Copper Alloy C65500-M20
Finish state
UNS C65500 · ASTM B98, B96 · EN CuSi3Mn, CW116C
M20 = as hot rolled
Pick for large extruded sections, forging stock and weld-fabricated parts where no temper control is needed.
Values for the M20 condition
Other C65500 tempers and conditions
C65500 is listed in 10 conditions; see the grade overview at C65500.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Fully softened, coarse-grain C65500 with the lowest strength and highest ductility of the annealed tempers, intended for severe cold forming and deep drawing. | 150 | 395 | 62 | 76 HB | 7 % IACS |
ODefault Annealed | Most stocked condition for deep drawing, spinning, severe bending and welded fabrication. | 165 | 400 | 60 | 78 HB | 7 % IACS |
Light annealed | Fine-grain (≈0.025 mm) light anneal of C65500 that restores most ductility while keeping strength and hardness slightly above the fully soft state. | 170 | 415 | 55 | 85 HB | 7 % IACS |
As hot forged and air cooled | Hot-forged C65500 silicon bronze cooled in air, giving a recrystallised structure with moderate strength, good ductility and excellent weldability. | 175 | 415 | 35 | 95 HB | 7 % IACS |
M20This page As hot rolled | Pick for large extruded sections, forging stock and weld-fabricated parts where no temper control is needed. | 190 | 420 | 50 | 90 HB | 7 % IACS |
Quarter hard | Light cold work when moderate strength must be combined with continued bending/forming. | 275 | 470 | 35 | 120 HB | 6.9 % IACS |
Half hard | General-purpose strength/ductility compromise for bolts, screws, marine shafting and machined parts. | 345 | 540 | 22 | 150 HB | 7 % IACS |
Full hard | Choose for maximum strength in rod, wire and fasteners where little further forming is required. | 450 | 660 | 13 | 185 HB | 7 % IACS |
Extra hard | Heavily drawn wire and strip for springy clips and high-strength small sections. | 550 | 740 | 8 | 19 HRC | 6.8 % IACS |
Spring hard | Spring temper wire for marine springs, meshes and fasteners needing high elastic limit. | 650 | 830 | 5 | 21 HRC | 6.7 % IACS |
What is C65500-M20?
C65500-M20 is C65500 supplied in the M20 condition — pick for large extruded sections, forging stock and weld-fabricated parts where no temper control is needed. C65500-M20 has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 57% of copper alloy grades. Elongation at break is 50% and the elastic modulus is 103 GPa (14.9 Msi). C65500-M20 has a density of 8.53 g/cm³ (0.308 lb/in³), lighter than 62% of copper alloy grades. It melts at 971°C (1,780 °F). O is the default condition FabDigit quotes; M20 is available on request or by drawing note.
Advantages
- Readily welded — 90/100, better than 98% of copper alloy grades
- Ductile — tolerates forming and impact — 50%, better than 97% of copper alloy grades
- Forms and bends easily — 85/100, better than 85% of copper alloy grades
- Good corrosion resistance — 72/100, better than 84% of copper alloy grades
Limitations
- Poor heat conductor — 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 86% of copper alloy grades
- Low electrical conductivity — 7 % IACS, worse than 86% of copper alloy grades
C65500-M20 properties
Typical room-temperature values for C65500-M20; 20 are specific to this condition. Other listed values are C65500 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C65500-M20 has a density of 8.53 g/cm³ (0.308 lb/in³), lighter than 62% of copper alloy grades. It melts at 971°C (1,780 °F).
Mechanical13
C65500-M20 has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 57% of copper alloy grades. Elongation at break is 50% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
C65500-M20 is rated for continuous service to 200°C (392 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 86% of copper alloy grades. Thermal expansion is 18 µm/m·K (10 µin/in·°F).
Electrical3
C65500-M20 conducts electricity at 7 % IACS, worse than 86% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (72/100), better than 84% of copper alloy grades.
Sustainability4
Producing a kilogram of C65500-M20 takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 69% of copper alloy grades. Typical recycled content is 40%.
