Copper Alloy C51900
UNS C51900 · EN CuSn6, CW452K
C51900 is a 6 % tin phosphor bronze (CuSn6, CW452K, EN 2.1020) — solid-solution strengthened by tin and deoxidised with phosphorus — stocked as strip, wire and rod in tempers from O60 through H10 and spring tempers.
Values for the H02 condition
C51900 tempers and conditions
C51900 is supplied in 10 conditions, soft to hard. H02 is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick for deep drawing, severe forming or coining before final heat treatment. | 180 | 380 | 60 | 95 HB | — |
Quarter hard | Pick when moderate bending or forming is still needed but higher strength than annealed is wanted. | 340 | 450 | 35 | 128 HB | 15 % IACS |
Light-drawn wire/rod | Pick for wire and small rod that must still be coiled or headed after drawing. | 400 | 500 | 22 | 150 HB | 15 % IACS |
H02Default Half hard | Default stocked strip temper: balanced strength and bendability for contacts, clips and washers. | 450 | 520 | 20 | 155 HB | 15 % IACS |
Full hard | Pick for flat springs and contacts with only gentle bends, where higher elastic limit matters. | 530 | 600 | 10 | 175 HB | 14.5 % IACS |
Extra hard | Pick where near-spring strength is needed but full spring temper is too brittle to form. | 590 | 655 | 7 | 193 HB | 14 % IACS |
Spring hard | Standard temper for connector springs, diaphragms and clips loaded in bending fatigue. | 630 | 695 | 5 | 200 HB | 14 % IACS |
Extra spring hard | Highest cold-rolled strength; use for flat springs bent only along the rolling direction. | 670 | 730 | 3 | 210 HB | 14 % IACS |
spring temper, stress-relieved (low-temperature bake) | Pick for formed springs that must hold load: a 180–230 °C bake raises the elastic limit and cuts stress relaxation. | 670 | 710 | 5 | 19 HRC | 14 % IACS |
Hard drawn | Pick for helical compression/extension springs and woven mesh needing maximum wire strength. | 690 | 760 | 4 | 218 HB | 14 % IACS |
What is C51900?
C51900 is a 6 % tin phosphor bronze (CuSn6, CW452K, EN 2.1020) — solid-solution strengthened by tin and deoxidised with phosphorus — stocked as strip, wire and rod in tempers from O60 through H10 and spring tempers. Engineers select it for spring contacts, connectors and bushings, where the harder conditions give about 450 MPa yield, 520 MPa tensile, HRB 78 and 20 % elongation. Machinability is only ~20 % of free-cutting brass, fusion welding is poor, and it cannot be anodised; C51000 forms more easily, while C52100 carries higher spring loads. C51900 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 910°C (1,670 °F). C51900 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — stronger than 86% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 115 GPa (16.7 Msi).
What is C51900 used for?
- Springs & contacts
- Connectors
- Bushings
Advantages
- High strength — 450 MPa (65.3 ksi), better than 86% of copper alloy grades
Limitations
- Difficult to machine — 25/100, worse than 86% of copper alloy grades
C51900 properties
Typical room-temperature values for C51900-H02; bars are the position among copper alloy grades.
Physical3
C51900 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 910°C (1,670 °F).
Mechanical14
C51900 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — stronger than 86% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
C51900 is rated for continuous service to 200°C (392 °F). It conducts heat at 67 W/m·K (38.7 BTU/hr·ft·°F), worse than 56% of copper alloy grades. Thermal expansion is 18.5 µm/m·K (10.3 µin/in·°F).
Electrical3
C51900 conducts electricity at 15 % IACS, worse than 54% 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 C51900 takes about 62 MJ of energy and emits 4.2 kg of CO₂ — more than 76% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C51900's machinability is poor (25/100, worse than 86% of copper alloy grades); weldability fair (45/100); formability good (55/100).
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. C51900 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C51900
Is C51900 easy to machine?
Machinability only ~20 % of free-cutting brass — gummy, work-hardening chips; use sharp positive-rake tools, high speed, light feeds and flood coolant.
Can C51900 be welded?
Solder and braze excellently and resistance-weld well; oxyacetylene and TIG/MIG welding are poor because of tin oxide and hot-shortness, so avoid fusion joints in springs.
Can C51900 be formed, bent or molded?
Excellent cold formability in O60/H01; hard and spring tempers must be bent with the bend axis transverse to rolling and often need a 180–230 °C post-form stress relief to set the shape.
Manufacturability
The process limits FabDigit applies to C51900. Every C51900 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
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 | Better55 / 100 |
|---|---|
| Weldability | Better45 / 100 |
| Bendable | Yes |
C51900 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 | 5 – 7 | 6 |
| Pdeoxidizer; raises strength | 0.03 – 0.35 | 0.2 |
| Zn | ≤ 0.3 | |
| Fe | ≤ 0.1 | |
| Pb | ≤ 0.05 | |
| CuCu + named elements 99.5 % min | balance |
What surface finishes work on C51900?
Not anodizable; readily electroplated with tin, nickel, silver or gold after cyanide-free cleaning, and polishes to a bright bronze finish (bright-dip or lacquer to stop tarnish).
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 C51900 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- CuSn6CW452K2.1020
- Also called
- Phosphor BronzePhosphor Bronze 6%C
How much does C51900 cost?
C51900 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.
C51900 — frequently asked
What is C51900 used for?
C51900 is typically used for springs & contacts, connectors and bushings. In short: spring-grade phosphor bronze.
What is the yield strength of C51900?
C51900 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — stronger than 86% of copper alloy grades. Strength varies by condition: see the 10 listed tempers.
Is C51900 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 86% of copper alloy grades). Machinability only ~20 % of free-cutting brass — gummy, work-hardening chips; use sharp positive-rake tools, high speed, light feeds and flood coolant.
Can C51900 be welded?
With care — weldability is rated fair (45/100). Solder and braze excellently and resistance-weld well; oxyacetylene and TIG/MIG welding are poor because of tin oxide and hot-shortness, so avoid fusion joints in springs.
What surface finishes work on C51900?
Not anodizable; readily electroplated with tin, nickel, silver or gold after cyanide-free cleaning, and polishes to a bright bronze finish (bright-dip or lacquer to stop tarnish).
Can C51900 be formed, bent or molded?
Excellent cold formability in O60/H01; hard and spring tempers must be bent with the bend axis transverse to rolling and often need a 180–230 °C post-form stress relief to set the shape.
What is the maximum service temperature of C51900?
C51900 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 C51900-H02 and C51900-O60?
H02 is the default condition — default stocked strip temper: balanced strength and bendability for contacts, clips and washers. O60: pick for deep drawing, severe forming or coining before final heat treatment. Yield strength is 450 MPa in H02 versus 180 MPa in O60.
How much does C51900 cost?
C51900 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 C51900?
Yes — C51900 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. 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)
- EN 1654 / EN 1652 — Copper and copper alloys, strip for springs and connectors (CuSn6, CW452K) — CEN (2019)
- GB/T 2059 / GB/T 2040 — (QSn6.5-0.1) — SAC (2017)
- C51900 alloy datasheet — Copper Development Association (copper.org) (2023)
- CuSn6 Werkstoff-Datenblatt — Deutsches Kupferinstitut (2005)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys — ASM International (1990)
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.