Copper Alloy C55281
UNS C55281
C55281 is a copper-silver-phosphorus brazing filler with moderate silver content, used for copper-to-copper and copper-to-brass joints where wetting must be better than plain phos-copper.
Reference datasheet — C55281 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 AS-BRAZED condition
C55281 tempers and conditions
C55281 is supplied in one standard condition, AS-BRAZED. AS-BRAZED is the default FabDigit quotes; the values on this page are for it.
Supply forms, finishes and certifications
Ways C55281 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FLUX-COATED | Flux-Coated Rod | Supply form |
POWDER-PASTE | Powder / Paste | Supply form |
PREFORM | Preform / Ring | Supply form |
ROD | Bare Rod / Wire | Supply form |
STRIP | Strip / Foil | Supply form |
What is C55281?
C55281 is a copper-silver-phosphorus brazing filler with moderate silver content, used for copper-to-copper and copper-to-brass joints where wetting must be better than plain phos-copper. It is stocked as bare and flux-coated rod, strip, stamped preforms and powder paste; as-brazed values are about 250 MPa tensile strength, 6 % elongation, 85 HB, 50 W/m·K thermal conductivity, 10 % IACS and service to 150 °C, with a moderate corrosion-resistance rating of 55. Like all phos-coppers it is unsuitable for steel, stainless steel and nickel alloys. C55280 is the nearest lower-silver alternative. C55281 has a density of 8.1 g/cm³ (0.293 lb/in³), lighter than 86% of copper alloy grades. It melts at 645°C (1,193 °F). C55281 has a yield strength of 170 MPa (24.7 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 62% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 105 GPa (15.2 Msi).
What is C55281 used for?
- copper and brass tube brazing
- electrical fittings
- instrumentation lines
Limitations
- High embodied carbon — 11 kg CO₂/kg, worse than 99% of copper alloy grades
- Limited service temperature — 150°C (302 °F), worse than 96% of copper alloy grades
- Hard to polish — 60/100, worse than 92% of copper alloy grades
- Limited ductility — 6%, worse than 89% of copper alloy grades
C55281 properties
Typical room-temperature values for C55281-AS-BRAZED; bars are the position among copper alloy grades.
Physical3
C55281 has a density of 8.1 g/cm³ (0.293 lb/in³), lighter than 86% of copper alloy grades. It melts at 645°C (1,193 °F).
Mechanical9
C55281 has a yield strength of 170 MPa (24.7 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 62% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 105 GPa (15.2 Msi).
Thermal6
C55281 is rated for continuous service to 150°C (302 °F). It conducts heat at 50 W/m·K (28.9 BTU/hr·ft·°F), worse than 66% of copper alloy grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical3
C55281 conducts electricity at 10 % IACS, worse than 74% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 86% of copper alloy grades.
Sustainability4
Producing a kilogram of C55281 takes about 125 MJ of energy and emits 11 kg of CO₂ — more than 98% of copper alloy grades. Typical recycled content is 30%.
Manufacturability4
C55281's formability fair (35/100).
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. C55281 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C55281
Is C55281 easy to machine?
The filler is not machined into finished parts; the phos-copper fillet that squeezes out of a joint is hard and brittle and is best removed by filing or grinding.
Can C55281 be welded?
This is a brazing filler, not a welding consumable; copper-to-copper joints need no flux, brass and bronze require a phos-copper flux, and it must never be used on steel, stainless steel or nickel alloys.
Can C55281 be formed, bent or molded?
It can be drawn to wire, rolled to strip and stamped into preform rings, but ductility is limited, so control the reduction per pass and anneal between passes.
C55281 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 |
|---|---|---|
| AgAWS A5.8 BCuP-3 | 4.8 – 5.2 | 5 |
| Pself-fluxing action on copper | 5.8 – 6.2 | 6 |
| Other (total)maximum total impurities | ≤ 0.15 | |
| Cu | balance |
What surface finishes work on C55281?
Joints can be pickled to remove residue and then nickel- or tin-plated; sulfur-bearing polishing compounds and acid residues must be washed off completely to prevent joint corrosion.
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 C55281 cost?
C55281 is a high-cost copper alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C55281 — frequently asked
What is C55281 used for?
C55281 is typically used for copper and brass tube brazing, electrical fittings and instrumentation lines. In short: moderate-silver phos-copper; wets brass better than Cu-P; flux-coated forms available.
What is the yield strength of C55281?
C55281 has a typical yield strength of 170 MPa (24.7 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 62% of copper alloy grades.
Is C55281 easy to machine?
The filler is not machined into finished parts; the phos-copper fillet that squeezes out of a joint is hard and brittle and is best removed by filing or grinding.
Can C55281 be welded?
This is a brazing filler, not a welding consumable; copper-to-copper joints need no flux, brass and bronze require a phos-copper flux, and it must never be used on steel, stainless steel or nickel alloys.
What surface finishes work on C55281?
Joints can be pickled to remove residue and then nickel- or tin-plated; sulfur-bearing polishing compounds and acid residues must be washed off completely to prevent joint corrosion.
Can C55281 be formed, bent or molded?
It can be drawn to wire, rolled to strip and stamped into preform rings, but ductility is limited, so control the reduction per pass and anneal between passes.
What is the maximum service temperature of C55281?
C55281 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does C55281 cost?
C55281 is a high-cost copper alloy ($$$$), 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
- AWS A5.8M/A5.8 Specification for Filler Metals for Brazing and Braze Welding — American Welding Society (2019)
- GB/T 6418 (2008)
- Brazing Handbook, 5th ed. — American Welding Society (2007)
- ASM Handbook Vol.6: Welding, Brazing, and Soldering — ASM International (1993)
- CDA/UNS Alloy Data — C55281 — Copper Development Association (2023)
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.