Copper Alloy PBC2
PBC2 (C90700, CAC502B) is a high-tin phosphor bronze casting alloy in which a hard delta phase and phosphorus deoxidation provide wear resistance and load-carrying capacity for gearing.
Reference datasheet — PBC2 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 SC condition
PBC2 tempers and conditions
PBC2 is supplied in 5 conditions, soft to hard. SC is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Stress relieved | Use for precision gears/bushings where casting residual stress would cause distortion during finish machining. | 150 | 295 | 16 | 78 HB | 11 % IACS |
SCDefault Sand cast | General-purpose condition for one-off and low-volume worm wheels, gear rims and bearing blanks. | 152 | 300 | 15 | 80 HB | 11 % IACS |
PBC2B, higher-phosphorus variant | Pick when maximum hardness and anti-galling performance are required for heavily loaded worm wheels; slightly less ductile. | 165 | 295 | 8 | 90 HB | 10 % IACS |
Permanent mold / chill cast | Choose for repeat production of small gears/bushings needing finer structure and higher hardness than sand cast. | 185 | 330 | 12 | 95 HB | 11 % IACS |
Centrifugally cast | Best for large worm-gear rims and bushing sleeves: dense, porosity-free wall with the highest strength/hardness of the cast forms. | 207 | 345 | 14 | 102 HB | 11 % IACS |
Supply forms, finishes and certifications
Ways PBC2 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 |
What is PBC2?
PBC2 (C90700, CAC502B) is a high-tin phosphor bronze casting alloy in which a hard delta phase and phosphorus deoxidation provide wear resistance and load-carrying capacity for gearing. Typical values are 152 MPa yield, 300 MPa tensile, 15 % elongation, 80 HB, 11 % IACS conductivity and service to 250 °C, supplied as sand, permanent-mould, centrifugal and continuous castings and in a stress-relieved condition. It cannot be cold formed and welds poorly, so parts are cast to near-net shape and finish-machined. Where seawater strength is also required, nickel-aluminium bronze AlBC3 (C95500) is the usual step up. PBC2 has a density of 8.77 g/cm³ (0.317 lb/in³), heavier than 52% of copper alloy grades. It melts at 831°C (1,528 °F). PBC2 has a yield strength of 152 MPa (22 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 67% of copper alloy grades. Elongation at break is 15% and the elastic modulus is 103 GPa (14.9 Msi).
What is PBC2 used for?
- worm gears
- wear plates
- high-load bushings
Limitations
- Difficult to machine — 22/100, worse than 94% of copper alloy grades
- Limited formability — 10/100, worse than 89% of copper alloy grades
- Hard to polish — 65/100, worse than 87% of copper alloy grades
- High embodied carbon — 5 kg CO₂/kg, worse than 86% of copper alloy grades
- Difficult to weld — 25/100, worse than 78% of copper alloy grades
PBC2 properties
Typical room-temperature values for PBC2-SC; bars are the position among copper alloy grades.
Physical3
PBC2 has a density of 8.77 g/cm³ (0.317 lb/in³), heavier than 52% of copper alloy grades. It melts at 831°C (1,528 °F).
Mechanical15
PBC2 has a yield strength of 152 MPa (22 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 67% of copper alloy grades. Elongation at break is 15% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
PBC2 is rated for continuous service to 250°C (482 °F). It conducts heat at 71 W/m·K (41 BTU/hr·ft·°F), worse than 54% of copper alloy grades. Thermal expansion is 18.4 µm/m·K (10.2 µin/in·°F).
Electrical3
PBC2 conducts electricity at 11 % IACS, worse than 68% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of PBC2 takes about 70 MJ of energy and emits 5 kg of CO₂ — more than 84% of copper alloy grades. Typical recycled content is 45%.
Manufacturability8
PBC2's machinability is poor (22/100, worse than 94% of copper alloy grades); weldability poor (25/100); formability not recommended (10/100).
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. PBC2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with PBC2
Is PBC2 easy to machine?
Machinability ~20 % of free-cutting brass; the hard δ phase makes chips short but abrasive — use sharp carbide, positive rake, moderate speed with flood coolant, and expect good surface finish for bearing bores.
Can PBC2 be welded?
Poor fusion weldability (hot-short, tin oxide/porosity); repair by braze welding with phosphor-bronze rod and preheat 150–200 °C, or use silver brazing/soldering instead.
Can PBC2 be formed, bent or molded?
Not cold formable — supply as sand, permanent-mold, centrifugal or continuous castings; wide freezing range demands chills, generous risers and directional solidification to avoid tin sweat and microporosity.
PBC2 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 |
|---|---|---|
| SnJIS CAC502A / ASTM C90700 10–12 % | 9 – 12 | 11 |
| PCAC502B (PBC2B): 0.15–0.50 % | 0.05 – 0.35 | 0.2 |
| Znimpurity limit | ≤ 0.5 | |
| Pb0.20 max in JIS CAC502A | ≤ 0.5 | |
| Fe | ≤ 0.15 | |
| Ni | ≤ 1 | |
| Sb | ≤ 0.2 | |
| Al | ≤ 0.01 | |
| Si | ≤ 0.01 | |
| S | ≤ 0.05 | |
| Cu | ≥ 87 (balance) |
What surface finishes work on PBC2?
No anodizing; finish by machining/burnishing, chemical patina or lacquer, and tin or nickel plate where contact corrosion with steel is a concern.
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 PBC2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- C90700
How much does PBC2 cost?
PBC2 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.
PBC2 — frequently asked
What is PBC2 used for?
PBC2 is typically used for worm gears, wear plates and high-load bushings. In short: high-wear gear bronze; highest-tin bearing bronze; hardest of the tin bronzes.
What is the yield strength of PBC2?
PBC2 has a typical yield strength of 152 MPa (22 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 67% of copper alloy grades. Strength varies by condition: see the 5 listed tempers.
Is PBC2 easy to machine?
Not especially — machinability is rated poor (22/100, worse than 94% of copper alloy grades). Machinability ~20 % of free-cutting brass; the hard δ phase makes chips short but abrasive — use sharp carbide, positive rake, moderate speed with flood coolant, and expect good surface finish for bearing bores.
Can PBC2 be welded?
Not readily — weldability is rated poor (25/100). Poor fusion weldability (hot-short, tin oxide/porosity); repair by braze welding with phosphor-bronze rod and preheat 150–200 °C, or use silver brazing/soldering instead.
What surface finishes work on PBC2?
No anodizing; finish by machining/burnishing, chemical patina or lacquer, and tin or nickel plate where contact corrosion with steel is a concern.
Can PBC2 be formed, bent or molded?
Not cold formable — supply as sand, permanent-mold, centrifugal or continuous castings; wide freezing range demands chills, generous risers and directional solidification to avoid tin sweat and microporosity.
What is the maximum service temperature of PBC2?
PBC2 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 PBC2-SC and PBC2-CF?
SC is the default condition — general-purpose condition for one-off and low-volume worm wheels, gear rims and bearing blanks. CF: best for large worm-gear rims and bushing sleeves: dense, porosity-free wall with the highest strength/hardness of the cast forms. Yield strength is 152 MPa in SC versus 207 MPa in CF.
How much does PBC2 cost?
PBC2 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 H 5120 — Copper alloy castings (CAC502A/B, formerly PBC2/PBC2B) — JISC (2016)
- ASTM B505/B505M — Continuous cast copper alloys (C90700) — ASTM (2018)
- ASTM B427 — Gear bronze alloy castings — ASTM (2019)
- CDA alloy datasheet C90700 — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
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.