While there is no universally defined threshold for an acceptable difference in anodic index, a commonly referenced guideline suggests that a difference of 0.15 volts (V) or less is generally considered acceptable for minimizing galvanic corrosion. This guideline ensures that the potential difference between the two metals is small enough to minimize the galvanic coupling effect.
For Climate Controlled Indoor Environments:
A difference of up to 0.50V is considered generally acceptable.
For Indoor but non-climate-controlled environments, where humidity may be moderate:
A difference of up to 0.25V is considered generally acceptable.
Harsh Environments, like salt-water contact, very high heat, and humidity:
A difference of up to 0.15V is considered generally acceptable.
All applications and industries are unique. These guidelines are for “general” applications and should not be used as a technical guide in critical applications such as Aerospace flying parts. See Design Considerations for Galvanic Corrosion for further information and recommended mitigation practices.
Galvanic Corrosion Between Metal and Non-Metal Materials
Galvanic corrosion is not limited to metals. It can also occur between dissimilar materials, such as metal and non-metal combinations, like metal and carbon fiber composites. Similar considerations regarding material compatibility and electrical potential differences apply in these cases.