Two-material lookup
Check Galvanic Compatibility
Exact matrix lookup from MIL-STD-889D Tables I–III; no voltage-difference approximation.
Select the source table that matches the material surface conditions, then choose both materials. A class of 0 is compatible under the standard’s stated test criterion; classes 1–6 are incompatible under that criterion.
Scope matters
MIL-STD-889D states that these classifications come from static immersed testing in ASTM D1141 artificial seawater without heavy metals, using a 1:1 exposed anode-to-cathode area ratio for the tabulated corrosion rates. Do not treat a class as a universal atmospheric, freshwater, chemical, buried, concrete, or natural-seawater rating.
MIL-STD-889D Tables I–III
Galvanic Compatibility Reference Matrices
The number in each populated cell is the standard’s corrosion-rate class for the anodic member of that couple.
Use the checker above for a fast pair result. Use these matrices to audit the exact source relationship. An em dash is not a zero; in Tables I and II it means reverse the row-column orientation.
No row materials match this search.
Table I — Bare-material compatibility matrix
Scroll horizontally to view cathodic material columns and vertically to view anodic material rows. Numbered columns correspond to the numbered material rows.
| Anodic material | Cathodic material number | ||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mg EV31 | Mg WE43 | Mg AZ31B | Zinc | Zn-Ni Plated | Al5083 | Cadmium | Al6061 | CP Aluminum | A356 | 1020 Steel | Al7075 | A36 Steel | 1018 Steel | 1008 Steel | Al7050 | B7 Steel | MIL-11356 Steel | 4340 Steel | HY80 Steel | Tin | Al2024 | Ti-6Al-4V | Brass, Yellow | Bronze | NiAl, C630 | CuBe | CP Copper | PH 13-8 | 304SS | PH 15-5 | 304SS Passivated | 410SS | Inconel® 600 | A286 Passivated | PH 17-4 | 316SS | 316SS Passivated | Monel® 400 | 410SS Passivated | A286 | PH 17-4 Passivated | PH 13-8 Passivated | PH 15-5 Passivated | Silver | Graphite | Platinum | |
| 1. Mg EV31 | — | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 |
| 2. Mg WE43 | — | — | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 |
| 3. Mg AZ31B | — | — | — | 5 | 6 | 6 | 6 | 5 | 5 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 |
| 4. Zinc | — | — | — | — | 5 | 3 | 5 | 3 | 4 | 3 | 5 | 5 | 5 | 6 | 6 | 3 | 6 | 5 | 6 | 5 | 5 | 4 | 4 | 5 | 5 | 5 | 5 | 5 | 6 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 3 | 6 | 6 |
| 5. Zn-Ni Plated | — | — | — | — | — | 3 | 5 | 3 | 4 | 4 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | 5 | 5 | 5 | 4 | 4 | 4 | 5 | 5 | 5 | 5 | 5 | 6 | 4 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | 4 | 4 | 5 | 6 |
| 6. Al5083 | — | — | — | — | — | — | 3 | 2 | 2 | 2 | 3 | 4 | 5 | 5 | 5 | 2 | 4 | 3 | 4 | 3 | 2 | 3 | 2 | 4 | 4 | 4 | 4 | 4 | 5 | 3 | 5 | 4 | 4 | 3 | 3 | 4 | 5 | 4 | 3 | 4 | 4 | 3 | 4 | 3 | 3 | 5 | 5 |
| 7. Cadmium | — | — | — | — | — | — | — | 4 | 5 | 4 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | 5 | 5 | 5 | 5 | 6 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 6 | 5 |
| 8. Al6061 | — | — | — | — | — | — | — | — | 2 | 2 | 3 | 4 | 5 | 5 | 5 | 2 | 4 | 3 | 4 | 3 | 2 | 3 | 2 | 4 | 4 | 4 | 4 | 4 | 5 | 3 | 5 | 4 | 4 | 3 | 3 | 4 | 5 | 4 | 3 | 4 | 4 | 3 | 4 | 3 | 3 | 5 | 5 |
| 9. CP Aluminum | — | — | — | — | — | — | — | — | — | 2 | 3 | 4 | 5 | 5 | 5 | 2 | 4 | 3 | 4 | 3 | 2 | 3 | 2 | 4 | 4 | 4 | 4 | 4 | 5 | 3 | 5 | 4 | 4 | 3 | 3 | 4 | 5 | 4 | 3 | 4 | 4 | 3 | 4 | 3 | 3 | 5 | 5 |
