Copper Alloy C18400-O61
Heat-treated state
UNS C18400
O61 = annealed
Standard soft mill-annealed condition for bending, riveting and staking where high conductivity but only modest strength is needed.
Values for the O61 condition
Other C18400 tempers and conditions
C18400 is listed in 7 conditions; see the grade overview at C18400.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O61This page Annealed | Standard soft mill-annealed condition for bending, riveting and staking where high conductivity but only modest strength is needed. | 85 | 230 | 42 | 55 HB | 80 % IACS |
Solution heat treated | Choose for maximum formability/deep forming before the customer performs the ageing (precipitation) treatment; conductivity is low until aged. | 95 | 240 | 40 | 60 HB | 42 % IACS |
Solution heat treated and cold worked, half hard | Cold-drawn half-hard rod/wire for straightness and moderate strength where a customer ageing step is not planned. | 330 | 380 | 14 | 110 HB | 75 % IACS |
TF00Default Solution heat treated and precipitation hardened | The standard stocked electrode/contact condition: ~80% IACS with roughly 470 MPa tensile — pick it for spot-welding electrodes and current-carrying structural parts. | 380 | 470 | 18 | 140 HB | 82 % IACS |
Solution heat treated and cold worked, full hard | Hard-drawn unaged wire/rod where springiness and dimensional straightness matter more than peak strength. | 390 | 430 | 10 | 125 HB | 74 % IACS |
TD01 and precipitation hardened | Cold work before ageing raises yield strength above TF00 while keeping ~80% IACS — used for contact arms, commutator segments and high-load electrode holders. | 450 | 515 | 15 | 150 HB | 80 % IACS |
TD04 and precipitation hardened | Highest-strength commercial condition for small rod, wire and strip where maximum yield strength with high conductivity is needed. | 485 | 550 | 12 | 160 HB | 80 % IACS |
What is C18400-O61?
C18400-O61 is C18400 heat treated to O61 — standard soft mill-annealed condition for bending, riveting and staking where high conductivity but only modest strength is needed. C18400-O61 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 42% and the elastic modulus is 115 GPa (16.7 Msi). C18400-O61 has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,070°C (1,958 °F). TF00 is the default condition FabDigit quotes; O61 is available on request or by drawing note.
Advantages
- High service temperature — 350°C (662 °F), better than 95% of copper alloy grades
- Ductile — tolerates forming and impact — 42%, better than 86% of copper alloy grades
- Forms and bends easily — 85/100, better than 85% of copper alloy grades
- Conducts heat well — 320 W/m·K (184.9 BTU/hr·ft·°F), better than 84% of copper alloy grades
- High electrical conductivity — 80 % IACS, better than 84% of copper alloy grades
Limitations
- Low strength — 85 MPa (12.3 ksi), worse than 89% of copper alloy grades
C18400-O61 properties
Typical room-temperature values for C18400-O61; 13 are specific to this condition. Other listed values are C18400 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C18400-O61 has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,070°C (1,958 °F).
Mechanical12
C18400-O61 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 42% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
C18400-O61 is rated for continuous service to 350°C (662 °F). It conducts heat at 320 W/m·K (184.9 BTU/hr·ft·°F), better than 84% of copper alloy grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical3
C18400-O61 conducts electricity at 80 % IACS, better than 84% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 69% of copper alloy grades.
Sustainability4
Producing a kilogram of C18400-O61 takes about 57 MJ of energy and emits 3.8 kg of CO₂ — less than 52% of copper alloy grades. Typical recycled content is 30%.
Manufacturability8
C18400-O61's machinability is fair (35/100, better than 51% of copper alloy grades); weldability fair (45/100); formability excellent (85/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C18400-O61
Is C18400 easy to machine?
Machines like tough copper — gummy chips; use sharp positive-rake carbide, high speed, generous coolant; machine in the aged (TF00/TH01) temper for best finish.
Can C18400 be welded?
Excellent for resistance welding as an electrode material; GTAW/EBW possible with He shielding and low heat input but the HAZ over-ages and loses ~30–40% strength, so re-age after welding where possible.
Can C18400 be formed, bent or molded?
Form, deep-draw or head in the TB00/O61 soft tempers then solution treat (~980–1000 °C, water quench) and age (~450–500 °C, 2–4 h) for final properties.
What surface finishes work on C18400?
No anodizing; use bright dip/pickle to remove Cr-rich oxide, then nickel or silver plating for contacts, or leave bare — natural patina forms in service.
C18400 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 |
|---|---|---|
| Crprecipitation-hardening element | 0.4 – 1.2 | 0.8 |
| Fe | ≤ 0.15 | — |
| Si | ≤ 0.1 | — |
| Al | ≤ 0.1 | — |
| Zn | ≤ 0.1 | — |
| Pb | ≤ 0.05 | — |
| CuCu + named elements 99.5 % min (Ag counted as Cu) | balance | — |
C18400-O61 — frequently asked
What is C18400-O61 used for?
C18400-O61 is typically used for resistance welding electrodes, electrical contacts, electrode tips and caps, switchgear current-carrying parts, connector bodies and conductive fixture components. In short: 82 % IACS chromium copper; 400 °C electrode service; age-hardenable, 18 % elongation.
What is the yield strength of C18400-O61?
C18400-O61 has a typical yield strength of 85 MPa (12.3 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 89% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C18400-O61 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Machines like tough copper — gummy chips; use sharp positive-rake carbide, high speed, generous coolant; machine in the aged (TF00/TH01) temper for best finish.
Can C18400-O61 be welded?
With care — weldability is rated fair (45/100). Excellent for resistance welding as an electrode material; GTAW/EBW possible with He shielding and low heat input but the HAZ over-ages and loses ~30–40% strength, so re-age after welding where possible.
What surface finishes work on C18400-O61?
No anodizing; use bright dip/pickle to remove Cr-rich oxide, then nickel or silver plating for contacts, or leave bare — natural patina forms in service.
Can C18400-O61 be formed, bent or molded?
Form, deep-draw or head in the TB00/O61 soft tempers then solution treat (~980–1000 °C, water quench) and age (~450–500 °C, 2–4 h) for final properties.
What is the maximum service temperature of C18400-O61?
C18400-O61 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C18400-TF00 and C18400-O61?
TF00 is the default condition — the standard stocked electrode/contact condition: ~80% IACS with roughly 470 MPa tensile — pick it for spot-welding electrodes and current-carrying structural parts. O61: standard soft mill-annealed condition for bending, riveting and staking where high conductivity but only modest strength is needed. Yield strength is 380 MPa in TF00 versus 85 MPa in O61.
Sources
- ASTM B224 — Classification of Coppers — ASTM International (2021)
- ASTM B133 / B187 — Copper rod, bar and shapes — ASTM International (2020)
- CDA Alloy Datasheet — Chromium Copper (C182xx/C184xx) — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties of Nonferrous Alloys — ASM International (1990)
- RWMA Class 2 electrode material bulletin — Resistance Welder Manufacturers' Association (2015)
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.