Toolchest · Datasheet

Accumath Toolchest — Galvanic Series in Seawater: Notes

Dataset file: accumath-galvanic-series.csv Built: 2026-10-20

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Source

• MIL-STD-889C, "Dissimilar Metals," Department of Defense Standard Practice, dated 22 August 2016, superseding MIL-STD-889B (7 July 1976). US government work — public domain. Preparing activity: Naval Air Warfare Center Aircraft Division (NAWCAD).
• Series data: Table II, "Galvanic series of selected metals in sea water" (pp. 7–8). The standard credits Table II to Army Missile Command Report ARS-TR-67-11, "Practical Galvanic Series."
• Group data: Table I, "Guide to use of joined structural metals and alloys, and protective systems for service in sea water, marine atmosphere, and industrial atmosphere" (p. 6).
• Copies consulted were the ASSIST-sourced PDF of the standard (assist.dla.mil), mirrored publicly. No third-party galvanic chart was used for any value in this dataset.

What the dataset contains

The Table II series exactly as published: 93 entries, ranked 1 = most anodic (active, corrodes preferentially) through 93 = most cathodic (noble, least active). Material names are reproduced as the standard prints them, including its spellings (e.g., "MG Alloy HK-31A", "Titanium 5A1, 2.5 Sn").

Why revision C and not the current revision D

MIL-STD-889D (21 July 2021) is the current revision, but this dataset is built on 889C, for two documented reasons:

1. No public full text of 889D could be retrieved. It is listed commercially (IHS/GlobalSpec) and distributed through the DoD ASSIST system, which requires interactive account access; repeated searching on 2026-10-20 found no openly downloadable copy.
2. 889D abolished the potential-based galvanic series. Per the D revision's scope and NAVAIR's own briefings, 889D rates couple compatibility by measured galvanic current / corrosion rate (severity classes 0–6, from mixed-potential analysis of 47 materials in artificial seawater per ASTM D1141, static immersion). It publishes no corrosion-potential series table of the kind recorded here. MIL-STD-889C is the last revision that publishes the galvanic series in sea water.

If the 889D couple-severity ratings are ever wanted as a separate dataset, the document itself will have to be pulled from ASSIST firsthand — its numbers were not taken from any secondary tool or summary.

Potential columns and reference electrode — intentionally blank

potential_min_V, potential_max_V, and reference_electrode are blank on every row, by design:

• MIL-STD-889C Table II publishes order only — no numeric corrosion potentials and no reference electrode.
• Numeric potential ranges were not imported from other galvanic charts. Published seawater charts variously report steady-state potentials against a saturated calomel or Ag/AgCl electrode, in flowing or quiescent seawater, and disagree with each other in detail; mixing any of them into this table would falsify the provenance of every row.
• Caution: MIL-STD-889C Appendix B, Table B-I lists standard electrode potentials (unit-activity aqueous metal ions, 25 °C, at equilibrium). That is a different physical quantity from a seawater corrosion potential and was deliberately not entered into these columns.

Groups (Table I letters)

Table I sorts joined structural metals into lettered families, A (most anodic) through T (most noble):

Group	Table I family	Group	Table I family
A	Magnesium	K	Stainless steels — austenitic, PH, super strength, heat resistant
B	Zinc, zinc coating	L	Brass-lead, bronze
C	Cadmium, beryllium	M	Brass-low copper, bronze-low copper
D	Aluminum, aluminum-Mg, aluminum-Zn	N	Brass-high copper, bronze-high copper
E	Aluminum-copper	O	Copper-high nickel, Monel
F	Steels — carbon, low alloy	P	Nickel, cobalt
G	Lead	Q	Titanium
H	Tin, tin-lead, indium	R	Silver
I	Stainless steels — martensitic, ferritic	S	Palladium, rhodium, gold, platinum
J	Chromium, molybdenum, tungsten	T	Graphite

Mapping method: the standard does not print a group letter next to each Table II alloy, so each Table II entry was mapped to its Table I family by alloy class as the families are named — wrought aluminum by designation series (2xxx → E aluminum-copper; 1xxx/3xxx/5xxx/6xxx/7xxx and the cast alloys → D), stainless steels by metallurgical class (410/430 → I; the austenitic and precipitation-hardening grades, including AM350, AM355, A286/286 and Carpenter 20 → K), copper alloys by copper content (the ~60–65% Cu brasses → M low-copper; the ≥85% Cu brasses/bronzes → N high-copper; 70/30 copper-nickel and Monel 400 → O).

83 of 93 rows carry a group. The 10 left blank, because Table I assigns them no family:

• Uranium; Uranium 8% Mo; Tantalum; Niobium (Columbium) 1% Zr — not in Table I.
• Iron, cast — Table I group F names steels, not cast iron.
• Copper (plated, cast or wrought); Copper 110 — Table I has no plain-copper family (copper appears only through its brass, bronze, and copper-nickel families).
• Brass plated — alloy unspecified.
• Nickel-silver (18% Ni) — not named in Table I.
• Admiralty brass — its ~71% copper falls between Table I's low-copper (M) and high-copper (N) brass groups, which the standard does not bound numerically.

Table I itself is a pairwise couple chart (each cell covers one joined pair, for sea water, marine atmosphere, and industrial atmosphere): "G" in a cell signifies a compatible same-metal couple, bare; "C"/"I" mark compatible / incompatible couples; numbers in cells refer to the protective systems of the standard's Appendix A. That matrix is not reproduced in this dataset — only the per-material family letters are carried.

Errata reproduced as printed

• "Al alloy 1160-1114" appears twice in Table II (dataset ranks 8 and 22) in the standard as published. Both instances are retained, in the printed positions; the rank-22 row is flagged in its notes cell. This appears to be an erratum in the standard itself.

How to read the series (per MIL-STD-889C §5.1)

• Separation is the driving force. The farther apart two joined metals sit in the series, the greater the potential difference between them, and the faster the anodic member (the one nearer rank 1) is attacked. The cathodic member is protected at the anode's expense. Metals close together in the series have potentials near one another and interact least (§3.3, §5.1.1, §5.1.2).
• Position in the series is not a corrosion rate. The series ranks tendency, not speed; the standard notes that kinetic factors such as polarization also govern what actually happens (§3.3).
• Area ratio matters (§5.1.3). Attack concentrates where a small anode is coupled to a large cathode — the worst practical case. A large anode coupled to a small cathode spreads the attack thin. This is why the standard's joining rule runs one way: make fasteners of the more noble metal (stainless bolts in aluminum sheet), never the reverse.
• The series is environment-specific (§5.1.1). A galvanic series applies to one electrolyte. These rankings are for sea water; a different order ensues in fresh water, soil, or any other environment, and seawater values do not transfer to those services.
• Surface condition moves an alloy. Stainless steels are listed twice — in the active and passive conditions — many ranks apart (e.g., 304 active at rank 41, 304 passive at rank 72). Which entry applies depends on the surface state actually in service. Dataset notes cells cross-reference each active/passive pair.
• Compatibility is not immunity. Per §3.3, even closely positioned couples are not completely free of galvanic action.

Legal basis

MIL-STD-889C is a US Department of Defense standard — a US government work, public domain (17 U.S.C. § 105). The dataset records published facts (series order and family groupings) into Accumath's own table structure, with the source named on every row; no claim of DoD endorsement is made.