Copper Alloy C69400
UNS C69400 · ASTM B371
C69400 is a silicon-modified red brass (Cu-Si-Zn) covered by ASTM B371, using silicon instead of lead for strength.
Reference datasheet — C69400 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 M30 condition
C69400 tempers and conditions
C69400 is supplied in 6 conditions, soft to hard. M30 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick when maximum ductility for cold heading, bending or spinning is needed before final sizing. | 205 | 480 | 35 | 115 HB | 7 % IACS |
As hot rolled | Condition of net-shape hot-forged valve stems and fittings before machining; properties close to as-extruded. | 310 | 590 | 25 | 155 HB | 6.7 % IACS |
M30Default As hot extruded | Standard stock condition for silicon red brass rod, bar and shapes per ASTM B371 — best balance of strength and ductility. | 345 | 620 | 25 | 165 HB | 6.7 % IACS |
Half hard | Cold-drawn rod for better straightness, tighter tolerance and higher yield strength with useful residual ductility. | 415 | 655 | 20 | 180 HB | 6.6 % IACS |
Drawn and stress relieved | Drawn rod given a low-temperature stress relief to cut residual stress and SCC risk while keeping most cold-work strength. | 430 | 660 | 18 | 183 HB | 6.5 % IACS |
Full hard | Highest-strength drawn condition for valve stems and threaded parts where wear and thread strength govern. | 470 | 700 | 15 | 195 HB | 6.5 % IACS |
What is C69400?
C69400 is a silicon-modified red brass (Cu-Si-Zn) covered by ASTM B371, using silicon instead of lead for strength. The default temper gives 345 MPa yield, 620 MPa tensile, 25% elongation and 165 HB (80 HRB), and it is normally supplied as hot-extruded tube, rod and forging stock for lead-free potable-water parts. Machinability is about 30% of C36000 and cold formability is only fair, so parts are usually hot-forged and then finish-machined; electrical conductivity is low at 6.7% IACS. Where lead content is permitted, C36000 machines far faster. C69400 has a density of 8.3 g/cm³ (0.3 lb/in³), lighter than 80% of copper alloy grades. It melts at 820°C (1,508 °F). C69400 has a yield strength of 345 MPa (50 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 73% of copper alloy grades. Elongation at break is 25% and the elastic modulus is 103 GPa (14.9 Msi).
What is C69400 used for?
- plumbing tube
- fittings
- lead-free water system components
Limitations
- Poor heat conductor — 28.5 W/m·K (16.5 BTU/hr·ft·°F), worse than 95% of copper alloy grades
- Low electrical conductivity — 6.7 % IACS, worse than 89% of copper alloy grades
C69400 properties
Typical room-temperature values for C69400-M30; bars are the position among copper alloy grades.
Physical3
C69400 has a density of 8.3 g/cm³ (0.3 lb/in³), lighter than 80% of copper alloy grades. It melts at 820°C (1,508 °F).
Mechanical12
C69400 has a yield strength of 345 MPa (50 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 73% of copper alloy grades. Elongation at break is 25% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
C69400 is rated for continuous service to 200°C (392 °F). It conducts heat at 28.5 W/m·K (16.5 BTU/hr·ft·°F), worse than 95% of copper alloy grades. Thermal expansion is 20.2 µm/m·K (11.2 µin/in·°F).
Electrical3
C69400 conducts electricity at 6.7 % IACS, worse than 89% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 64% of copper alloy grades.
Sustainability4
Producing a kilogram of C69400 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%.
Manufacturability8
C69400's machinability is poor (30/100, worse than 67% of copper alloy grades); weldability fair (45/100); formability fair (40/100).
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. C69400 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C69400
Is C69400 easy to machine?
Machinability ≈30% of C36000 — use sharp positive-rake carbide, high speed with generous coolant; chips are stringy, so chipbreakers and reduced feeds are needed versus leaded brass.
Can C69400 be welded?
Solders and brazes readily; GTAW/GMAW with silicon-bronze filler is acceptable, but oxyacetylene welding is not recommended because of zinc/silicon loss.
Can C69400 be formed, bent or molded?
Excellent hot extrudability and hot forgeability at ~700–800 °C; cold formability only fair, so limit cold reductions and anneal between heavy operations.
C69400 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 |
|---|---|---|
| Cuincludes Ag | 80 – 83 | 81.5 |
| Si | 3.5 – 4.5 | 4 |
| Pblow-lead / lead-free plumbing grades often ≤0.09 | ≤ 0.3 | 0.05 |
| Fe | ≤ 0.2 | 0.05 |
| Znremainder, ~12–16% | balance |
What surface finishes work on C69400?
Polishes to a bright golden finish; accepts nickel/chrome plating well — passivate with benzotriazole or lacquer to avoid tarnish, no anodizing.
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).
Equivalent designations
Standards and trade names that resolve to Copper Alloy C69400 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- B371
How much does C69400 cost?
C69400 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.
C69400 — frequently asked
What is C69400 used for?
C69400 is typically used for plumbing tube, fittings and lead-free water system components. In short: lead-free plumbing brass; high-strength silicon brass; hot-forged, not free-cutting.
What is the yield strength of C69400?
C69400 has a typical yield strength of 345 MPa (50 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 73% of copper alloy grades. Strength varies by condition: see the 6 listed tempers.
Is C69400 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 67% of copper alloy grades). Machinability ≈30% of C36000 — use sharp positive-rake carbide, high speed with generous coolant; chips are stringy, so chipbreakers and reduced feeds are needed versus leaded brass.
Can C69400 be welded?
With care — weldability is rated fair (45/100). Solders and brazes readily; GTAW/GMAW with silicon-bronze filler is acceptable, but oxyacetylene welding is not recommended because of zinc/silicon loss.
What surface finishes work on C69400?
Polishes to a bright golden finish; accepts nickel/chrome plating well — passivate with benzotriazole or lacquer to avoid tarnish, no anodizing.
Can C69400 be formed, bent or molded?
Excellent hot extrudability and hot forgeability at ~700–800 °C; cold formability only fair, so limit cold reductions and anneal between heavy operations.
What is the maximum service temperature of C69400?
C69400 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 C69400-M30 and C69400-O60?
M30 is the default condition — standard stock condition for silicon red brass rod, bar and shapes per ASTM B371 — best balance of strength and ductility. O60: pick when maximum ductility for cold heading, bending or spinning is needed before final sizing. Yield strength is 345 MPa in M30 versus 205 MPa in O60.
How much does C69400 cost?
C69400 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
- ASTM B371/B371M — Copper-Zinc-Silicon Alloy Rod — ASTM International (2019)
- CDA Alloy Datasheet C69400 (Silicon Red Brass) — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
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.