Copper Alloy C51100-O60
Temper
UNS C51100 · EN CW450K, CuSn4
O60 = soft annealed
Pick for deep drawing, severe bending or forming before a final stress-relief; lowest strength, maximum ductility.
Values for the O60 condition
Other C51100 tempers and conditions
C51100 is listed in 7 conditions; see the grade overview at C51100.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O60This page 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-O60?
C51100-O60 is C51100 in the O60 temper — pick for deep drawing, severe bending or forming before a final stress-relief; lowest strength, maximum ductility. C51100-O60 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 48% and the elastic modulus is 110 GPa (16 Msi). C51100-O60 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). H04 is the default condition FabDigit quotes; O60 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 48%, better than 97% of copper alloy grades
- Forms and bends easily — 92/100, better than 91% of copper alloy grades
Limitations
- Difficult to machine — 22/100, worse than 94% of copper alloy grades
C51100-O60 properties
Typical room-temperature values for C51100-O60; 11 are specific to this condition. Other listed values are C51100 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C51100-O60 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-O60 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 48% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
C51100-O60 is rated for continuous service to 200°C (392 °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-O60 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-O60 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-O60's machinability is poor (22/100, worse than 94% of copper alloy grades); weldability good (55/100); formability excellent (92/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C51100-O60
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.
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.
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 | — |
C51100-O60 — frequently asked
What is C51100-O60 used for?
C51100-O60 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-O60?
C51100-O60 has a typical yield strength of 140 MPa (20.3 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 74% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C51100-O60 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-O60 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-O60?
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-O60 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-O60?
C51100-O60 is rated for continuous use to about 200°C (392 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.