Ever wondered why that aluminum boat cleat with stainless steel screws corroded so quickly? Or why your copper plumbing disintegrated where it connected to steel pipes? The culprit is galvanic corrosion \u2013 nature’s own battery effect that can destroy metal components with surprising speed.<\/p>\n\n\n\n
When two different metals touch in a damp environment, whether it’s sea spray, humidity, or full immersion, they create a natural electrical circuit. One metal becomes the sacrificial anode, essentially dissolving itself to protect its neighbor. This isn’t random chance \u2013 it follows the predictable hierarchy known as the galvanic series.<\/p>\n\n\n\n
The anodic index (or galvanic potential) measures a metal’s tendency to corrode in the presence of another metal when coupled in an electrolyte. Metals with more negative values are more anodic (more likely to corrode) and serve as sacrificial anodes when connected to metals with more positive values.<\/p>\n\n\n\n
| Metal\/Alloy<\/th>\n | Anodic Index (V)<\/th>\n <\/tr>\n <\/thead>\n |
|---|---|
| Magnesium<\/td>\n | -1.75<\/td>\n <\/tr>\n |
| Magnesium alloys<\/td>\n | -1.60 to -1.63<\/td>\n <\/tr>\n |
| Zinc<\/td>\n | -1.10<\/td>\n <\/tr>\n |
| Aluminum 1100<\/td>\n | -0.96<\/td>\n <\/tr>\n |
| Cadmium<\/td>\n | -0.80<\/td>\n <\/tr>\n |
| Aluminum 2024<\/td>\n | -0.75<\/td>\n <\/tr>\n |
| Mild steel<\/td>\n | -0.70<\/td>\n <\/tr>\n |
| Cast iron<\/td>\n | -0.69<\/td>\n <\/tr>\n |
| SS 410 (Active)<\/td>\n | -0.65<\/td>\n <\/tr>\n |
| Low alloy steel<\/td>\n | -0.60<\/td>\n <\/tr>\n |
| SS 304 (Active)<\/td>\n | -0.58<\/td>\n <\/tr>\n |
| SS 316 (Active)<\/td>\n | -0.57<\/td>\n <\/tr>\n |
| Austenitic stainless steel (active)<\/td>\n | -0.56<\/td>\n <\/tr>\n |
| Lead<\/td>\n | -0.55<\/td>\n <\/tr>\n |
| SS 430<\/td>\n | -0.50<\/td>\n <\/tr>\n |
| Tin<\/td>\n | -0.49<\/td>\n <\/tr>\n |
| Nickel (active)<\/td>\n | -0.40<\/td>\n <\/tr>\n |
| Brass<\/td>\n | -0.40<\/td>\n <\/tr>\n |
| Copper<\/td>\n | -0.35<\/td>\n <\/tr>\n |
| Bronze<\/td>\n | -0.33<\/td>\n <\/tr>\n |
| Inconel (Passive)<\/td>\n | -0.22<\/td>\n <\/tr>\n |
| Nickel (passive)<\/td>\n | -0.20<\/td>\n <\/tr>\n |
| Monel<\/td>\n | -0.15<\/td>\n <\/tr>\n |
| Titanium<\/td>\n | -0.15<\/td>\n <\/tr>\n |
| Silver<\/td>\n | -0.15<\/td>\n <\/tr>\n |
| SS 304 (Passive)<\/td>\n | -0.08<\/td>\n <\/tr>\n |
| SS 316L (Passive)<\/td>\n | -0.05<\/td>\n <\/tr>\n |
| Austenitic stainless steel (passive)<\/td>\n | -0.05<\/td>\n <\/tr>\n |
| Gold<\/td>\n | +0.00<\/td>\n <\/tr>\n |
| Platinum<\/td>\n | +0.15<\/td>\n <\/tr>\n |
| Graphite<\/td>\n | +0.25<\/td>\n <\/tr>\n <\/tbody>\n<\/table>\n\n |