Copper Alloy M1-M20
Finish state
M20 = as hot rolled
Hot-rolled plate and hot-extruded busbar sections supplied without further processing; nearly annealed properties with mill scale.
Values for the M20 condition
Other M1 tempers and conditions
M1 is listed in 10 conditions; see the grade overview at M1.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O60Default Soft annealed | Default stock condition for sheet, strip, tube and magnet wire when maximum ductility, conductivity and formability are needed. | 75 | 235 | 45 | 45 HB | 101 % IACS |
M20This page As hot rolled | Hot-rolled plate and hot-extruded busbar sections supplied without further processing; nearly annealed properties with mill scale. | 80 | 235 | 40 | 48 HB | 100 % IACS |
Eighth hard | Lightly rolled strip when slightly higher stiffness/strength than annealed is wanted but deep forming is still required. | 175 | 250 | 30 | 60 HB | 100 % IACS |
Quarter hard | Quarter-hard strip/sheet for parts that need moderate springback control with good bendability. | 205 | 262 | 25 | 70 HB | 99 % IACS |
Half hard | Most common intermediate temper for busbar, gaskets, formed brackets and tube needing strength plus some bendability. | 250 | 290 | 14 | 85 HB | 98 % IACS |
Full hard | Fully cold-worked sheet, rod and busbar for load-carrying conductors, commutator segments and machined parts. | 310 | 345 | 6 | 100 HB | 97 % IACS |
Hard drawn | Standard hard-drawn condition for overhead line wire, trolley wire and drawn tube where tensile strength and sag resistance are required. | 340 | 400 | 3 | 105 HB | 97 % IACS |
Extra hard | Heavier reduction than H04 for flat springs, contacts and stampings where flatness under load matters. | 345 | 365 | 4 | 105 HB | 97 % IACS |
Spring hard | Spring-temper strip for conductive springs, gaskets and EMI contacts where stiffness beats formability. | 350 | 380 | 4 | 115 HB | 97 % IACS |
Extra spring hard | Maximum cold-worked strip temper; highest strength available in unalloyed copper, essentially non-formable. | 365 | 390 | 4 | 118 HB | 97 % IACS |
What is M1-M20?
M1-M20 is M1 supplied in the M20 condition — hot-rolled plate and hot-extruded busbar sections supplied without further processing; nearly annealed properties with mill scale. M1-M20 has a yield strength of 80 MPa (11.6 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 90% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 115 GPa (16.7 Msi). M1-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,065°C (1,949 °F). O60 is the default condition FabDigit quotes; M20 is available on request or by drawing note.
Advantages
- Conducts heat well — 391 W/m·K (225.9 BTU/hr·ft·°F), better than 98% of copper alloy grades
- High electrical conductivity — 100 % IACS, better than 96% of copper alloy grades
- Forms and bends easily — 85/100, better than 85% of copper alloy grades
- Ductile — tolerates forming and impact — 40%, better than 84% of copper alloy grades
Limitations
- Low strength — 80 MPa (11.6 ksi), worse than 90% of copper alloy grades
- Difficult to machine — 25/100, worse than 86% of copper alloy grades
M1-M20 properties
Typical room-temperature values for M1-M20; 18 are specific to this condition. Other listed values are M1 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
M1-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,065°C (1,949 °F).
Mechanical12
M1-M20 has a yield strength of 80 MPa (11.6 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 90% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
M1-M20 is rated for continuous service to 200°C (392 °F). It conducts heat at 391 W/m·K (225.9 BTU/hr·ft·°F), better than 98% of copper alloy grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical3
M1-M20 conducts electricity at 100 % IACS, better than 96% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 58% of copper alloy grades.
Sustainability4
Producing a kilogram of M1-M20 takes about 55 MJ of energy and emits 3.6 kg of CO₂ — less than 72% of copper alloy grades. Typical recycled content is 35%.
Manufacturability8
M1-M20's machinability is poor (25/100, worse than 86% of copper alloy grades); weldability fair (40/100); formability excellent (85/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M1-M20
Is M1 easy to machine?
