Copper Alloy C18900
UNS C18900
C18900 is a lightly alloyed copper with small silicon additions, part of the C10000–C19999 wrought copper family and available from O60 through H08.
Reference datasheet — C18900 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 H04 condition
C18900 tempers and conditions
C18900 is supplied in 6 conditions, soft to hard. H04 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Choose for welding wire/rod, deep drawing, bending and any forming operation needing maximum ductility. | 95 | 275 | 45 | 55 HB | 47 % IACS |
As hot rolled | As-extruded/hot-worked mill condition for large rod and shapes that will be machined or further cold drawn. | 130 | 285 | 38 | 62 HB | 46 % IACS |
Quarter hard | Light cold work for parts that still need moderate bending but higher strength than annealed. | 230 | 315 | 25 | 80 HB | 46 % IACS |
Half hard | General-purpose balance of strength and residual formability for machined and formed contact parts. | 305 | 355 | 15 | 98 HB | 45 % IACS |
H04Default Full hard | Standard stocked condition for rod, wire and contact tips where maximum strength, hardness and wear resistance are needed. | 370 | 405 | 8 | 115 HB | 45 % IACS |
Spring hard | Heavily drawn wire condition for springy contacts and high-strength conductor wire; very limited ductility. | 425 | 455 | 4 | 130 HB | 44 % IACS |
What is C18900?
C18900 is a lightly alloyed copper with small silicon additions, part of the C10000–C19999 wrought copper family and available from O60 through H08. It provides 370 MPa yield, 405 MPa tensile, 8% elongation, 115 HB (66 HRB) and a 117 GPa modulus while retaining 45% IACS and 180 W/m·K, with a corrosion resistance score of 68 that suits marine hardware. Weldability is good (80), but formability (35) and machinability (32) are modest and service is limited to about 200 °C; plain copper such as C11000 is the choice when conductivity outweighs strength. C18900 has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,030°C (1,886 °F). C18900 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 405 MPa (58.7 ksi) — stronger than 75% of copper alloy grades. Elongation at break is 8% and the elastic modulus is 117 GPa (17 Msi).
What is C18900 used for?
- electrical connectors
- fasteners requiring conductivity
- marine hardware
Advantages
- Readily welded — 80/100, better than 93% of copper alloy grades
- High electrical conductivity — 45 % IACS, better than 77% of copper alloy grades
- High strength — 370 MPa (53.7 ksi), better than 75% of copper alloy grades
- Conducts heat well — 180 W/m·K (104 BTU/hr·ft·°F), better than 75% of copper alloy grades
Limitations
- Limited ductility — 8%, worse than 83% of copper alloy grades
C18900 properties
Typical room-temperature values for C18900-H04; bars are the position among copper alloy grades.
Physical3
C18900 has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,030°C (1,886 °F).
Mechanical14
C18900 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 405 MPa (58.7 ksi) — stronger than 75% of copper alloy grades. Elongation at break is 8% and the elastic modulus is 117 GPa (17 Msi).
Thermal6
C18900 is rated for continuous service to 200°C (392 °F). It conducts heat at 180 W/m·K (104 BTU/hr·ft·°F), better than 75% of copper alloy grades. Thermal expansion is 17.6 µm/m·K (9.78 µin/in·°F).
Electrical3
C18900 conducts electricity at 45 % IACS, better than 77% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 69% of copper alloy grades.
Sustainability4
Producing a kilogram of C18900 takes about 57 MJ of energy and emits 3.7 kg of CO₂ — less than 52% of copper alloy grades. Typical recycled content is 35%.
Manufacturability8
C18900's machinability is poor (32/100, worse than 57% of copper alloy grades); weldability very good (80/100); 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. C18900 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C18900
Is C18900 easy to machine?
Gummy like most non-leaded coppers — use sharp positive-rake carbide, high speed, generous feed and flood coolant; rating ≈ 20 % of AISI 1212 and best in H02/H04 tempers.
Can C18900 be welded?
Readily joined by GTAW/GMAW with matching or ErCu/ErCuSi filler; preheat thick sections for the high thermal conductivity, and expect full loss of cold-worked strength in the HAZ.
Can C18900 be formed, bent or molded?
Excellent cold formability in O60 (deep draw, roll, bend); in H04 keep bend radii ≥ 2t and interanneal at 450–600 °C for severe work.
C18900 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 |
|---|---|---|
| Snsolid-solution strengthener | 0.6 – 0.9 | 0.75 |
| Sideoxidiser and strengthener | 0.1 – 0.3 | 0.2 |
| Mndeoxidiser / arc stabiliser in weld wire | 0.02 – 0.2 | 0.1 |
| Presidual | ≤ 0.05 | |
| Feresidual | ≤ 0.05 | |
| Pbresidual | ≤ 0.02 | |
| CuCu + named elements ≥ 99.5 %; Ag counted as Cu | ≥ 98 (balance) |
What surface finishes work on C18900?
Not anodisable; takes bright polish, Ni/Sn/Ag electroplate and chemical patina well — degrease thoroughly and pickle to remove the tenacious Si-bearing oxide before plating.
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).
How much does C18900 cost?
C18900 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.
C18900 — frequently asked
What is C18900 used for?
C18900 is typically used for electrical connectors, fasteners requiring conductivity and marine hardware. In short: weldable silicon-bearing copper; strength with 45% IACS; marine-capable lightly alloyed copper.
What is the yield strength of C18900?
C18900 has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 405 MPa (58.7 ksi) — stronger than 75% of copper alloy grades. Strength varies by condition: see the 6 listed tempers.
Is C18900 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 57% of copper alloy grades). Gummy like most non-leaded coppers — use sharp positive-rake carbide, high speed, generous feed and flood coolant; rating ≈ 20 % of AISI 1212 and best in H02/H04 tempers.
Can C18900 be welded?
Yes — weldability is rated very good (80/100). Readily joined by GTAW/GMAW with matching or ErCu/ErCuSi filler; preheat thick sections for the high thermal conductivity, and expect full loss of cold-worked strength in the HAZ.
What surface finishes work on C18900?
Not anodisable; takes bright polish, Ni/Sn/Ag electroplate and chemical patina well — degrease thoroughly and pickle to remove the tenacious Si-bearing oxide before plating.
Can C18900 be formed, bent or molded?
Excellent cold formability in O60 (deep draw, roll, bend); in H04 keep bend radii ≥ 2t and interanneal at 450–600 °C for severe work.
What is the maximum service temperature of C18900?
C18900 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 C18900-H04 and C18900-O60?
H04 is the default condition — standard stocked condition for rod, wire and contact tips where maximum strength, hardness and wear resistance are needed. O60: choose for welding wire/rod, deep drawing, bending and any forming operation needing maximum ductility. Yield strength is 370 MPa in H04 versus 95 MPa in O60.
How much does C18900 cost?
C18900 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
- UNS C18900 alloy data (Copper Development Association alloy database) — CDA / copper.org (2023)
- ASTM B224 – Classification of Coppers — ASTM International (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
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.