Weight %. Silicon replaces lead: the hard kappa phase breaks chips and suppresses dezincification with no arsenic inhibitor.
| Element | Symbol | Min % | Max % | Typical % |
|---|---|---|---|---|
| Copper | Cu | 75.0 | 78.0 | 76.5 |
| Zinc | Zn | Balance | ~20 | |
| Silicon ✓ | Si | 2.7 | 3.5 | 3.0 |
| Phosphorus | P | 0.02 | 0.15 | 0.05 |
| Lead (max) ✓ | Pb | — | 0.10 | ≤0.05 |
| Property | Condition | Value | Unit |
|---|---|---|---|
| Tensile Strength (Rm) | R360 | 450–600 | MPa |
| Proof Stress (Rp0.2) | R360 | ≥180 | MPa |
| Elongation (A) | R360 | ≥15 | % |
| Hardness | typical | 120–150 | HB |
| Machinability | vs C36000 = 100 | ~80% | — |
| Density | — | 8.30 | g/cm³ |
| Thermal Conductivity | — | ~70 | W/(m·K) |
| Melting Range | solidus–liquidus | 870–900 | °C |
| Standard | Designation |
|---|---|
| EN (Europe) | CW724R / CuZn21Si3P |
| UNS / ASTM (USA) | C69300 — ASTM B371 |
| ASTM silicon sibling | C6802 / CuZn17Si4 |
| DIN (Germany) | CuZn21Si3P |
| DZR test method | ISO 6509-1 (CuCl₂) |
CW724R (CuZn21Si3P) replaces lead with silicon: the hard kappa phase breaks chips during machining, giving around 80% machinability — the best of the lead-free grades — while keeping lead at or below 0.10%. It is fully RoHS compliant without relying on Exemption 6(c).
Yes — intrinsically. With only ~21% zinc and the silicon-stabilised microstructure, CW724R resists dezincification without arsenic additions, which is why it is widely specified for potable water fittings in both soft and chlorinated supplies.
With lead ≤0.10%, CW724R satisfies the US NSF/ANSI 372 weighted-average limit of 0.25% for wetted surfaces and aligns with the EU Drinking Water Directive (2020/2184) direction on lead. Final product approval (NSF 61, WRAS, ACS, KIWA) is granted to the finished fitting, which the buyer or assembler must list.
Plan for roughly 20–30% lower cutting speeds and feeds versus free-machining leaded brass, sharper tooling, and closer attention to chip evacuation. Brassland machines CW724R routinely on both fixed-head and Swiss lathes — equivalents are C69300 (US) and other EN 12164 silicon brass listings.
Lead-free, DZR, no exemption required. ISO 9001:2015. Quote within 24 hours.
Request a QuoteComposition ranges, mechanical properties, machinability ratings and regulatory data on this page are cross-referenced against the publishers below. Tolerances and minimum values are taken from the relevant published standard at the time of writing — for procurement specification, always reference the current published edition.
Last reviewed: June 2026. EN/ISO/ASTM standards are updated periodically. This datasheet reflects the editions listed; for safety-critical or contract-critical applications, always verify against the current published edition of the standard. For project-specific deviations or supplier-specific composition windows, request a Type 3.1 mill certificate (EN 10204) with your order.