| 10. A356 | — | — | — | — | — | — | — | — | — | — | 3 | 4 | 5 | 5 | 5 | 2 | 4 | 3 | 4 | 3 | 2 | 3 | 2 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 5 | 4 | 4 | 3 | 3 | 4 | 5 | 4 | 3 | 4 | 4 | 3 | 4 | 3 | 3 | 5 | 4 |
| 11. 1020 Steel | — | — | — | — | — | — | — | — | — | — | — | 4 | 5 | 5 | 5 | 3 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 4 | 5 | 3 | 4 | 4 | 4 | 3 | 3 | 4 | 4 | 4 | 3 | 4 | 4 | 3 | 4 | 3 | 3 | 5 | 4 |
| 12. Al7075 | — | — | — | — | — | — | — | — | — | — | — | — | 5 | 5 | 5 | 4 | 5 | 5 | 5 | 5 | 4 | 5 | 4 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 5 | 5 |
| 13. A36 Steel | — | — | — | — | — | — | — | — | — | — | — | — | — | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| 14. 1018 Steel | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 5 | 4 | 5 | 5 | 5 | 5 | 4 | 5 | 4 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| 15. 1008 Steel | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| 16. Al7050 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 4 | 3 | 4 | 3 | 2 | 3 | 2 | 4 | 4 | 4 | 4 | 4 | 5 | 3 | 5 | 4 | 4 | 3 | 3 | 5 | 5 | 4 | 3 | 4 | 4 | 3 | 4 | 3 | 3 | 5 | 5 |
| 17. B7 Steel | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 4 | 4 | 4 | 3 | 4 | 3 | 4 | 4 | 4 | 4 | 4 | 5 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 5 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 5 | 4 |
| 18. MIL-11356 Steel | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 4 | 3 | 3 | 3 | 3 | 4 | 4 | 3 | 3 | 4 | 4 | 3 | 4 | 4 | 4 | 3 | 3 | 4 | 4 | 4 | 3 | 3 | 4 | 3 | 3 | 3 | 3 | 5 | 4 |
| 19. 4340 Steel | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 4 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 4 | 3 | 5 | 4 |
| 20. HY80 Steel | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 4 | 3 | 5 | 4 |
| 21. Tin | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 1 | 4 | 4 | 4 | 4 | 4 | 2 | 3 | 3 | 3 | 3 | 2 | 2 | 3 | 3 | 3 | 2 | 3 | 3 | 3 | 3 | 2 | 3 | 5 | 5 |
| 22. Al2024 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 5 | 4 | 4 | 3 | 4 | 4 | 5 | 4 | 3 | 4 | 4 | 4 | 4 | 3 | 3 | 5 | 5 |
| 23. Ti-6Al-4V | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 2 | 3 | 2 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 |
| 24. Brass, Yellow | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 5 |
| 25. Bronze | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 |
| 26. NiAl, C630 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 4 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 5 |
| 27. CuBe | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 |
| 28. CP Copper | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 |
| 29. PH 13-8 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 |
| 30. 304SS | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 31. PH 15-5 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 |
| 32. 304SS Passivated | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 |
| 33. 410SS | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 34. Inconel® 600 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 |
| 35. A286 Passivated | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 36. PH 17-4 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 37. 316SS | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 38. 316SS Passivated | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 39. Monel® 400 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 |
