Copper Alloy C18000
UNS C18000
C18000 is a nickel–silicon–chromium precipitation-hardening (age-hardening) copper alloy.
Values for the H condition
C18000 tempers and conditions
C18000 is supplied in 3 conditions, soft to hard. H is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated | Soft solution-treated stock for forming, deep machining or heavy cold work before the ageing treatment. | 140 | 345 | 32 | 90 HB | 27 % IACS |
HDefault Hardened | Standard stocked condition: best balance of ~690 MPa strength with ~48 % IACS conductivity for welding electrodes, electrode holders and mould components. | 585 | 690 | 12 | 200 HB | 48 % IACS |
TD04 and precipitation hardened | Choose for maximum strength/hardness in drawn rod, wire or small-section electrodes where ductility is less critical. | 690 | 760 | 8 | 225 HB | 46 % IACS |
What is C18000?
C18000 is a nickel–silicon–chromium precipitation-hardening (age-hardening) copper alloy. After solution treatment and ageing it gives about 690 MPa tensile and 585 MPa yield at 12 % elongation, 200 HB (95 HRB), together with 45–52 % IACS conductivity, 200 W/m·K and good resistance to softening at temperature; usual forms are rod, plate and forged electrode blanks. It is used for RWMA Class 3 resistance-welding electrodes and holders, continuous-casting mould components, mould inserts and high-current conductive structure. Machinability is moderate, fusion welding is poor (braze or bolt instead), service is limited to about 400 °C, and longer exposure above roughly 450 °C over-ages and softens it; C18200 is the higher-conductivity, lower-strength alternative. C18000 has a density of 8.78 g/cm³ (0.317 lb/in³), heavier than 53% of copper alloy grades. It melts at 1,030°C (1,886 °F). C18000 has a yield strength of 585 MPa (84.8 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 93% of copper alloy grades. Elongation at break is 12% and the elastic modulus is 131 GPa (19 Msi).
What is C18000 used for?
- Resistance welding electrodes and holders (RWMA Class 3)
- Continuous-casting mould components
- Mould and die inserts
- Switchgear components
- Resistance welding tips
- High-current conductive structural parts
Advantages
- High service temperature — 400°C (752 °F), better than 97% of copper alloy grades
- High strength — 585 MPa (84.8 ksi), better than 93% of copper alloy grades
- Stiff — 131 GPa (19 Msi), better than 91% of copper alloy grades
- Conducts heat well — 200 W/m·K (115.6 BTU/hr·ft·°F), better than 78% of copper alloy grades
- High electrical conductivity — 48 % IACS, better than 78% of copper alloy grades
C18000 properties
Typical room-temperature values for C18000-H; bars are the position among copper alloy grades.
Physical3
C18000 has a density of 8.78 g/cm³ (0.317 lb/in³), heavier than 53% of copper alloy grades. It melts at 1,030°C (1,886 °F).
Mechanical12
C18000 has a yield strength of 585 MPa (84.8 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 93% of copper alloy grades. Elongation at break is 12% and the elastic modulus is 131 GPa (19 Msi).
Thermal6
C18000 is rated for continuous service to 400°C (752 °F). It conducts heat at 200 W/m·K (115.6 BTU/hr·ft·°F), better than 78% of copper alloy grades. Thermal expansion is 17.6 µm/m·K (9.78 µin/in·°F).
Electrical3
C18000 conducts electricity at 48 % IACS, better than 78% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 68% of copper alloy grades.
Sustainability4
Producing a kilogram of C18000 takes about 56 MJ of energy and emits 4 kg of CO₂ — less than 61% of copper alloy grades. Typical recycled content is 30%.
Manufacturability6
C18000's machinability is fair (50/100, better than 69% of copper alloy grades); weldability fair (35/100); formability poor (30/100).
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. C18000 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C18000
Is C18000 easy to machine?
Machines better than pure copper — use sharp carbide tools, positive rake, high speed and generous coolant; machine in the aged condition for good finish and to avoid post-age distortion.
Can C18000 be welded?
Fusion welding is generally not recommended (over-ageing and porosity); join by brazing, silver soldering or mechanical/press fits, and re-age locally if heat-affected.
Can C18000 be formed, bent or molded?
Form, bend or cold-draw in the TB00 solution-treated state, then age ~450–500 °C for 2–3 h; hardened material has limited cold ductility.
Manufacturability
The process limits FabDigit applies to C18000. Every C18000 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair50 / 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 | Better30 / 100 |
|---|---|
| Weldability | Better35 / 100 |
| Bendable | Yes |
C18000 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 | 1.8 – 3 | 2.4 |
| Si | 0.4 – 0.8 | 0.6 |
| Cr | 0.1 – 0.8 | 0.4 |
| CuCu + named elements 99.5 % min (Ag counted as Cu) | balance |
What surface finishes work on C18000?
Not anodisable; takes bright polish, electroless/electrolytic Ni or Cr plating, or chemical blackening — degrease well because Cr/Si surface oxides hinder plating adhesion.
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 C18000 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Cu-Cr-Ni-Si
How much does C18000 cost?
C18000 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.
C18000 — frequently asked
What is C18000 used for?
C18000 is typically used for resistance welding electrodes and holders (RWMA Class 3), continuous-casting mould components, mould and die inserts, switchgear components, resistance welding tips and high-current conductive structural parts. In short: oxidation resistant copper.
What is the yield strength of C18000?
C18000 has a typical yield strength of 585 MPa (84.8 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 93% of copper alloy grades. Strength varies by condition: see the 3 listed tempers.
Is C18000 easy to machine?
Reasonably — machinability is rated fair (50/100, better than 69% of copper alloy grades). Machines better than pure copper — use sharp carbide tools, positive rake, high speed and generous coolant; machine in the aged condition for good finish and to avoid post-age distortion.
Can C18000 be welded?
With care — weldability is rated fair (35/100). Fusion welding is generally not recommended (over-ageing and porosity); join by brazing, silver soldering or mechanical/press fits, and re-age locally if heat-affected.
What surface finishes work on C18000?
Not anodisable; takes bright polish, electroless/electrolytic Ni or Cr plating, or chemical blackening — degrease well because Cr/Si surface oxides hinder plating adhesion.
Can C18000 be formed, bent or molded?
Form, bend or cold-draw in the TB00 solution-treated state, then age ~450–500 °C for 2–3 h; hardened material has limited cold ductility.
What is the maximum service temperature of C18000?
C18000 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 C18000-H and C18000-TB00?
H is the default condition — standard stocked condition: best balance of ~690 MPa strength with ~48 % IACS conductivity for welding electrodes, electrode holders and mould components. TB00: soft solution-treated stock for forming, deep machining or heavy cold work before the ageing treatment. Yield strength is 585 MPa in H versus 140 MPa in TB00.
How much does C18000 cost?
C18000 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.
Can FabDigit make parts in C18000?
Yes — C18000 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
- Copper Alloy C18000 datasheet (UNS C18000) — Copper Development Association (copper.org) (2023)
- ASTM B441 / B422 – copper-nickel-silicon-chromium rod, bar and plate — ASTM International (2019)
- RWMA Bulletin 16 – Resistance Welding Electrode Materials, Class 3 — AWS / RWMA (2017)
- ASM Handbook Vol.2 — Properties of Nonferrous Alloys — ASM International (1990)
- CuNi2SiCr / C18000 electrode and mould alloy datasheet — Copper alloy producers (typical values) (2022)
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.