Copper Alloy PBC2 CAC502B
Grade
CAC502B = pBC2B, higher-phosphorus variant
Pick when maximum hardness and anti-galling performance are required for heavily loaded worm wheels; slightly less ductile.
Values for the CAC502B condition
Other PBC2 tempers and conditions
PBC2 is listed in 5 conditions; see the grade overview at PBC2.
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 |
CAC502BThis page 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 |
What is PBC2 CAC502B?
PBC2 CAC502B is PBC2 in the CAC502B grade — pick when maximum hardness and anti-galling performance are required for heavily loaded worm wheels; slightly less ductile. PBC2 CAC502B has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 295 MPa (42.8 ksi) — weaker than 64% of copper alloy grades. Elongation at break is 8% and the elastic modulus is 103 GPa (14.9 Msi). PBC2 CAC502B 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). SC is the default condition FabDigit quotes; CAC502B is available on request or by drawing note.
Limitations
- Difficult to machine — 22/100, worse than 94% of copper alloy grades
- Limited formability — 8/100, worse than 94% of copper alloy grades
- Difficult to weld — 20/100, worse than 88% 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
PBC2 CAC502B properties
Typical room-temperature values for PBC2 CAC502B; 21 are specific to this condition. Other listed values are PBC2 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
PBC2 CAC502B 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 CAC502B has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 295 MPa (42.8 ksi) — weaker than 64% of copper alloy grades. Elongation at break is 8% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
PBC2 CAC502B is rated for continuous service to 250°C (482 °F). It conducts heat at 66 W/m·K (38.1 BTU/hr·ft·°F), worse than 57% of copper alloy grades. Thermal expansion is 18.4 µm/m·K (10.2 µin/in·°F).
Electrical3
PBC2 CAC502B conducts electricity at 10 % IACS, worse than 74% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (63/100), better than 52% of copper alloy grades.
Sustainability4
Producing a kilogram of PBC2 CAC502B 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 CAC502B's machinability is poor (22/100, worse than 94% of copper alloy grades); weldability poor (20/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PBC2 CAC502B
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.
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.
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) | — |
PBC2 CAC502B — frequently asked
What is PBC2 CAC502B used for?
PBC2 CAC502B 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 CAC502B?
PBC2 CAC502B has a typical yield strength of 165 MPa (23.9 ksi) and a tensile strength of 295 MPa (42.8 ksi) — weaker than 64% of copper alloy grades. Strength varies by condition: see the 5 listed tempers.
Is PBC2 CAC502B 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 CAC502B be welded?
Not readily — weldability is rated poor (20/100). 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 CAC502B?
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 CAC502B 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 CAC502B?
PBC2 CAC502B 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.