Copper Alloy C51000
UNS C51000 · ASTM B139, B103 · EN CuSn5, CW451K · JIS C5101, C5111
C51000 is the classic 5 % tin, phosphorus-deoxidized wrought bronze (CuSn5P, "Phosphor Bronze A"), supplied mainly as strip, wire and rod.
Values for the O condition
C51000 tempers and conditions
C51000 is supplied in 9 conditions, soft to hard. O is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ODefault Annealed | Pick for deep drawing, severe bending or forming before a final stress-relief/age. | 140 | 340 | 60 | 80 HB | 15 % IACS |
Soft annealed | Fully 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 | 330 | 62 | 60 HB | 15 % IACS |
As hot rolled | Mill-condition hot-rolled C51000 phosphor bronze plate/bar: soft, ductile and highly formable, with strength only slightly above the fully annealed state. | 180 | 350 | 48 | 70 HB | 15 % IACS |
Quarter hard | Compromise temper when moderate strength must survive a fairly sharp form. | 310 | 415 | 32 | 110 HB | 14.5 % IACS |
Half hard | Most common general-purpose strip temper for stamped parts needing strength plus mild bending. | 415 | 480 | 22 | 78 HRB | 15 % IACS |
Full hard | Use for high-strength flat stock, hard-drawn wire and rod where forming is limited to gentle bends. | 515 | 560 | 12 | 87 HRB | — |
Extra hard | Step between hard and spring temper for flat springs with only straight-line forming. | 560 | 620 | 8 | 11 HRC | 13.8 % IACS |
Spring hard | Standard temper for contact springs, diaphragms and clips; stress-relieve after forming to hold load. | 600 | 670 | 4 | 13 HRC | 13.5 % IACS |
Extra spring hard | Maximum-strength strip for the highest contact forces in thin gauges; forming essentially limited to flat blanking. | 630 | 720 | 3 | 15 HRC | 13.2 % IACS |
What is C51000?
C51000 is the classic 5 % tin, phosphorus-deoxidized wrought bronze (CuSn5P, "Phosphor Bronze A"), supplied mainly as strip, wire and rod. It combines high strength and excellent spring/elastic properties with good cold formability, seawater corrosion resistance and low stress relaxation, which is why it dominates connector contacts, springs, diaphragms, bellows and fasteners. Limits are modest electrical/thermal conductivity (~15 % IACS), poor machinability compared with leaded brasses, and softening/relaxation above roughly 120–150 °C in spring tempers. C51000 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 954°C (1,749 °F). C51000 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 60% and the elastic modulus is 110 GPa (16 Msi).
What is C51000 used for?
- Electrical connector contacts
- Precision strip springs and spring clips
- Switch and relay blades
- Diaphragms
- Bellows
- Fasteners and washers
- Marine fittings
Advantages
- Ductile — tolerates forming and impact — 60%, better than 99% of copper alloy grades
- Forms and bends easily — 90/100, better than 89% of copper alloy grades
Limitations
- Difficult to machine — 25/100, worse than 86% of copper alloy grades
- High embodied carbon — 4.3 kg CO₂/kg, worse than 77% of copper alloy grades
C51000 properties
Typical room-temperature values for C51000-O; bars are the position among copper alloy grades.
Physical3
C51000 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 954°C (1,749 °F).
Mechanical11
C51000 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 60% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
C51000 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 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 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's machinability is poor (25/100, worse than 86% 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.
Strength versus weight in the copper alloy family
Yield strength against density for every copper alloy grade FabDigit runs. C51000 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C51000
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.
Manufacturability
The process limits FabDigit's quote engine applies to C51000. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better25 / 100 |
|---|---|
| ISO material group | N.5 |
| Cutting speed (rough / finish) | 180 / 220 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 6× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better90 / 100 |
|---|---|
| Weldability | Better45 / 100 |
| Bendable | Yes |
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 |
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.
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).
Passivation
Plating
Organic Coating
Equivalent designations
Standards and trade names that resolve to Copper Alloy C51000 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- B139B103
- EN / DIN / Werkstoff-Nr.
- CuSn5CW451K
- JIS
- C5101C5111
- Trade names
- Phosphor Bronze A
- Also called
- Phosphor Bronze
- Similar grades
- 2.1030C5102QSn4-0.3QSn4-3
How much does C51000 cost?
C51000 is a specialty-cost copper alloy ($$$$$), pricier than about 58% 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.
C51000 — frequently asked
What is C51000 used for?
C51000 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?
C51000 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 9 listed tempers.
Is C51000 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 86% 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 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?
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 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?
C51000 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.
How much does C51000 cost?
C51000 is a specialty-cost copper alloy ($$$$$), pricier than about 58% 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.
Can FabDigit make parts in C51000?
Yes — C51000 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; 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.