Copper Alloy C51000 · temper · default condition
Copper Alloy C51000-O
Properties of the O condition, compared with the other C51000 tempers.
Pick for deep drawing, severe bending or forming before a final stress-relief/age.
What is C51000-O?
C51000-O is C51000 in the O temper — pick for deep drawing, severe bending or forming before a final stress-relief/age. C51000-O has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 73% of copper alloy grades. Elongation at break is 60% and the elastic modulus is 110 GPa (16 Msi). C51000-O has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 67% of copper alloy grades. It melts at 954°C (1,749 °F).
Advantages
- Ductile — tolerates forming and impact — 60%, better than 99% of copper alloy grades
- Forms and bends easily — 90/100, better than 87% of copper alloy grades
Limitations
- Difficult to machine — 25/100, worse than 85% of copper alloy grades
- High embodied carbon — 4.3 kg CO₂/kg, worse than 78% of copper alloy grades
C51000-O properties
Typical room-temperature values for C51000-O — 11 properties are specific to this condition; the rest are grade-level values shared by every C51000 temper. Each bar shows where the value sits among the copper alloy grades in FabDigit's library — further right is higher.
Physical3
C51000-O has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 67% of copper alloy grades. It melts at 954°C (1,749 °F).
Mechanical11
C51000-O has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 73% of copper alloy grades. Elongation at break is 60% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
C51000-O is rated for continuous service to 200°C (392 °F). It conducts heat at 69 W/m·K (39.9 BTU/hr·ft·°F), worse than 56% of copper alloy grades. Thermal expansion is 17.8 µm/m·K (9.89 µin/in·°F).
Electrical3
C51000-O conducts electricity at 15 % IACS, worse than 54% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 69% of copper alloy grades.
Sustainability4
Producing a kilogram of C51000-O takes about 68 MJ of energy and emits 4.3 kg of CO₂ — more than 83% of copper alloy grades. Typical recycled content is 40%.
Manufacturability8
C51000-O's machinability is poor (25/100, worse than 85% of copper alloy grades); weldability fair (45/100); formability excellent (90/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other C51000 tempers and conditions
C51000 is also supplied in 8 other conditions. The full side-by-side table is on the C51000 overview.
- ODefaultPick for deep drawing, severe bending or forming before a final stress-relief/age.140 MPa yield · 80 HB
- H10Maximum-strength strip for the highest contact forces in thin gauges; forming essentially limited to flat blanking.630 MPa yield · 95 HRB
- H08Standard temper for contact springs, diaphragms and clips; stress-relieve after forming to hold load.600 MPa yield · 93 HRB
- H06Step between hard and spring temper for flat springs with only straight-line forming.560 MPa yield · 91 HRB
- H04Use for high-strength flat stock, hard-drawn wire and rod where forming is limited to gentle bends.515 MPa yield · 87 HRB
- H02Most common general-purpose strip temper for stamped parts needing strength plus mild bending.415 MPa yield · 78 HRB
- H01Compromise temper when moderate strength must survive a fairly sharp form.310 MPa yield · 60 HRB
- M20Mill-condition hot-rolled C51000 phosphor bronze plate/bar: soft, ductile and highly formable, with strength only slightly above the fully annealed state.180 MPa yield · 70 HB
- O60Fully recrystallised soft-anneal temper per ASTM B601 O60, giving the lowest strength and maximum ductility for deep drawing, bending and forming of C51000 strip, wire and rod.140 MPa yield · 60 HB
Working with C51000-O
Is C51000 easy to machine?
Gummy and abrasive to tooling — rating ~20 % of free-cutting brass; use sharp positive-rake carbide, high speed, light feed and good coolant, or switch to C54400 for turned parts.
Can C51000 be welded?
Best joined by soft soldering (excellent) or brazing/GTAW with phosphor-bronze filler; oxyacetylene welding is not recommended and hot-short cracking plus tin oxide inclusions must be controlled.
Can C51000 be formed, bent or molded?
Excellent cold formability in O/H01 tempers (deep draws, coining); harder tempers need generous bend radii, grain-direction control and a 175–230 °C stress-relief bake after forming to limit springback and relaxation.
What surface finishes work on C51000?
Not anodizable; takes bright tin, nickel, silver and gold plating readily, buffs to a warm bronze luster, and may be chemically blackened or lacquered for decorative use.
C51000 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 | 4.2 – 5.8 | 5 |
| Pdeoxidizer, raises strength | 0.03 – 0.35 | 0.15 |
| Zn | ≤ 0.3 | — |
| Fe | ≤ 0.1 | — |
| Pb | ≤ 0.05 | — |
| CuCu + named elements 99.5 % min; Ag counted as Cu | balance | — |
C51000-O — frequently asked
What is C51000-O used for?
C51000-O is typically used for electrical connector contacts, precision strip springs and spring clips, switch and relay blades, diaphragms, bellows and fasteners and washers. In short: best spring-tempered bronze.
What is the yield strength of C51000-O?
C51000-O has a typical yield strength of 140 MPa (20.3 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 73% of copper alloy grades. Strength varies by condition: see the 9 listed tempers.
Is C51000-O easy to machine?
Not especially — machinability is rated poor (25/100, worse than 85% of copper alloy grades). Gummy and abrasive to tooling — rating ~20 % of free-cutting brass; use sharp positive-rake carbide, high speed, light feed and good coolant, or switch to C54400 for turned parts.
Can C51000-O be welded?
With care — weldability is rated fair (45/100). Best joined by soft soldering (excellent) or brazing/GTAW with phosphor-bronze filler; oxyacetylene welding is not recommended and hot-short cracking plus tin oxide inclusions must be controlled.
What surface finishes work on C51000-O?
Not anodizable; takes bright tin, nickel, silver and gold plating readily, buffs to a warm bronze luster, and may be chemically blackened or lacquered for decorative use.
Can C51000-O be formed, bent or molded?
Excellent cold formability in O/H01 tempers (deep draws, coining); harder tempers need generous bend radii, grain-direction control and a 175–230 °C stress-relief bake after forming to limit springback and relaxation.
What is the maximum service temperature of C51000-O?
C51000-O 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 C51000-O and C51000-H10?
O is the default condition — pick for deep drawing, severe bending or forming before a final stress-relief/age. H10: maximum-strength strip for the highest contact forces in thin gauges; forming essentially limited to flat blanking. Yield strength is 140 MPa in O versus 630 MPa in H10.
Can FabDigit make parts in C51000-O?
Yes — C51000-O is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B103/B103M — Phosphor Bronze Plate, Sheet, Strip and Rolled Bar — ASTM International (2019)
- ASTM B139/B139M — Phosphor Bronze Rod, Bar and Shapes — ASTM International (2017)
- C51000 alloy datasheet — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- EN 1654 / CW451K CuSn5 strip for springs and connectors — CEN (2019)
- GB/T 2059 / GB/T 2049 (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.