Plumbing & valves
Faucets, valves, fittings, hose barbs. The default plumbing hardware brass for 100+ years (now low-lead variants for drinking water).
Free-cutting brass · UNS C36000
Brass C360
Free-machining brass — the original screw-machine alloy. Lead inclusions break chips short and let cutting speeds run as fast as the spindle. Standard for fittings, valve trim, fasteners, plumbing hardware, and any high-volume turned part where machining speed dominates cost.
UTS
410 MPa
Density
8.50 g/cc
Cond.
26% IACS
Mach.
100 /100
When to use
Pick C360 when machining cost dominates.
C360 is the reason screw machines exist. The 3% lead content forms tiny inclusions that act as internal chip-breakers — every cut produces clean, short chips and a polished surface. Cycle times on a Swiss-type lathe are often 2-3× faster than 316L stainless or 4140 steel for equivalent geometry.
The trade-offs are real: the lead content makes C360 RoHS-restricted for EU consumer products, and lead exposure is regulated for drinking water (NSF 61 / lead-free per Reduction of Lead in Drinking Water Act, 0.25% Pb max). For those markets use a low-lead brass such as C69300 (Eco Brass) or C27450 (lead-free brass).
Strengths
Why screw shops love it.
- Mach 100/100The reference standard for free-machining. Cycle times often 2-3× faster than stainless for equivalent geometry.
- Cold workableHeaded, drawn, knurled, swaged readily in cold-drawn condition. Wide range of post-machining ops.
- Excellent corrosionResists fresh water, atmosphere, and most non-oxidizing media. Standard plumbing hardware material.
- Solderable & weldableJoins easily to other copper alloys with standard soldering. Brazes well.
- Cosmetic finishPolishes to mirror finish; easily plated. Often the visible alloy in decorative hardware.
- AntimicrobialEPA-registered antimicrobial like other copper alloys.
Trade-offs
What you watch.
- Lead content + RoHS3% Pb. Restricted under EU RoHS for many consumer applications. Use a low-lead alloy such as C69300 (Eco Brass) for European markets.
- Drinking water restrictedReduction of Lead in Drinking Water Act limits Pb to 0.25%. C360 fails — use C27450, C69300 (eco-brass), or NSF-61 certified low-lead alloys.
- Lower strength than stainlessUTS 410 MPa — ~70% of 316L. Don't use as a structural element.
- Density penalty8.5 g/cc — heavier than steel. Not a weight-savings material.
- Stress-corrosion (ammonia)Susceptible to stress-corrosion cracking in ammonia atmospheres. Don't use in HVAC equipment exposed to ammonia.
- Galvanic vs steel/aluminumGalvanic differential is real in wet environments. Use isolation washers.
Specs
Mechanical, physical & chemical data.
Mechanical
Properties (cold-drawn)
| Ultimate tensile strength | 410 MPa (60 ksi) |
|---|---|
| Yield strength (0.5% extension) | 310 MPa (45 ksi) |
| Elongation at break | 25% |
| Modulus of elasticity | 97 GPa |
| Shear modulus | 37 GPa |
| Hardness | 78 HRB / 143 HV |
| Compressive strength | 365 MPa |
| Fatigue limit10⁸ cycles | 140 MPa |
Source: Copper Development Association. Annealed: UTS 360 MPa, hardness 60 HRB, elongation 53%.
Physical & thermal
At room temperature
| Density | 8.50 g/cc (0.307 lb/in³) |
|---|---|
| Melting range | 885 – 900 °C |
| Specific heat | 0.380 J/g·°C |
| Thermal conductivity | 115 W/m·K |
| CTE (20–300 °C) | 20.5 µm/m·°C |
| Electrical conductivity | 26% IACS |
| Magnetic | Diamagnetic |
Conductivity ~26% IACS — much higher than steel, lower than C110 copper. Useful when machinability AND moderate conductivity matter.
Composition
Chemistry, weight %
| Copper (Cu) | 60.0 – 63.0 |
|---|---|
| Zinc (Zn) | balance (~36%) |
| Lead (Pb) | 2.5 – 3.7 |
| Iron (Fe) | 0.35 max |
| Tin (Sn) | incidental |
The 3% Pb is the free-machining feature — distributes as fine droplets that break chips. Without lead, brass is much harder to machine.
Specifications
Common purchase specs.
ASTM B16
Bar, rod for screw machine
ASTM B453
Bar — leaded brass
AMS 4610
Brass bar
MIL-B-19951
Brass — naval
UNS C36000 / CDA 360
Standard designations
DIN CuZn39Pb3 / 2.0401
European equivalent
JIS C3604
Japanese equivalent
NSF 61 (low-lead variant)
Drinking water — use a low-lead alloy such as C69300 (Eco Brass)
Machining
Machining considerations.
C360 cuts as fast as the spindle and tooling allow. Sharp tools, neutral or slight positive rake, light coolant. The chips are small and clean by themselves — no chip-breaker geometry needed.
Cutting speed
500–1,200 SFM with carbide (CDA data runs higher); HSS lower. Spindle-limited on Swiss lathes.
Feed rate
Aggressive constant feed. C360 doesn't work-harden.
Tooling
HSS works fine for low-medium volume. Carbide for production. Sharp polished edges.
Coolant
Light water-soluble or mist. Some shops run dry on Swiss lathes.
Knurling
Forms beautifully. Standard on screw-machine fittings.
Threading
Single-point or roll forms — both clean. Cut taps work in soft brass.
Lead dust
Machine with proper ventilation and dust collection. Leaded chips are a respiratory concern.
Don't bend cold
C360 work-hardens with cold deformation — anneal before forming if substantial bending is required.
Applications
Where C360 shows up.
Fasteners & inserts
Threaded inserts, fittings, captive fasteners. High-volume turned hardware where machining cost dominates.
Decorative hardware
Door handles, trim, jewelry findings, lighting hardware. Polishes to mirror finish; takes plating well.
Compare
Related materials.
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