Copper Alloy C70700-M20
Finish state
UNS C70700
M20 = as hot rolled
Mill hot-rolled plate for welded seawater vessels, tube sheets and offshore piping spools.
Values for the M20 condition
Other C70700 tempers and conditions
C70700 is listed in 9 conditions; see the grade overview at C70700.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed to 0.025 mm grain size | Grain-size-controlled soft temper for deep-drawn parts and tube that must be expanded or bent tightly. | 110 | 305 | 44 | 62 HB | 9.5 % IACS |
O61Default Annealed | Default condition for seawater condenser/heat-exchanger tube and formed fittings needing maximum ductility. | 115 | 310 | 42 | 65 HB | 9.5 % IACS |
M20This page As hot rolled | Mill hot-rolled plate for welded seawater vessels, tube sheets and offshore piping spools. | 125 | 305 | 35 | 70 HB | 9.5 % IACS |
Quarter hard | Light temper strip for formed components needing a little extra stiffness and yield. | 240 | 345 | 30 | 100 HB | 9.3 % IACS |
Light drawn tube | Standard light-drawn tube temper giving higher pressure rating while still allowing bending and expansion. | 275 | 345 | 25 | 100 HB | 9.4 % IACS |
Drawn and stress-relieved tube | Drawn then stress-relieved for dimensional stability and reduced residual stress in long condenser tubes. | 275 | 370 | 22 | 105 HB | 9.4 % IACS |
Half hard | General-purpose hard strip for flat parts, washers and clamps where moderate forming is still needed. | 330 | 395 | 15 | 125 HB | 9.3 % IACS |
Hard drawn | Hard-drawn tube or rod for high-pressure lines and machined fittings where ductility is secondary. | 380 | 415 | 12 | 145 HB | 9.3 % IACS |
Full hard | Choose for maximum strength and spring-back in flat or drawn products with no further forming. | 395 | 435 | 10 | 150 HB | 9.3 % IACS |
What is C70700-M20?
C70700-M20 is C70700 supplied in the M20 condition — mill hot-rolled plate for welded seawater vessels, tube sheets and offshore piping spools. C70700-M20 has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 305 MPa (44.2 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 35% and the elastic modulus is 124 GPa (18 Msi). C70700-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,100°C (2,012 °F). O61 is the default condition FabDigit quotes; M20 is available on request or by drawing note.
Advantages
- 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
- Good corrosion resistance — 78/100, better than 94% of copper alloy grades
- Forms and bends easily — 80/100, better than 83% of copper alloy grades
- Ductile — tolerates forming and impact — 35%, better than 80% of copper alloy grades
Limitations
- High embodied carbon — 4.8 kg CO₂/kg, worse than 84% of copper alloy grades
- Poor heat conductor — 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 82% of copper alloy grades
- Low strength — 125 MPa (18.1 ksi), worse than 77% of copper alloy grades
- Low electrical conductivity — 9.5 % IACS, worse than 76% of copper alloy grades
C70700-M20 properties
Typical room-temperature values for C70700-M20; 20 are specific to this condition. Other listed values are C70700 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C70700-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,100°C (2,012 °F).
Mechanical14
C70700-M20 has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 305 MPa (44.2 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 35% and the elastic modulus is 124 GPa (18 Msi).
Thermal6
C70700-M20 is rated for continuous service to 350°C (662 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 82% of copper alloy grades. Thermal expansion is 17.1 µm/m·K (9.5 µin/in·°F).
Electrical3
C70700-M20 conducts electricity at 9.5 % IACS, worse than 76% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), better than 94% of copper alloy grades.
Sustainability4
Producing a kilogram of C70700-M20 takes about 70 MJ of energy and emits 4.8 kg of CO₂ — more than 84% of copper alloy grades. Typical recycled content is 30%.
Manufacturability8
C70700-M20's machinability is poor (28/100, worse than 78% of copper alloy grades); weldability excellent (88/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C70700-M20
Is C70700 easy to machine?
Gummy and work-hardening — use sharp positive-rake carbide, high feed/low speed, rigid setups and copious coolant; rating ≈20 % of AISI 1212.
Can C70700 be welded?
Readily GTAW/GMAW welded with 70/30 CuNi (ERCuNi) filler, no preheat, low interpass temperature; keep joints clean and free of sulphur, lead and oil.
Can C70700 be formed, bent or molded?
Excellent cold formability in O61/OS tempers — deep drawing, tube bending and expansion are routine; interanneal at 700–850 °C with rapid cooling.
What surface finishes work on C70700?
Not anodizable; supplied bright or pickled, takes tin/nickel electroplating and solders easily. In seawater allow the protective oxide film to form on clean surfaces before high-velocity service.
C70700 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 reported together in most specs | 9 – 11 | 10 |
| Feiron in solid solution gives impingement resistance | 1 – 1.8 | 1.4 |
| Mndeoxidizer / sulphur scavenger | 0.3 – 1 | 0.6 |
| Zn | ≤ 0.5 | — |
| Pbkept low for weldability | ≤ 0.03 | — |
| C | ≤ 0.05 | — |
| S | ≤ 0.02 | — |
| P | ≤ 0.02 | — |
| Curemainder, ≈88 % including any silver | balance | — |
C70700-M20 — frequently asked
What is C70700-M20 used for?
C70700-M20 is typically used for marine tubing, heat exchanger tubes and fittings. In short: 90/10 Cu-Ni tube grade; interchangeable with C70600; weld and form, not machine.
What is the yield strength of C70700-M20?
C70700-M20 has a typical yield strength of 125 MPa (18.1 ksi) and a tensile strength of 305 MPa (44.2 ksi) — weaker than 77% of copper alloy grades. Strength varies by condition: see the 9 listed tempers.
Is C70700-M20 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 78% of copper alloy grades). Gummy and work-hardening — use sharp positive-rake carbide, high feed/low speed, rigid setups and copious coolant; rating ≈20 % of AISI 1212.
Can C70700-M20 be welded?
Yes — weldability is rated excellent (88/100). Readily GTAW/GMAW welded with 70/30 CuNi (ERCuNi) filler, no preheat, low interpass temperature; keep joints clean and free of sulphur, lead and oil.
What surface finishes work on C70700-M20?
Not anodizable; supplied bright or pickled, takes tin/nickel electroplating and solders easily. In seawater allow the protective oxide film to form on clean surfaces before high-velocity service.
Can C70700-M20 be formed, bent or molded?
Excellent cold formability in O61/OS tempers — deep drawing, tube bending and expansion are routine; interanneal at 700–850 °C with rapid cooling.
What is the maximum service temperature of C70700-M20?
C70700-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 C70700-O61 and C70700-H04?
O61 is the default condition — default condition for seawater condenser/heat-exchanger tube and formed fittings needing maximum ductility. H04: choose for maximum strength and spring-back in flat or drawn products with no further forming. Yield strength is 115 MPa in O61 versus 395 MPa in H04.
Sources
- ASTM B111/B111M — Copper and Copper-Alloy Seamless Condenser Tubes — ASTM International (2021)
- ASTM B171/B171M — Copper-Alloy Plate and Sheet for Pressure Vessels and Condensers — ASTM International (2018)
- ASTM B466/B466M — Seamless Copper-Nickel Pipe and Tube — ASTM International (2020)
- CDA UNS alloy datasheets — C70600/C70700 copper-nickel 10 % — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Copper-Nickel Alloys: Properties and Seawater Service Guidance — Nickel Institute / CDA UK (2020)
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.