Zinc Anode Alloy B418-I
Grade · default condition
ASTM B418 Type I, B418 Type II
B418-I = aSTM B418 Type I
Standard cast hull, bracelet and offshore anode for seawater and brackish water; Al+Cd additions prevent passivating film build-up.
Values for the B418-I condition
Other Zinc Anode Alloy tempers and conditions
Zinc Anode Alloy is listed in 2 conditions; see the grade overview at Zinc Anode Alloy.
- B418-II
- B418-I
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-IDefaultThis page 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 |
What is Zinc Anode Alloy B418-I?
Zinc Anode Alloy B418-I is Zinc Anode Alloy in the B418-I grade — standard cast hull, bracelet and offshore anode for seawater and brackish water; Al+Cd additions prevent passivating film build-up. Zinc Anode Alloy B418-I 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). Zinc Anode Alloy B418-I 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).
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 B418-I properties
Typical room-temperature values for Zinc Anode Alloy B418-I; 10 are specific to this condition. Other listed values are Zinc Anode Alloy reference data and may not represent this condition. Bars are the position among zinc alloy grades.
Physical3
Zinc Anode Alloy B418-I 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 B418-I 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 B418-I 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 B418-I 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 B418-I 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 B418-I'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. Confirm any required mill or lot documentation when quoting.
Working with Zinc Anode Alloy B418-I
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.
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.
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) | — |
Zinc Anode Alloy B418-I — frequently asked
What is Zinc Anode Alloy B418-I used for?
Zinc Anode Alloy B418-I 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 B418-I?
Zinc Anode Alloy B418-I 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 B418-I 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 B418-I 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 B418-I?
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 B418-I 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 B418-I?
Zinc Anode Alloy B418-I 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.