Copper Alloy BC3
GB BC3
BC3 (C92300) is a leaded tin bronze casting alloy from the Japanese gun-metal family, using tin and zinc for strength with a small lead addition for machinability and pressure tightness.
Reference datasheet — BC3 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 F-SC condition
BC3 tempers and conditions
BC3 is supplied in 4 conditions, soft to hard. F-SC is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
F-SCDefault F | Standard supply condition for valve bodies, pump housings and general pressure castings. | 145 | 290 | 18 | 75 HB | 12 % IACS |
F | Choose for repeat-run small parts needing tighter dimensions and a finer, slightly stronger structure than sand casting. | 155 | 300 | 16 | 80 HB | 12 % IACS |
F | For large-diameter sleeves, worm-gear rims and pump wear rings requiring pressure tightness over long sections. | 165 | 310 | 15 | 85 HB | 12 % IACS |
F | Best choice for machined bushings, bearings and wear rings — dense, porosity-free bar stock with the highest strength and hardness. | 175 | 320 | 13 | 90 HB | 12 % IACS |
Supply forms, finishes and certifications
Ways BC3 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Ingot | Remelt stock to BC3/CAC403 chemistry | Supply form |
What is BC3?
BC3 (C92300) is a leaded tin bronze casting alloy from the Japanese gun-metal family, using tin and zinc for strength with a small lead addition for machinability and pressure tightness. It is supplied as sand, permanent-mould, centrifugal and continuous castings as well as ingot, typically at 145 MPa yield, 290 MPa tensile, 18 % elongation and 75 HB, with service to 250 °C. Fusion welding is poor and strength is modest, so joints are brazed, soldered or bolted. Use lead-free BC2 (C90500) where lead content is restricted, or PBC2 (C90700) for higher gear and wear duty. BC3 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 854°C (1,569 °F). BC3 has a yield strength of 145 MPa (21 ksi) and a tensile strength of 290 MPa (42.1 ksi) — weaker than 72% of copper alloy grades. Elongation at break is 18% and the elastic modulus is 100 GPa (14.5 Msi).
What is BC3 used for?
- valve bodies
- pump castings
- bushings
Advantages
- Easy to machine — 62/100, better than 75% of copper alloy grades
Limitations
- Limited formability — 12/100, worse than 85% of copper alloy grades
- Low stiffness — 100 GPa (14.5 Msi), worse than 82% of copper alloy grades
BC3 properties
Typical room-temperature values for BC3-F-SC; bars are the position among copper alloy grades.
Physical3
BC3 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 854°C (1,569 °F).
Mechanical15
BC3 has a yield strength of 145 MPa (21 ksi) and a tensile strength of 290 MPa (42.1 ksi) — weaker than 72% of copper alloy grades. Elongation at break is 18% and the elastic modulus is 100 GPa (14.5 Msi).
Thermal6
BC3 is rated for continuous service to 250°C (482 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), worse than 69% of copper alloy grades. Thermal expansion is 18.2 µm/m·K (10.1 µin/in·°F).
Electrical3
BC3 conducts electricity at 12 % IACS, worse than 62% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 76% of copper alloy grades.
Sustainability4
Producing a kilogram of BC3 takes about 57 MJ of energy and emits 3.8 kg of CO₂ — less than 52% of copper alloy grades. Typical recycled content is 75%.
Manufacturability8
BC3's machinability is good (62/100, better than 75% of copper alloy grades); weldability poor (30/100); formability not recommended (12/100).
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 copper alloy family
Yield strength against density for every copper alloy grade FabDigit runs. BC3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with BC3
Is BC3 easy to machine?
Machines freely with sharp positive-rake carbide or HSS tooling at ~40 % of AISI 1212; small Pb content gives short chips, but keep feeds steady to avoid smearing the soft matrix.
Can BC3 be welded?
Fusion welding is poor (hot-short, Sn/Pb segregation); repair by GTAW with phosphor-bronze filler and preheat only on non-pressure areas, and prefer brazing or soldering for joints.
Can BC3 be formed, bent or molded?
Cast-only alloy — good fluidity and pressure tightness in sand, permanent-mould, centrifugal and continuous casting; use directional solidification and chills to control the wide freezing range and interdendritic shrinkage.
BC3 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 |
|---|---|---|
| Sn | 9 – 11 | 10 |
| Zn | 1 – 3 | 2 |
| Pbresidual/intentional lead for machinability; C92300 permits 0.30–1.0 | ≤ 1 | 0.5 |
| Ni | ≤ 1 | |
| Fe | ≤ 0.2 | |
| Sb | ≤ 0.2 | |
| Pdeoxidizer residual | ≤ 0.05 | |
| S | ≤ 0.05 | |
| Alkept very low to avoid casting defects | ≤ 0.01 | |
| Si | ≤ 0.01 | |
| Cubalance in JIS H5120 CAC403 | ≥ 86.5 (balance) |
What surface finishes work on BC3?
Not anodizable; finish by machining/polishing, chemical patina, tin or nickel plating for potable-water parts, or clear lacquer to retain the bronze colour.
Surface treatments FabDigit runs on copper 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).
Equivalent designations
Standards and trade names that resolve to Copper Alloy BC3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- C92300
How much does BC3 cost?
BC3 is a high-cost copper alloy ($$$$), pricier than about 78% 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.
BC3 — frequently asked
What is BC3 used for?
BC3 is typically used for valve bodies, pump castings and bushings. In short: free-machining gun metal; pressure-tight valve bronze; low-cost bearing casting.
What is the yield strength of BC3?
BC3 has a typical yield strength of 145 MPa (21 ksi) and a tensile strength of 290 MPa (42.1 ksi) — weaker than 72% of copper alloy grades. Strength varies by condition: see the 4 listed tempers.
Is BC3 easy to machine?
Reasonably — machinability is rated good (62/100, better than 75% of copper alloy grades). Machines freely with sharp positive-rake carbide or HSS tooling at ~40 % of AISI 1212; small Pb content gives short chips, but keep feeds steady to avoid smearing the soft matrix.
Can BC3 be welded?
Not readily — weldability is rated poor (30/100). Fusion welding is poor (hot-short, Sn/Pb segregation); repair by GTAW with phosphor-bronze filler and preheat only on non-pressure areas, and prefer brazing or soldering for joints.
What surface finishes work on BC3?
Not anodizable; finish by machining/polishing, chemical patina, tin or nickel plating for potable-water parts, or clear lacquer to retain the bronze colour.
Can BC3 be formed, bent or molded?
Cast-only alloy — good fluidity and pressure tightness in sand, permanent-mould, centrifugal and continuous casting; use directional solidification and chills to control the wide freezing range and interdendritic shrinkage.
What is the maximum service temperature of BC3?
BC3 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between BC3 F-SC and BC3 F-CC?
F-SC is the default condition — standard supply condition for valve bodies, pump housings and general pressure castings. F-CC: best choice for machined bushings, bearings and wear rings — dense, porosity-free bar stock with the highest strength and hardness. Yield strength is 145 MPa in F-SC versus 175 MPa in F-CC.
How much does BC3 cost?
BC3 is a high-cost copper alloy ($$$$), pricier than about 78% 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
- JIS H5120 Copper alloy castings (CAC403 / BC3) — JSA (2016)
- ASTM B584 Copper Alloy Sand Castings for General Applications (C92300) — ASTM (2022)
- CDA Alloy Datasheet C92300 (leaded tin bronze) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
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.