Copper Alloy C18900-M20
Finish state
UNS C18900
M20 = as hot rolled
As-extruded/hot-worked mill condition for large rod and shapes that will be machined or further cold drawn.
Values for the M20 condition
Other C18900 tempers and conditions
C18900 is listed in 6 conditions; see the grade overview at C18900.
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 |
M20This page 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-M20?
C18900-M20 is C18900 supplied in the M20 condition — as-extruded/hot-worked mill condition for large rod and shapes that will be machined or further cold drawn. C18900-M20 has a yield strength of 130 MPa (18.9 ksi) and a tensile strength of 285 MPa (41.3 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 38% and the elastic modulus is 117 GPa (17 Msi). C18900-M20 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). H04 is the default condition FabDigit quotes; M20 is available on request or by drawing note.
Advantages
- Readily welded — 85/100, better than 95% of copper alloy grades
- High service temperature — 300°C (572 °F), better than 85% of copper alloy grades
- Forms and bends easily — 80/100, better than 83% of copper alloy grades
- Ductile — tolerates forming and impact — 38%, better than 82% of copper alloy grades
- High electrical conductivity — 46 % IACS, better than 78% of copper alloy grades
Limitations
- Difficult to machine — 25/100, worse than 86% of copper alloy grades
- Low strength — 130 MPa (18.9 ksi), worse than 77% of copper alloy grades
C18900-M20 properties
Typical room-temperature values for C18900-M20; 20 are specific to this condition. Other listed values are C18900 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C18900-M20 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-M20 has a yield strength of 130 MPa (18.9 ksi) and a tensile strength of 285 MPa (41.3 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 38% and the elastic modulus is 117 GPa (17 Msi).
Thermal6
C18900-M20 is rated for continuous service to 300°C (572 °F). It conducts heat at 185 W/m·K (106.9 BTU/hr·ft·°F), better than 76% of copper alloy grades. Thermal expansion is 17.6 µm/m·K (9.78 µin/in·°F).
Electrical3
C18900-M20 conducts electricity at 46 % IACS, better than 78% 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-M20 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-M20's machinability is poor (25/100, worse than 86% of copper alloy grades); weldability excellent (85/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C18900-M20
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.
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.
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) | — |
C18900-M20 — frequently asked
What is C18900-M20 used for?
C18900-M20 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-M20?
C18900-M20 has a typical yield strength of 130 MPa (18.9 ksi) and a tensile strength of 285 MPa (41.3 ksi) — weaker than 77% of copper alloy grades. Strength varies by condition: see the 6 listed tempers.
Is C18900-M20 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 86% 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-M20 be welded?
Yes — weldability is rated excellent (85/100). 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-M20?
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-M20 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-M20?
C18900-M20 is rated for continuous use to about 300°C (572 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.