Copper Alloy C64700-O61
Heat-treated state
UNS C64700 · ASTM B411 · EN CuNi2Si
O61 = annealed
Softest condition for maximum forming/bending before any age hardening.
Values for the O61 condition
Other C64700 tempers and conditions
C64700 is listed in 9 conditions; see the grade overview at C64700.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O61This page Annealed | Softest condition for maximum forming/bending before any age hardening. | 125 | 330 | 45 | 80 HB | 42 % IACS |
Solution heat treated | Choose when parts must be deep-drawn, formed or machined before a customer-performed ageing cycle. | 140 | 340 | 45 | 85 HB | 25 % IACS |
Solution heat treated and cold worked, quarter hard | Light cold work before ageing; used when moderate stiffness plus some remaining formability is needed. | 310 | 415 | 25 | 115 HB | 26 % IACS |
Solution heat treated and cold worked, half hard | Half-hard drawn rod/wire for parts to be aged after light forming or heading. | 380 | 460 | 15 | 135 HB | 26 % IACS |
TF00Default Solution heat treated and precipitation hardened | Standard stocked condition: best balance of strength, ductility and ~38% IACS conductivity for fasteners, bushings and valve stems. | 415 | 550 | 18 | 165 HB | 38 % IACS |
Solution heat treated and cold worked, full hard | Hard-drawn, un-aged stock: good straightness and strength when ageing will be done after machining. | 450 | 515 | 10 | 155 HB | 27 % IACS |
TD01 and precipitation hardened | Light cold work plus ageing when strength above TF00 is needed with reasonable ductility. | 515 | 600 | 14 | 12 HRC | 39 % IACS |
TD02 and precipitation hardened | Half-hard plus age: common for springs, connectors and high-load bushings. | 570 | 655 | 11 | 18 HRC | 40 % IACS |
TD04 and precipitation hardened | Maximum-strength temper for wear parts, high-strength fasteners and welding-electrode holders; lowest ductility. | 655 | 725 | 8 | 22 HRC | 40 % IACS |
What is C64700-O61?
C64700-O61 is C64700 heat treated to O61 — softest condition for maximum forming/bending before any age hardening. C64700-O61 has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 130 GPa (18.9 Msi). C64700-O61 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,030°C (1,886 °F). TF00 is the default condition FabDigit quotes; O61 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 45%, better than 91% of copper alloy grades
- Stiff — 130 GPa (18.9 Msi), better than 89% of copper alloy grades
- Readily welded — 75/100, better than 89% of copper alloy grades
- Forms and bends easily — 85/100, better than 85% of copper alloy grades
- High electrical conductivity — 42 % IACS, better than 75% of copper alloy grades
Limitations
- Low strength — 125 MPa (18.1 ksi), worse than 77% of copper alloy grades
C64700-O61 properties
Typical room-temperature values for C64700-O61; 19 are specific to this condition. Other listed values are C64700 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C64700-O61 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,030°C (1,886 °F).
Mechanical13
C64700-O61 has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 130 GPa (18.9 Msi).
Thermal6
C64700-O61 is rated for continuous service to 250°C (482 °F). It conducts heat at 170 W/m·K (98.2 BTU/hr·ft·°F), better than 74% of copper alloy grades. Thermal expansion is 17.6 µm/m·K (9.78 µin/in·°F).
Electrical3
C64700-O61 conducts electricity at 42 % IACS, better than 75% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 58% of copper alloy grades.
Sustainability4
Producing a kilogram of C64700-O61 takes about 62 MJ of energy and emits 4 kg of CO₂ — more than 76% of copper alloy grades. Typical recycled content is 35%.
Manufacturability8
C64700-O61's machinability is poor (30/100, worse than 67% of copper alloy grades); weldability very good (75/100); formability excellent (85/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C64700-O61
Is C64700 easy to machine?
Machines like a tough medium-strength bronze (~30 % of free-cutting brass); use sharp positive-rake carbide, high speed, generous coolant — best chip control in the aged TF00/TH condition.
Can C64700 be welded?
GTAW/GMAW with matching or silicon-bronze filler is good; keep heat input low and re-age after welding since the HAZ over-ages and softens.
Can C64700 be formed, bent or molded?
Form, head or draw in the TB00/O61 condition, then age at ~450–500 °C for 2–3 h; cold forming in TH tempers risks cracking.
What surface finishes work on C64700?
Not anodizable — polishes to a bright bronze finish and accepts tin, nickel, silver or gold plating; passivate or lacquer to limit atmospheric tarnish.
C64700 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 |
|---|---|---|
| Ni | 1.6 – 2.2 | 1.9 |
| Si | 0.5 – 0.8 | 0.65 |
| Zn | ≤ 0.5 | — |
| Fe | ≤ 0.1 | — |
| Pb | ≤ 0.09 | — |
| Curemainder, Cu + named elements 99.5 % min (Ag counted as Cu) | balance | — |
C64700-O61 — frequently asked
What is C64700-O61 used for?
C64700-O61 is typically used for fasteners, springs and wear-resistant components. In short: age-hardening silicon bronze; strength with 38% IACS; wear-resistant weldable bronze.
What is the yield strength of C64700-O61?
C64700-O61 has a typical yield strength of 125 MPa (18.1 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 77% of copper alloy grades. Strength varies by condition: see the 9 listed tempers.
Is C64700-O61 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 67% of copper alloy grades). Machines like a tough medium-strength bronze (~30 % of free-cutting brass); use sharp positive-rake carbide, high speed, generous coolant — best chip control in the aged TF00/TH condition.
Can C64700-O61 be welded?
Yes — weldability is rated very good (75/100). GTAW/GMAW with matching or silicon-bronze filler is good; keep heat input low and re-age after welding since the HAZ over-ages and softens.
What surface finishes work on C64700-O61?
Not anodizable — polishes to a bright bronze finish and accepts tin, nickel, silver or gold plating; passivate or lacquer to limit atmospheric tarnish.
Can C64700-O61 be formed, bent or molded?
Form, head or draw in the TB00/O61 condition, then age at ~450–500 °C for 2–3 h; cold forming in TH tempers risks cracking.
What is the maximum service temperature of C64700-O61?
C64700-O61 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C64700-TF00 and C64700-O61?
TF00 is the default condition — standard stocked condition: best balance of strength, ductility and ~38% IACS conductivity for fasteners, bushings and valve stems. O61: softest condition for maximum forming/bending before any age hardening. Yield strength is 415 MPa in TF00 versus 125 MPa in O61.
Sources
- ASTM B411/B411M — Copper-Nickel-Silicon Alloy Rod and Bar — ASTM International (2020)
- CDA Alloy Datasheet C64700 (UNS) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- GB/T 5231 / JIS H3110 C1860 Corson alloy designations — SAC / JISC (2022)
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.