Copper Alloy C28500-O61
Heat-treated state
UNS C28500
O61 = annealed
General-purpose annealed condition for plate, sheet and rod that will be formed or machined then finished.
Values for the O61 condition
Other C28500 tempers and conditions
C28500 is listed in 8 conditions; see the grade overview at C28500.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick for maximum ductility when the part still needs some cold bending or upsetting after annealing. | 115 | 355 | 52 | 58 HB | 28 % IACS |
O61This page Annealed | General-purpose annealed condition for plate, sheet and rod that will be formed or machined then finished. | 140 | 370 | 48 | 65 HB | 28 % IACS |
M30Default As hot extruded | The usual stocked form: hot-extruded rod/bar sold as forging blanks and hardware stock. | 145 | 380 | 45 | 70 HB | 28 % IACS |
As hot rolled | Standard mill condition for Muntz-type plate used in marine sheathing, tube sheets and heavy hardware. | 150 | 380 | 45 | 72 HB | 28 % IACS |
As hot forged and air cooled | Condition of finished hot forgings (valve bodies, fittings) taken directly from the die with no post-heat treatment. | 155 | 385 | 40 | 75 HB | 28 % IACS |
Quarter hard | Light cold work for better straightness, surface finish and moderate strength in rod and sheet. | 275 | 420 | 28 | 105 HB | 27 % IACS |
Half hard | Choose when higher yield strength and wear resistance are needed and only mild bending is required. | 350 | 470 | 18 | 125 HB | 27 % IACS |
Full hard | Maximum strength condition for straight rod, springs-free hardware and wear surfaces; very little remaining ductility. | 410 | 540 | 10 | 150 HB | 26 % IACS |
What is C28500-O61?
C28500-O61 is C28500 heat treated to O61 — general-purpose annealed condition for plate, sheet and rod that will be formed or machined then finished. C28500-O61 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 370 MPa (53.7 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 48% and the elastic modulus is 105 GPa (15.2 Msi). C28500-O61 has a density of 8.39 g/cm³ (0.303 lb/in³), lighter than 76% of copper alloy grades. It melts at 899°C (1,650 °F). M30 is the default condition FabDigit quotes; O61 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 48%, better than 97% of copper alloy grades
- Low embodied carbon — 3.3 kg CO₂/kg, better than 90% of copper alloy grades
Limitations
- Needs corrosion protection — 45/100, worse than 98% of copper alloy grades
C28500-O61 properties
Typical room-temperature values for C28500-O61; 20 are specific to this condition. Other listed values are C28500 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C28500-O61 has a density of 8.39 g/cm³ (0.303 lb/in³), lighter than 76% of copper alloy grades. It melts at 899°C (1,650 °F).
Mechanical14
C28500-O61 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 370 MPa (53.7 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 48% and the elastic modulus is 105 GPa (15.2 Msi).
Thermal6
C28500-O61 is rated for continuous service to 200°C (392 °F). It conducts heat at 123 W/m·K (71.1 BTU/hr·ft·°F), better than 70% of copper alloy grades. Thermal expansion is 20.8 µm/m·K (11.6 µin/in·°F).
Electrical3
C28500-O61 conducts electricity at 28 % IACS, better than 69% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 98% of copper alloy grades.
Sustainability4
Producing a kilogram of C28500-O61 takes about 55 MJ of energy and emits 3.3 kg of CO₂ — less than 72% of copper alloy grades. Typical recycled content is 50%.
Manufacturability8
C28500-O61's machinability is fair (45/100, better than 64% of copper alloy grades); weldability fair (45/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C28500-O61
Is C28500 easy to machine?
Machines like a duplex brass — roughly 40 % of free-cutting C36000: use sharp positive-rake tools, high speed, light feeds and coolant; the β phase chips well but is gummier than leaded brass.
Can C28500 be welded?
Best joined by brazing or soldering; TIG/MIG with silicon-bronze filler is possible but zinc fuming, porosity and dezincified weld zones require extraction and low heat input.
Can C28500 be formed, bent or molded?
Excellent hot working at 620–780 °C (forge, extrude, hot roll); cold formability is limited — anneal at 425–600 °C between severe cold operations and stress-relieve to avoid SCC.
What surface finishes work on C28500?
Takes a bright mechanical polish and accepts Ni/Cr or decorative plating; not anodizable — protect with lacquer or chemical bronze/black finishes, and stress-relieve before plating to prevent cracking.
C28500 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 |
|---|---|---|
| Cu60/40 Muntz-type range; verify exact limits against the current CDA/ASTM registration for C28500 | 59 – 62 | 60.5 |
| Pbresidual/intentional low lead for hot-working and machining | ≤ 0.3 | 0.1 |
| Fe | ≤ 0.15 | 0.05 |
| Snresidual from scrap | ≤ 0.1 | — |
| Alresidual | ≤ 0.05 | — |
| Znnominally ~40 % | balance | — |
C28500-O61 — frequently asked
What is C28500-O61 used for?
C28500-O61 is typically used for forging blanks, hardware and structural extrusions. In short: hot-forgeable duplex brass; high elongation, 45%; strong hot-worked hardware alloy.
What is the yield strength of C28500-O61?
C28500-O61 has a typical yield strength of 140 MPa (20.3 ksi) and a tensile strength of 370 MPa (53.7 ksi) — weaker than 74% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C28500-O61 easy to machine?
Reasonably — machinability is rated fair (45/100, better than 64% of copper alloy grades). Machines like a duplex brass — roughly 40 % of free-cutting C36000: use sharp positive-rake tools, high speed, light feeds and coolant; the β phase chips well but is gummier than leaded brass.
Can C28500-O61 be welded?
With care — weldability is rated fair (45/100). Best joined by brazing or soldering; TIG/MIG with silicon-bronze filler is possible but zinc fuming, porosity and dezincified weld zones require extraction and low heat input.
What surface finishes work on C28500-O61?
Takes a bright mechanical polish and accepts Ni/Cr or decorative plating; not anodizable — protect with lacquer or chemical bronze/black finishes, and stress-relieve before plating to prevent cracking.
Can C28500-O61 be formed, bent or molded?
Excellent hot working at 620–780 °C (forge, extrude, hot roll); cold formability is limited — anneal at 425–600 °C between severe cold operations and stress-relieve to avoid SCC.
What is the maximum service temperature of C28500-O61?
C28500-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 C28500-M30 and C28500-H04?
M30 is the default condition — the usual stocked form: hot-extruded rod/bar sold as forging blanks and hardware stock. H04: maximum strength condition for straight rod, springs-free hardware and wear surfaces; very little remaining ductility. Yield strength is 145 MPa in M30 versus 410 MPa in H04.
Sources
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (Cu–Zn alloys) — ASM International (1990)
- CDA Copper Alloy Database — Muntz metal / 60-40 brass (C28000 family) — Copper Development Association (2023)
- ASTM B124/B124M — Copper and Copper-Alloy Forging Rod, Bar, and Shapes — ASTM (2020)
- ASTM B601 — Temper Designations for Copper and Copper Alloys — ASTM (2019)
- ASM Handbook Vol.13 — Corrosion (dezincification, SCC of brasses) — 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.