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 |
Note: EN 12164 caps CW724R lead at ≤0.10%, while the ASTM/UNS twin C69300 caps it at ≤0.09% — a genuine (small) difference between the twin standards, not an inconsistency.
| 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 | — | ~38 | W/(m·K) |
| Melting Range | solidus–liquidus | 855–900 | °C |
| Standard | Designation |
|---|---|
| EN (Europe) | CW724R / CuZn21Si3P |
| UNS / ASTM (USA) | C69300 — ASTM B371 |
| Lead-free bismuth alt. | C6802 — bismuth brass |
| 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.
Brassland machines CW724R into brass turned parts and CNC machined components to your drawing in Jamnagar, India, including precision turned brass components on 28+ Swiss-type lathes, with an EN 10204 3.1 certificate on every shipment.