Copper Alloy C51100
UNS C51100 · EN CW450K, CuSn4
C51100 (CW450K, CuSn4) is a phosphor bronze with about 4 % tin, leaner than C51000, giving good formability at somewhat lower strength.
Reference datasheet — C51100 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 H04 condition
C51100 tempers and conditions
C51100 is supplied in 7 conditions, soft to hard. H04 is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick for deep drawing, severe bending or forming before a final stress-relief; lowest strength, maximum ductility. | 140 | 340 | 48 | 65 HB | 20 % IACS |
As hot rolled | Mill as-hot-rolled plate/bar stock for machined or further-worked parts where temper control is not needed. | 150 | 330 | 45 | 70 HB | 20 % IACS |
Half hard | Balanced temper for formed contacts and light springs that still need 90° bends across grain. | 350 | 415 | 12 | 125 HB | 20 % IACS |
H04Default Full hard | The standard stocked strip/wire temper: good spring strength with enough ductility for stamped and lightly formed parts. | 435 | 470 | 6 | 150 HB | 20 % IACS |
Extra hard | Use for flat springs and clips needing higher elastic limit with only gentle forming with the grain. | 495 | 530 | 4 | 170 HB | 20 % IACS |
Spring hard | Classic spring-temper strip/wire for contact fingers, washers and diaphragms; form only along the grain. | 530 | 570 | 3 | 185 HB | 20 % IACS |
Extra spring hard | Highest cold-worked strength for flat springs and thin contact strip where almost no forming is required. | 560 | 600 | 3 | 195 HB | 20 % IACS |
What is C51100?
C51100 (CW450K, CuSn4) is a phosphor bronze with about 4 % tin, leaner than C51000, giving good formability at somewhat lower strength. Default-temper properties are 435 MPa yield, 470 MPa tensile, 6 % elongation, 150 HB and 20 % IACS with service to 150 °C, supplied as spring strip and coil in O60, M20 and H02 through H10 for stamped springs and contacts. Machinability is only ~20 % of free-cutting brass, conductivity is low for a contact alloy, and heavy tempers need bending with the rolling direction plus a stress-relief bake. C50100 is the alternative when conductivity outranks spring force. C51100 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 1,060°C (1,940 °F). C51100 has a yield strength of 435 MPa (63.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 84% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 110 GPa (16 Msi).
What is C51100 used for?
- springs
- electrical contacts
- gaskets
Advantages
- High strength — 435 MPa (63.1 ksi), better than 84% of copper alloy grades
Limitations
- Limited service temperature — 150°C (302 °F), worse than 96% of copper alloy grades
- Difficult to machine — 22/100, worse than 94% of copper alloy grades
- Limited ductility — 6%, worse than 89% of copper alloy grades
C51100 properties
Typical room-temperature values for C51100-H04; bars are the position among copper alloy grades.
Physical3
C51100 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 1,060°C (1,940 °F).
Mechanical13
C51100 has a yield strength of 435 MPa (63.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 84% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
C51100 is rated for continuous service to 150°C (302 °F). It conducts heat at 84 W/m·K (48.5 BTU/hr·ft·°F), better than 51% of copper alloy grades. Thermal expansion is 17.8 µm/m·K (9.89 µin/in·°F).
Electrical3
C51100 conducts electricity at 20 % IACS, better than 52% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 76% of copper alloy grades.
Sustainability4
Producing a kilogram of C51100 takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 69% of copper alloy grades. Typical recycled content is 35%.
Manufacturability7
C51100's machinability is poor (22/100, worse than 94% of copper alloy grades); weldability good (55/100); formability good (60/100).
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. C51100 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C51100
Is C51100 easy to machine?
Rated only ~20 % of free-cutting brass — gummy chips; use sharp positive-rake tools, high speed, light feed and good lubrication, or specify a leaded bronze for screw-machine work.
Can C51100 be welded?
Best joined by resistance spot/seam or GTAW with matching phosphor-bronze filler; keep heat low to avoid tin segregation, and solder/braze readily for electrical assemblies.
Can C51100 be formed, bent or molded?
Excellent stamping and bending in O60/H02; in H04 and above bend with the rolling direction and allow generous radii, then stress-relieve 175–200 °C to stabilize springs.
C51100 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 | 3.5 – 4.9 | 4.2 |
| Pdeoxidizer / solid-solution hardener | 0.03 – 0.35 | 0.1 |
| Zn | ≤ 0.3 | |
| Fe | ≤ 0.1 | |
| Pb | ≤ 0.05 | |
| CuCu + named elements 99.5 % min | balance |
What surface finishes work on C51100?
Takes tin, nickel, silver and gold plating well for contact surfaces; polishes to a bright bronze finish and can be chemically darkened, but not anodizable.
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 C51100 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- CW450KCuSn4
How much does C51100 cost?
C51100 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.
C51100 — frequently asked
What is C51100 used for?
C51100 is typically used for springs, electrical contacts and gaskets. In short: formable 4 % tin bronze; spring-temper contact strip; low conductivity, 20 % IACS.
What is the yield strength of C51100?
C51100 has a typical yield strength of 435 MPa (63.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 84% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C51100 easy to machine?
Not especially — machinability is rated poor (22/100, worse than 94% of copper alloy grades). Rated only ~20 % of free-cutting brass — gummy chips; use sharp positive-rake tools, high speed, light feed and good lubrication, or specify a leaded bronze for screw-machine work.
Can C51100 be welded?
Yes — weldability is rated good (55/100). Best joined by resistance spot/seam or GTAW with matching phosphor-bronze filler; keep heat low to avoid tin segregation, and solder/braze readily for electrical assemblies.
What surface finishes work on C51100?
Takes tin, nickel, silver and gold plating well for contact surfaces; polishes to a bright bronze finish and can be chemically darkened, but not anodizable.
Can C51100 be formed, bent or molded?
Excellent stamping and bending in O60/H02; in H04 and above bend with the rolling direction and allow generous radii, then stress-relieve 175–200 °C to stabilize springs.
What is the maximum service temperature of C51100?
C51100 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.
What is the difference between C51100-H04 and C51100-O60?
H04 is the default condition — the standard stocked strip/wire temper: good spring strength with enough ductility for stamped and lightly formed parts. O60: pick for deep drawing, severe bending or forming before a final stress-relief; lowest strength, maximum ductility. Yield strength is 435 MPa in H04 versus 140 MPa in O60.
How much does C51100 cost?
C51100 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 B103/B103M — Phosphor Bronze Plate, Sheet, Strip and Rolled Bar — ASTM International (2019)
- ASTM B159/B159M — Phosphor Bronze Wire — ASTM International (2018)
- EN 1652 / EN 12163 — CW450K (CuSn4) — CEN (2016)
- Copper Alloy C51100 property sheet — Copper Development Association (copper.org) (2024)
- ASM Handbook Vol. 2 — Properties of Copper and Copper Alloys — ASM International (1990)
- GB/T 2059 / GB/T 2049 QSn4-0.3 — SAC (2017)
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.