Copper Alloy C12500-M20
Finish state
UNS C12500
M20 = as hot rolled
Cheapest mill condition for heavy plate and roofing sheet where temper control is not critical.
Values for the M20 condition
Other C12500 tempers and conditions
C12500 is listed in 12 conditions; see the grade overview at C12500.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed to 0.050 mm grain size | Soft, coarse-grain anneal for deep drawing and severe forming. | 69 | 220 | 45 | 42 HB | 100 % IACS |
As hot extruded | Standard as-extruded condition for bus bar, forging stock and machined fittings. | 70 | 215 | 50 | 42 HB | 99 % IACS |
Annealed to 0.025 mm grain size | Fine-grain soft temper — better surface finish after forming than OS050. | 76 | 235 | 45 | 45 HB | 100 % IACS |
M20This page As hot rolled | Cheapest mill condition for heavy plate and roofing sheet where temper control is not critical. | 85 | 235 | 45 | 48 HB | 99 % IACS |
1/8 hard | Slight stiffening while keeping near-soft formability; good for roll-formed profiles. | 170 | 250 | 30 | 62 HB | 98 % IACS |
Quarter hard | Balanced temper for bent brackets, gutters and moderately formed parts. | 205 | 265 | 25 | 70 HB | 98 % IACS |
Half hard | Most common cold-worked sheet/strip temper — usable strength with some bendability. | 250 | 290 | 14 | 82 HB | 97 % IACS |
Three-quarter hard | Stiffer flat product for gaskets, washers and lightly formed hardware. | 275 | 315 | 10 | 89 HB | 97 % IACS |
H04Default Full hard | Default stocked temper for bar, bus bar and hard sheet where strength and straightness matter. | 310 | 345 | 6 | 95 HB | 97 % IACS |
Extra hard | Higher cold reduction for flat springs, contacts and stiff strip; very limited bending. | 340 | 365 | 4 | 100 HB | 97 % IACS |
Spring hard | Spring-rolled strip for gaskets, shim and low-stress spring contacts. | 350 | 380 | 4 | 105 HB | 96 % IACS |
Extra spring hard | Maximum cold-worked strength available in thin strip/wire; essentially no formability. | 365 | 395 | 3 | 110 HB | 96 % IACS |
What is C12500-M20?
C12500-M20 is C12500 supplied in the M20 condition — cheapest mill condition for heavy plate and roofing sheet where temper control is not critical. C12500-M20 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 117 GPa (17 Msi). C12500-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). H04 is the default condition FabDigit quotes; M20 is available on request or by drawing note.
Advantages
- High electrical conductivity — 99 % IACS, better than 95% of copper alloy grades
- Conducts heat well — 387 W/m·K (223.6 BTU/hr·ft·°F), better than 94% of copper alloy grades
- Ductile — tolerates forming and impact — 45%, better than 91% of copper alloy grades
- Low embodied carbon — 3.3 kg CO₂/kg, better than 90% of copper alloy grades
- Forms and bends easily — 88/100, better than 87% of copper alloy grades
Limitations
- Difficult to machine — 19/100, worse than 100% of copper alloy grades
- Low strength — 85 MPa (12.3 ksi), worse than 89% of copper alloy grades
C12500-M20 properties
Typical room-temperature values for C12500-M20; 11 are specific to this condition. Other listed values are C12500 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C12500-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
C12500-M20 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 117 GPa (17 Msi).
Thermal6
C12500-M20 is rated for continuous service to 200°C (392 °F). It conducts heat at 387 W/m·K (223.6 BTU/hr·ft·°F), better than 94% of copper alloy grades. Thermal expansion is 17.7 µm/m·K (9.83 µin/in·°F).
Electrical3
C12500-M20 conducts electricity at 99 % IACS, better than 95% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 69% of copper alloy grades.
Sustainability4
Producing a kilogram of C12500-M20 takes about 53 MJ of energy and emits 3.3 kg of CO₂ — less than 85% of copper alloy grades. Typical recycled content is 45%.