| 40. 410SS Passivated | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 41. A286 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 0 | 1 |
| 42. PH 17-4 Passivated | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 0 | 1 |
| 43. PH 13-8 Passivated | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 | 1 |
| 44. PH 15-5 Passivated | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 0 | 0 | 0 |
| 45. Silver | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 3 |
| 46. Graphite | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 |
| 47. Platinum | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Table II — Treated-material compatibility matrix
| Anodic treated material | Cathodic treated material | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| a Mg WE43 T* | b Mg EV31 T* | c Mg AZ31B T* | d Al5083 Cr+6 | e Al6061 Cr+6 | f Al5083 Cr3+ | g Al7075 Cr6+ | h Al6061 Cr+3 | i Cadmium w CC | j Al7075 Cr+3 | k Zn-Ni w CC | l Al2024 Cr6+ | m Al2024 Cr3+ | n Electroless Ni | |
| a. Mg WE43 T* | — | 5 | 5 | 5 | 5 | 6 | 5 | 5 | 5 | 5 | 6 | 5 | 5 | 6 |
| b. Mg EV31 T* | — | — | 4 | 5 | 5 | 6 | 5 | 5 | 5 | 5 | 6 | 5 | 5 | 6 |
| c. Mg AZ31B T* | — | — | — | 5 | 4 | 5 | 5 | 5 | 5 | 4 | 6 | 5 | 5 | 6 |
| d. Al5083 Cr+6 | — | — | — | — | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 3 |
| e. Al6061 Cr+6 | — | — | — | — | — | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 3 |
| f. Al5083 Cr3+ | — | — | — | — | — | — | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| g. Al7075 Cr6+ | — | — | — | — | — | — | — | 2 | 2 | 2 | 2 | 2 | 2 | 4 |
| h. Al6061 Cr+3 | — | — | — | — | — | — | — | — | 2 | 2 | 2 | 2 | 3 | 3 |
| i. Cadmium w CC | — | — | — | — | — | — | — | — | — | 1 | 2 | 3 | 3 | 4 |
| j. Al7075 Cr+3 | — | — | — | — | — | — | — | — | — | — | 2 | 2 | 2 | 4 |
| k. Zn-Ni w CC | — | — | — | — | — | — | — | — | — | — | — | 3 | 3 | 4 |
| l. Al2024 Cr6+ | — | — | — | — | — | — | — | — | — | — | — | — | 2 | 3 |
| m. Al2024 Cr3+ | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 |
| n. Electroless Ni | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Table III — Bare-versus-treated compatibility matrix
| Bare material | a. Mg WE43 T* | b. Mg EV31 T* | c. Mg AZ31B T* | d. Al5083 Cr+6 | e. Al6061 Cr+6 | f. Al5083 Cr3+ | g. Al7075 Cr6+ | h. Al6061 Cr+3 | i. Cadmium w CC | j. Al7075 Cr+3 | k. Zn-Ni w CC | l. Al2024 Cr6+ | m. Al2024 Cr3+ | n. Electroless Ni |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. Mg EV31 | 5 | 5 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 |
| 2. Mg WE43 | 5 | 5 | 5 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 |
| 3. Mg AZ31B | 5 | 5 | 5 | 5 | 5 | 6 | 5 | 5 | 5 | 5 | 6 | 5 | 5 | 6 |
| 4. Zinc | 5 | 5 | 5 | 2 | 2 | 2 | 3 | 3 | 4 | 2 | 4 | 3 | 3 | 5 |
| 5. Zn-Ni Plated | 6 | 6 | 6 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 5 |
| 6. Al5083 | 6 | 6 | 5 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 2 | 3 | 4 |
| 7. Cadmium | 6 | 6 | 6 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 5 | 5 | 5 | 5 |
| 8. Al6061 | 5 | 5 | 4 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 2 | 2 | 3 |
| 9. CP Aluminum | 5 | 5 | 5 | 2 | 2 | 2 | 2 | 2 | 3 | 2 | 3 | 3 | 3 | 4 |
| 10. A356 | 5 | 5 | 4 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 3 |
