Copper Alloy C47940-O50
Temper
UNS C47940 · ASTM B124
O50 = light annealed
Stress-relieved/light-annealed rod for parts that will be bent or upset and where SCC risk must be reduced.
Values for the O50 condition
Other C47940 tempers and conditions
C47940 is listed in 6 conditions; see the grade overview at C47940.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Fully softened condition for maximum ductility in severe cold forming, heading or coining. | 140 | 380 | 48 | 85 HB | — |
O50This page Light annealed | Stress-relieved/light-annealed rod for parts that will be bent or upset and where SCC risk must be reduced. | 160 | 400 | 42 | 95 HB | — |
M30Default As hot extruded | Standard mill condition for forging stock and large-diameter rod; maximum ductility for subsequent hot forging. | 180 | 415 | 38 | 105 HB | 26 % IACS |
Extruded and drawn | Choose for straight, close-tolerance rod and hex with a modest strength gain over as-extruded. | 275 | 460 | 25 | 130 HB | — |
Half hard | Balanced strength and residual ductility for machined marine fittings and shafting. | 345 | 495 | 20 | 145 HB | — |
Full hard | Highest-strength rod condition for studs, pins and wear surfaces where forming is not needed. | 415 | 550 | 14 | 165 HB | — |
What is C47940-O50?
C47940-O50 is C47940 in the O50 temper — stress-relieved/light-annealed rod for parts that will be bent or upset and where SCC risk must be reduced. C47940-O50 has a yield strength of 160 MPa (23.2 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 65% of copper alloy grades. Elongation at break is 42% and the elastic modulus is 103 GPa (14.9 Msi). C47940-O50 has a density of 8.41 g/cm³ (0.304 lb/in³), lighter than 72% of copper alloy grades. It melts at 885°C (1,625 °F). M30 is the default condition FabDigit quotes; O50 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 42%, better than 86% of copper alloy grades
Limitations
- Difficult to weld — 25/100, worse than 78% of copper alloy grades
C47940-O50 properties
Typical room-temperature values for C47940-O50; 13 are specific to this condition. Other listed values are C47940 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C47940-O50 has a density of 8.41 g/cm³ (0.304 lb/in³), lighter than 72% of copper alloy grades. It melts at 885°C (1,625 °F).
Mechanical14
C47940-O50 has a yield strength of 160 MPa (23.2 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 65% of copper alloy grades. Elongation at break is 42% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
C47940-O50 is rated for continuous service to 200°C (392 °F). It conducts heat at 116 W/m·K (67 BTU/hr·ft·°F), better than 64% of copper alloy grades. Thermal expansion is 20.9 µm/m·K (11.6 µin/in·°F).
Electrical3
C47940-O50 conducts electricity at 26 % IACS, better than 63% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 58% of copper alloy grades.
Sustainability4
Producing a kilogram of C47940-O50 takes about 58 MJ of energy and emits 3.6 kg of CO₂ — more than 61% of copper alloy grades. Typical recycled content is 50%.
Manufacturability8
C47940-O50's machinability is fair (50/100, better than 69% of copper alloy grades); weldability poor (25/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C47940-O50
Is C47940 easy to machine?
Machines well with sharp positive-rake tooling and flood coolant; the small Pb addition gives free-ish chips but expect stringier chips than C36000 — plan ~55–60 % of 1212 speeds.
Can C47940 be welded?
Not recommended for fusion welding (zinc fume, hot cracking, lead-induced cracking); join by soldering, silver brazing or mechanical fastening.
Can C47940 be formed, bent or molded?
Excellent hot forgeability at about 650–760 °C — its primary use; cold forming limited to annealed/light tempers, and cold-worked parts should be stress-relieved near 260–300 °C to avoid SCC.
What surface finishes work on C47940?
Polishes to a bright yellow finish; accepts nickel, chrome, tin or clear-lacquer/benzotriazole protection — anodizing does not apply to copper alloys.
C47940 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 |
|---|---|---|
| Cualpha-beta naval brass base | 63 – 66 | 64.5 |
| Sndezincification inhibitor | 0.2 – 1 | 0.6 |
| Pbmachinability aid | 0.1 – 1 | 0.5 |
| Fegrain refinement / strength | 0.1 – 1 | 0.4 |
| Nicorrosion resistance | 0.1 – 1 | 0.4 |
| Alimpurity limit | ≤ 0.1 | — |
| Zn | balance | — |
C47940-O50 — frequently asked
What is C47940-O50 used for?
C47940-O50 is typically used for marine forgings, valve and pump components and fittings. In short: forging-grade naval brass; free-machining marine forgings; near-net-shape hot press alloy.
What is the yield strength of C47940-O50?
C47940-O50 has a typical yield strength of 160 MPa (23.2 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 65% of copper alloy grades. Strength varies by condition: see the 6 listed tempers.
Is C47940-O50 easy to machine?
Reasonably — machinability is rated fair (50/100, better than 69% of copper alloy grades). Machines well with sharp positive-rake tooling and flood coolant; the small Pb addition gives free-ish chips but expect stringier chips than C36000 — plan ~55–60 % of 1212 speeds.
Can C47940-O50 be welded?
Not readily — weldability is rated poor (25/100). Not recommended for fusion welding (zinc fume, hot cracking, lead-induced cracking); join by soldering, silver brazing or mechanical fastening.
What surface finishes work on C47940-O50?
Polishes to a bright yellow finish; accepts nickel, chrome, tin or clear-lacquer/benzotriazole protection — anodizing does not apply to copper alloys.
Can C47940-O50 be formed, bent or molded?
Excellent hot forgeability at about 650–760 °C — its primary use; cold forming limited to annealed/light tempers, and cold-worked parts should be stress-relieved near 260–300 °C to avoid SCC.
What is the maximum service temperature of C47940-O50?
C47940-O50 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 C47940-M30 and C47940-H04?
M30 is the default condition — standard mill condition for forging stock and large-diameter rod; maximum ductility for subsequent hot forging. H04: highest-strength rod condition for studs, pins and wear surfaces where forming is not needed. Yield strength is 180 MPa in M30 versus 415 MPa in H04.
Sources
- ASTM B124/B124M Copper and Copper Alloy Forging Rod, Bar and Shapes — ASTM International (2020)
- CDA/copper.org Alloy Database — wrought brass C47xxx group — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (Copper and Copper 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.