Which of the following causes galvanic corrosion between frame members?

Which of the following causes galvanic corrosion between frame members?

• A. Dissimilar metals in direct contact
• B. Coating failure
• C. Humidity exposure
• D. Over-tightening bolts

Answer: (A)

Dissimilar metals in direct contact create a galvanic cell, and when an electrolyte like moisture or road salt is present on a frame, electrons flow from the more active metal to the less active metal. The anodic metal corrodes while the cathodic metal is spared. That electrochemical action is what drives galvanic corrosion between frame members, especially at joints where different metals meet and moisture can linger. Coating failures or humidity alone can promote corrosion, but the galvanic effect specifically requires two different metals in contact. Over-tightening bolts isn’t the cause of galvanic corrosion.

Dissimilar metals in direct contact create a galvanic cell, and when an electrolyte like moisture or road salt is present on a frame, electrons flow from the more active metal to the less active metal. The anodic metal corrodes while the cathodic metal is spared. That electrochemical action is what drives galvanic corrosion between frame members, especially at joints where different metals meet and moisture can linger. Coating failures or humidity alone can promote corrosion, but the galvanic effect specifically requires two different metals in contact. Over-tightening bolts isn’t the cause of galvanic corrosion.