| 11. 1020 Steel | 6 | 6 | 6 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 3 | 3 | 3 | 3 |
| 12. Al7075 | 6 | 6 | 6 | 4 | 4 | 4 | 4 | 4 | 5 | 4 | 4 | 4 | 4 | 5 |
| 13. A36 Steel | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| 14. 1018 Steel | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| 15. 1008 Steel | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
| 16. Al7050 | 6 | 6 | 5 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 3 | 4 |
| 17. B7 Steel | 6 | 6 | 6 | 4 | 4 | 4 | 4 | 4 | 5 | 4 | 4 | 3 | 3 | 4 |
| 18. MIL-11356 Steel | 6 | 6 | 6 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 3 | 3 | 3 | 3 |
| 19. 4340 Steel | 6 | 6 | 6 | 4 | 4 | 4 | 4 | 4 | 5 | 4 | 4 | 3 | 3 | 4 |
| 20. HY80 Steel | 6 | 6 | 6 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 4 | 3 | 3 | 4 |
| 21. Tin | 6 | 6 | 5 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 1 | 1 | 2 |
| 22. Al2024 | 6 | 6 | 6 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 3 | 3 | 3 | 4 |
| 23. Ti-6Al-4V | 5 | 5 | 5 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 1 | 1 | 1 |
| 24. Brass, Yellow | 6 | 6 | 6 | 4 | 4 | 3 | 4 | 4 | 5 | 4 | 4 | 4 | 4 | 3 |
| 25. Bronze | 6 | 6 | 6 | 4 | 4 | 3 | 4 | 4 | 5 | 4 | 4 | 4 | 4 | 3 |
| 26. NiAl, C630 | 6 | 6 | 6 | 4 | 4 | 3 | 4 | 4 | 5 | 4 | 4 | 4 | 4 | 3 |
| 27. CuBe | 6 | 6 | 6 | 4 | 4 | 3 | 4 | 4 | 5 | 4 | 4 | 4 | 4 | 3 |
| 28. CP Copper | 6 | 6 | 6 | 4 | 4 | 3 | 4 | 4 | 5 | 4 | 5 | 4 | 4 | 3 |
| 29. PH 13-8 | 6 | 6 | 6 | 4 | 4 | 2 | 3 | 4 | 5 | 4 | 5 | 2 | 2 | 2 |
| 30. 304SS | 6 | 6 | 6 | 3 | 3 | 2 | 3 | 3 | 4 | 3 | 3 | 3 | 3 | 2 |
| 31. PH 15-5 | 6 | 6 | 6 | 5 | 4 | 2 | 5 | 5 | 5 | 5 | 5 | 4 | 4 | 2 |
| 32. 304SS Passivated | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 4 | 5 | 4 | 4 | 2 |
| 33. 410SS | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 4 | 5 | 4 | 4 | 2 |
| 34. Inconel® 600 | 6 | 6 | 6 | 3 | 3 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 2 | 2 |
| 35. A286 Passivated | 6 | 6 | 6 | 3 | 3 | 2 | 3 | 3 | 4 | 3 | 4 | 3 | 3 | 2 |
| 36. PH 17-4 | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 4 | 5 | 4 | 3 | 2 |
| 37. 316SS | 6 | 6 | 6 | 5 | 5 | 2 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 2 |
| 38. 316SS Passivated | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 4 | 4 | 4 | 3 | 2 |
| 39. Monel® 400 | 6 | 6 | 6 | 3 | 3 | 2 | 3 | 3 | 4 | 3 | 3 | 2 | 2 | 2 |
| 40. 410SS Passivated | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 4 | 4 | 3 | 3 | 2 |
| 41. A286 | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 4 | 4 | 4 | 3 | 2 |
| 42. PH 17-4 Passivated | 6 | 6 | 6 | 3 | 3 | 2 | 3 | 3 | 4 | 3 | 4 | 3 | 3 | 2 |
| 43. PH 13-8 Passivated | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 4 | 4 | 3 | 3 | 2 |
| 44. PH 15-5 Passivated | 6 | 6 | 6 | 3 | 3 | 2 | 3 | 3 | 4 | 3 | 4 | 3 | 3 | 2 |
| 45. Silver | 6 | 6 | 5 | 3 | 3 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 2 |
| 46. Graphite | 6 | 6 | 6 | 5 | 5 | 2 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 2 |
| 47. Platinum | 6 | 6 | 6 | 4 | 4 | 2 | 4 | 4 | 5 | 5 | 5 | 4 | 4 | 3 |
The source table explicitly warns that these class numbers are not a hierarchy of overall application risk and are not a substitute for the protection level selected by the Cognizant Engineering Authority or appropriate design authority. Table I uses the source’s spelling and ordering, except “Platinum” is normalized to the spelling used in Tables IV and V.
