Zinc Anode Alloy
ASTM B418 Type I, B418 Type II
Zinc Anode Alloy is a zinc–aluminium–cadmium/indium casting alloy formulated to ASTM B418 Type I and Type II (also MIL-DTL-18001) for stable, low-polarization dissolution as a sacrificial anode.
Reference datasheet — Zinc Anode Alloy is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the B418-I condition
Zinc Anode Alloy tempers and conditions
Zinc Anode Alloy is supplied in 2 conditions, soft to hard. B418-I is the default FabDigit quotes; the values on this page are for it.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ASTM B418 Type II | Choose for buried pipelines, water tanks, heat exchangers and potable-water service where Cd-free 99.99 % zinc is required. | 25 | 35 | 15 | 30 HB | 28 % IACS |
B418-IDefault ASTM B418 Type I | Standard cast hull, bracelet and offshore anode for seawater and brackish water; Al+Cd additions prevent passivating film build-up. | 50 | 80 | 8 | 38 HB | 26 % IACS |
Supply forms, finishes and certifications
Ways Zinc Anode Alloy is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
RIBBON | Extruded ribbon / rod anode | Supply form |
MIL-DTL-18001 | MIL-DTL-18001K | Certification |
What is Zinc Anode Alloy?
Zinc Anode Alloy is a zinc–aluminium–cadmium/indium casting alloy formulated to ASTM B418 Type I and Type II (also MIL-DTL-18001) for stable, low-polarization dissolution as a sacrificial anode. It is bought as cast hull, bracelet and bolt-on anodes and as extruded ribbon over a core wire, with a galvanized steel core for attachment. Mechanical values are low by design — 50 MPa yield, 80 MPa tensile, 8 % elongation, 38 HB, 110 W/m·K, 26 % IACS and a 50 °C service limit — so it is not a structural material. Iron and other impurities must stay low or the anode passivates; magnesium or aluminium anodes are the alternatives for fresh water and for high-current-demand offshore service. Zinc Anode Alloy has a density of 7.13 g/cm³ (0.258 lb/in³), heavier than 64% of zinc alloy grades. It melts at 419°C (786 °F). Zinc Anode Alloy has a yield strength of 50 MPa (7.25 ksi) and a tensile strength of 80 MPa (11.6 ksi) — weaker than 86% of zinc alloy grades. Elongation at break is 8% and the elastic modulus is 100 GPa (14.5 Msi).
What is Zinc Anode Alloy used for?
- ship hull anodes
- pipeline cathodic protection
- offshore structure anodes
- ballast tank protection
Limitations
- Limited service temperature — 50°C (122 °F), worse than 100% of zinc alloy grades
- Needs corrosion protection — 18/100, worse than 100% of zinc alloy grades
- Hard to polish — 35/100, worse than 100% of zinc alloy grades
- Low strength — 50 MPa (7.25 ksi), worse than 86% of zinc alloy grades
Zinc Anode Alloy properties
Typical room-temperature values for Zinc Anode Alloy-B418-I; bars are the position among zinc alloy grades.
Physical3
Zinc Anode Alloy has a density of 7.13 g/cm³ (0.258 lb/in³), heavier than 64% of zinc alloy grades. It melts at 419°C (786 °F).
Mechanical8
Zinc Anode Alloy has a yield strength of 50 MPa (7.25 ksi) and a tensile strength of 80 MPa (11.6 ksi) — weaker than 86% of zinc alloy grades. Elongation at break is 8% and the elastic modulus is 100 GPa (14.5 Msi).
Thermal6
Zinc Anode Alloy is rated for continuous service to 50°C (122 °F). It conducts heat at 110 W/m·K (63.6 BTU/hr·ft·°F), worse than 64% of zinc alloy grades. Thermal expansion is 30.5 µm/m·K (16.9 µin/in·°F).
Electrical3
Zinc Anode Alloy conducts electricity at 26 % IACS, worse than 86% of zinc alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), worse than 100% of zinc alloy grades.
Sustainability4
Producing a kilogram of Zinc Anode Alloy takes about 53 MJ of energy and emits 3.4 kg of CO₂ — less than 68% of zinc alloy grades. Typical recycled content is 8%.
Manufacturability8
Zinc Anode Alloy's machinability is very good (80/100, better than 64% of zinc alloy grades); weldability poor (20/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the zinc alloy family
Yield strength against density for every zinc alloy grade FabDigit runs. Zinc Anode Alloy is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Zinc Anode Alloy
Is Zinc Anode Alloy easy to machine?
