Copper Alloy C68400
UNS C68400
C68400 is a high-strength silicon-manganese brass strengthened by a hard silicide phase, supplied as rod, bar and forgings for marine hardware and heavy-duty fasteners.
Reference datasheet — C68400 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the H02 condition
C68400 tempers and conditions
C68400 is supplied in 9 conditions, soft to hard. H02 is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick when maximum ductility for bending, spinning or deep drawing is needed before final forming. | 200 | 460 | 32 | 100 HB | 15 % IACS |
As hot rolled | Pick for hot-rolled plate/flats where strength requirements are modest and further machining follows. | 230 | 480 | 28 | 115 HB | 15 % IACS |
As hot extruded | Standard condition for large-diameter rod, hollows and shapes; best hot-worked ductility, lowest cold-work stresses. | 250 | 500 | 26 | 120 HB | 15 % IACS |
Quarter hard | Light cold draw for straight, close-tolerance rod that still needs to be bent or headed. | 290 | 530 | 24 | 135 HB | 14.5 % IACS |
Light drawn | Light-drawn tube temper for hollow marine fittings that still need bending or expanding. | 300 | 540 | 22 | 140 HB | 15 % IACS |
H02Default Half hard | Default stocked rod/bar temper — best balance of strength, straightness and machinability for marine hardware and fasteners. | 340 | 570 | 20 | 150 HB | 14.5 % IACS |
Cold drawn and stress relieved | Choose when residual stresses must be lowered to resist stress-corrosion cracking in ammonia or marine service. | 350 | 560 | 20 | 150 HB | 15 % IACS |
Full hard | Pick for maximum strength and wear resistance in shafts, valve stems and bushings with little further forming. | 450 | 650 | 12 | 180 HB | 14 % IACS |
Extra hard | Heavily drawn small-diameter rod/wire for springy or high-load fastener applications; very limited ductility. | 540 | 720 | 8 | 200 HB | 14 % IACS |
What is C68400?
C68400 is a high-strength silicon-manganese brass strengthened by a hard silicide phase, supplied as rod, bar and forgings for marine hardware and heavy-duty fasteners. Default properties are 570 MPa tensile, 340 MPa yield, 20 % elongation and 150 HB (80 HRB), combining structural strength with brass corrosion resistance. Cold formability is modest (rating 45) and fusion welding is restricted by zinc fuming, so hot forging plus brazed or mechanical joints dominate. C67400 is the nearest higher-hardness manganese-aluminum alternative. C68400 has a density of 8.35 g/cm³ (0.302 lb/in³), lighter than 77% of copper alloy grades. It melts at 865°C (1,589 °F). C68400 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 570 MPa (82.7 ksi) — stronger than 71% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 103 GPa (14.9 Msi).
What is C68400 used for?
- marine hardware
- heavy-duty fasteners
- structural components
Limitations
- Poor heat conductor — 45 W/m·K (26 BTU/hr·ft·°F), worse than 76% of copper alloy grades
C68400 properties
Typical room-temperature values for C68400-H02; bars are the position among copper alloy grades.
Physical3
C68400 has a density of 8.35 g/cm³ (0.302 lb/in³), lighter than 77% of copper alloy grades. It melts at 865°C (1,589 °F).
Mechanical14
C68400 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 570 MPa (82.7 ksi) — stronger than 71% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
C68400 is rated for continuous service to 200°C (392 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), worse than 76% of copper alloy grades. Thermal expansion is 20.5 µm/m·K (11.4 µin/in·°F).
Electrical3
C68400 conducts electricity at 14.5 % IACS, worse than 55% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C68400 takes about 50 MJ of energy and emits 3.4 kg of CO₂ — less than 89% of copper alloy grades. Typical recycled content is 50%.
Manufacturability8
C68400's machinability is fair (35/100, better than 51% of copper alloy grades); weldability fair (45/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the copper alloy family
Yield strength against density for every copper alloy grade FabDigit runs. C68400 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C68400
Is C68400 easy to machine?
Machines like unleaded high-strength brass (~30 % of AISI 1212): use sharp, positive-rake carbide, high speed with light feeds, and copious coolant to avoid gummy chips and built-up edge.
Can C68400 be welded?
Fusion welding is restricted by zinc fuming and porosity; prefer brazing, silver soldering or GTAW with silicon-bronze filler, low heat input and good extraction.
Can C68400 be formed, bent or molded?
Best hot worked at ~650–750 °C (extrusion, forging); cold formability is limited by the hard silicide phase, so allow interanneals at ~500–600 °C between draws.
C68400 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-Zn α+β matrix; exact registry limits should be confirmed against the governing standard | 55 – 60 | 57.5 |
| Siforms hard Cu-Zn-Si silicide phase for strength/wear | 0.5 – 1.5 | 1 |
| Mnsolid-solution and Mn-Si intermetallic strengthening | 1.5 – 3 | 2 |
| Fegrain refiner / impurity limit | ≤ 0.5 | 0.2 |
| Al | ≤ 0.5 | 0.2 |
| Sn | ≤ 0.5 | |
| Pbkept low; not a free-cutting grade | ≤ 0.2 | |
| Zn | balance |
What surface finishes work on C68400?
Polishes and buffs well and takes Ni/Cr or decorative electroplate readily; anodizing is not applicable — protect with clear lacquer or chemical patina, and stress-relieve before service in ammonia-bearing atmospheres.
Surface treatments FabDigit runs on copper alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
How much does C68400 cost?
C68400 is a high-cost copper alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C68400 — frequently asked
What is C68400 used for?
C68400 is typically used for marine hardware, heavy-duty fasteners and structural components. In short: high-strength silicon brass; marine fastener grade; limited cold formability.
What is the yield strength of C68400?
C68400 has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 570 MPa (82.7 ksi) — stronger than 71% of copper alloy grades. Strength varies by condition: see the 9 listed tempers.
Is C68400 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Machines like unleaded high-strength brass (~30 % of AISI 1212): use sharp, positive-rake carbide, high speed with light feeds, and copious coolant to avoid gummy chips and built-up edge.
Can C68400 be welded?
With care — weldability is rated fair (45/100). Fusion welding is restricted by zinc fuming and porosity; prefer brazing, silver soldering or GTAW with silicon-bronze filler, low heat input and good extraction.
What surface finishes work on C68400?
Polishes and buffs well and takes Ni/Cr or decorative electroplate readily; anodizing is not applicable — protect with clear lacquer or chemical patina, and stress-relieve before service in ammonia-bearing atmospheres.
Can C68400 be formed, bent or molded?
Best hot worked at ~650–750 °C (extrusion, forging); cold formability is limited by the hard silicide phase, so allow interanneals at ~500–600 °C between draws.
What is the maximum service temperature of C68400?
C68400 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 C68400-H02 and C68400-H06?
H02 is the default condition — default stocked rod/bar temper — best balance of strength, straightness and machinability for marine hardware and fasteners. H06: heavily drawn small-diameter rod/wire for springy or high-load fastener applications; very limited ductility. Yield strength is 340 MPa in H02 versus 540 MPa in H06.
How much does C68400 cost?
C68400 is a high-cost copper alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (wrought brass section) — ASM International (1990)
- ASTM B36/B124/B927 — wrought brass rod, bar, shapes and temper designations (ASTM B601) — ASTM International (2020)
- CDA/UNS copper alloy designation listings (C6xxxx high-strength brasses) — Copper Development Association (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.