Manufacturability8
C12500-M20's machinability is poor (19/100, worse than 100% of copper alloy grades); weldability fair (35/100); formability excellent (88/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C12500-M20
Is C12500 easy to machine?
Gummy and low-rated (~20 % of free-cutting brass): use sharp positive-rake tools, high speed, generous coolant, or switch to C14500/C36000 for screw-machine work.
Can C12500 be welded?
Oxygen-bearing copper — prefer brazing/soldering or friction/resistance joining; GTAW/GMAW is possible with deoxidised filler (ERCu) but risks hydrogen embrittlement and porosity, and heating above 400 °C in reducing atmospheres must be avoided.
Can C12500 be formed, bent or molded?
Excellent cold formability in OS tempers (deep draw, spin, roll-form); interanneal at 400–600 °C when total cold reduction exceeds ~50 %.
What surface finishes work on C12500?
Not anodisable; takes bright polishing, chemical patina/oxidation blackening, tin, nickel or silver plating, and clear lacquer to slow natural tarnish.
C12500 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.
| Element | Spec limit (wt %) |
|---|---|
| Ooxygen present as Cu2O (tough pitch); typically 0.02–0.05 %, not a specified limit | ≈ 0.04 |
| Sb | ≤ 0.01 |
| As | ≤ 0.01 |
| Bi | ≤ 0 |
| Fe | ≤ 0.01 |
| Pb | ≤ 0.01 |
| Ni | ≤ 0.05 |
| Se | ≤ 0 |
| S | ≤ 0 |
| Sn | ≤ 0.05 |
| Te | ≤ 0.03 |
| Zn | ≤ 0.05 |
| CuCu + Ag, fire-refined tough pitch | ≥ 99.88 (balance) |
C12500-M20 — frequently asked
What is C12500-M20 used for?
C12500-M20 is typically used for builder's hardware, general sheet and wire products and roofing. In short: low-cost general-purpose copper; 97 % IACS without ETP purity; excellent cold formability.
What is the yield strength of C12500-M20?
C12500-M20 has a typical yield strength of 85 MPa (12.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 89% of copper alloy grades. Strength varies by condition: see the 12 listed tempers.
Is C12500-M20 easy to machine?
Not especially — machinability is rated poor (19/100, worse than 100% of copper alloy grades). Gummy and low-rated (~20 % of free-cutting brass): use sharp positive-rake tools, high speed, generous coolant, or switch to C14500/C36000 for screw-machine work.
Can C12500-M20 be welded?
With care — weldability is rated fair (35/100). Oxygen-bearing copper — prefer brazing/soldering or friction/resistance joining; GTAW/GMAW is possible with deoxidised filler (ERCu) but risks hydrogen embrittlement and porosity, and heating above 400 °C in reducing atmospheres must be avoided.
What surface finishes work on C12500-M20?
Not anodisable; takes bright polishing, chemical patina/oxidation blackening, tin, nickel or silver plating, and clear lacquer to slow natural tarnish.
Can C12500-M20 be formed, bent or molded?
Excellent cold formability in OS tempers (deep draw, spin, roll-form); interanneal at 400–600 °C when total cold reduction exceeds ~50 %.
What is the maximum service temperature of C12500-M20?
C12500-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 C12500-H04 and C12500-OS050?
H04 is the default condition — default stocked temper for bar, bus bar and hard sheet where strength and straightness matter. OS050: soft, coarse-grain anneal for deep drawing and severe forming. Yield strength is 310 MPa in H04 versus 69 MPa in OS050.
Sources
- ASTM B5 — Electrolytic Tough Pitch / Fire-Refined Copper Refinery Shapes — ASTM International (2021)
- ASTM B152/B152M — Copper Sheet, Strip, Plate and Rolled Bar — ASTM International (2019)
- CDA Alloy Datasheet C12500 (Fire-Refined Tough Pitch Copper) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
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.