How to Read the Galvanic Corrosion Chart
- Match the surface condition first. Use Table I for the standard’s bare-material matrix, Table II when both listed surfaces are treated, and Table III for a listed bare-versus-treated couple.
- Find the exact material designations. Do not substitute a nearby alloy, stainless grade, plating, or conversion coating when the requested designation is absent.
- Read the class, not just the distance in the galvanic series. Class 0 is compatible under the MIL-STD-889D test criterion. Any class above 0 is incompatible under that criterion.
- Confirm polarity. Tables I and II place the anode in the row and cathode in the column. Table III uses Table IV to determine which member is anodic.
- Carry the scope with the result. The test solution, exposed-area ratio, treatment state, and actual service environment can change field behavior.
What the Compatibility Classes Mean
The class is a band for the calculated corrosion rate of the anodic member under the standard’s test basis. It is not a general-purpose “low, medium, high” risk score.
| Class | Published corrosion-rate band | Standard interpretation |
|---|---|---|
| 0 | <0.009 mil/year | Galvanically compatible |
| 1 | 0.01–0.09 mil/year | Galvanically incompatible |
| 2 | 0.1–0.9 mil/year | Galvanically incompatible |
| 3 | 1–4.99 mil/year | Galvanically incompatible |
| 4 | 5–9.99 mil/year | Galvanically incompatible |
| 5 | 10–99.99 mil/year | Galvanically incompatible |
| 6 | >100 mil/year | Galvanically incompatible |
Because the source publishes bands, the checker reports the band rather than inventing an exact corrosion rate.
Galvanic Series: Active vs Noble Materials
MIL-STD-889D Table IV orders selected material and surface states from more active/anodic toward more noble/cathodic in immersed ASTM D1141 artificial seawater without heavy metals. The checker uses this order to resolve polarity for Table III.
Do not use series separation to calculate compatibility. The standard says Table IV is for determining the anodic member, not for determining compatibility.
| Position | Material / surface state | Selected role |
|---|---|---|
| 1 | Magnesium WE-43 Tagnite | — |
| 2 | Magnesium EV-31 | — |
| 3 | Magnesium EV-31 Tagnite | — |
| 4 | Magnesium WE-43 | — |
| 5 | Magnesium AZ31-B Tagnite | — |
| 6 | Magnesium AZ31-B | — |
| 7 | Al5083 Cr+6 | — |
| 8 | Zinc | — |
| 9 | Al6061 Cr+6 | — |
| 10 | Al5083 Cr+3 | — |
| 11 | Al7075 Cr+6 | — |
| 12 | Zn-Ni Plated | — |
| 13 | Al6061 Cr+3 | — |
| 14 | Al5083 | — |
| 15 | Cadmium | — |
| 16 | Al6061 | — |
| 17 | Cadmium w/ Conversion Coating | — |
| 18 | Aluminum | — |
| 19 | Al7075 Cr+3 | — |
| 20 | A356 | — |
| 21 | 1020 Steel | — |
| 22 | Al7075 | — |
| 23 | Zn-Ni with Conversion Coating | — |
| 24 | A36 Steel | — |
| 25 | 1018 Steel | — |
| 26 | 1008 Steel | — |
| 27 | Al7050 | — |
| 28 | B7 Steel | — |
| 29 | MIL-11356 Steel | — |
| 30 | 4340 Steel | — |
| 31 | HY80 Steel | — |
| 32 | Tin | — |
| 33 | Al2024 | — |
| 34 | Al2024 Cr+6 | — |
| 35 | Al2024 Cr+3 | — |
| 36 | Ti-6Al-4V | — |
| 37 | Electroless Nickel | — |
| 38 | Brass, Yellow | — |
| 39 | Bronze | — |
| 40 | NiAl Alloy C630 | — |
| 41 | CuBe | — |
| 42 | Copper | — |
| 43 | PH 13-8 | — |
| 44 | 304SS | — |
| 45 | PH 15-5 | — |
| 46 | Passivated 304SS | — |
| 47 | 410SS | — |
