Copper Alloy C90900
UNS C90900
C90900 is a high-tin bronze casting alloy used where hardness and wear resistance matter more than toughness.
Reference datasheet — C90900 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 M01 condition
C90900 tempers and conditions
C90900 is supplied in 4 conditions, soft to hard. M01 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 |
|---|---|---|---|---|---|---|
M01Default As sand cast | Standard stocked condition for gear blanks, worm wheels and bushings poured in sand moulds. | 152 | 275 | 5 | 80 HB | 10.5 % IACS |
As plaster cast | Use for repeat-run small parts where a chilled, finer structure and better surface are wanted. | 165 | 295 | 5 | 88 HB | 10.5 % IACS |
As centrifugally cast | Choose for dense, porosity-free bushings, sleeves and gear rims of rotational shape. | 170 | 305 | 6 | 90 HB | 10.5 % IACS |
As continuous cast | Best choice for stock bar and tube: highest density and hardness, minimal machining allowance. | 180 | 310 | 6 | 95 HB | 10.5 % IACS |
What is C90900?
C90900 is a high-tin bronze casting alloy used where hardness and wear resistance matter more than toughness. Castings provide 152 MPa yield, 275 MPa tensile, about 80 HB and 5% elongation, which suits lightly loaded gears, worm wheels and bushings running at low speed. The hard delta phase makes the alloy brittle and crack-sensitive, it is cast-only, and arc or gas welding is poor. C90800 covers similar gear duty at slightly higher tensile strength, while a leaded bearing bronze such as C93200 is preferable for conformable plain bearings. C90900 has a density of 8.79 g/cm³ (0.318 lb/in³), heavier than 54% of copper alloy grades. It melts at 830°C (1,526 °F). C90900 has a yield strength of 152 MPa (22 ksi) and a tensile strength of 275 MPa (39.9 ksi) — weaker than 67% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 103 GPa (14.9 Msi).
What is C90900 used for?
- gears
- worm wheels
- bushings
Advantages
- High service temperature — 260°C (500 °F), better than 75% of copper alloy grades
Limitations
- Limited formability — 5/100, worse than 98% of copper alloy grades
- Limited ductility — 5%, worse than 93% of copper alloy grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 89% of copper alloy grades
- Hard to polish — 65/100, worse than 87% of copper alloy grades
- Difficult to weld — 22/100, worse than 83% of copper alloy grades
C90900 properties
Typical room-temperature values for C90900-M01; bars are the position among copper alloy grades.
Physical3
C90900 has a density of 8.79 g/cm³ (0.318 lb/in³), heavier than 54% of copper alloy grades. It melts at 830°C (1,526 °F).
Mechanical15
C90900 has a yield strength of 152 MPa (22 ksi) and a tensile strength of 275 MPa (39.9 ksi) — weaker than 67% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
C90900 is rated for continuous service to 260°C (500 °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
C90900 conducts electricity at 10.5 % IACS, worse than 72% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C90900 takes about 85 MJ of energy and emits 5.5 kg of CO₂ — more than 92% of copper alloy grades. Typical recycled content is 65%.
Manufacturability8
C90900's machinability is poor (32/100, worse than 57% of copper alloy grades); weldability poor (22/100); formability not recommended (5/100).
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. C90900 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C90900
Is C90900 easy to machine?
Machines to a short, brittle chip at ~30 % of free-cutting brass; use sharp positive-rake carbide, moderate speeds and rigid setups to avoid chipping the hard delta phase.
Can C90900 be welded?
Poor arc/gas weldability — hot-short and crack prone; repair by low-heat brazing or preheated GTAW with matching tin-bronze filler, then stress relieve.
Can C90900 be formed, bent or molded?
Cast only, not workable cold; wide freezing range requires chills, generous risers and directional solidification to avoid tin sweat and interdendritic shrinkage.
C90900 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 | 12 – 14 | 13 |
| Pb | ≤ 0.25 | |
| Zn | ≤ 0.25 | |
| Fe | ≤ 0.15 | |
| Niincl. Co | ≤ 0.5 | |
| Sb | ≤ 0.2 | |
| S | ≤ 0.05 | |
| P | ≤ 0.05 | |
| Al | ≤ 0.01 | |
| Si | ≤ 0.01 | |
| CuCu + named elements = 99.4 % min | ≥ 85 (balance) |
What surface finishes work on C90900?
Takes a fine polish and bronze patina; can be tin-, nickel- or chrome-plated after copper strike, and is easily soft-soldered.
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).
How much does C90900 cost?
C90900 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.
C90900 — frequently asked
What is C90900 used for?
C90900 is typically used for gears, worm wheels and bushings. In short: hard, wear-resistant tin bronze; light-duty gear castings; low elongation, cast only.
What is the yield strength of C90900?
C90900 has a typical yield strength of 152 MPa (22 ksi) and a tensile strength of 275 MPa (39.9 ksi) — weaker than 67% of copper alloy grades. Strength varies by condition: see the 4 listed tempers.
Is C90900 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 57% of copper alloy grades). Machines to a short, brittle chip at ~30 % of free-cutting brass; use sharp positive-rake carbide, moderate speeds and rigid setups to avoid chipping the hard delta phase.
Can C90900 be welded?
Not readily — weldability is rated poor (22/100). Poor arc/gas weldability — hot-short and crack prone; repair by low-heat brazing or preheated GTAW with matching tin-bronze filler, then stress relieve.
What surface finishes work on C90900?
Takes a fine polish and bronze patina; can be tin-, nickel- or chrome-plated after copper strike, and is easily soft-soldered.
Can C90900 be formed, bent or molded?
Cast only, not workable cold; wide freezing range requires chills, generous risers and directional solidification to avoid tin sweat and interdendritic shrinkage.
What is the maximum service temperature of C90900?
C90900 is rated for continuous use to about 260°C (500 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C90900-M01 and C90900-M07?
M01 is the default condition — standard stocked condition for gear blanks, worm wheels and bushings poured in sand moulds. M07: best choice for stock bar and tube: highest density and hardness, minimal machining allowance. Yield strength is 152 MPa in M01 versus 180 MPa in M07.
How much does C90900 cost?
C90900 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
- ASTM B427 — Gear Bronze Alloy Castings — ASTM International (2020)
- ASTM B505/B505M — Continuous Cast Copper Alloy Castings — ASTM International (2018)
- CDA Alloy Datasheet C90900 — 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.