Copper Alloy C18400
UNS C18400
C18400 is a chromium copper (supplied alongside C18200) with additional minor alloying, age hardened to 380 MPa yield, 470 MPa tensile and 140 HB (78 HRB) while holding 82 % IACS and 324 W/m·K.
Reference datasheet — C18400 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the TF00 condition
C18400 tempers and conditions
C18400 is supplied in 7 conditions, soft to hard. TF00 is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
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?
C18400 is a chromium copper (supplied alongside C18200) with additional minor alloying, age hardened to 380 MPa yield, 470 MPa tensile and 140 HB (78 HRB) while holding 82 % IACS and 324 W/m·K. It is used as bar, rod and forgings for resistance welding electrodes and electrical contacts that must stay hard at service temperatures up to 400 °C and still conduct. Elongation is 18 %, machinability rates 45 and weldability 45; the fusion-weld heat-affected zone over-ages, so re-aging is needed after welding. C18100 chromium-zirconium copper is the next step when higher strength and 450 °C softening resistance are required. C18400 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). C18400 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 77% of copper alloy grades. Elongation at break is 18% and the elastic modulus is 115 GPa (16.7 Msi).
What is C18400 used for?
- Resistance welding electrodes
- Electrical contacts
- Electrode tips and caps
- Switchgear current-carrying parts
- Connector bodies
- Conductive fixture components
Advantages
- High service temperature — 400°C (752 °F), better than 97% of copper alloy grades
- Conducts heat well — 324 W/m·K (187.2 BTU/hr·ft·°F), better than 85% of copper alloy grades
- High electrical conductivity — 82 % IACS, better than 85% of copper alloy grades
- High strength — 380 MPa (55.1 ksi), better than 77% of copper alloy grades
C18400 properties
Typical room-temperature values for C18400-TF00; bars are the position among copper alloy grades.
Physical3
C18400 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 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 77% of copper alloy grades. Elongation at break is 18% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
C18400 is rated for continuous service to 400°C (752 °F). It conducts heat at 324 W/m·K (187.2 BTU/hr·ft·°F), better than 85% of copper alloy grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical3
C18400 conducts electricity at 82 % IACS, better than 85% 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 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's machinability is fair (45/100, better than 64% of copper alloy grades); weldability fair (45/100); formability fair (35/100).
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. C18400 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C18400
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.
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 |
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.
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).
Equivalent designations
Standards and trade names that resolve to Copper Alloy C18400 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- C18200
How much does C18400 cost?
C18400 is a high-cost copper alloy ($$$$), pricier than about 78% 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.
C18400 — frequently asked
What is C18400 used for?
C18400 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?
C18400 has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 77% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C18400 easy to machine?
Reasonably — machinability is rated fair (45/100, better than 64% 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 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?
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 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?
C18400 is rated for continuous use to about 400°C (752 °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.
How much does C18400 cost?
C18400 is a high-cost copper alloy ($$$$), pricier than about 78% 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.
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; 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.