Copper Alloy C31600-O61
Heat-treated state
UNS C31600
O61 = annealed
Intermediate anneal for rod/section that still needs moderate cold forming with slightly higher strength than O60.
Values for the O61 condition
Other C31600 tempers and conditions
C31600 is listed in 7 conditions; see the grade overview at C31600.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick for maximum ductility: heading, staking, riveting, severe bending or deep upsetting of rod. | 95 | 280 | 45 | 55 HB | 40 % IACS |
As hot extruded | Economical condition for large sections and shapes that will be fully machined; lowest strength, no residual drawing stress. | 110 | 290 | 40 | 60 HB | 38 % IACS |
O61This page Annealed | Intermediate anneal for rod/section that still needs moderate cold forming with slightly higher strength than O60. | 125 | 300 | 40 | 65 HB | 38 % IACS |
Quarter hard | Use when bending or moderate forming must be combined with better straightness and strength than annealed rod. | 205 | 315 | 30 | 78 HB | 38 % IACS |
H02Default Half hard | Standard stock condition for screw-machine rod and electrical hardware: best balance of strength, chip control and residual formability. | 275 | 350 | 20 | 95 HB | 38 % IACS |
Full hard | Choose for maximum strength and stiffness of threaded fasteners, studs and contact pins where little forming follows. | 345 | 415 | 10 | 112 HB | 37 % IACS |
Extra hard | Small-diameter wire/rod where peak hardness and spring-back are wanted and ductility is not required. | 400 | 450 | 6 | 122 HB | 37 % IACS |
What is C31600-O61?
C31600-O61 is C31600 heat treated to O61 — intermediate anneal for rod/section that still needs moderate cold forming with slightly higher strength than O60. C31600-O61 has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 115 GPa (16.7 Msi). C31600-O61 has a density of 8.78 g/cm³ (0.317 lb/in³), heavier than 53% of copper alloy grades. It melts at 1,004°C (1,839 °F). H02 is the default condition FabDigit quotes; O61 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 40%, better than 84% of copper alloy grades
- Forms and bends easily — 82/100, better than 83% of copper alloy grades
- Easy to machine — 74/100, better than 80% of copper alloy grades
Limitations
- Difficult to weld — 20/100, worse than 88% of copper alloy grades
- Low strength — 125 MPa (18.1 ksi), worse than 77% of copper alloy grades
C31600-O61 properties
Typical room-temperature values for C31600-O61; 20 are specific to this condition. Other listed values are C31600 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C31600-O61 has a density of 8.78 g/cm³ (0.317 lb/in³), heavier than 53% of copper alloy grades. It melts at 1,004°C (1,839 °F).
Mechanical11
C31600-O61 has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 77% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
C31600-O61 is rated for continuous service to 200°C (392 °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 18.4 µm/m·K (10.2 µin/in·°F).
Electrical3
C31600-O61 conducts electricity at 38 % IACS, better than 73% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 68% of copper alloy grades.
Sustainability4
Producing a kilogram of C31600-O61 takes about 55 MJ of energy and emits 3.6 kg of CO₂ — less than 72% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C31600-O61's machinability is very good (74/100, better than 80% of copper alloy grades); weldability poor (20/100); formability very good (82/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C31600-O61
Is C31600 easy to machine?
Excellent free-cutting behaviour (~80 % of C36000): use positive-rake carbide or HSS, high speed, light feed and flood coolant; lead gives short chips and fine threads.
Can C31600 be welded?
Do not fusion weld — lead causes hot cracking; join by soft soldering (excellent), silver brazing with care, or mechanical/crimped joints.
Can C31600 be formed, bent or molded?
Cold form in O60/H01 (heading, riveting, moderate bends); hot working is not recommended because of lead-induced hot shortness.
What surface finishes work on C31600?
Buffs to a bright bronze color but lead smear limits mirror polish; tin, nickel or gold plate for contacts and use benzotriazole/lacquer to control tarnish.
C31600 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 |
|---|---|---|
| CuCu + sum of named elements ≥ 99.5 % | 87.5 – 90.5 | 89 |
| Pbfree-machining phase | 1.3 – 2.5 | 1.9 |
| NiNi + Co counted together | 0.7 – 1.2 | 1 |
| Pwith Ni forms strengthening phosphide | 0.04 – 0.1 | 0.06 |
| Fe | ≤ 0.1 | — |
| Znremainder, nominally ~8–9 % | balance | — |
C31600-O61 — frequently asked
What is C31600-O61 used for?
C31600-O61 is typically used for hardware fittings, decorative fittings and precision turned parts. In short: nickel-strengthened leaded bronze; free-cutting, score 80; better corrosion than C31400.
What is the yield strength of C31600-O61?
C31600-O61 has a typical yield strength of 125 MPa (18.1 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 77% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C31600-O61 easy to machine?
Yes — machinability is rated very good (74/100, better than 80% of copper alloy grades). Excellent free-cutting behaviour (~80 % of C36000): use positive-rake carbide or HSS, high speed, light feed and flood coolant; lead gives short chips and fine threads.
Can C31600-O61 be welded?
Not readily — weldability is rated poor (20/100). Do not fusion weld — lead causes hot cracking; join by soft soldering (excellent), silver brazing with care, or mechanical/crimped joints.
What surface finishes work on C31600-O61?
Buffs to a bright bronze color but lead smear limits mirror polish; tin, nickel or gold plate for contacts and use benzotriazole/lacquer to control tarnish.
Can C31600-O61 be formed, bent or molded?
Cold form in O60/H01 (heading, riveting, moderate bends); hot working is not recommended because of lead-induced hot shortness.
What is the maximum service temperature of C31600-O61?
C31600-O61 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 C31600-H02 and C31600-O60?
H02 is the default condition — standard stock condition for screw-machine rod and electrical hardware: best balance of strength, chip control and residual formability. O60: pick for maximum ductility: heading, staking, riveting, severe bending or deep upsetting of rod. Yield strength is 275 MPa in H02 versus 95 MPa in O60.
Sources
- ASTM B140/B140M — Copper-Zinc-Lead (Leaded Red Brass / Hardware Bronze) Rod, Bar and Shapes — ASTM International (2019)
- Copper Alloy C31600 alloy data (UNS registration) — Copper Development Association / copper.org (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASTM B301/B301M — Free-Cutting Copper Rod, Bar, Wire and Shapes — ASTM International (2018)
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.