Manufacturability8
C65500-M20's machinability is poor (30/100, worse than 67% of copper alloy grades); weldability excellent (90/100); formability excellent (85/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C65500-M20
Is C65500 easy to machine?
Rated only ~30 % of free-cutting brass — gummy and work-hardening; use sharp positive-rake tools, rigid setups, moderate speed with generous coolant and avoid dwell.
Can C65500 be welded?
One of the best-welding copper alloys: GTAW/GMAW with ERCuSi-A filler, no preheat on thin sections, keep interpass low and avoid overheating to limit Si oxide film; brazing and silver soldering also good, resistance welding fair.
Can C65500 be formed, bent or molded?
Excellent cold formability in O temper (deep draw, spin, roll thread, cold head); hot work 700–875 °C only, since Si narrows the hot ductility window; anneal 480–700 °C and quench or air cool.
What surface finishes work on C65500?
Takes a bright mechanical polish and accepts statuary/brown chemical patinas, oxidizing dips and clear lacquer; electroplates (Ni, Cr) readily after activation — anodizing is not applicable.
C65500 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 |
|---|---|---|
| Si | 2.8 – 3.8 | 3.1 |
| Mn | 0.5 – 1.3 | 0.9 |
| Fe | ≤ 0.8 | — |
| Zn | ≤ 1.5 | — |
| NiNi + Co, max | ≤ 0.6 | — |
| Sn | ≤ 0.6 | — |
| Pb | ≤ 0.05 | — |
| Curemainder, 94.8 % min incl. Ag | ≥ 94.8 (balance) | — |
C65500-M20 — frequently asked
What is C65500-M20 used for?
C65500-M20 is typically used for silicon bronze fasteners and bolts, propeller shafts, chemical process vessels, anchor chain, underwater structural hardware and welding filler rod. In short: heavy marine structural bronze.
What is the yield strength of C65500-M20?
C65500-M20 has a typical yield strength of 190 MPa (27.6 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 57% of copper alloy grades. Strength varies by condition: see the 10 listed tempers.
Is C65500-M20 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 67% of copper alloy grades). Rated only ~30 % of free-cutting brass — gummy and work-hardening; use sharp positive-rake tools, rigid setups, moderate speed with generous coolant and avoid dwell.
Can C65500-M20 be welded?
Yes — weldability is rated excellent (90/100). One of the best-welding copper alloys: GTAW/GMAW with ERCuSi-A filler, no preheat on thin sections, keep interpass low and avoid overheating to limit Si oxide film; brazing and silver soldering also good, resistance welding fair.
What surface finishes work on C65500-M20?
Takes a bright mechanical polish and accepts statuary/brown chemical patinas, oxidizing dips and clear lacquer; electroplates (Ni, Cr) readily after activation — anodizing is not applicable.
Can C65500-M20 be formed, bent or molded?
Excellent cold formability in O temper (deep draw, spin, roll thread, cold head); hot work 700–875 °C only, since Si narrows the hot ductility window; anneal 480–700 °C and quench or air cool.
What is the maximum service temperature of C65500-M20?
C65500-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 C65500-O and C65500-H08?
O is the default condition — most stocked condition for deep drawing, spinning, severe bending and welded fabrication. H08: spring temper wire for marine springs, meshes and fasteners needing high elastic limit. Yield strength is 165 MPa in O versus 650 MPa in H08.
Can FabDigit make parts in C65500-M20?
Yes — C65500-M20 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B98/B98M Copper-Silicon Alloy Rod, Bar and Shapes — ASTM International (2019)
- ASTM B96/B96M Copper-Silicon Alloy Plate, Sheet, Strip and Bar — ASTM International (2016)
- EN 12163/12167 CuSi3Mn (CW116C) — CEN (2016)
- C65500 alloy datasheet (properties, tempers, machinability) — Copper Development Association (copper.org) (2024)
- ASM Handbook Vol.2 — Properties of Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- GB/T 5231 / GB/T 13808 QSi3-1 — (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.