| 48 | Inconel® 600 | — |
| 49 | Passivated A286 | — |
| 50 | PH 17-4 | — |
| 51 | 316SS | — |
| 52 | 316SS Passivated | — |
| 53 | Monel® 400 | — |
| 54 | 410SS Passivated | — |
| 55 | A286 | — |
| 56 | PH 17-4 Passivated | — |
| 57 | PH 13-8 Passivated | — |
| 58 | PH 15-5 Passivated | — |
| 59 | Silver | — |
| 60 | Graphite | — |
| 61 | Platinum | — |
Why Environment and Surface Condition Matter
A galvanic series is electrolyte-specific. MIL-STD-889D reports data generated under static immersion in artificial seawater prepared in accordance with ASTM D1141 without heavy metals. ASTM’s substitute-ocean-water practice is a laboratory solution, not a guarantee that natural seawater or another environment will produce the same corrosion rate.
Surface treatments also change electrochemical behavior. That is why the standard separates bare, treated, and bare-versus-treated pairings instead of treating “aluminum,” “stainless steel,” or “magnesium” as single universal entries.
- Electrical path
- The two conductive materials must be electrically connected for a galvanic couple to form.
- Electrolyte path
- A conductive liquid or moisture film must complete the electrochemical circuit.
- Surface state
- Passivation, conversion coatings, plating, and other treatments can shift polarization behavior.
Anode-to-Cathode Area Ratio
The tabulated compatibility data use a 1:1 exposed anode-to-cathode area ratio. Real assemblies often do not. A small anodic area connected to a much larger cathodic area can concentrate attack on the anode, while a relatively large anode coupled to a small cathode is generally more favorable.
Fastener example: MIL-STD-889D specifically gives stainless-steel bolts or screws fastening aluminum sheet as the favorable orientation compared with the reverse geometry, because stainless steel is cathodic to the aluminum and the cathode should be kept smaller than the anode where practical.
Do not scale the class number linearly with area ratio. The standard provides a separate engineering method for determining an allowable A/C ratio for incompatible couples, and the appropriate design authority still determines required protection.
Worked Galvanic-Corrosion Examples
Example 1 — 1020 steel with Inconel 600
Assumption: Use the Table I source conditions and a 1:1 exposed area ratio.
The Table I intersection gives Class 3, which corresponds to 1–4.99 mil/year for the anodic member. 1020 steel is the anodic member in this pairing.
Interpretation: Class 3 is incompatible under the standard. The result does not itself specify the protection system; the design authority must determine protection for the real environment and geometry.
Sanity check: Appendix C of MIL-STD-889D uses the same 1020 steel/Inconel 600 pair as an area-ratio example and identifies it as Class 3.
Example 2 — 304SS with 316SS
Assumption: Use the Table I source conditions for the listed material states.
The Table I intersection gives Class 0, corresponding to <0.009 mil/year under the MIL-STD-889D compatibility criterion.
Interpretation: This pair is compatible under that test criterion. It does not prove immunity from local corrosion, crevice corrosion, contamination, or behavior in another electrolyte.
Sanity check: The result stays in the source’s Class 0 band; no exact corrosion rate is inferred from the band.