Very soft and free-cutting; use sharp, high-rake tools and light cuts — anodes are usually cast to net shape so machining is limited to core trimming and mounting faces.
Can Zinc Anode Alloy be welded?
Zinc is not welded; anodes are attached via cast-in galvanized steel cores or straps that are welded/bolted to the structure, and core-to-steel joints must stay electrically continuous.
Can Zinc Anode Alloy be formed, bent or molded?
Gravity/permanent-mould cast at 450–480 °C with the steel core preheated and grit-blasted; ribbon grades are hot-extruded over a core wire. Keep melt Fe low and avoid overheating to prevent dross and impurity pickup.
Zinc Anode Alloy chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| AlType I only; Type II max 0.005 | 0.1 – 0.5 | 0.35 |
| CdType I only; Type II max 0.003 | 0.03 – 0.07 | 0.05 |
| FeType II max 0.0014; iron is the most damaging impurity | ≤ 0.01 | 0 |
| PbType II max 0.003 | ≤ 0.01 | 0 |
| CuType II max 0.002 | ≤ 0.01 | 0 |
| ZnType I 99.0 min (balance); Type II 99.99 min high-grade zinc | ≥ 99 (balance) |
What surface finishes work on Zinc Anode Alloy?
Supply bare and grit-blasted — no paint, primer, oil or anodizing on the working surface; only the mounting core/straps may be coated.
Surface treatments FabDigit runs on zinc alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Equivalent designations
Standards and trade names that resolve to Zinc Anode Alloy in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- B418 Type IB418 Type II
- Also called
- MIL-A-18001MIL-DTL-18001
How much does Zinc Anode Alloy cost?
Zinc Anode Alloy is a premium-cost zinc alloy ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Zinc Anode Alloy — frequently asked
What is Zinc Anode Alloy used for?
Zinc Anode Alloy is typically used for ship hull anodes, pipeline cathodic protection, offshore structure anodes and ballast tank protection. In short: standard seawater sacrificial anode; low, stable polarization; not a structural alloy.
What is the yield strength of Zinc Anode Alloy?
Zinc Anode Alloy has a typical yield strength of 50 MPa (7.25 ksi) and a tensile strength of 80 MPa (11.6 ksi) — weaker than 86% of zinc alloy grades. Strength varies by condition: see the 2 listed tempers.
Is Zinc Anode Alloy easy to machine?
Yes — machinability is rated very good (80/100, better than 64% of zinc alloy grades). Very soft and free-cutting; use sharp, high-rake tools and light cuts — anodes are usually cast to net shape so machining is limited to core trimming and mounting faces.
Can Zinc Anode Alloy be welded?
Not readily — weldability is rated poor (20/100). Zinc is not welded; anodes are attached via cast-in galvanized steel cores or straps that are welded/bolted to the structure, and core-to-steel joints must stay electrically continuous.
What surface finishes work on Zinc Anode Alloy?
Supply bare and grit-blasted — no paint, primer, oil or anodizing on the working surface; only the mounting core/straps may be coated.
Can Zinc Anode Alloy be formed, bent or molded?
Gravity/permanent-mould cast at 450–480 °C with the steel core preheated and grit-blasted; ribbon grades are hot-extruded over a core wire. Keep melt Fe low and avoid overheating to prevent dross and impurity pickup.
What is the maximum service temperature of Zinc Anode Alloy?
Zinc Anode Alloy is rated for continuous use to about 50°C (122 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Zinc Anode Alloy B418-I and Zinc Anode Alloy B418-II?
B418-I is the default condition — standard cast hull, bracelet and offshore anode for seawater and brackish water; Al+Cd additions prevent passivating film build-up. B418-II: choose for buried pipelines, water tanks, heat exchangers and potable-water service where Cd-free 99.99 % zinc is required. Yield strength is 50 MPa in B418-I versus 25 MPa in B418-II.
How much does Zinc Anode Alloy cost?
Zinc Anode Alloy is a premium-cost zinc alloy ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM B418 — Standard Specification for Cast and Wrought Galvanic Zinc Anodes — ASTM International (2022)
- MIL-DTL-18001K — Anodes, Corrosion Preventive, Zinc; Slab, Disc and Rod Shaped — US DoD (2012)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Zinc and Zinc Alloys) — ASM International (1990)
- NACE SP0169 — Control of External Corrosion on Underground or Submerged Metallic Piping Systems — AMPP/NACE (2013)
- International Zinc Association LCA data for primary zinc — IZA (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.