the steel combines
with available oxygen to form iron oxide. Moisture acts as an electrolyte that will
influence the rate of this reaction.
The rate or speed of the corroding process can be accelerated by increased temperature, increased quantities of the electrolyte and contact with other metals.
Therefore, when selecting a metal for fastener use, its total environment, including the materials the fastener will be holding together, must be considered.
Sources of Information - IFI Fastener Standards, 6th Edition and Corrosion Engineering by Mars G. Fontana, McGraw-Hill Book Company, Copyright 1986.
|