Ways to Reduce Galvanic Corrosion
Choose a compatible couple
Where practical, start with a listed pair that meets the compatibility criterion for the relevant source scope rather than relying on protection to compensate for an incompatible couple.
Interrupt the electrical path
For joints that do not need electrical continuity, use appropriate insulating washers, sleeves, gaskets, films, or barriers so the metals are not electrically coupled.
Block the electrolyte
Seal faying edges and joints against liquid entry and use approved coatings, primers, sealants, or resin systems suitable for the service environment.
Control exposed area
Avoid a tiny anode connected to a large cathode. Fastener and sheet geometry can matter as much as the material names themselves.
Protective coating, finish, sealant, and isolation selections can have electrical, thermal, mechanical, maintenance, and environmental constraints. MIL-STD-889D assigns final protection decisions to the Cognizant Engineering Authority or appropriate design authority.
Engineering References and Dataset Scope
Primary data basis: MIL-STD-889D Tables I–IV; source status checked against DLA ASSIST on 15 August 2026.
The page reproduces and reorganizes the federal standard’s tabulated compatibility classes for engineering lookup. ASTM documents are cited for method/environment context only; their proprietary tables or figures are not reproduced.
- DLA ASSIST — MIL-STD-889, Galvanic Compatibility of Electrically Conductive MaterialsActive document record; Revision D validated by Notice 1 dated 29 April 2026. Scope states static immersion in ASTM D1141 artificial seawater without heavy metals.
- MIL-STD-889D, 21 July 2021 — public-release PDF copy used for Table I–IV transcription checksEvidence locators: §5.3–5.5, Tables I–IV, §6.1, §6.5–6.7, Appendix C.
- ASTM G82 — Standard Guide for Development and Use of a Galvanic Series for Predicting Galvanic Corrosion PerformanceMethodology reference only. No ASTM figure or compiled table is reproduced here.
- ASTM D1141 — Standard Practice for Preparation of Substitute Ocean WaterReferenced because MIL-STD-889D identifies ASTM D1141 artificial seawater as the test solution basis.
Dataset and Source-Check Details
- Publisher
- Turn2Engineering
- Primary standard
- MIL-STD-889D
- Current validation notice
- Revision D Notice 1, 29 Apr 2026
- Source checked
- 15 Aug 2026
- Reference conditions
- Static immersion; ASTM D1141 artificial seawater without heavy metals; 1:1 A/C for tabulated rates
- Compatibility threshold
- Class 0: <0.009 mil/year
- Interpolation
- None
- Extrapolation
- Prohibited for unlisted materials/surface states
- Full CSV
- Disabled pending a separate final publication-rights review for bulk export
- Normalization
- “Platinum” follows Tables IV/V spelling; Table I/III PDF display contains “Platnium”
Galvanic Corrosion Chart FAQ
There is no universal “never pair” list: the exact alloy or conductive material, surface treatment, electrolyte, exposed-area ratio, and service conditions matter, so use a source-matched compatibility table rather than a generic metal-family rule.
The more anodic member is preferentially attacked when the dissimilar conductive materials are electrically connected through a conductive electrolyte; the checker identifies that member using the applicable source-table orientation or Table IV ordering.
Do not answer that pair generically: select the exact listed aluminum alloy and stainless grade/surface condition, then interpret the resulting class within the stated artificial-seawater and area-ratio scope.
No. MIL-STD-889D Revision D changed the compatibility method because galvanic-potential difference alone does not include electrochemical kinetics; the standard instead bases its classes on the calculated corrosion rate of the anodic member.
A galvanic cell needs both electrical contact between dissimilar conductive materials and an electrolyte path, so eliminating either path can prevent galvanic current even though other corrosion mechanisms may still be possible.
Use the Class as a Source-Bounded Lookup, Not a Universal Risk Score
The fastest workflow is to choose the correct MIL-STD-889D table for the surface conditions, look up the exact material pair, identify the anodic member, and then carry the environmental and area-ratio limitations into the design decision. If the material or treatment is not listed, do not substitute a “similar” row or infer a class from galvanic-series spacing.