Gummy and stringy — use sharp positive-rake HSS or polished-flute carbide, high speed, low feed pressure and generous coolant; harder tempers (H04+) cut noticeably cleaner than annealed.
Can M1 be welded?
GTAW/GMAW possible with high preheat (200–500 °C) and helium-rich shielding, but the ~0.03 % oxygen makes ETP copper prone to porosity and hydrogen embrittlement — use phosphorus-deoxidised filler or choose brazing/soldering instead.
Can M1 be formed, bent or molded?
Outstanding cold formability in O60: deep drawing, spinning, roll forming and tight bends (≈0–0.5 t); interanneal at 400–600 °C when total reduction exceeds ~60 %, and expect strong springback in H04 and above.
What surface finishes work on M1?
Not anodisable; typical finishes are bright polish plus clear lacquer, chemical patina/blackening, or electroplated tin, nickel and silver for contacts and busbar joints.
M1 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 |
|---|---|---|
| Otough-pitch oxygen content; M1r/M1f variants are deoxidised | ≤ 0.05 | 0.03 |
| Bi | ≤ 0 | — |
| Sb | ≤ 0 | — |
| As | ≤ 0 | — |
| Fe | ≤ 0.01 | — |
| Ni | ≤ 0 | — |
| Pb | ≤ 0.01 | — |
| Sn | ≤ 0 | — |
| S | ≤ 0 | — |
| Zn | ≤ 0 | — |
| P | ≤ 0 | — |
| Agcounted within Cu content | ≤ 0 | — |
| CuCu + Ag, per GOST 859-2001 grade M1 | ≥ 99.9 (balance) | — |
M1-M20 — frequently asked
What is M1-M20 used for?
M1-M20 is typically used for electrical wire, busbars, heat exchangers and general copper hardware. In short: CIS-standard electrolytic copper; 101 % IACS conductivity; poor machinability rating.
What is the yield strength of M1-M20?
M1-M20 has a typical yield strength of 80 MPa (11.6 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 90% of copper alloy grades. Strength varies by condition: see the 10 listed tempers.
Is M1-M20 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 86% of copper alloy grades). Gummy and stringy — use sharp positive-rake HSS or polished-flute carbide, high speed, low feed pressure and generous coolant; harder tempers (H04+) cut noticeably cleaner than annealed.
Can M1-M20 be welded?
With care — weldability is rated fair (40/100). GTAW/GMAW possible with high preheat (200–500 °C) and helium-rich shielding, but the ~0.03 % oxygen makes ETP copper prone to porosity and hydrogen embrittlement — use phosphorus-deoxidised filler or choose brazing/soldering instead.
What surface finishes work on M1-M20?
Not anodisable; typical finishes are bright polish plus clear lacquer, chemical patina/blackening, or electroplated tin, nickel and silver for contacts and busbar joints.
Can M1-M20 be formed, bent or molded?
Outstanding cold formability in O60: deep drawing, spinning, roll forming and tight bends (≈0–0.5 t); interanneal at 400–600 °C when total reduction exceeds ~60 %, and expect strong springback in H04 and above.
What is the maximum service temperature of M1-M20?
M1-M20 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 M1-O60 and M1-H10?
O60 is the default condition — default stock condition for sheet, strip, tube and magnet wire when maximum ductility, conductivity and formability are needed. H10: maximum cold-worked strip temper; highest strength available in unalloyed copper, essentially non-formable. Yield strength is 75 MPa in O60 versus 365 MPa in H10.
Sources
- GOST 859-2001 Copper — Grades (M00, M0, M1, M2, M3) — Interstate Standard / Gosstandart (2001)
- ASTM B152/B152M Standard Specification for Copper Sheet, Strip, Plate and Rolled Bar — ASTM International (2019)
- EN 13601 Copper and copper alloys — Rod, bar and wire for general electrical purposes — CEN (2021)
- C11000 Electrolytic Tough Pitch Copper alloy datasheet — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (copper and copper alloys) — ASM International (2005)
- GB/T 5231 (T2 comparison) — SAC (2022)
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.