Copper Alloy C99750 M-AC
Heat-treated state · default condition
UNS C99750 · ASTM B584, B763
M-AC = as Cast
Standard stocked condition for decorative and general-purpose C99750 castings; best ductility and easiest machining.
Values for the M-AC condition
Other C99750 tempers and conditions
C99750 is listed in 3 conditions; see the grade overview at C99750.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
M-ACDefaultThis page As Cast | Standard stocked condition for decorative and general-purpose C99750 castings; best ductility and easiest machining. | 234 | 455 | 25 | 130 HB | 3.5 % IACS |
As continuous cast | Pick for machined bushings, sleeves and wear rings — denser, finer structure than sand cast with slightly higher strength and hardness. | 280 | 490 | 18 | 145 HB | 4 % IACS |
Solution heat treated and precipitation hardened | Choose when castings must carry higher loads or resist wear — roughly 35–40 % strength gain at the cost of ductility and machinability. | 415 | 620 | 10 | 200 HB | 4.5 % IACS |
What is C99750 M-AC?
C99750 M-AC is C99750 heat treated to M-AC — standard stocked condition for decorative and general-purpose C99750 castings; best ductility and easiest machining. C99750 M-AC has a yield strength of 234 MPa (33.9 ksi) and a tensile strength of 455 MPa (66 ksi) — stronger than 51% of copper alloy grades. Elongation at break is 25% and the elastic modulus is 100 GPa (14.5 Msi). C99750 M-AC has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 89% of copper alloy grades. It melts at 871°C (1,600 °F).
Advantages
- Low embodied carbon — 3.2 kg CO₂/kg, better than 92% of copper alloy grades
Limitations
- Low electrical conductivity — 3.5 % IACS, worse than 99% of copper alloy grades
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 98% of copper alloy grades
- Low stiffness — 100 GPa (14.5 Msi), worse than 82% of copper alloy grades
C99750 M-AC properties
Typical room-temperature values for C99750 M-AC; 33 are specific to this condition. Other listed values are C99750 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C99750 M-AC has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 89% of copper alloy grades. It melts at 871°C (1,600 °F).
Mechanical12
C99750 M-AC has a yield strength of 234 MPa (33.9 ksi) and a tensile strength of 455 MPa (66 ksi) — stronger than 51% of copper alloy grades. Elongation at break is 25% and the elastic modulus is 100 GPa (14.5 Msi).
Thermal6
C99750 M-AC is rated for continuous service to 250°C (482 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 98% of copper alloy grades. Thermal expansion is 20 µm/m·K (11.1 µin/in·°F).
Electrical3
C99750 M-AC conducts electricity at 3.5 % IACS, worse than 99% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C99750 M-AC takes about 45 MJ of energy and emits 3.2 kg of CO₂ — less than 97% of copper alloy grades. Typical recycled content is 70%.
Manufacturability8
C99750 M-AC's machinability is fair (35/100, better than 51% of copper alloy grades); weldability fair (45/100); formability poor (25/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C99750 M-AC
Is C99750 easy to machine?
Free-machining thanks to 0.5–2.5 % Pb — use sharp carbide tooling, moderate speeds and generous coolant; high-Mn matrix work-hardens if tools rub.
Can C99750 be welded?
Fusion welding is difficult (Al oxide film, Pb hot-cracking, Zn fumes); use GTAW with Al-bronze filler and preheat only for repair, or braze/mechanically fasten instead.
Can C99750 be formed, bent or molded?
Casting alloy with good fluidity — sand, permanent-mould, centrifugal and continuous casting all practical; degas melt, control Mn losses and feed heavy sections to avoid shrinkage porosity.
What surface finishes work on C99750?
Polishes to a bright silvery-white finish that needs no plating for decorative use; accepts nickel/chrome plating and clear lacquer, but not anodising.
C99750 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 |
|---|---|---|
| Cu | 55 – 61 | 58 |
| Mnprimary strengthener, gives white colour | 17 – 23 | 20 |
| Al | 0.5 – 2.5 | 1.5 |
| Pbfree-machining addition | 0.5 – 2.5 | 1.5 |
| NiNi + Co | ≤ 5 | 1 |
| Fe | ≤ 1 | 0.4 |
| Znremainder, typically 17–23 % | balance | — |
C99750 M-AC — frequently asked
What is C99750 M-AC used for?
C99750 M-AC is typically used for decorative hardware, marine deck fittings and architectural castings. In short: machinable white brass; higher strength than C99700; service to 250 °C.
What is the yield strength of C99750 M-AC?
C99750 M-AC has a typical yield strength of 234 MPa (33.9 ksi) and a tensile strength of 455 MPa (66 ksi) — stronger than 51% of copper alloy grades. Strength varies by condition: see the 3 listed tempers.
Is C99750 M-AC easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Free-machining thanks to 0.5–2.5 % Pb — use sharp carbide tooling, moderate speeds and generous coolant; high-Mn matrix work-hardens if tools rub.
Can C99750 M-AC be welded?
With care — weldability is rated fair (45/100). Fusion welding is difficult (Al oxide film, Pb hot-cracking, Zn fumes); use GTAW with Al-bronze filler and preheat only for repair, or braze/mechanically fasten instead.
What surface finishes work on C99750 M-AC?
Polishes to a bright silvery-white finish that needs no plating for decorative use; accepts nickel/chrome plating and clear lacquer, but not anodising.
Can C99750 M-AC be formed, bent or molded?
Casting alloy with good fluidity — sand, permanent-mould, centrifugal and continuous casting all practical; degas melt, control Mn losses and feed heavy sections to avoid shrinkage porosity.
What is the maximum service temperature of C99750 M-AC?
C99750 M-AC 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 C99750 M-AC and C99750-TF00?
M-AC is the default condition — standard stocked condition for decorative and general-purpose C99750 castings; best ductility and easiest machining. TF00: choose when castings must carry higher loads or resist wear — roughly 35–40 % strength gain at the cost of ductility and machinability. Yield strength is 234 MPa in M-AC versus 415 MPa in TF00.
Sources
- ASTM B584 — Copper Alloy Sand Castings for General Applications — ASTM International (2022)
- ASTM B763 — Copper Alloy Sand Castings for Valve Applications — ASTM International (2020)
- CDA/UNS Copper Alloy Datasheets (C997xx white manganese brasses) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
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.