Copper Alloy C70620-M20
Finish state
UNS C70620
M20 = as hot rolled
Mill hot-worked plate, tube shell or extrusion, taken as-processed; used where subsequent forming, welding or machining will follow.
Values for the M20 condition
Other C70620 tempers and conditions
C70620 is listed in 7 conditions; see the grade overview at C70620.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O60Default Soft annealed | Standard condition for condenser/heat-exchanger tube, U-bends and cold-formed parts; maximum ductility and best corrosion consistency. | 120 | 310 | 40 | 65 HB | 9.5 % IACS |
M20This page As hot rolled | Mill hot-worked plate, tube shell or extrusion, taken as-processed; used where subsequent forming, welding or machining will follow. | 135 | 320 | 35 | 70 HB | 9.5 % IACS |
Quarter hard | Light temper for tube and strip needing higher yield strength while retaining useful bendability. | 255 | 365 | 20 | 95 HB | 9.5 % IACS |
Cold worked and stress relieved | Cold-drawn tube given a low-temperature stress relief to cut residual stress before seawater or condensate service. | 330 | 400 | 15 | 110 HB | 9 % IACS |
Half hard | General structural temper for strip, sheet and drawn tube where strength matters more than deep forming. | 360 | 415 | 12 | 120 HB | 9.5 % IACS |
Extra hard | Heavily cold-worked strip/tube for high-strength, wear- and pressure-resisting parts with only slight forming. | 450 | 490 | 6 | 150 HB | 9.5 % IACS |
Spring hard | Maximum cold-worked strength for springy strip, clips and diaphragms in marine/condensate environments. | 485 | 525 | 4 | 165 HB | 9.5 % IACS |
What is C70620-M20?
C70620-M20 is C70620 supplied in the M20 condition — mill hot-worked plate, tube shell or extrusion, taken as-processed; used where subsequent forming, welding or machining will follow. C70620-M20 has a yield strength of 135 MPa (19.6 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 76% of copper alloy grades. Elongation at break is 35% and the elastic modulus is 124 GPa (18 Msi). C70620-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). O60 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
- Good corrosion resistance — 78/100, better than 94% of copper alloy grades
- High service temperature — 315°C (599 °F), better than 92% 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 — 5.2 kg CO₂/kg, worse than 88% 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 — 135 MPa (19.6 ksi), worse than 76% of copper alloy grades
- Low electrical conductivity — 9.5 % IACS, worse than 76% of copper alloy grades
C70620-M20 properties
Typical room-temperature values for C70620-M20; 15 are specific to this condition. Other listed values are C70620 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C70620-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
C70620-M20 has a yield strength of 135 MPa (19.6 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 76% of copper alloy grades. Elongation at break is 35% and the elastic modulus is 124 GPa (18 Msi).
Thermal6
C70620-M20 is rated for continuous service to 315°C (599 °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
C70620-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 C70620-M20 takes about 70 MJ of energy and emits 5.2 kg of CO₂ — more than 84% of copper alloy grades. Typical recycled content is 25%.
Manufacturability8
C70620-M20's machinability is poor (30/100, worse than 67% 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 C70620-M20
Is C70620 easy to machine?
Gummy and work-hardening — rate ≈20 % of free-cutting brass; use sharp positive-rake carbide, moderate speed, heavy feed and generous coolant to avoid built-up edge.
Can C70620 be welded?
Designed for welding: GTAW/GMAW with C7158 (65/35 Cu-Ni) filler, no preheat, low interpass temperature, argon back-purge; keep joints oil- and sulphur-free to avoid hot cracking.
Can C70620 be formed, bent or molded?
Excellent cold formability in O60 (deep drawing, U-bending, expansion); work-hardens fast, so interstage anneal at 700–850 °C with rapid cooling; hot work 850–950 °C.
What surface finishes work on C70620?
Not anodizable; pickle in sulphuric/hydrogen-peroxide or inhibited nitric to remove weld oxide, then form the protective film with clean-water commissioning (or FeSO₄ dosing); takes a good mechanical or electro-polish.
C70620 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 |
|---|---|---|
| Niincludes Co | 9 – 11 | 10 |
| Feiron addition gives impingement resistance | 1 – 1.8 | 1.5 |
| Mncontrolled range (deoxidation, weldability) | 0.5 – 1 | 0.7 |
| Zn | ≤ 0.5 | — |
| Pbtightened vs C70600 for weldability | ≤ 0.02 | — |
| C | ≤ 0.05 | — |
| S | ≤ 0.02 | — |
| P | ≤ 0.02 | — |
| CuCu + Ag remainder, ≈86.5 % min | balance | — |
C70620-M20 — frequently asked
What is C70620-M20 used for?
C70620-M20 is typically used for nuclear plant condenser tubes, power plant heat exchangers and marine piping. In short: nuclear-grade 90/10 cupronickel; tighter Fe/Mn than C70600; excellent seawater weldability.
What is the yield strength of C70620-M20?
C70620-M20 has a typical yield strength of 135 MPa (19.6 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 76% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C70620-M20 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 67% of copper alloy grades). Gummy and work-hardening — rate ≈20 % of free-cutting brass; use sharp positive-rake carbide, moderate speed, heavy feed and generous coolant to avoid built-up edge.
Can C70620-M20 be welded?
Yes — weldability is rated excellent (88/100). Designed for welding: GTAW/GMAW with C7158 (65/35 Cu-Ni) filler, no preheat, low interpass temperature, argon back-purge; keep joints oil- and sulphur-free to avoid hot cracking.
What surface finishes work on C70620-M20?
Not anodizable; pickle in sulphuric/hydrogen-peroxide or inhibited nitric to remove weld oxide, then form the protective film with clean-water commissioning (or FeSO₄ dosing); takes a good mechanical or electro-polish.
Can C70620-M20 be formed, bent or molded?
Excellent cold formability in O60 (deep drawing, U-bending, expansion); work-hardens fast, so interstage anneal at 700–850 °C with rapid cooling; hot work 850–950 °C.
What is the maximum service temperature of C70620-M20?
C70620-M20 is rated for continuous use to about 315°C (599 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C70620-O60 and C70620-H08?
O60 is the default condition — standard condition for condenser/heat-exchanger tube, U-bends and cold-formed parts; maximum ductility and best corrosion consistency. H08: maximum cold-worked strength for springy strip, clips and diaphragms in marine/condensate environments. Yield strength is 120 MPa in O60 versus 485 MPa in H08.
Sources
- ASTM B466/B466M – Seamless Copper-Nickel Pipe and Tube — ASTM International (2020)
- ASTM B111/B111M – Copper and Copper-Alloy Seamless Condenser Tubes — ASTM International (2021)
- ASTM B171 / B402 – Cu-Ni plate and sheet for condensers — ASTM International (2018)
- CDA alloy datasheet C70600 / C70620 (UNS registration) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties of Copper and Copper Alloys — ASM International (1990)
- Copper-Nickel Alloys for Seawater Systems (technical guide) — Copper Development Association / Nickel Institute (2019)
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.