Copper Alloy C18700-M20
Finish state
UNS C18700 · EN CW113C
M20 = as hot rolled
Mill hot-worked bar before drawing; used for large sections and forging stock.
Values for the M20 condition
Other C18700 tempers and conditions
C18700 is listed in 7 conditions; see the grade overview at C18700.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick for maximum conductivity, riveting, staking or upsetting of machined heads. | 69 | 221 | 45 | 42 HB | 96 % IACS |
M20This page As hot rolled | Mill hot-worked bar before drawing; used for large sections and forging stock. | 85 | 230 | 40 | 48 HB | 96 % IACS |
Light drawn | Light draw for straightness and size control while keeping good bending ductility. | 165 | 250 | 32 | 60 HB | 96 % IACS |
Quarter hard | Intermediate temper when the machined part still needs moderate forming or crimping. | 195 | 262 | 28 | 68 HB | 95 % IACS |
Half hard | Best compromise of chip control, strength and residual ductility for screw-machine parts that get bent or staked. | 220 | 276 | 25 | 78 HB | 95 % IACS |
H04Default Full hard | Standard stocked temper for free-machining copper rod/bar: stiffest chip break, straightest bar, highest strength. | 275 | 315 | 15 | 90 HB | 95 % IACS |
Spring hard | Heavy-drawn wire/small-diameter rod for header and multi-spindle feedstock needing maximum straightness and strength. | 340 | 380 | 5 | 100 HB | 94 % IACS |
What is C18700-M20?
C18700-M20 is C18700 supplied in the M20 condition — mill hot-worked bar before drawing; used for large sections and forging stock. C18700-M20 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 115 GPa (16.7 Msi). C18700-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,075°C (1,967 °F). H04 is the default condition FabDigit quotes; M20 is available on request or by drawing note.
Advantages
- Conducts heat well — 372 W/m·K (214.9 BTU/hr·ft·°F), better than 91% of copper alloy grades
- High electrical conductivity — 96 % IACS, better than 91% of copper alloy grades
- Easy to machine — 80/100, better than 86% of copper alloy grades
- Ductile — tolerates forming and impact — 40%, better than 84% of copper alloy grades
Limitations
- Difficult to weld — 15/100, worse than 94% of copper alloy grades
- Low strength — 85 MPa (12.3 ksi), worse than 89% of copper alloy grades
C18700-M20 properties
Typical room-temperature values for C18700-M20; 19 are specific to this condition. Other listed values are C18700 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C18700-M20 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,075°C (1,967 °F).
Mechanical13
C18700-M20 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
C18700-M20 is rated for continuous service to 200°C (392 °F). It conducts heat at 372 W/m·K (214.9 BTU/hr·ft·°F), better than 91% of copper alloy grades. Thermal expansion is 17.7 µm/m·K (9.83 µin/in·°F).
Electrical3
C18700-M20 conducts electricity at 96 % IACS, better than 91% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (64/100), better than 52% of copper alloy grades.
Sustainability4
Producing a kilogram of C18700-M20 takes about 57 MJ of energy and emits 3.6 kg of CO₂ — less than 52% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C18700-M20's machinability is very good (80/100, better than 86% of copper alloy grades); weldability poor (15/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C18700-M20
Is C18700 easy to machine?
Excellent for high-speed screw machining — run 2–4× the speed of ETP copper with sharp positive-rake tools, light feeds and flood emulsion; lead gives short chips instead of copper's stringy swarf.
Can C18700 be welded?
Not recommended for fusion welding or brazing — lead causes hot cracking and porosity; join by soft soldering, crimping or mechanical fastening.
Can C18700 be formed, bent or molded?
Cold bending, upsetting and staking are possible in O60/H02 but the lead phase limits severe cold work; hot work only below ~750 °C to avoid lead hot-shortness.
What surface finishes work on C18700?
Solders and tin/nickel/silver plates readily after acid pickle; polish to a bright finish and protect with benzotriazole or lacquer against tarnish — no anodizing.
C18700 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 |
|---|---|---|
| Pbfree lead particles for chip breaking | 0.8 – 1.5 | 1 |
| PEN CW113C (CuPb1P) specifies 0.003–0.012 % P as deoxidizer; ASTM C18700 may be tough-pitch | ≤ 0.02 | 0.01 |
| CuCu + Ag + Pb ≥ 99.9 % per ASTM B301 / UNS C18700 | ≥ 99.9 (balance) | — |
C18700-M20 — frequently asked
What is C18700-M20 used for?
C18700-M20 is typically used for screw machine parts, precision machined electrical components and fittings. In short: best-machining conductive copper; 95 % IACS after machining; not fusion weldable.
What is the yield strength of C18700-M20?
C18700-M20 has a typical yield strength of 85 MPa (12.3 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 89% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C18700-M20 easy to machine?
Yes — machinability is rated very good (80/100, better than 86% of copper alloy grades). Excellent for high-speed screw machining — run 2–4× the speed of ETP copper with sharp positive-rake tools, light feeds and flood emulsion; lead gives short chips instead of copper's stringy swarf.
Can C18700-M20 be welded?
Not readily — weldability is rated poor (15/100). Not recommended for fusion welding or brazing — lead causes hot cracking and porosity; join by soft soldering, crimping or mechanical fastening.
What surface finishes work on C18700-M20?
Solders and tin/nickel/silver plates readily after acid pickle; polish to a bright finish and protect with benzotriazole or lacquer against tarnish — no anodizing.
Can C18700-M20 be formed, bent or molded?
Cold bending, upsetting and staking are possible in O60/H02 but the lead phase limits severe cold work; hot work only below ~750 °C to avoid lead hot-shortness.
What is the maximum service temperature of C18700-M20?
C18700-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 C18700-H04 and C18700-O60?
H04 is the default condition — standard stocked temper for free-machining copper rod/bar: stiffest chip break, straightest bar, highest strength. O60: pick for maximum conductivity, riveting, staking or upsetting of machined heads. Yield strength is 275 MPa in H04 versus 69 MPa in O60.
Sources
- ASTM B301/B301M — Free-Cutting Copper Rod, Bar, Wire and Shapes — ASTM International (2018)
- EN 12164 / EN 13601 — Copper and copper alloys, rod for free machining and electrical purposes (CW113C) — CEN (2016)
- UNS C18700 alloy datasheet (properties, tempers, machinability rating) — Copper Development Association (copper.org) (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.