Copper Alloy C77400-OS025
Temper
UNS C77400
OS025 = annealed to 0.025 mm grain size
Fine-grain anneal for a smoother formed surface and less orange peel on plated parts.
Values for the OS025 condition
Other C77400 tempers and conditions
C77400 is listed in 8 conditions; see the grade overview at C77400.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed to 0.035 mm grain size | Softest commercial strip temper — pick for deep drawing and severe forming of hollowware/flatware blanks. | 170 | 415 | 40 | 100 HB | — |
OS025This page Annealed to 0.025 mm grain size | Fine-grain anneal for a smoother formed surface and less orange peel on plated parts. | 195 | 430 | 36 | 108 HB | 11.5 % IACS |
Quarter hard | Light cold work for stamped and moderately drawn plating blanks needing more stiffness than annealed strip. | 340 | 460 | 20 | 125 HB | 11 % IACS |
H02Default Half hard | Most widely stocked strip temper — balances stamping/bending formability with useful strength for flatware and hardware. | 440 | 515 | 10 | 145 HB | — |
Full hard | Choose for flat blanking, wear surfaces and parts requiring high strength with only slight bending. | 550 | 620 | 3 | 175 HB | — |
Extra hard | For flat springy parts, slide-fastener elements and stampings that need high yield with minimal forming. | 620 | 690 | 2 | 11 HRC | 11 % IACS |
Spring hard | Spring temper strip for contacts, clips and flexures where high elastic limit matters more than formability. | 660 | 725 | 2 | 13 HRC | 10.5 % IACS |
Extra spring hard | Maximum cold-rolled strength for flat springs and fastener parts; essentially no bending capability across the grain. | 700 | 760 | 1.5 | 16 HRC | 10.5 % IACS |
What is C77400-OS025?
C77400-OS025 is C77400 in the OS025 temper — fine-grain anneal for a smoother formed surface and less orange peel on plated parts. C77400-OS025 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 56% of copper alloy grades. Elongation at break is 36% and the elastic modulus is 125 GPa (18.1 Msi). C77400-OS025 has a density of 8.7 g/cm³ (0.314 lb/in³), lighter than 56% of copper alloy grades. It melts at 960°C (1,760 °F). H02 is the default condition FabDigit quotes; OS025 is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 85/100, better than 92% of copper alloy grades
- Forms and bends easily — 90/100, better than 89% of copper alloy grades
- Ductile — tolerates forming and impact — 36%, better than 82% of copper alloy grades
Limitations
- Difficult to machine — 20/100, worse than 98% of copper alloy grades
- High embodied carbon — 4.6 kg CO₂/kg, worse than 82% of copper alloy grades
- Poor heat conductor — 45 W/m·K (26 BTU/hr·ft·°F), worse than 76% of copper alloy grades
C77400-OS025 properties
Typical room-temperature values for C77400-OS025; 19 are specific to this condition. Other listed values are C77400 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C77400-OS025 has a density of 8.7 g/cm³ (0.314 lb/in³), lighter than 56% of copper alloy grades. It melts at 960°C (1,760 °F).
Mechanical12
C77400-OS025 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 56% of copper alloy grades. Elongation at break is 36% and the elastic modulus is 125 GPa (18.1 Msi).
Thermal5
C77400-OS025 is rated for continuous service to 200°C (392 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), worse than 76% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C77400-OS025 conducts electricity at 11.5 % IACS, worse than 65% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (63/100), better than 52% of copper alloy grades.
Sustainability4
Producing a kilogram of C77400-OS025 takes about 60 MJ of energy and emits 4.6 kg of CO₂ — more than 69% of copper alloy grades. Typical recycled content is 40%.
Manufacturability6
C77400-OS025's machinability is poor (20/100, worse than 98% of copper alloy grades); weldability fair (50/100); formability excellent (90/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C77400-OS025
Is C77400 easy to machine?
Machinability only about 20 % of free-cutting brass — use sharp, high-rake tools, positive feed and good lubrication to avoid gummy, stringy chips.
Can C77400 be welded?
Resistance and brazing/soldering are the preferred joining routes; gas and arc fusion welding risk zinc fume loss and porosity, so keep heat input low and ventilate.
Can C77400 be formed, bent or molded?
Excellent cold formability in annealed and quarter-hard tempers (deep drawing, coining, spinning); interanneal at 600–750 °C and stress-relieve cold-worked parts to avoid ammonia SCC.
What surface finishes work on C77400?
Takes a bright white polish and is the classic base metal for silver, nickel and chrome electroplating; degrease and lightly acid-activate before plating.
C77400 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 |
|---|---|---|
| Cu | 43 – 47 | 45 |
| NiNi + Co | 9 – 11 | 10 |
| Fe | ≤ 0.5 | — |
| Mn | ≤ 0.5 | — |
| Pb | ≤ 0.05 | — |
| Znremainder, nominally ~45 % | balance | — |
C77400-OS025 — frequently asked
What is C77400-OS025 used for?
C77400-OS025 is typically used for silver-plated flatware blanks, zippers, hardware and decorative items. In short: classic silver-plating base metal; strip-form nickel silver; strong yet still drawable.
What is the yield strength of C77400-OS025?
C77400-OS025 has a typical yield strength of 195 MPa (28.3 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 56% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C77400-OS025 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 98% of copper alloy grades). Machinability only about 20 % of free-cutting brass — use sharp, high-rake tools, positive feed and good lubrication to avoid gummy, stringy chips.
Can C77400-OS025 be welded?
With care — weldability is rated fair (50/100). Resistance and brazing/soldering are the preferred joining routes; gas and arc fusion welding risk zinc fume loss and porosity, so keep heat input low and ventilate.
What surface finishes work on C77400-OS025?
Takes a bright white polish and is the classic base metal for silver, nickel and chrome electroplating; degrease and lightly acid-activate before plating.
Can C77400-OS025 be formed, bent or molded?
Excellent cold formability in annealed and quarter-hard tempers (deep drawing, coining, spinning); interanneal at 600–750 °C and stress-relieve cold-worked parts to avoid ammonia SCC.
What is the maximum service temperature of C77400-OS025?
C77400-OS025 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 C77400-H02 and C77400-OS035?
H02 is the default condition — most widely stocked strip temper — balances stamping/bending formability with useful strength for flatware and hardware. OS035: softest commercial strip temper — pick for deep drawing and severe forming of hollowware/flatware blanks. Yield strength is 440 MPa in H02 versus 170 MPa in OS035.
Sources
- ASTM B122/B122M — Copper-Nickel-Zinc (Nickel Silver) Plate, Sheet, Strip and Rolled Bar — ASTM (2022)
- ASTM B151/B151M — Copper-Nickel-Zinc and Copper-Nickel Rod and Bar — ASTM (2019)
- CDA Alloy Database — C77400 nickel silver 45-10 — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol.2 — Properties of Nonferrous Alloys (Nickel Silvers) — ASM International (1990)
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.