Copper Alloy BC6
GB BC6
BC6 (JIS H5120, nearest US grade C90300) is a leaded tin bronze casting alloy comparable to Navy-G bronze, with about 5 % lead for free machining and pressure-tight castings.
Reference datasheet — BC6 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-SAND condition
BC6 tempers and conditions
BC6 is supplied in 2 conditions, soft to hard. F-SAND 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 |
|---|---|---|---|---|---|---|
F-SANDDefault F | Standard sand-cast condition for valve bodies, pump housings and marine fittings; most widely stocked and quoted. | 110 | 250 | 25 | 60 HB | 15 % IACS |
Permanent mould / chill cast | Pick for medium-volume small fittings needing tighter dimensions and a finer, slightly stronger chill-cast structure. | 120 | 260 | 20 | 65 HB | 15 % IACS |
Supply forms, finishes and certifications
Ways BC6 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CC | Continuous cast bar/tube | Surface finish |
IC | Investment / precision cast | Surface finish |
CE | Centrifugal cast | Certification |
What is BC6?
BC6 (JIS H5120, nearest US grade C90300) is a leaded tin bronze casting alloy comparable to Navy-G bronze, with about 5 % lead for free machining and pressure-tight castings. Properties of 110 MPa yield, 250 MPa tensile, 25 % elongation and 60 HB, together with a machinability score of 85 (~84 % of C36000), make it a default choice for pump and valve parts to about 230 °C, produced by sand, chill, centrifugal, continuous and investment casting. The lead content makes fusion welding unreliable and can restrict use in lead-free potable-water systems; an unleaded tin bronze is then the substitute. BC6 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 854°C (1,569 °F). BC6 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 82% of copper alloy grades. Elongation at break is 25% and the elastic modulus is 96 GPa (13.9 Msi).
What is BC6 used for?
- pump bodies
- valve fittings
- marine components
Advantages
- Easy to machine — 85/100, better than 93% of copper alloy grades
Limitations
- Hard to polish — 60/100, worse than 92% of copper alloy grades
- Low stiffness — 96 GPa (13.9 Msi), worse than 91% of copper alloy grades
- Difficult to weld — 20/100, worse than 88% of copper alloy grades
- Low strength — 110 MPa (16 ksi), worse than 82% of copper alloy grades
- High embodied carbon — 4.6 kg CO₂/kg, worse than 82% of copper alloy grades
BC6 properties
Typical room-temperature values for BC6-F-SAND; bars are the position among copper alloy grades.
Physical3
BC6 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 854°C (1,569 °F).
Mechanical15
BC6 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 82% of copper alloy grades. Elongation at break is 25% and the elastic modulus is 96 GPa (13.9 Msi).
Thermal6
BC6 is rated for continuous service to 230°C (446 °F). It conducts heat at 72 W/m·K (41.6 BTU/hr·ft·°F), worse than 52% of copper alloy grades. Thermal expansion is 18 µm/m·K (10 µin/in·°F).
Electrical3
BC6 conducts electricity at 15 % IACS, worse than 54% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 69% of copper alloy grades.
Sustainability4
Producing a kilogram of BC6 takes about 62 MJ of energy and emits 4.6 kg of CO₂ — more than 76% of copper alloy grades. Typical recycled content is 75%.
Manufacturability7
BC6's machinability is excellent (85/100, better than 93% of copper alloy grades); weldability poor (20/100); formability poor (15/100).
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. BC6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with BC6
Is BC6 easy to machine?
Excellent free-cutting behaviour (~84 % of C36000); use sharp positive-rake tools, high speed, light feed, and soluble-oil or dry cutting — lead gives short chips and fine bore finishes.
Can BC6 be welded?
Fusion welding is poor because of the 5 % lead (hot cracking, porosity); repair by brazing or low-fume TIG with matched filler only on non-critical, non-pressure areas.
Can BC6 be formed, bent or molded?
Cast-only alloy with wide freezing range — excellent fluidity and pressure tightness in sand, chill, centrifugal and continuous casting; not cold formable.
BC6 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 |
|---|---|---|
| CuJIS H5120 CAC406 | 83 – 87 | 85 |
| Sn | 4 – 6 | 5 |
| Pbfree-machining / pressure-tightness aid; restricted by lead-free potable-water rules | 4 – 6 | 5 |
| Fe | ≤ 0.3 | |
| Nicounted with Cu in some editions | ≤ 1 | |
| Sb | ≤ 0.2 | |
| P | ≤ 0.05 | |
| Al | ≤ 0.01 | |
| Si | ≤ 0.01 | |
| S | ≤ 0.05 | |
| Zn | ≥ 4 (balance) |
What surface finishes work on BC6?
Machines to a good matte finish; readily soldered, tin- or nickel-plated and chemically patinated/lacquered; polishing is limited by lead smear and micro-porosity.
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 BC6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- C90300
How much does BC6 cost?
BC6 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.
BC6 — frequently asked
What is BC6 used for?
BC6 is typically used for pump bodies, valve fittings and marine components. In short: best-machining cast bronze; pressure-tight pump bronze; not fusion weldable.
What is the yield strength of BC6?
BC6 has a typical yield strength of 110 MPa (16 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 82% of copper alloy grades. Strength varies by condition: see the 2 listed tempers.
Is BC6 easy to machine?
Yes — machinability is rated excellent (85/100, better than 93% of copper alloy grades). Excellent free-cutting behaviour (~84 % of C36000); use sharp positive-rake tools, high speed, light feed, and soluble-oil or dry cutting — lead gives short chips and fine bore finishes.
Can BC6 be welded?
Not readily — weldability is rated poor (20/100). Fusion welding is poor because of the 5 % lead (hot cracking, porosity); repair by brazing or low-fume TIG with matched filler only on non-critical, non-pressure areas.
What surface finishes work on BC6?
Machines to a good matte finish; readily soldered, tin- or nickel-plated and chemically patinated/lacquered; polishing is limited by lead smear and micro-porosity.
Can BC6 be formed, bent or molded?
Cast-only alloy with wide freezing range — excellent fluidity and pressure tightness in sand, chill, centrifugal and continuous casting; not cold formable.
What is the maximum service temperature of BC6?
BC6 is rated for continuous use to about 230°C (446 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between BC6 F-SAND and BC6-PM?
F-SAND is the default condition — standard sand-cast condition for valve bodies, pump housings and marine fittings; most widely stocked and quoted. PM: pick for medium-volume small fittings needing tighter dimensions and a finer, slightly stronger chill-cast structure. Yield strength is 110 MPa in F-SAND versus 120 MPa in PM.
How much does BC6 cost?
BC6 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 (CAC406 / former BC6) — JSA (2016)
- ASTM B584 Standard Specification for Copper Alloy Sand Castings (C83600) — ASTM (2021)
- CDA Alloy Datasheet C83600 (85-5-5-5 leaded red brass) — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials (Copper alloys in seawater) — ASM International (2005)
- GB/T 1176 (ZCuSn5Pb5Zn5) — SAC (2013)
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.