Identify risky combinations of dissimilar metals and evaluate galvanic corrosion risk under different service conditions.
| Combination | Typical Concern | Wet / Marine Service | Common Control |
|---|---|---|---|
| Aluminum + Copper | Strong galvanic difference | High concern | Electrical isolation / coating |
| Aluminum + Stainless Steel | Aluminum can become anodic | Moderate to high | Isolation, sealant, coatings |
| Zinc + Copper | Zinc can corrode preferentially | High concern | Isolation / suitable plating |
| Carbon Steel + Copper | Steel can become anodic | Moderate to high | Isolation / moisture control |
| Carbon Steel + Stainless Steel | Steel may become anodic | Moderate concern | Isolation and coatings |
| Aluminum + Titanium | Large potential difference | Moderate to high | Isolation / protective barriers |
| Stainless Steel + Copper | Potential galvanic coupling | Moderate concern | Isolation where necessary |
What is galvanic corrosion? Galvanic corrosion occurs when dissimilar metals are electrically connected while exposed to an electrolyte. The more anodic metal generally corrodes preferentially.
Which metal combinations are most risky? Combinations with a substantial galvanic potential difference can be risky when continuously electrically connected in a conductive environment. Aluminum-copper, zinc-copper and aluminum-stainless combinations deserve particular attention in wet service.
Is aluminum and stainless steel a bad combination? It can be in wet or marine environments. Aluminum can become the anodic member of the couple and may experience accelerated corrosion near the contact area.
Can copper touch carbon steel? Direct contact can be problematic in conductive wet environments because carbon steel is generally more anodic than copper. Isolation is often appropriate.
Does seawater increase galvanic corrosion? Yes. Seawater is a conductive electrolyte and can support significant galvanic currents between dissimilar metals.
Why is a small anode with a large cathode dangerous? The galvanic current can become concentrated over the relatively small anodic surface, increasing the local corrosion rate.
Does galvanic corrosion happen without water? A sustained galvanic cell normally requires an electrolyte. Dry conditions greatly reduce the risk, but condensation or contamination can create localized electrolytes.
Does electrical isolation stop galvanic corrosion? Effective electrical isolation can interrupt the galvanic circuit and greatly reduce galvanic corrosion caused by direct metal-to-metal coupling.
Can coatings prevent galvanic corrosion? Yes, if the coating system remains intact and provides the required electrical and environmental separation. Damaged or partial coatings require careful consideration.
Does this tool calculate corrosion rate? No. It identifies compatibility risk. Actual corrosion rates require detailed electrochemical and environmental information for the exact materials and conditions.