Copper Alloy C81700-M
Heat-treated state
UNS C81700 · ASTM B824
M = thermomechanically controlled processed
Pick for low-stress, dimensionally stable parts or when the casting will be heat treated later by the user.
Values for the M condition
Other C81700 tempers and conditions
C81700 is listed in 3 conditions; see the grade overview at C81700.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated | Pick when heavy machining, straightening or forming is done before the customer performs the precipitation age. | 125 | 330 | 25 | 70 HB | 25 % IACS |
MThis page Thermomechanically controlled processed | Pick for low-stress, dimensionally stable parts or when the casting will be heat treated later by the user. | 140 | 310 | 20 | 75 HB | 30 % IACS |
TF00Default Solution heat treated and precipitation hardened | Standard supply condition: full strength, hardness and ~45 % IACS conductivity for tooling, electrodes and bushings. | 515 | 655 | 5 | 20 HRC | 45 % IACS |
What is C81700-M?
C81700-M is C81700 heat treated to M — pick for low-stress, dimensionally stable parts or when the casting will be heat treated later by the user. C81700-M has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 130 GPa (18.9 Msi). C81700-M has a density of 8.75 g/cm³ (0.316 lb/in³), lighter than 51% of copper alloy grades. It melts at 1,030°C (1,886 °F). TF00 is the default condition FabDigit quotes; M is available on request or by drawing note.
Advantages
- Stiff — 130 GPa (18.9 Msi), better than 89% of copper alloy grades
Limitations
- High embodied carbon — 4.5 kg CO₂/kg, worse than 79% of copper alloy grades
C81700-M properties
Typical room-temperature values for C81700-M; 10 are specific to this condition. Other listed values are C81700 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C81700-M has a density of 8.75 g/cm³ (0.316 lb/in³), lighter than 51% of copper alloy grades. It melts at 1,030°C (1,886 °F).
Mechanical12
C81700-M has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 130 GPa (18.9 Msi).
Thermal6
C81700-M is rated for continuous service to 250°C (482 °F). It conducts heat at 145 W/m·K (83.8 BTU/hr·ft·°F), better than 72% of copper alloy grades. Thermal expansion is 17.5 µm/m·K (9.72 µin/in·°F).
Electrical3
C81700-M conducts electricity at 30 % IACS, better than 71% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 58% of copper alloy grades.
Sustainability4
Producing a kilogram of C81700-M takes about 70 MJ of energy and emits 4.5 kg of CO₂ — more than 84% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C81700-M's machinability is fair (45/100, better than 64% of copper alloy grades); weldability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C81700-M
Is C81700 easy to machine?
Machines like a hard bronze — carbide tooling, positive rake, flood coolant; beryllium-containing swarf and dust must be wet-collected and handled under an occupational-health programme.
Can C81700 be welded?
GTAW/GMAW with matching Cu-Be filler is possible under preheat; the heat-affected zone loses ageing response, so re-solution + re-age for full properties.
Can C81700 be formed, bent or molded?
Supplied as sand, permanent-mould or centrifugal castings with good fluidity; solution treat ~790–815 °C, water quench, then age ~480–500 °C for 2–3 h.
What surface finishes work on C81700?
Not anodisable; polishes to a bright copper finish and takes Ni/Cr or electroless-nickel plating, chemical blackening or clear lacquer for tarnish control.
C81700 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 |
|---|---|---|
| Below-beryllium level; verify against current CDA/ASTM B770 registration | 0.4 – 0.8 | 0.6 |
| CoCo (may be partly replaced by Ni) as grain refiner/hardener | 2.4 – 2.7 | 2.5 |
| Agsilver addition raises softening resistance | 0.9 – 1.1 | 1 |
| Si | ≤ 0.2 | — |
| Fe | ≤ 0.1 | — |
| Al | ≤ 0.1 | — |
| CuCu (incl. Ag) approx. 94 % min | balance | — |
C81700-M — frequently asked
What is C81700-M used for?
C81700-M is typically used for plastic mold cores, bushings, bearing components and continuous casting dies. In short: lower-cost cast beryllium copper; wear resistance with 45 % IACS; age-hardenable cast tooling alloy.
What is the yield strength of C81700-M?
C81700-M has a typical yield strength of 140 MPa (20.3 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 74% of copper alloy grades. Strength varies by condition: see the 3 listed tempers.
Is C81700-M easy to machine?
Reasonably — machinability is rated fair (45/100, better than 64% of copper alloy grades). Machines like a hard bronze — carbide tooling, positive rake, flood coolant; beryllium-containing swarf and dust must be wet-collected and handled under an occupational-health programme.
Can C81700-M be welded?
With care — weldability is rated fair (45/100). GTAW/GMAW with matching Cu-Be filler is possible under preheat; the heat-affected zone loses ageing response, so re-solution + re-age for full properties.
What surface finishes work on C81700-M?
Not anodisable; polishes to a bright copper finish and takes Ni/Cr or electroless-nickel plating, chemical blackening or clear lacquer for tarnish control.
Can C81700-M be formed, bent or molded?
Supplied as sand, permanent-mould or centrifugal castings with good fluidity; solution treat ~790–815 °C, water quench, then age ~480–500 °C for 2–3 h.
What is the maximum service temperature of C81700-M?
C81700-M is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C81700-TF00 and C81700-TB00?
TF00 is the default condition — standard supply condition: full strength, hardness and ~45 % IACS conductivity for tooling, electrodes and bushings. TB00: pick when heavy machining, straightening or forming is done before the customer performs the precipitation age. Yield strength is 515 MPa in TF00 versus 125 MPa in TB00.
Sources
- ASTM B770 — Copper-Beryllium Alloy Sand Castings for General Applications — ASTM International (2019)
- ASTM B824 — General Requirements for Copper Alloy Castings — ASTM International (2021)
- CDA Cast Copper Alloy Datasheets (C817xx / C820xx family) — 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.