Copper Alloy C71580-M20
Finish state
UNS C71580
M20 = as hot rolled
Plate and heavy bar in the as-hot-worked state; used for weld-fabricated tube sheets and pressure parts where a stress-relief anneal is not required.
Values for the M20 condition
Other C71580 tempers and conditions
C71580 is listed in 7 conditions; see the grade overview at C71580.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O61Default Annealed | Default stock condition for plate, tube, bar and fittings — maximum ductility for forming, expanding and welding. | 150 | 380 | 42 | 80 HB | 4.6 % IACS |
Annealed to 0.025 mm grain size | Grain-size-controlled anneal for sheet/strip that must be deep drawn or spun with a fine, uniform surface finish. | 165 | 395 | 40 | 85 HB | 4.6 % IACS |
M20This page As hot rolled | Plate and heavy bar in the as-hot-worked state; used for weld-fabricated tube sheets and pressure parts where a stress-relief anneal is not required. | 170 | 400 | 38 | 85 HB | 4.6 % IACS |
As-welded deposit | Properties of undiluted deposited weld metal when the grade is supplied as CuNi filler rod or wire for joining 70/30 and 90/10 CuNi. | 220 | 400 | 30 | 90 HB | 4.4 % IACS |
Light drawn | Light cold-drawn condensor/heat-exchanger tube — straighter and stiffer than annealed while still expandable into tube sheets. | 275 | 450 | 25 | 115 HB | 4.5 % IACS |
Drawn and stress-relieved | Cold-drawn then low-temperature stress relieved — higher proof strength with reduced residual stress for pressure tube and shafting. | 380 | 480 | 20 | 130 HB | 4.5 % IACS |
Hard drawn | Heavily cold-worked rod, wire and tube for maximum strength and wear resistance; very limited remaining ductility. | 540 | 585 | 8 | 170 HB | 4.5 % IACS |
What is C71580-M20?
C71580-M20 is C71580 supplied in the M20 condition — plate and heavy bar in the as-hot-worked state; used for weld-fabricated tube sheets and pressure parts where a stress-relief anneal is not required. C71580-M20 has a yield strength of 170 MPa (24.7 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 62% of copper alloy grades. Elongation at break is 38% and the elastic modulus is 152 GPa (22 Msi). C71580-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,170°C (2,138 °F). O61 is the default condition FabDigit quotes; M20 is available on request or by drawing note.
Advantages
- Stiff — 152 GPa (22 Msi), better than 99% of copper alloy grades
- Good corrosion resistance — 82/100, better than 98% of copper alloy grades
- Readily welded — 88/100, better than 97% of copper alloy grades
- High service temperature — 350°C (662 °F), better than 95% of copper alloy grades
- Ductile — tolerates forming and impact — 38%, better than 82% of copper alloy grades
Limitations
- Low electrical conductivity — 4.6 % IACS, worse than 96% of copper alloy grades
- High embodied carbon — 6.5 kg CO₂/kg, worse than 94% of copper alloy grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 93% of copper alloy grades
C71580-M20 properties
Typical room-temperature values for C71580-M20; 20 are specific to this condition. Other listed values are C71580 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C71580-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,170°C (2,138 °F).
Mechanical14
C71580-M20 has a yield strength of 170 MPa (24.7 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 62% of copper alloy grades. Elongation at break is 38% and the elastic modulus is 152 GPa (22 Msi).
Thermal6
C71580-M20 is rated for continuous service to 350°C (662 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 93% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C71580-M20 conducts electricity at 4.6 % IACS, worse than 96% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 98% of copper alloy grades.
Sustainability4
Producing a kilogram of C71580-M20 takes about 88 MJ of energy and emits 6.5 kg of CO₂ — more than 92% of copper alloy grades. Typical recycled content is 30%.
Manufacturability8
C71580-M20's machinability is poor (28/100, worse than 78% of copper alloy grades); weldability excellent (88/100); formability very good (78/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C71580-M20
Is C71580 easy to machine?
Gummy and work-hardening — use positive-rake sharp carbide, heavy feeds, low-to-moderate speed (~40–70 m/min) and generous coolant; avoid dwelling.
Can C71580 be welded?
GTAW/GMAW with matching CuNi (ERCuNi/ENiCu type) filler, no preheat, low interpass (<150 °C), clean oxide-free joints — sulphur and lead contamination causes hot cracking.
Can C71580 be formed, bent or molded?
Excellent cold formability in O61; springback is high, and interanneal near 700–850 °C followed by rapid cooling after ~50 % reduction.
What surface finishes work on C71580?
Takes a good buffed finish; not anodisable — passivate, tin/nickel plate, or develop the protective seawater film with ferrous-sulphate dosing during commissioning.
C71580 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 |
|---|---|---|
| NiNi + Co counted together in most registrations | 29 – 33 | 30.5 |
| Feiron level trimmed vs C71500 for weld/casting soundness | 0.4 – 1 | 0.7 |
| Mndeoxidiser / sulphur scavenger | 0.3 – 1 | 0.6 |
| Zn | ≤ 0.05 | — |
| Pb | ≤ 0.02 | — |
| C | ≤ 0.05 | — |
| S | ≤ 0.02 | — |
| P | ≤ 0.02 | — |
| Si | ≤ 0.25 | — |
| Curemainder; confirm exact registered limits against the current CDA/ASTM chemistry sheet for C71580 | balance | — |
C71580-M20 — frequently asked
What is C71580-M20 used for?
C71580-M20 is typically used for pipe fittings, flanges and marine hardware. In short: fitting-grade 70/30 Cu-Ni; weld-friendly CuNi30Fe; pairs with C71500 piping.
What is the yield strength of C71580-M20?
C71580-M20 has a typical yield strength of 170 MPa (24.7 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 62% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C71580-M20 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 78% of copper alloy grades). Gummy and work-hardening — use positive-rake sharp carbide, heavy feeds, low-to-moderate speed (~40–70 m/min) and generous coolant; avoid dwelling.
Can C71580-M20 be welded?
Yes — weldability is rated excellent (88/100). GTAW/GMAW with matching CuNi (ERCuNi/ENiCu type) filler, no preheat, low interpass (<150 °C), clean oxide-free joints — sulphur and lead contamination causes hot cracking.
What surface finishes work on C71580-M20?
Takes a good buffed finish; not anodisable — passivate, tin/nickel plate, or develop the protective seawater film with ferrous-sulphate dosing during commissioning.
Can C71580-M20 be formed, bent or molded?
Excellent cold formability in O61; springback is high, and interanneal near 700–850 °C followed by rapid cooling after ~50 % reduction.
What is the maximum service temperature of C71580-M20?
C71580-M20 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 C71580-O61 and C71580-H80?
O61 is the default condition — default stock condition for plate, tube, bar and fittings — maximum ductility for forming, expanding and welding. H80: heavily cold-worked rod, wire and tube for maximum strength and wear resistance; very limited remaining ductility. Yield strength is 150 MPa in O61 versus 540 MPa in H80.
Sources
- CDA/UNS Copper Alloy Data — 70/30 Copper-Nickel family — Copper Development Association (2023)
- ASTM B466/B466M — Seamless Copper-Nickel Pipe and Tube — ASTM (2020)
- ASTM B171/B171M — Copper-Alloy Plate and Sheet for Condensers and Heat Exchangers — ASTM (2018)
- AWS A5.7/A5.7M — Copper and Copper-Alloy Bare Welding Rods and Electrodes — AWS (2011)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Guide to Copper-Nickel Alloys for Seawater Service — Nickel Institute / CDA (2018)
- GB/T 2040 / GB/T 8890 — SAC (2017)
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.